Standards for Tubular Exchangers by TEMA

NO WARRANTY EXPRESSED OR IMPLIED The Standards herein are recommended by The Tubular Exchanger Manufacturers Association Inc to assist users engineers and designers who specify design and install tubular exchangers These standards are based upon sound engineering principles research and field experience in the manufacture design installation and use of tubular exchangers These standards may be subject to revision as further investigation or experience may show is necessary or desirable Nothing herein shall constitute a warranty of any kind expressed or implied and warranty responsibility of any kind is expressly denied TEMA is a trademark of the Tubular Exchanger Manufacturers Association Inc Copyright 2019 Tubular Exchanger Manufacturers Association All rights reserved This book or any part thereof may not be reproduced in any form without the written permission of the publisher Unauthorized copies subject to statutory penalties of 750 to 30000 plus additional penalties Printed in the United States of America MEMBERS OF THE TUBULAR EXCHANGER MANUFACTURERS ASSOCIATION INC Comprising Manufacturers of Various Types of Shell and Tube Heat Exchanger Equipment Brask Inc 2300 Louis Alleman Parkway Sulphur LA 70663 CustOFab Inc 8888 West 21st Street Sand Springs OK 74063 Dunn Heat Exchangers Inc 410 21st Street South Texas City TX 775923028 Energy Exchanger Company 1844 N Garnett Road Tulsa OK 74116 Fabsco Shell and Tube LLC PO Box 988 Sapulpa OK 74066 Graham Corporation 20 Florence Avenue Batavia NY 14020 Heat Transfer Equipment Co 1515 N 93rd E Avenue Tulsa OK 74115 HughesAnderson Heat Exchangers Inc 1001 N Fulton Avenue Tulsa OK 74115 Kennedy Tank Manufacturing Co Inc 833 East Sumner Avenue Indianapolis IN 46227 Krueger Engineering Mfg Co Inc 12001 Hirsch Rd Houston TX 77050 Joseph Oat Corporation 2500 Broadway Camden NJ 08104 Ohmstede Ltd 895 N Main St Beaumont TX 77701 Perry Products Corp 25 Hainesport Mt Laurel Road Hainesport NJ 08036 RAS Process Equipment 324 Meadowbrook Road Robbinsville NJ 08691 Southern Heat Exchanger Corporation PO Box 1850 Tuscaloosa AL 35403 Steeltek Inc 4141 S Jackson Tulsa OK 74107 Thermal Engineering International USA Inc Struthers Wells 18000 Studebaker Road Suite 400 Cerritos CA 90703 Ward Vessel and Exchanger Corporation PO Box 44568 Charlotte NC 28215 STANDARDS OF THE TUBULAR EXCHANGER MANUFACTURERS ASSOCIATION TEMA TENTH EDITION TUBULAR EXCHANGER MANUFACTURERS ASSOCIATION INC Richard C Byrne Secretary wwwtemaorg TUBULAR EXCHANGER MANUFACTURERS ASSOCIATION CONTRIBUTING MEMBER COMPANIES AND TECHNICAL COMMITTEE MEMBERS Brask Inc Sangeeta Bakshi Jay Hennessey Energy Exchanger Co Miles Duvall Fabsco Shell and Tube LLC Sam Davis Graham Corporation Pete Brade Heat Transfer Equipment Co Daniel Gaddis Kyle Stein HughesAnderson Heat Exchangers Inc Jerry Barham Kennedy Tank Manufacturing Co Inc JD Smith Krueger Engineering Mfg Co Inc Cris Smelley Joseph Oat Corporation Lawrence Bower Perry Products Corp Ashok Shah RAS Process Equipment Jeff Polizzi Southern Heat Exchanger Corporation Jeremy Wolfe Ward Vessel and Exchanger Corp Bill Huffman PREFACE Tenth Edition 2019 The Tenth Edition of the TEMA Standards was prepared by the Technical Committee of the Tubular Exchange Manufacturers Association In addition to updated graphics and charts with a modernized appearance numerical analysis of flexible shell elements comprehensive rules for the design of horizontal saddle supports dimensional data for various standard flanges guidelines for distributor belts and a fouling mitigation design study have been added The Editor acknowledges with appreciation the contributions by Tony Paulin and Fred Hendrix at Paulin Research Group PRG for assistance with the Flexible Shell Element numerical analysis and the Heat Transfer Research Institute HTRI for their guidance on distributor belts and with fouling mitigation The Editor also acknowledges with appreciation the many years of service and contributions by Jim Harrison to the TEMA Technical Committee Daniel Gaddis Editor Section Membership List iii Technical Committee iv Preface v Notes to Users vi 1 N NOMENCLATURE 1 Size Numbering and Type DesignationRecommended Practice 11 2 Nomenclature of Heat Exchanger Components 13 2 F FABRICATION TOLERANCES 1 External Dimensions Nozzle and Support Locations 21 2 Recommended Fabrication Tolerances 22 3 Tubesheets Partitions Covers and Flanges 23 4 Flange Face Permissible Imperfections 23 5 Peripheral Gasket Surface Flatness 23 3 G GENERAL FABRICATION AND PERFORMANCE INFORMATION 1 Shop Operation 34 2 Inspection 34 3 Nameplates 34 4 Drawings and Code Data Reports 34 5 Guarantees 35 6 Preparation of Heat Exchangers for Shipment 36 7 General Construction Features of TEMA Standard Heat Exchangers 37 4 E INSTALLATION OPERATION AND MAINTENANCE 1 Performance of Heat Exchangers 41 2 Installation of Heat Exchangers 41 3 Operation of Heat Exchangers 42 4 Maintenance of Heat Exchangers 44 5 Changes to Configuration of Heat Exchangers 48 5 RCB MECHANICAL STANDARDS TEMA CLASS RCB HEAT EXCHANGERS 1 Scope and General Requirements 511 2 Tubes 521 3 Shells and Shell Covers 531 4 Baffles and Support Plates 541 5 Floating End Construction 551 6 Gaskets 561 7 Tubesheets 571 8 Flexible Shell Elements 581 9 Channels Covers and Bonnets 591 10 Nozzles 5101 11 End Flanges and Bolting 5111 6 V FLOW INDUCED VIBRATION 1 Scope and General 61 2 Vibration Damage Patterns 61 3 Failure Regions 61 4 Dimensionless Numbers 62 5 Natural Frequency 63 6 Axial Tube Stress 65 7 Effective Tube Mass 610 8 Damping 613 FLOW INDUCED VIBRATION continued 9 Shell Side Velocity Distribution 615 10 Estimate of Critical Flow Velocity 618 11 Vibration Amplitude 620 12 Acoustic Vibration 621 13 Design Considerations 625 14 Selected References 627 NOTES TO USERS OF THE TEMA STANDARDS Three classes of Mechanical Standards R C and B reflecting acceptable designs for various service applications are presented The user should refer to the definition of each class and choose the one that best fits the specific need Corresponding subject matter in the three classes of Mechanical Standards is covered by paragraphs identically numbered except for the class prefix letter Paragraph numbers preceded by RCB indicates that all three classes are identical Any reference to a specific paragraph must be preceded by the class designation The Recommended Good Practice section has been prepared to assist the designer in areas outside the scope of the basic Standards Paragraphs in the Standards having additional information in the RGP section are marked with an asterisk The reference paragraph in the RGP section has the identical paragraph number but with an RGP prefix It is the intention of the Tubular Exchanger Manufacturers Association that this edition of its Standards may be used beginning with the date of issuance and that its requirements supersede those of the previous edition six months from such date of issuance except for heat exchangers contracted for prior to the end of the six month period For this purpose the date of issuance is April 8 2019 Questions by registered users on interpretation of the TEMA Standards should be submitted online at wwwtemaorg Questions requiring development of new or revised technical information will only be answered through an addendum or a new edition of the Standards Upon agreement between purchaser and fabricator exceptions to TEMA requirements are acceptable An exchanger may still be considered as meeting TEMA requirements as long as the exception is documented HEAT EXCHANGER NOMENCLATURE SECTION 1 N1 SIZE NUMBERING AND TYPE DESIGNATION RECOMMENDED PRACTICE It is recommended that heat exchanger size and type be designated by numbers and letters as described below N11 SIZE Sizes of shells and tube bundles shall be designated by numbers describing shell and tube bundle diameters and tube lengths as follows N111 NOMINAL DIAMETER The nominal diameter shall be the inside diameter of the shell in inches mm rounded to the nearest integer For kettle reboilers the nominal diameter shall be the port diameter followed by the shell diameter each rounded to the nearest integer N112 NOMINAL LENGTH The nominal length shall be the tube length in inches mm Tube length for straight tubes shall be taken as the actual overall length For Utubes the length shall be taken as the approximate straight length from end of tube to bend tangent N12 TYPE Type designation for complete assemblies shall be by letters describing front end stationary head types shell types and rear end head types in that order as indicated in Figure N12 Type designations shall be used as applicable for partial heat exchanger assemblies N13 TYPICAL EXAMPLES N131 Splitring floating head exchanger with removable channel and cover single pass shell 23 14 591 mm inside diameter with tubes 16 4877 mm long SIZE 23192 5914877 TYPE AES N132 Utube exchanger with bonnet type stationary head split flow shell 19 483 mm inside diameter with tubes 7 2134 mm straight SIZE 1984 4832134 TYPE BGU N133 Pullthrough floating head kettle type reboiler having stationary head integral with tubesheet 23 584 mm port diameter and 37 940 mm inside shell diameter with tubes 16 4877 mm long SIZE 2337192 5849404877 TYPE CKT N134 Fixed tubesheet exchanger with removable channel and cover bonnet type rear head two pass shell 33 18 841 mm inside diameter with tubes 8 2438 mm long SIZE 3396 8412438 TYPE AFM N135 Fixed tubesheet exchanger having stationary and rear heads integral with tubesheets single pass shell 17 432 mm inside diameter with tubes 16 4877 mm long SIZE 17192 4324877 TYPE NEN N14 SPECIAL DESIGNS Special designs are not covered and may be described as best suits the manufacturer For example a single tube pass fixed tubesheet exchanger with conical heads may be described as TYPE BEM with Conical Heads A pullthrough floating head exchanger with an integral shell cover may be described as TYPE AET with Integral Shell Cover GENERAL INFORMATION See detailed Table of Contents 91 SECTION 1 HEAT EXCHANGER NOMENCLATURE FIGURE N12 RECOMMENDED GOOD PRACTICE G711 Horizontal Vessel Supports 102 G712 Vertical Vessel Supports 1017 G72 Lifting Lugs 1022 G73 Wind and Seismic Design 1024 RCB2 Plugging Tubes in Tube Bundles 1024 RCB4 Entrance and Exit Areas 1024 RCB7 Tubesheets 1031 RCB106 Nozzle Loadings 1032 RCB115 Flange Design 1032 RCB12 Finite Element Analysis Guidelines 1033 T2 Fouling 1034 HEAT EXCHANGER NOMENCLATURE SECTION 1 N2 NOMENCLATURE OF HEAT EXCHANGER COMPONENTS For the purpose of establishing standard terminology Figure N2 illustrates various types of heat exchangers Typical parts and connections for illustrative purposes only are numbered for identification in Table N2 SECTION 1 HEAT EXCHANGER NOMENCLATURE FIGURE N2 continued HEAT EXCHANGER NOMENCLATURE FIGURE N2 continued SECTION 1 1 3 5 34 6 7 8 12 27 28 39 9 AKT 36 1 5 10 12 34 35 35 12 34 39 AJW 36 1 3 10 12 34 35 35 12 34 15 SECTION 1 HEAT EXCHANGER NOMENCLATURE This page intentionally blank 16 Tubular Exchanger Manufacturers Association Inc wwwtemaorg HEAT EXCHANGER FABRICATION TOLERANCES SECTION 2 F1 EXTERNAL DIMENSIONS NOZZLE AND SUPPORT LOCATIONS Standard tolerances for process flow nozzles and support locations and projections are shown in Figure F1 Dimensions in are millimeters FIGURE F1 12 127 14 64 14 64 14 64 14 64 14 64 14 64 18 32 18 32 NOMINAL NOZZLE SIZE G MAX 2 4 INCLUSIVE 116 16 6 12 INCLUSIVE 332 24 14 36 INCLUSIVE 316 48 OVER 36 14 64 NOTE THIS TABLE APPLIES TO NOZZLES CONNECTING TO EXTERNAL PIPING ONLY CONNECTION NOZZLE ALIGNMENT AND SUPPORT TOLERANCES wwwtemaorg Tubular Exchanger Manufacturers Association Inc 21 SECTION 2 HEAT EXCHANGER FABRICATION TOLERANCES F2 RECOMMENDED FABRICATION TOLERANCES Fabrication tolerances normally required to maintain process flow nozzle and support locations are shown in Figure F2 These tolerances may be adjusted as necessary to meet the tolerances shown in Figure F1 Dimensions in are millimeters FIGURE F2 HEAT EXCHANGER FABRICATION TOLERANCES SECTION 2 F3 TUBESHEETS PARTITIONS COVERS AND FLANGES The standard clearances and tolerances applying to tubesheets partitions covers and flanges are shown in Figure F3 Dimensions in are millimeters FIGURE F3 SECTION 2 HEAT EXCHANGER FABRICATION TOLERANCES FIGURE F4 PERMISSIBLE IMPERFECTIONS IN FLANGE FACING FINISH FOR RAISED FACE AND LARGE MALE AND FEMALE FLANGES NPS Maximum Radial Projections of Imperfections Which Are No Deeper Than the Bottom of the Serrations inmm Maximum Depth and Maximum Radial Projection of Imperfections Which Are Deeper Than the Bottom of the Serrations inmm GENERAL FABRICATION AND PERFORMANCE INFORMATION SECTION 3 DEFINITIONS 1 Baffle is a device to direct the shell side fluid across the tubes for optimum heat transfer 2 Double Tubesheet Construction is a type of construction in which two 2 spaced tubesheets or equivalent are employed in lieu of the single tubesheet at one or both ends of the heat exchanger 3 Effective Shell and Tube Side Design Pressures are the resultant load values expressed as uniform pressures used in the determination of tubesheet thickness for fixed tubesheet heat exchangers and are functions of the shell design pressure the tube side design pressure the equivalent differential expansion pressure and the equivalent bolting pressure 4 Equivalent Bolting Pressure is the pressure equivalent resulting from the effects of bolting loads imposed on tubesheets in a fixed tubesheet heat exchanger when the tubesheets are extended for bolting as flanged connections 5 Equivalent Differential Expansion Pressure is the pressure equivalent resulting from the effect of tubesheet loadings in a fixed tubesheet heat exchanger imposed by the restraint of differential thermal expansion between shell and tubes 6 Expanded Tube Joint is the tubetotubesheet joint achieved by mechanical or explosive expansion of the tube into the tube hole in the tubesheet 7 Expansion Joint J Factor is the ratio of the spring rate of the expansion joint to the sum of the axial spring rate of the shell and the spring rate of the expansion joint Refer to section A151 8 Flange Load Concentration Factors are factors used to compensate for the uneven application of bolting moments due to large bolt spacing 9 Minimum and Maximum Baffle and Support Spacings are design limitations for the spacing of baffles to provide for mechanical integrity and thermal and hydraulic effectiveness of the bundle The possibility for induced vibration has not been considered in establishing these values 10 Normal Operating Conditions of a shell and tube heat exchanger are the thermal and hydraulic performance requirements generally specified for sizing the heat exchanger 11 Pulsating Fluid Conditions are conditions of flow generally characterized by rapid fluctuations in pressure and flow rate resulting from sources outside of the heat exchanger 12 Seismic Loadings are forces and moments resulting in induced stresses on any member of a heat exchanger due to pulse mode or complex waveform accelerations to the heat exchanger such as those resulting from earthquakes 13 Shell and Tube Mean Metal Temperatures are the average metal temperatures through the shell and tube thicknesses integrated over the length of the heat exchanger for a given steady state operating condition 14 ShutDown is the condition of operation which exists from the time of steady state operating conditions to the time that flow of both process streams has ceased 15 StartUp is the condition of operation which exists from the time that flow of either or both process streams is initiated to the time that steady state operating conditions are achieved 16 Support plate is a device to support the bundle or to reduce unsupported tube span without consideration for heat transfer 17 Tubesheet Ligament is the shortest distance between edge of adjacent tube holes in the tube pattern 18 Welded Tube Joint is a tubetotubesheet joint where the tube is welded to the tubesheet wwwtemaorg Tubular Exchanger Manufacturers Association Inc 31 SECTION 3 GENERAL FABRICATION AND PERFORMANCE INFORMATION FIGURE G52 HEAT EXCHANGER SPECIFICATION SHEET 1 Job No 2 Customer Reference No 3 Address Proposal No 4 Plant Location Date Rev 5 Service of Unit Item No 6 Size Type HorVert 7 SurfUnit GrossEff sq ft ShellsUnit SurfShell GrossEff sq ft 8 PERFORMANCE OF ONE UNIT Shell Side Tube Side 9 Fluid Allocation 10 Fluid Name 11 Fluid Quantity Total lbhr 12 Vapor InOut 13 Liquid 14 Steam 15 Water 16 Noncondensable 17 Temperature F 18 Specific Gravity 19 Viscosity Liquid cP 20 Molecular Weight Vapor 21 Molecular Weight Noncondensable 22 Specific Heat BTU lb F 23 Thermal Conductivity BTU hr sq ft F 24 Latent Heat BTU lb F 25 Inlet Pressure psia 26 Velocity ft sec 27 Pressure Drop Allow Calc psi 28 Fouling Resistance Min hr sq ft F BTU 29 Heat Exchanged BTU hr MTD Corrected 30 Transfer Rate Service Clean BTU hr sq ft F 31 CONSTRUCTION OF ONE SHELL 32 Shell Side Tube Side 33 Design Test Pressure psig 34 Design Temp MaxMin F 35 No Passes per Shell 36 Corrosion Allowance in 37 Connections In 38 Size Out 39 Rating Intermediate 40 Tube No OD inThk MinA vg inLength ftPitch in 430 60 90 45 41 Tube Type Material 42 Shell ID OD in Shell Cover Integ Remov 43 Channel or Bonnet Channel Cover 44 TubesheetStationary TubesheetFloating 45 Floating Head Cover Impingement Protection 46 BafflesCross Type Cut DiamArea Spacing cc Inlet in 47 BafflesLong Seal Type 48 SupportsTube UBend Type 49 Bypass Seal Arrangement TubetoTubesheet Joint 50 Expansion Joint Type 51 pvInlet Nozzle Bundle Entrance 52 GasketsShell Side Tube Side 53 Floating Head 54 Code Requirements TEMA Class 55 Weight Shell Filled with Water Bundle lb 56 Remarks 32 wwwtemaorg Tubular Exchanger Manufacturers Association Inc GENERAL FABRICATION AND PERFORMANCE INFORMATION SECTION 3 FIGURE G52M HEAT EXCHANGER SPECIFICATION SHEET 1 Job No 2 Customer Reference No 3 Address Proposal No 4 Plant Location Date Rev 5 Service of Unit Item No 6 Size Type HorVert 7 SurfUnit GrossEff Sq m ShellsUnit SurfShell GrossEff sq m 8 PERFORMANCE OF ONE UNIT Shell Side Tube Side 9 Fluid Allocation 10 Fluid Name 11 Fluid Quantity Total kgHr 12 Vapor InOut 13 Liquid 14 Steam 15 Water 16 Noncondensable 17 Temperature InOut C 18 Specific Gravity 19 Viscosity Liquid cP 20 Molecular Weight Vapor 21 Molecular Weight Noncondensable 22 Specific Heat Jkg C 23 Thermal Conductivity Wm C 24 Latent Heat Jkg C 25 Inlet Pressure kPaabs 26 Velocity msec 27 Pressure Drop Allow Calc kPa 28 Fouling Resistance Min Sq m C W 29 Heat Exchanged W MTD Corrected C 30 Transfer Rate Service Clean WSq m C 31 CONSTRUCTION OF ONE SHELL 32 Shell Side Tube Side 33 Design Test Pressure kPag 34 Design Temp MaxMin C 35 No Passes per Shell 36 Corrosion Allowance mm 37 Connections In 38 Size Out 39 Rating Intermediate 40 Tube No OD mmThk MinAvg mmLength mmPitch mm 430 60 90 45 41 Tube Type Material 42 Shell ID OD mm Shell Cover Integ Remov 43 Channel or Bonnet Channel Cover 44 TubesheetStationary TubesheetFloating 45 Floating Head Cover Impingement Protection 46 BafflesCross Type Cut DiamArea Spacing cc Inlet mm 47 BafflesLong Seal Type 48 SupportsTube UBend Type 49 Bypass Seal Arrangement TubetoTubesheet Joint 50 Expansion Joint Type 51 pvInlet Nozzle Bundle Entrance 52 GasketsShell Side Tube Side 53 Floating Head 54 Code Requirements TEMA Class 55 Weight Shell Filled with Water Bundle kg 56 Remarks 33 wwwtemaorg Tubular Exchanger Manufacturers Association Inc SECTION 3 GENERAL FABRICATION AND PERFORMANCE INFORMATION G1 SHOP OPERATION The detailed methods of shop operation are left to the discretion of the manufacturer in conformity with these Standards G2 INSPECTION G21 MANUFACTURERS INSPECTION Inspection and testing of units will be provided by the manufacturer unless otherwise specified The manufacturer shall carry out the inspections required by the Code customer specifications and also inspections required by state and local codes when the purchaser specifies the plant location G22 PURCHASERS INSPECTION The purchaser shall have the right to make inspections during fabrication and to witness any tests when he has so requested Advance notification shall be given as agreed between the manufacturer and the purchaser Inspection by the purchaser shall not relieve the manufacturer of his responsibilities Any additional tests required by the purchaser above those already agreed to will be to the purchasers account Cost for remedial work as a result of these additional tests will also be to the purchasers account G3 NAMEPLATES G31 MANUFACTURERS NAMEPLATE A suitable manufacturers nameplate of corrosion resistant material shall be permanently attached to the head end or the shell of each TEMA exchanger The nameplate may be attached via a bracket welded to the exchanger and shall be visible outside any insulation G311 NAMEPLATE DATA In addition to all data required by the Code a nameplate shall also include the following if provided Users equipment identification Users order number G312 SUPPLEMENTAL INFORMATION The manufacturer shall supply supplemental information where it is pertinent to the operation or testing of the exchanger This would include information pertaining to differential design and test pressure conditions restrictions on operating conditions for fixed tubesheet type exchangers or other restrictive conditions applicable to the design andor operation of the unit or its components Such information can be noted on the nameplate or on a supplemental plate attached to the exchanger at the nameplate location G32 PURCHASERS NAMEPLATE Purchasers nameplates when used are to be supplied by the purchaser and supplement rather than replace the manufacturers nameplate G4 DRAWINGS AND ASME CODE DATA REPORTS G41 DRAWINGS FOR APPROVAL AND CHANGE The manufacturer shall submit an outline drawing containing information necessary for the customer to locate piping to the exchanger and footings or structure necessary to support the exchanger The outline shall be submitted for the customers approval and shall show the following information as a minimum nozzles sizes and locations flange ratings for nozzles overall dimensions support locations and base plate dimensions and exchanger weight Other drawings may be furnished as agreed upon by the purchaser and the manufacturer The drawing will be submitted electronically in PDF format unless another format is agreed upon by the purchaser and the manufacturer It is anticipated that a reasonable number of minor changes may be required due to customer comments to this initial submittal Any changes that cause additional expense are chargeable to the customer and it is the manufacturers responsibility to advise the customer of the commercial impact Purchasers approval of drawings does not relieve the manufacturer of responsibility for compliance with this Standard and applicable Code requirements The GENERAL FABRICATION AND PERFORMANCE INFORMATION SECTION 3 manufacturer shall not make any changes on the approved drawings without express agreement of the purchaser G42 DRAWINGS FOR RECORD After approval of drawings the manufacturer shall furnish drawings for record The drawings will be submitted electronically in PDF format unless another format is agreed upon by the purchaser and the manufacturer G43 PROPRIETARY RIGHTS TO DRAWINGS The drawings and the design indicated by them are to be considered the property of the manufacturer and are not to be used or reproduced without his permission except by the purchaser for his own internal use G44 CODE DATA REPORTS After completion of fabrication and inspection of an exchanger to its Code the manufacturer shall furnish copies of the Code Manufacturers Data Report or Certification as agreed upon by the purchaser and the manufacturer G5 GUARANTEES G51 GENERAL The specific terms of the guarantees shall be agreed upon by the manufacturer and purchaser Unless otherwise agreed upon by the manufacturer and purchaser in writing the following paragraphs in this section will be applicable and will govern even over the contrary terms of any other writing between the manufacturer and the purchaser unless that writing specifically states that it is intended to override the provisions of this section G52 PERFORMANCE The purchaser shall in writing furnish the manufacturer with all information needed for clear understanding of performance requirements including any special requirements The manufacturer shall guarantee thermal performance and mechanical design of a heat exchanger when operated at the design conditions specified by the purchase order or shown on the exchanger specification sheet furnished by the manufacturer Figure G52 G52M This guarantee shall extend for a period of twelve 12 months after shipping date Notwithstanding this guarantee the manufacturer shall have no responsibility or liability for excessive fouling of the apparatus by material such as coke silt scale or any foreign substance that may be deposited and the manufacturer shall have no responsibility or liability for any other performance problem wholly or partially caused by circumstances beyond the manufacturers complete control or that the manufacturer did not have the ability to prevent Without limiting the generality of the foregoing such circumstances shall include i faulty installation of the exchanger by anyone other than the manufacturer ii any modification or repair made to the exchanger by the purchaser or anyone other than the manufacturer and iii combination of the exchanger with other equipment not furnished by the manufacturer The thermal guarantee shall not be applicable to exchangers where the thermal performance rating was made by anyone other than the manufacturer G521 THERMAL PERFORMANCE TEST A performance test shall be made if it is established after operation for a sufficient period of time that the performance of the exchanger does not meet the written performance requirements previously furnished by the purchaser to the manufacturer provided the thermal performance rating was made by the manufacturer Test conditions and procedures shall be selected by agreement between the purchaser and the manufacturer to permit extrapolation of the test results to the specified design conditions G522 DEFECTIVE PARTS The manufacturer shall repair or replace FOB his plant any parts proven defective within the guarantee period but does not assume liability for the cost of removing defective parts or reinstalling replacement parts The manufacturer shall be responsible only for the direct costs associated with repair of its defect or nonconforming product Finished materials and accessories purchased from other manufacturers including tubes are warranted only to the extent of the original manufacturers warranty to the heat exchanger fabricator The manufacturer will endeavor to provide the purchaser with a copy of any warranty information given to the manufacturer by suppliers of parts incorporated into the exchanger by the manufacturer but cannot be responsible for the accuracy or completeness of that information G53 DAMAGES EXCLUSION In no event shall the manufacturer be held liable for any indirect special incidental punitive exemplary or consequential damages such as damages for loss of goodwill work stoppage lost profits lost revenue loss of clients lost business or lost opportunity or any other similar damages of any and every nature under any theory of liability whether in contract tort strict liability or any other theory G54 CORROSION AND VIBRATION The manufacturer assumes no responsibility for deterioration of any part or parts of the equipment due to corrosion erosion flow induced tube vibration or any other causes regardless of when such deterioration occurs after leaving the manufacturers premises except as provided for in Paragraphs G52 and G522 G55 REPLACEMENT AND SPARE PARTS When replacement or spare tube bundles shells or other parts are purchased the manufacturer guarantees satisfactory fit of such parts only if he was the original manufacturer Parts fabricated to drawings furnished by the purchaser shall be guaranteed to meet the dimensions and tolerances specified G56 DISCLAIMER OF WARRANTY While the manufacturer provides guarantees as specifically offered by the manufacturer to the purchaser in writing the manufacturer makes no other warranties or guarantees and assumes no liability in connection with any other warranty or guarantee express or implied WITHOUT LIMITING THE GENERALITY OF THE FOREGOING THE MANUFACTURER SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE IN CONNECTION WITH THE SALE OF EXCHANGERS WHETHER OR NOT THE MANUFACTURER HAS BEEN ADVISED OF SUCH PURPOSE G57 AGGREGATE LIABILITY The aggregate total liability of manufacturer to customer for any direct loss cost claim or damages of any kind related to any failure of performance by a heat exchanger shall not exceed the amount the purchaser has paid to the manufacturer for the exchanger G58 INDEMNIFICATION Notwithstanding any other contract language to the contrary the manufacturer shall have no liability to indemnify defend or hold the purchaser harmless against thirdparty claims costs losses and expenses relating in any way to the transaction between the manufacturer and the purchaser or to heat exchanger performance G6 PREPARATION OF HEAT EXCHANGERS FOR SHIPMENT G61 CLEANING Internal and external surfaces are to be free from loose scale and other foreign material that is readily removable by hand or power brushing G62 DRAINING Water oil or other liquids used for cleaning or hydrostatic testing are to be drained from all units before shipment This is not to imply that the units must be completely dry G63 FLANGE PROTECTION All exposed machined contact surfaces shall be coated with a removable rust preventative and protected against mechanical damage by suitable covers G64 THREADED CONNECTION PROTECTION All threaded connections are to be suitably plugged GENERAL FABRICATION AND PERFORMANCE INFORMATION SECTION 3 G65 DAMAGE PROTECTION The exchanger and any spare parts are to be suitably protected to prevent damage during shipment G66 EXPANSION JOINT PROTECTION External thin walled expansion bellows shall be equipped with a protective cover which does not restrain movement G7 GENERAL CONSTRUCTION FEATURES OF TEMA STANDARD HEAT EXCHANGERS G71 SUPPORTS All heat exchangers are to be provided with supports The supports should be designed to accommodate the weight of the unit and contents including the flooded weight during hydrostatic test For purposes of support design forces from external nozzle loadings wind and seismic events are assumed to be negligible unless the purchaser specifically details the requirements When these additional loads and forces are required to be considered they need not be assumed to occur simultaneously unless combinations are specifically defined The references under Paragraph G713 may be used for calculating resulting stresses in the support structure and attachment Acceptable methods for horizontal supports and vertical lugs are shown in the RGP section G711 HORIZONTAL UNITS For units with removable tube bundles supports should be designed to withstand a pulling force equal to 112 times the weight of the tube bundle Horizontal units are normally provided with at least two saddle type supports with holes for anchor bolts The holes in all but one of the supports are to be elongated to accommodate axial movement of the unit under operating conditions Other types of support may be used if all design criteria are met and axial movement is accommodated G712 VERTICAL UNITS Vertical units are to be provided with supports adequate to meet design requirements The supports may be of the lug annular ring leg or skirt type If the unit is to be located in a supporting structure the supports should be of sufficient size to allow clearance for the body flanges G713 REFERENCES 1 Zick L P Stresses in Large Horizontal Cylindrical Pressure Vessels on Two Saddle Supports Pressure Vessel and Piping Design and Analysis ASME 1972 2 Vinet R and Dore R Stresses and Deformations in a Cylindrical Shell Lying on a Continuous Rigid Support Paper No 75AM1 Journal of Applied Mechanics Trans ASME 3 Krupka V An Analysis for Lug or Saddle Supported Cylindrical Pressure Vessels Proceedings of the First International Conference on Pressure Vessel Technology pp 491500 4 Singh K P Soler A I Mechanical Design of Heat Exchangers and Pressure Vessel Components Chapter 17 Arcturus Publishers Inc 5 Bijlaard P P Stresses from Local Loadings in Cylindrical Pressure Vessels Trans ASME Vol 77 No 6 August 1955 6 Wichman K R Hopper A G and Mershon J L Local Stresses in Spherical and Cylindrical Shells due to External Loadings Welding Research Council Bulletin No 107 Rev 1 7 Rodabaugh E C Dodge W G and Moore S E Stress Indices at Lug Supports on Piping Systems Welding Research Council Bulletin No 198 8 Brownell L E and Young E H Process Equipment Design John Wiley Sons Inc SECTION 3 GENERAL FABRICATION AND PERFORMANCE INFORMATION 9 Jawad M H and Farr J R Structural Analysis and Design of Process Equipment John Wiley and Sons Inc 1984 10 Bednar H H Pressure Vessel Design Handbook Van Nostrand Reinhold Company 11 Blodgett O W Design of Welded Structures The James F Lincoln Arc Welding Foundation 1966 12 Moss Dennis R Pressure Vessel Design Manual Illustrated Procedures for Solving Major Pressure Vessel Design Problems Edition 3 Publisher Gulf Pub Co December 18 2003 13 ASME Section VIII Division 2 Part 4153 G72 LIFTING DEVICES Channels bonnets and covers which weigh over 60 lbs 272 Kg are to be provided with lifting lugs rings or tapped holes for eyebolts Unless otherwise specified these lifting devices are designed to lift only the component to which they are directly attached Lugs for lifting the complete unit are not normally provided When lifting lugs or trunnions are required by the purchaser to lift the complete unit the device must be adequately designed 1 The purchaser shall inform the manufacturer about the way in which the lifting device will be used The purchaser shall be notified of any limitations of the lifting device relating to design or method of rigging 2 Liquid penetrant examination of the lifting device attachment weld should be considered on large heavy units 3 The design load shall incorporate an appropriate impact factor 4 Platetype lifting lugs should be oriented to minimize bending stresses 5 The hole diameter in the lifting device must be large enough to accept a shackle pin having a load rating greater than the design load 6 The effect on the unit component to which the lifting device is attached should be considered It may be necessary to add a reinforcing plate annular ring or pad to distribute the load 7 The adequacy of the exchanger to accommodate the lifting loads should be evaluated G73 WIND SEISMIC DESIGN For wind and seismic forces to be considered in the design of a heat exchanger the purchaser must specify the design requirements in the inquiry The Recommended Good Practice section of these Standards provides the designer with a discussion on this subject and selected references for design application INSTALLATION OPERATION AND MAINTENANCE SECTION 4 E1 PERFORMANCE OF HEAT EXCHANGERS Satisfactory operation of heat exchangers can be obtained only from units which are properly designed and have builtin quality Correct installation and preventive maintenance are user responsibilities E11 PERFORMANCE FAILURES The failure of heat exchanger equipment to perform satisfactorily may be caused by one or more factors such as 1 Excessive fouling 2 Air or gas binding resulting from improper piping installation or lack of suitable vents 3 Operating conditions differing from design conditions 4 Maldistribution of flow in the unit 5 Excessive clearances between the baffles and shell andor tubes due to corrosion 6 Improper thermal design The users best assurance of satisfactory performance lies in dependence upon manufacturers competent in the design and fabrication of heat transfer equipment E2 INSTALLATION OF HEAT EXCHANGERS E21 HEAT EXCHANGER SETTINGS E211 CLEARANCE FOR DISMANTLING For straight tube exchangers fitted with removable bundles provide sufficient clearance at the stationary head end to permit removal of the bundle from the shell and provide adequate space beyond the rear head to permit removal of the shell cover andor floating head cover For fixed tubesheet exchangers provide sufficient clearance at one end to permit withdrawal and replacement of the tubes and enough space beyond the head at the opposite end to permit removal of the bonnet or channel cover For Utube heat exchangers provide sufficient clearance at the stationary head end to permit withdrawal of the tube bundle or at the opposite end to permit removal of the shell E212 FOUNDATIONS Foundations must be adequate so that exchangers will not settle and impose excessive strains on the exchanger Foundation bolts should be set to allow for setting inaccuracies In concrete footings pipe sleeves at least one size larger than bolt diameter slipped over the bolt and cast in place are best for this purpose as they allow the bolt center to be adjusted after the foundation has set E213 FOUNDATION BOLTS Foundation bolts should be loosened at one end of the unit to allow free expansion of shells Slotted holes in supports are provided for this purpose E214 LEVELING Exchangers must be set level and square so that pipe connections may be made without forcing E22 CLEANLINESS PROVISIONS E221 CONNECTION PROTECTORS All exchanger openings should be inspected for foreign material Protective plugs and covers should not be removed until just prior to installation E222 DIRT REMOVAL The entire system should be clean before starting operation Under some conditions the use of strainers in the piping may be required E223 CLEANING FACILITIES Convenient means should be provided for cleaning the unit as suggested under Maintenance of Heat Exchangers Paragraph E4 SECTION 4 INSTALLATION OPERATION AND MAINTENANCE E23 FITTINGS AND PIPING E231 BYPASS VALVES It may be desirable for purchaser to provide valves and bypasses in the piping system to permit inspection and repairs E232 TEST CONNECTIONS When not integral with the exchanger nozzles thermometer well and pressure gage connections should be installed close to the exchanger in the inlet and outlet piping E233 VENTS Vent valves should be provided by purchaser so units can be purged to prevent vapor or gas binding Special consideration must be given to discharge of hazardous or toxic fluids E234 DRAINS Drains may discharge to atmosphere if permissible or into a vessel at lower pressure They should not be piped to a common closed manifold E235 PULSATION AND VIBRATION In all installations care should be taken to eliminate or minimize transmission of fluid pulsations and mechanical vibrations to the heat exchangers E236 SAFETY RELIEF DEVICES When specified by the purchaser the manufacturer will provide the necessary connections for the safety relief devices The size and type of the required connections will be specified by the purchaser The purchaser will provide and install the required relief devices E3 OPERATION OF HEAT EXCHANGERS E31 DESIGN AND OPERATING CONDITIONS Equipment must not be operated at conditions which exceed those specified on the nameplates E32 OPERATING PROCEDURES Before placing any exchanger in operation reference should be made to the exchanger drawings specification sheets and nameplates for any special instructions Local safety and health regulations must be considered Improper startup or shutdown sequences particularly of fixed tubesheet units may cause leaking of tubetotubesheet andor bolted flanged joints E321 STARTUP OPERATION Most exchangers with removable tube bundles may be placed in service by first establishing circulation of the cold medium followed by the gradual introduction of the hot medium During startup all vent valves should be opened and left open until all passages have been purged of air and are completely filled with fluid For fixed tubesheet exchangers fluids must be introduced in a manner to minimize differential expansion between the shell and tubes E322 SHUTDOWN OPERATION For exchangers with removable bundles the units may be shut down by first gradually stopping the flow of the hot medium and then stopping the flow of the cold medium If it is necessary to stop the flow of cold medium the circulation of hot medium through the exchanger should also be stopped For fixed tubesheet exchangers the unit must be shut down in a manner to minimize differential expansion between shell and tubes When shutting down the system all units should be drained completely when there is the possibility of freezing or corrosion damage To guard against water hammer condensate should be drained from steam heaters and similar apparatus during startup or shutdown To reduce water retention after drainage the tube side of water cooled exchangers should be blown out with air E323 TEMPERATURE SHOCKS Exchangers normally should not be subjected to abrupt temperature fluctuations Hot fluid must not be suddenly introduced when the unit is cold nor cold fluid suddenly introduced when the unit is hot INSTALLATION OPERATION AND MAINTENANCE SECTION 4 E324 BOLTED JOINTS Heat exchangers are pressure tested before leaving the manufacturers shop in accordance with Code requirements However normal relaxing of the gasketed joints may occur in the interval between testing in the manufacturers shop and installation at the jobsite Therefore all external bolted joints may require retightening after installation and if necessary after the exchanger has reached operating temperature E3241 It is possible for the bolt stress to decrease after initial tightening because of slow creep or relaxation of the gasket particularly in the case of the softer gasket materials E3242 Excessive initial bolt stress can cause yielding of the bolt itself This is especially likely with bolts of small diameter or bolting having relatively low yield values such as stainless steels E3243 ASME PCC1 Appendices N and P provide additional guidance for the reuse of bolts and for troubleshooting flanged joint leakage incidents E3244 Selection of the appropriate bolt stress andor torque shall be done so as to provide sufficient preload to seat the gasket within the capacity of the flange Acceptable methods for this selection include but are not limited to past experience recommendations from gasket manufacturers considerations from ASME Code Appendix S using guidelines from ASME PCC1 Section 10 and Appendix O or using WRC Bulletin 538 When using the Joint Component Approach as shown in ASME PCC1 O4 or WRC538 it is recommended that this approach be performed during the flange design as this approach may increase flange thickness Gasket seating stress values for use in ASME PCC1 O4 can be found from gasket manufacturers and PVP papers PVP201428434 for GMGC CMGC and Spiral wound gaskets Acceptable methods for converting bolt stress to target torque include but are not limited to ASME PCC1 Section 12 and Appendices J and K E325 RECOMMENDED BOLT TIGHTENING PROCEDURE E3251 All gasket joint surfaces shall be clean and free of oil or debris If the gasket requires assistance to be held in place for installation grease shall not be used Any tape applied to a spiral wound gasket for shipping or assembly shall be removed prior to installing the gasket No tape string or other object will be allowed to remain on the gasket surface once assembly is complete ASME PCC1 Section 6 provides additional guidance for the installation of gaskets E3252 Thoroughly clean threads nut faces and the flange where nut face bears If roughness burrs or any irregularity is present dress it out to smooth a surface as possible E3253 Thoroughly lubricate threads on studs nuts and contacting surfaces on nuts and flange ASME PCC1 Section 7 provides additional guidance for the lubrication of fasteners E3254 The joint shall be snugged up squarely so the entire flange face bears uniformly on the gasket ASME PCC1 Section 5 and Appendix E provide additional guidance for the alignment of joints E3255 Tightening of the bolts shall be applied in at least three equally spaced increments using a cross bolting pattern as illustrated in Figure E3255 or a pattern as recommended by ASME PCC1 Sections 8 through 11 E3256 When the cross bolting pattern is used and is complete a circular chase pattern shall be applied until no nut rotation occurs SECTION 4 INSTALLATION OPERATION AND MAINTENANCE FIGURE E3255 START 1 6 9 59 56 51 48 43 35 32 27 24 19 11 8 3 58 53 50 45 42 37 34 29 26 21 18 13 5 10 2 60 44 47 52 55 39 36 31 28 23 20 15 12 7 4 14 17 22 33 38 41 46 49 54 57 E412 DISASSEMBLY FOR INSPECTION OR CLEANING Before disassembly the user must assure himself that the unit has been depressurized vented and drained neutralized andor purged of hazardous material To inspect the inside of the tubes and also make them accessible for cleaning the following procedures should be used 1 Front End Stationary Head a Type A C D N remove cover only b Type B remove bonnet 2 Rear End Head a Type L N P remove cover only b Type M remove bonnet c Type S T remove shell cover and floating head cover d Type W remove channel cover or bonnet E413 LOCATING TUBE LEAKS The following procedures may be used to locate perforated or split tubes and leaking joints between tubes and tubesheets In most cases the entire front face of each tubesheet will be accessible for inspection The point where water escapes indicates a defective tube or tubetotubesheet joint 1 Units with removable channel cover Remove channel cover and apply hydraulic pressure in the shell 2 Units with bonnet type head For fixed tubesheet units where tubesheets are an integral part of the shell remove bonnet and apply hydraulic pressure in the shell For fixed tubesheet units where tubesheets are not an integral part of the shell and for units with removable bundles remove bonnet rebolt tubesheet to shell or install test flange or gland whichever is applicable and apply hydraulic pressure in the shell See Figure E4131 for examples of some typical test flanges and test glands E413 LOCATING TUBE LEAKS contd 3 Units with Type S or T floating head Remove channel cover or bonnet shell cover and floating head cover Install test ring and bolt in place with gasket and packing Apply hydraulic pressure in the shell A typical test ring is shown in Figure E4132 When a test ring is not available it is possible to locate leaks in the floating head end by removing the shell cover and applying hydraulic pressure in the tubes Leaking tube joints may then be located by sighting through the tube lanes Care must be exercised when testing partially assembled exchangers to prevent over extension of expansion joints or overloading of tubes andor tubetotubesheet joints 4 Hydrostatic test should be performed so that the temperature of the metal is over 60F 16C or as permitted by the applicable code E42 TUBE BUNDLE REMOVAL AND HANDLING To avoid possible damage during removal of a tube bundle from a shell a pulling device should be attached to eyebolts screwed into the tubesheet If the tubesheet does not have tapped holes for eyebolts steel rods or cables inserted through tubes and attached to bearing plates may be used The bundle should be supported on the tube baffles supports or tubesheets to prevent damage to the tubes Gasket and packing contact surfaces should be protected E43 CLEANING TUBE BUNDLES E431 CLEANING METHODS The heat transfer surfaces of heat exchangers should be kept reasonably clean to assure satisfactory performance Convenient means for cleaning should be made available Heat exchangers may be cleaned by either chemical or mechanical methods The method selected must be the choice of the operator of the plant and will depend on the type of deposit and the facilities available in the plant Following are several cleaning procedures that may be considered 1 Circulating hot wash oil or light distillate through tubes or shell at high velocity may effectively remove sludge or similar soft deposits 2 Some salt deposits may be washed out by circulating hot fresh water 3 Commercial cleaning compounds are available for removing sludge or scale provided hot wash oil or water is not available or does not give satisfactory results 4 High pressure water jet cleaning 5 Scrapers rotating wire brushes and other mechanical means for removing hard scale coke or other deposits 6 Employ services of a qualified organization that provides cleaning services These organizations will check the nature of the deposits to be removed furnish proper solvents andor acid solutions containing inhibitors and provide equipment and personnel for a complete cleaning job E5 CHANGES TO CONFIGURATION OF HEAT EXCHANGERS It may be desirable to change the configuration of the heat exchanger upgrade materials increase the design pressures andor temperatures or change the gasket types when replacing or reworking components of an existing heat exchanger Reasons for these changes may range from a need to increase performance to take advantage of new alloys to support changes in other parts of the plant to solve chronic problems in the heat exchanger itself or for economic considerations Whenever changes are made to components of the heat exchanger consideration should be given to the effect on the overall design of the heat exchanger It is always advisable to consult the rules of the jurisdiction where the equipment is installed prior to making any changes The requirements of the Code and TEMA shall also be satisfied Some particular areas of concern are flange rating material thickness unsupported tube length channel nozzle locations pass partition configuration and clearance between the end of the removable bundle and the shell RCB1 SCOPE AND GENERAL REQUIREMENTS RCB11 SCOPE OF STANDARDS RCB111 GENERAL The TEMA Mechanical Standards are applicable to shell and tube heat exchangers which do not exceed any of the following criteria 1 inside diameters of 100 in 2540 mm 2 product of nominal diameter in mm and design pressure psi kPa of 100000 175 x 106 3 a design pressure of 3000 psi 20684 kPa The intent of these parameters is to limit the maximum shell wall thickness to approximately 3 in 76 mm and the maximum stud diameter to approximately 4 in 102 mm Criteria contained in these Standards may be applied to units which exceed the above parameters R112 DEFINITION OF TEMA CLASS R EXCHANGERS The TEMA Mechanical Standards for Class R heat exchangers specify design and fabrication of unfired shell and tube heat exchangers for the generally severe requirements of petroleum and related processing applications C112 DEFINITION OF TEMA CLASS C EXCHANGERS The TEMA Mechanical Standards for Class C heat exchangers specify design and fabrication of unfired shell and tube heat exchangers for the generally moderate requirements of commercial and general process applications B112 DEFINITION OF TEMA CLASS B EXCHANGERS The TEMA Mechanical Standards for Class B heat exchangers specify design and fabrication of unfired shell and tube heat exchangers for chemical process service RCB132 PNEUMATIC TEST When liquid cannot be tolerated as a test medium the exchanger may be given a pneumatic test in accordance with the Code It must be recognized that air or gas is hazardous when used as a pressure testing medium The pneumatic test pressure and temperature shall be in accordance with the Code RCB133 SUPPLEMENTARY AIR TEST When a supplementary air or gas test is specified by the purchaser it shall be preceded by the hydrostatic test required by Paragraph RCB131 The test pressure and temperature shall be as agreed upon by the purchaser and manufacturer but shall not exceed that required by Paragraph RCB132 RCB14 METAL TEMPERATURES RCB141 METAL TEMPERATURE LIMITATIONS FOR PRESSURE PARTS The metal temperature limitations for various metals are those prescribed by the Code RCB142 DESIGN TEMPERATURE OF HEAT EXCHANGER PARTS RCB1421 FOR PARTS NOT IN CONTACT WITH BOTH FLUIDS Design temperatures for the shell and tube sides shall be specified separately by the purchaser The Code provides the allowable stress limits for parts to be designed at the specified design temperature RCB1422 FOR PARTS IN CONTACT WITH BOTH FLUIDS The design temperature is the design metal temperature and is used to establish the Code stress limits for design The design metal temperature shall be based on the operating temperatures of the shell side and the tube side fluids except when the purchaser specifies some other design metal temperature When the design metal temperature is less than the higher of the design temperatures referred to in Paragraph RCB1421 the design metal temperature and the affected parts shall be shown on the manufacturers nameplates as described in Paragraph G31 RCB1423 MINIMUM DESIGN METAL TEMPERATURE The minimum design metal temperature shall be specified by the purchaser Consideration should be given to operating temperatures low ambient temperatures and upset conditions such as auto refrigeration when specifying the minimum design metal temperatures Minimum design metal temperatures shall be used to evaluate if impact testing is required for the various heat exchanger components MECHANICAL STANDARDS TEMA CLASS R C B SECTION 5 RCB15 STANDARD CORROSION ALLOWANCES The standard corrosion allowances used for the various heat exchanger parts are as follows unless the conditions of service make a different allowance more suitable and such allowance is specified by the purchaser RCB151 CARBON STEEL PARTS R1511 PRESSURE PARTS All carbon steel pressure parts except as noted below are to have a corrosion allowance of 18 32 mm CB1511 PRESSURE PARTS All carbon steel pressure parts except as noted below are to have a corrosion allowance of 116 16 mm RCB1512 INTERNAL FLOATING HEAD COVERS Internal floating head covers are to have the corrosion allowance on all wetted surfaces except gasket seating surfaces Corrosion allowance need not be added to the recommended minimum edge distance in Table D5 or D5M RCB1513 TUBESHEETS Tubesheets are to have the corrosion allowance on each side with the provision that on the grooved side of a grooved tubesheet the depth of the gasketed groove may be considered as available for corrosion allowance RCB1514 EXTERNAL COVERS Where flat external covers are grooved the depth of the gasketed groove may be considered as available for corrosion allowance RCB1515 END FLANGES Corrosion allowance shall be applied only to the inside diameter of flanges where exposed to the fluids RCB1516 NONPRESSURE PARTS Nonpressure parts such as tierods spacers baffles and support plates are not required to have corrosion allowance RCB1517 TUBES BOLTING AND FLOATING HEAD BACKING DEVICES Tubes bolting and floating head backing devices are not required to have corrosion allowance RCB1518 PASS PARTITION PLATES AND WELDEDIN LONG BAFFLES Pass partition plates and weldedin long baffles are not required to have corrosion allowance RCB152 ALLOY PARTS Alloy parts are not required to have corrosion allowance R153 CAST IRON PARTS Cast iron pressure parts shall have a corrosion allowance of 18 32 mm CB153 CAST IRON PARTS Cast iron pressure parts shall have a corrosion allowance of 116 16 mm RCB16 SERVICE LIMITATIONS RB161 CAST IRON PARTS Cast iron shall be used only for water service at pressures not exceeding 150 psi 1034 kPa SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B C161 CAST IRON PARTS Cast iron shall not be used for pressures exceeding 150 psi 1034 kPa or for lethal or flammable fluids at any pressure RCB162 EXTERNAL PACKED JOINTS Packed joints shall not be used when the purchaser specifies that the fluid in contact with the joint is lethal or flammable RCB17 ANODES Selection and placement of anodes is not the responsibility of the heat exchanger manufacturer If a heat exchanger is to be furnished with anodes when requesting a quotation the purchaser is responsible for furnishing the heat exchanger manufacturer the following information 1 Method of anode attachment 2 Quantity of anodes required 3 Size and manufacturer of the anodes 4 Anode material 5 Sketch of anode locations and spacing If the heat exchanger manufacturer chooses to install anodes for a customer the manufacturer is not responsible for the suitability of the anodes for the service it is installed in the life of the anodes the corrosion protection provided by the anode or any subsequent damage to the heat exchanger attributed to the anode the method of anode installation or the installed location of the anode in the heat exchanger MECHANICAL STANDARDS TEMA CLASS R C B SECTION 5 RCB2 TUBES RCB21 TUBE LENGTH The following tube lengths for both straight and Utube exchangers are commonly used 96 2438 120 3048 144 3658 192 4877 and 240 6096 in mm Other lengths may be used Also see Paragraph N112 RCB22 TUBE DIAMETERS AND GAGES RCB221 BARE TUBES TABLE RCB221 BARE TUBE DIAMETERS AND GAGES OD in mm Copper and Copper Alloys Carbon Steel Aluminum and Aluminum Alloys Other Alloys BWG BWG BWG 14 64 27 27 24 24 22 22 38 95 22 22 20 20 18 18 12 127 20 20 18 18 58 159 20 18 20 18 16 18 16 14 16 34 191 20 16 18 18 16 16 14 16 12 14 78 222 18 18 14 16 16 14 14 10 12 1 254 18 16 14 16 12 14 1 14 318 16 14 14 12 12 12 1 12 381 16 14 14 14 12 12 2 508 14 14 14 12 12 12 Notes 1 Wall thickness shall be specified as either minimum or average 2 Characteristics of tubing are shown in Tables D7 and D7M RCB222 INTEGRALLY FINNED TUBES The nominal fin diameter shall not exceed the outside diameter of the unfinend section Tubes shall be specified as both thickness under fin and at plain end SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B RCB23 UTUBES RCB231 UBEND REQUIREMENTS When Ubends are formed it is normal for the tube wall at the outer radius to thin Unless the minimum tube wall thickness in the bend can be otherwise guaranteed the required tube wall thickness in the bent portion before bending shall be verified by the following formula t₀ t₁ 1 d₀ C R where t₀ Required tube wall thickness prior to bending in mm t₁ Minimum tube wall thickness calculated by Code rules for a straight tube subjected to the same pressure and metal temperature in mm d₀ Outside tube diameter in mm C Thinning constant 4 typical for the following materials carbon steel low alloy ferritic stainless austenitic stainless other relatively nonworkhardening materials and copper alloys 2 typical for the following materials martensitic stainless duplex stainless super austenitic stainless titanium high nickel alloys and other workhardening materials Note different constants may be used based upon other considerations of tube thinning and previous experience R Mean radius of bend in mm More than one tube gage or dual gage tubes may be used in a tube bundle Flattening at the bend shall not exceed 10 of the nominal tube outside diameter For tube bends with R 2d₀ flattening may exceed 10 when the material is highly susceptible to work hardening or when the straight tube thickness is d₀12 Special consideration based upon bending experience may be required Special consideration may also be required for materials having low ductility RCB232 BEND SPACING RCB2321 CENTERTOCENTER DIMENSION The centertocenter dimensions between parallel legs of Utubes shall be such that they can be inserted into the baffle assembly without damage to the tubes RCB2322 BEND INTERFERENCE The assembly of bends shall be of workmanlike appearance Metaltometal contact between bends in the same plane shall not be permitted RCB233 HEAT TREATMENT Cold work in forming Ubends may induce embrittlement or susceptibility to stress corrosion in certain materials andor environments Heat treatment to alleviate such conditions may be performed by agreement between manufacturer and purchaser MECHANICAL STANDARDS TEMA CLASS R C B SECTION 5 RCB24 TUBE PATTERN Standard tube patterns are shown in Figure RCB24 FIGURE RCB24 30 60 90 45 TRIANGULAR ROTATED TRIANGULAR SQUARE ROTATED SQUARE Note Flow arrows are perpendicular to the baffle cut edge RCB241 SQUARE PATTERN In removable bundle units when mechanical cleaning of the tubes is specified by the purchaser tube lanes should be continuous RCB242 TRIANGULAR PATTERN Triangular or rotated triangular pattern should not be used when the shell side is to be cleaned mechanically R25 TUBE PITCH Tubes shall be spaced with a minimum centertocenter distance of 125 times the outside diameter of the tube When mechanical cleaning of the tubes is specified by the purchaser minimum cleaning lanes of 14 64 mm shall be provided C25 TUBE PITCH Tubes shall be spaced with a minimum centertocenter distance of 125 times the outside diameter of the tube Where the tube diameters are 58 159 mm or less and tubetotubesheet joints are expanded only the minimum centertocenter distance may be reduced to 120 times the outside diameter B25 TUBE PITCH Tubes shall be spaced with a minimum centertocenter distance of 125 times the outside diameter of the tube When mechanical cleaning of the tubes is specified by the purchaser and the nominal shell diameter is 12 in 305 mm or less minimum cleaning lanes of 316 48 mm shall be provided For shell diameters greater than 12 in 305 mm minimum cleaning lanes of 14 64 mm shall be provided SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B 524 Tubular Exchanger Manufacturers Association Inc wwwtemaorg This page intentionally blank RCB3 SHELLS AND SHELL COVERS RCB31 SHELLS RCB311 SHELL DIAMETERS It shall be left to the discretion of each manufacturer to establish a system of standard shell diameters within the TEMA Mechanical Standards in order to achieve the economies peculiar to its individual design and manufacturing facilities RCB312 TOLERANCES RCB3121 PIPE SHELLS The inside diameter of pipe shells shall be in accordance with applicable ASTMASME pipe specifications RCB3122 PLATE SHELLS The inside diameter of any plate shell shall not exceed the design inside diameter by more than 18 32 mm as determined by circumferential measurement RCB313 MINIMUM SHELL THICKNESS Shell thickness is determined by the Code design formulas plus corrosion allowance but in no case shall the nominal thickness of shells be less than that shown in the applicable table The nominal total thickness for clad shells shall be the same as for carbon steel shells TABLE R313 MINIMUM SHELL THICKNESS Dimensions in Inches mm Minimum Thickness Nominal Shell Diameter Carbon Steel Alloy Pipe Plate 6 152 SCH 40 18 32 812 203305 SCH 30 18 32 1329 330737 SCH STD 38 95 316 48 3039 762991 716 111 14 64 4060 10161524 12 127 516 79 6180 15492032 12 127 516 79 81100 20572540 12 127 38 95 Schedule 5S is permissible for 6 inch 152 mm and 8 inch 203 mm shell diameters RCB32 SHELL COVER THICKNESS Nominal thickness of shell cover heads before forming shall be at least equal to the thickness of the shell as shown in the applicable table wwwtemaorg Tubular Exchanger Manufacturers Association Inc 531 SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B This page intentionally blank RCB4 BAFFLES AND SUPPORT PLATES RCB41 TYPE OF TRANSVERSE BAFFLES The segmental or multisegmental type of baffle or tube support plate is standard Other type baffles are permissible Baffle cut is defined as the segment opening height expressed as a percentage of the shell inside diameter or as a percentage of the total net free area inside the shell shell cross sectional area minus total tube area The number of tube rows that overlap for multisegmental baffles should be adjusted to give approximately the same net free area flow through each baffle Baffles shall be cut near the centerline of a row of tubes of a pass lane of a tube lane or outside the tube pattern Baffles shall have a workmanlike finish on the outside diameter Typical baffle cuts are illustrated in Figure RCB41 Baffle cuts may be vertical horizontal or rotated FIGURE RCB41 BAFFLE CUTS FOR SEGMENTAL BAFFLES HORIZONTAL VERTICAL ROTATED BAFFLE CUTS FOR MULTISEGMENTAL BAFFLES DOUBLE SEGMENTAL TRIPLE SEGMENTAL RCB42 TUBE HOLES IN BAFFLES AND SUPPORT PLATES Where the maximum unsupported tube length is 36 in 914 mm or less or for tubes larger in diameter than 1 14 in 318 mm OD standard tube holes are to be 132 inch 08 mm over the OD of the tubes Where the unsupported tube length exceeds 36 in 914 mm for tubes 1 14 in 318 mm diameter and smaller standard tube holes are to be 116 inch 04 mm over the OD of the tubes For pulsating conditions tube holes may be smaller than standard Any burrs shall be removed and the tube holes given a workmanlike finish Baffle holes will have an overtolerance of 0010 inch 03 mm except that 4 of the holes are allowed an overtolerance of 0015 inch 04 mm wwwtemaorg Tubular Exchanger Manufacturers Association Inc 541 RCB43 TRANSVERSE BAFFLE AND SUPPORT PLATE TO SHELL CLEARANCE The transverse baffle and support plate clearance shall be such that the difference between the shell design inside diameter and the outside diameter of the baffle shall not exceed that indicated in Table RCB43 However where such clearance has no significant effect on shell side heat transfer coefficient or mean temperature difference these maximum clearances may be increased to twice the tabulated values See Paragraph RCB443 TABLE RCB441 BAFFLE OR SUPPORT PLATE THICKNESS Dimensions in Inches mm Nominal Shell ID Unsupported tube length between central baffles End spaces between tubesheets and baffles are not a consideration 24 610 and Under Over 24 610 to 36 914 Over 36 914 to 48 1219 Over 48 1219 to 60 1524 Over 60 1524 Inclusive 614 152356 18 32 316 48 14 64 38 95 38 95 1528 381711 316 48 14 64 38 95 38 95 12 127 2938 737965 14 64 516 79 38 95 12 127 58 159 3960 9911524 14 64 38 95 12 127 58 159 58 159 61100 15492540 14 64 38 95 12 127 58 159 34 191 R442 LONGITUDINAL BAFFLES R4421 LONGITUDINAL BAFFLES WITH LEAF SEALS Longitudinal baffles with leaf or other type seals shall not be less than 14 64 mm nominal metal thickness R4422 WELDEDIN LONGITUDINAL BAFFLES The thickness of longitudinal baffles that are welded to the shell cylinder shall be determined as shown in Paragraph R4422 CB4423 LONGITUDINAL BAFFLE WELD SIZE Weldedin longitudinal baffles shall be attached with fillet welds on each side with a minimum leg of 34 t from Paragraph R4422 Other types of attachments are allowed but shall be of equivalent strength TABLE RCB452 MAXIMUM UNSUPPORTED STRAIGHT TUBE SPANS Dimensions in Inches mm Tube OD Tube Materials and Temperature Limits F C Carbon Steel High Alloy Steel 750 399 Low Alloy Steel 850 454 NickelCopper 600 316 Nickel 850 454 NickelChromiumIron 1000 538 Aluminum Aluminum Alloys Copper Copper Alloys Titanium Alloys At Code Maximum Allowable Temperature 14 64 26 660 22 559 38 95 35 889 30 762 12 127 44 1118 38 965 58 159 52 1321 45 1143 34 191 60 1524 52 1321 78 222 69 1753 60 1524 1 254 74 1880 64 1626 1 14 318 88 2235 76 1930 1 12 381 100 2540 87 2210 2 508 125 3175 110 2794 2 12 635 125 3175 110 2794 3 762 125 3175 110 2794 Notes 1 Above the metal temperature limits shown maximum spans shall be reduced in direct proportion to the fourth root of the ratio of elastic modulus at design temperature to elastic modulus at tabulated limit temperature 2 In the case of circumferentially finned tubes the tube OD shall be the diameter at the root of the fins and the corresponding tabulated or interpolated span shall be reduced in direct proportion to the fourth root of the ratio of the weight per unit length of the tube if stripped of fins to that of the actual finned tube 3 The maximum unsupported tube spans in Table RCB452 do not consider potential flow induced vibration problems Refer to Section 6 for vibration criteria RCB453 BAFFLE SPACING Baffles normally shall be spaced uniformly spanning the effective tube length When this is not possible the baffles nearest the ends of the shell andor tubesheets shall be located as close as practical to the shell nozzles The remaining baffles normally shall be spaced uniformly RCB454 UTUBE REAR SUPPORT The support plates or baffles adjacent to the bends in Utube exchangers shall be so located that for any individual bend the sum of the bend diameter plus the straight lengths measured along both legs from supports to bend tangents does not exceed the maximum unsupported span determined from Paragraph RCB452 Where bend diameters prevent compliance special provisions in addition to the above shall be made for support of the bends RCB455 SPECIAL CASES When crushing conditions are specified by the purchaser unsupported spans shall be as short as pressure drop restrictions permit If the span under these circumstances approaches the maximum permitted by Paragraph RCB452 consideration should be given to alternative flow arrangements which would permit shorter spans under the same pressure drop restrictions RCB4626 DISTRIBUTOR BELT IMPINGEMENT PROTECTION AREAS For determining the shell or bundle exit or entrance areas the methods used for calculating these areas for bundles without impingement plates may be used considering the size and shape of the distributor openings in the inner shell RCB463 TUBE SIDE Consideration shall be given to the need for special devices to prevent erosion of the tube ends under any of the following conditions 1 Use of an axial inlet nozzle 2 Liquid pV² in the inlet nozzle is in excess of 6000 8928 3 When there is twophase flow RCB47 TIE RODS AND SPACERS Tie rods and spacers or other equivalent means of tying the baffle system together shall be provided to retain all transverse baffles and tube support plates securely in position R471 NUMBER AND SIZE OF TIE RODS Table R471 shows suggested tie rod count and diameter for various sizes of heat exchangers Other combinations of tie rod number and diameter with equivalent net area are permissible however no fewer than four tie rods and no diameter less than 38 95 mm shall be used Any baffle segment requires a minimum of three points of support TABLE R471 TIE ROD STANDARDS Dimensions in Inches mm Nominal Shell Diameter Tie Rod Diameter Minimum Number of Tie Rods 6 15 152381 38 95 4 16 27 406686 38 95 6 28 33 711838 12 127 6 34 48 8641219 12 127 8 49 60 12451524 12 127 10 61 100 15492540 58 159 12 CB471 NUMBER AND SIZE OF TIE RODS Table CB471 shows suggested tie rod count and diameter for various sizes of heat exchangers Other combinations of tie rod number and diameter with equivalent net area are permissible however no fewer than four tie rods and no diameter less than 38 95 mm shall be used above 15 381 mm nominal shell diameter Any baffle segment requires a minimum of three points of support TABLE CB471 TIE ROD STANDARDS Dimensions in Inches mm Nominal Shell Diameter Tie Rod Diameter Minimum Number of Tie Rods 6 15 152381 14 64 4 16 27 406686 38 95 6 28 33 711838 12 127 6 34 48 8641219 12 127 8 49 60 12451524 12 127 10 61 100 15492540 58 159 12 RCB48 BYPASS SEALING When required by thermal design bypass clearances that exceed 58 16 mm should be sealed as follows 1 When the distance between baffle cut edges is six tube pitches or less a single seal located approximately halfway between the baffle cuts should be provided 2 When the distance between baffle cut edges exceeds six tube pitches multiple seals should be provided A seal should be located every five to seven tube pitches between the baffle cuts with the outermost seals not more than 3 76 mm from each baffle cut edge 3 Seals shall be located to minimize obstruction of mechanical cleaning lanes or should be readily removable Continuous cleaning lanes should be maintained for square 90 degree and rotatedsquare 45 degree patterns RCB481 PERIPHERAL BYPASS SEALING WHEN CLEARANCES EXCEED 58 16 mm Peripheral bypass seals should be installed so that the seal clearance SC Figure RCB48 does not exceed the greater of 14 6 mm or the nominal clearance between the tubes Peripheral bypass seals shall not restrict the bundle inlet or outlet flows RCB482 INTERNAL BYPASS SEALING WHEN CLEARANCES EXCEED 58 16 mm Internal bypass seals should be installed so that SC does not exceed the greater of 14 6 mm or the nominal clearance between tubes Pass lanes parallel to the baffle cuts do not require seal devices RCB483 TYPES OF BYPASS SEALS Sealing devices may be any combination of seal bars skid bars dummy tubes dummy rods or tie rods Seal bars shall have a minimum thickness of the lesser of 14 6 mm or the transverse baffle thickness The minimum dummy tube thickness shall be the lesser of nominal 0065 16 mm or the heat transfer tube thickness Dummy rods shall have a minimum diameter of 38 95 mm RCB484 BYPASS SEAL ATTACHMENT Sealing devices shall be securely attached to the bundle skeleton As a minimum peripheral bar type sealing devices should be attached to one side of every third baffle with intermittent fillet welds Peripheral bar type sealing devices shall have a radius or bevel on the leading and trailing edges to prevent damage when inserting or removing the bundle Tube and rod type sealing devices should be securely welded to at least one baffle tie rods that are attached to the tubesheet and used as sealing devices are exempt from the welding requirement Tube type sealing devices shall have one end securely closed by crimping welding etc to prevent bypass FIGURE RCB48 DISTANCE BETWEEN BAFFLE CUTS SEAL BARS SC SC SC SC PERIPHERAL BAFFLE EDGE SC DUMMY TUBES DUMMY RODS OR TIE RODS BAFFLE CUT SKID BARS THE NOMINAL CLEARANCE BETWEEN TUBES EQUALS THE TUBE PITCH MINUS THE TUBE DIAMETER RCB49 KETTLE TYPE REBOILERS RCB491 BUNDLE HOLD DOWNS Bundle hold downs may be provided When provided on Utube bundles the preferred location is over a baffle at the Ubend end When provided on a floating head bundle the preferred location is over the floating head Some methods are shown in Figure RCB49 other methods which satisfy the intent are acceptable RCB492 BUNDLE SKID ALIGNMENT DEVICES Bundles may need an alignment device Bundles that require skid bars may need skid rails Some methods are shown in Figure RCB9 other methods that satisfy the intent are acceptable FIGURE RCB49 HOLD DOWN ANGLES IN SHELL ALIGNMENT ROD IN SHELL SKID BARS IN BUNDLE SKID RAILS IN SHELL HOLD DOWN WRAP IN SHELL ALIGNMENT BAR IN SHELL HOLD DOWN ALIGNMENT BARS IN SHELL CROSSSECTION END VIEW OF TUBE BUNDLE AND SHELL SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B 5410 Tubular Exchanger Manufacturers Association Inc wwwtemaorg This page intentionally blank RCB5 FLOATING END CONSTRUCTION H CB2 in mm RCB515 TUBE BUNDLE SUPPORTS SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B MECHANICAL STANDARDS TEMA CLASS R C B SECTION 5 SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B RCB6 GASKETS RCB61 TYPE OF GASKETS Gaskets shall be selected which have a continuous periphery with no radial leak paths This shall not exclude gaskets made continuous by welding or other methods which produce a homogeneous bond Gaskets made integral by welding are often harder in the welds than in the base material Hardness limitations may be specified by the exchanger manufacturer R62 GASKET MATERIALS Metal basedbound gaskets shall be used for internal floating head joints all joints for pressures of 300 psi 2068 kPa and over and for all joints in contact with hydrocarbons Other gasket materials may be specified by agreement between purchaser and manufacturer When two gasketed joints are compressed by the same bolting provisions shall be made so that both gaskets seal but neither gasket is crushed at the required bolt load CB62 GASKET MATERIALS For design pressures of 300 psi 2068 kPa and lower sheet gaskets may be used for external joints unless temperature or corrosive nature of contained fluid indicates otherwise Metal basedbound gaskets shall be used for all joints for design pressures greater than 300 psi 2068 kPa and for internal floating head joints Other gasket materials may be specified by agreement between purchaser and manufacturer When two gasketed joints are compressed by the same bolting provisions shall be made so that both gaskets seal but neither gasket is crushed at the required bolt load RCB63 PERIPHERAL GASKETS RC631 The minimum width of peripheral ring gaskets for external joints shall be 38 95 mm for shell sizes through 23 in 584 mm nominal diameter and 12 127 mm for all larger shell sizes B631 The minimum width of peripheral ring gaskets for external joints shall be 38 95 mm for shell sizes through 23 in 584 mm nominal diameter and 12 127 mm for all larger shell sizes Full face gaskets shall be used for all cast iron flanges RCB632 The minimum width of peripheral ring gaskets for internal joints shall be 14 64 mm for all shell sizes RCB64 PASS PARTITION GASKETS The width of gasket web for pass partitions of channels bonnets and floating heads shall be not less than 14 64 mm for nominal diameters less than 24 610 mm and not less than 38 95 mm for all larger shell sizes wwwtemaorg Tubular Exchanger Manufacturers Association Inc 561 R66 GASKET JOINT DETAILS Gasketed joints shall be of a confined type A confined gasket requires a solid metal retaining element that prevents a direct radial leak path to the environment in the event of gasket extrusion or blowout This confining element can be via a recess in the flange face per Figures RCB65 and F3 or it can be via an outer retaining ring which is not used as the primary sealing element gasket of the joint as shown for a spiral wound gasket in Figure RCB65 A solid metal gasket which projects beyond the raised face of a raised face flange and extends to the inside of the bolts will meet the definition above for a confined joint A solid metal gasket on a flat face flange in which the entire gasket width is effective as a sealing element does not meet the criteria of a confined joint and is by definition an unconfined gasket CB65 GASKET JOINT DETAILS Gasket joints shall be of a confined or unconfined type FIGURE RCB65 CONFINED GASKET UNCONFINED GASKET For dimensions and tolerances see Figure F3 RCB66 SPARE GASKETS Unless specifically stated otherwise spare gaskets include only main body flange gaskets and floating head gasket wwwtemaorg Tubular Exchanger Manufacturers Association Inc 562 RCB7 TUBESHEETS RCB71 TUBESHEET THICKNESS The tubesheet thickness shall be per Code rules When the Code does not include rules for tubesheets ASME Code Part UHX Appendix A of this Standard or the manufacturers method may be used R711 MINIMUM TUBESHEET THICKNESS WITH EXPANDED TUBE JOINTS In no case shall the total thickness minus corrosion allowance in the areas into which tubes are to be expanded of any tubesheet be less than the outside diameter of tubes In no case shall the total tubesheet thickness including corrosion allowance be less than 34 191 mm C711 MINIMUM TUBESHEET THICKNESS WITH EXPANDED TUBE JOINTS In no case shall the total thickness minus corrosion allowance in the areas into which tubes are to be expanded of any tubesheet be less than threefourths of the tube outside diameter for tubes of 1 254 mm OD and smaller 78 222 mm for 1 14 318 mm OD 1 254 mm for 1 12 381 mm OD or 1 14 318 mm for 2 508 mm OD B711 MINIMUM TUBESHEET THICKNESS WITH EXPANDED TUBE JOINTS In no case shall the total thickness minus corrosion allowance in the areas into which tubes are to be expanded of any tubesheet be less than threefourths of the tube outside diameter for tubes of 1 254 mm OD and smaller 78 222 mm for 1 14 318 mm OD 1 254 mm for 1 12 381 mm OD or 1 14 318 mm for 2 508 mm OD In no case shall the total tubesheet thickness including corrosion allowance be less than 34 191 mm RCB712 DOUBLE TUBESHEETS Double tubesheets may be used where the operating conditions indicate their desirability The diversity of construction types makes it impractical to specify design rules for all cases Paragraphs RCB7124 RCB7125 and RCB7126 provide the design rules for determining the thickness of double tubesheets for some of the most commonly used construction types RCB7121 MINIMUM THICKNESS Neither component of a double tubesheet shall have a thickness less than that required by Paragraph R711 C711 or B711 RCB7122 VENTS AND DRAINS Double tubesheets of the edge welded type shall be provided with vent and drain connections at the high and low points of the enclosed space RCB7123 SPECIAL PRECAUTIONS When double tubesheets are used special attention shall be given to the ability of the tubes to withstand without damage the mechanical and thermal loads imposed on them by the construction RCB7124 INTEGRAL DOUBLE TUBESHEETS The tubesheets are connected in a manner which distributes axial load and radial thermal expansion loads between tubesheets by means of an interconnecting element capable of preventing individual radial growth of tubesheets It is assumed that the element is rigid enough to mutually transfer all thermal and mechanical radial loads between the tubesheets Additionally it is understood that the tubes are rigid enough to mutually transfer all mechanically and thermal axial loads between the tubesheets wwwtemaorg Tubular Exchanger Manufacturers Association Inc 571 Calculate the total combined tubesheet thickness T per Paragraph A13 where T Greater of the thickness in mm resulting from A131 or A132 using the following variable definitions G Per A13 in mm using worst case values of shell side or tube side tubesheets at their respective design temperature S Lower of the Code allowable stress psi kPa for either component tubesheet at its respective design temperature F Per A13 using worst case values of shell side or tube side tubesheets at their respective design temperature All other variables are per A13 Establish the thickness of each individual tubesheet so that t2 t1 T and the minimum individual tubesheet thicknesses t1 and t2 shall be the greater of R711 C711 B711 or A133 as applicable The radial shear stress τ psi kPa at attachment due to differential thermal expansion of tubesheets shall not exceed 80 of the lower Code allowable stress S of either of the tubesheet materials or the interconnecting element at their respective design temperature The shear is defined as τ Fₑ tₑ 08S Metric τ Fₑ 10⁶ 08S tₑ Thickness of interconnecting element in mm The combined stresses from bending due to differential thermal expansion of tubesheets and axial tension due to thermal expansion of tubes shall not exceed 15 times the Code allowable stress S of the interconnecting element The combined total stress of interconnecting element σₑ psi kPa is given by σₑ σᵦ σₜₑ 15S The stress due to axial thermal expansion of tubes σₜₑ psi kPa is defined as σₜₑ Fₑ Aₑ Metric σₜₑ Fₑ Aₑ 10⁶ RCB71254 TUBE STRESS CONSIDERATIONS AXIAL STRESS The axial stresses in the tubes due to thermal expansion and pressure load shall not exceed the Code allowable stress S of the tubes at design temperature The total combined stress of the tubes σT psi kPa is given by σT σo σTT S The axial stress due to pressure σP psi kPa is defined as σP Pπ G² Nd₀² 4Aₜ where P Greater of shell side or tube side design pressure psi kPa G Per Paragraph A13 in mm N Number of tubes d₀ Tube OD between tubesheets in mm The stress due to axial thermal expansion of tubes σTT psi kPa is defined as σTT Fₜₑ Aₜ Metric σTT Fₜₑ Aₜ x 10⁶ RCB7125 CONNECTED DOUBLE TUBESHEETS The tubesheets are connected in a manner which distributes axial load between tubesheets by means of an interconnecting cylinder The effect of the differential radial growth between tubesheets is a major factor in tube stresses and spacing between tubesheets It is assumed the interconnecting cylinder and tubes are rigid enough to mutually transfer all mechanical and thermal axial loads between the tubesheets RCB71251 TUBESHEET THICKNESS Calculate the total combined tubesheet thickness T per Paragraph A13 where T Greater of the thickness in mm resulting from Paragraphs A131 or A132 using variables as defined in Paragraph RCB71241 Establish the thickness of each individual tubesheet so that t₂ t₁ T and the minimum individual tubesheet thickness t₁ and t₂ shall be the greater of Paragraph R711 C711 B711 or A133 when applicable t₁ Thickness of tube side tubesheet in mm t₂ Thickness of shell side tubesheet in mm SECTION 5 MECHANICAL STANDARDS TEMA CLASS R C B RCB7126 SEPARATE DOUBLE TUBESHEETS The tubesheets are connected only by the interconnecting tubes The effect of differential radial growth between tubesheets is a major factor in tube stresses and spacing between tubesheets It is assumed that no loads are transferred between the tubesheets FIGURE RCB7126 RCB71261 TUBESHEET THICKNESS Calculate tube side tubesheet thickness per Paragraph A13 Use all variables as defined per TEMA neglecting all considerations of shell side design conditions Calculate shell side tubesheet thickness per Paragraph A13 Use all variables as defined per TEMA neglecting all considerations of tube side design conditions RCB71262 MINIMUM SPACING BETWEEN TUBESHEETS The minimum spacing g in mm between tubesheets required to avoid overstress of tubes resulting from differential thermal growth of individual tubesheets is given by g daDrEt 027Yr RCB72 TUBE HOLES IN TUBESHEETS RCB721 TUBE HOLE DIAMETERS AND TOLERANCES Tube holes in tubesheets shall be finished to the diameters and tolerances shown in Tables RCB721 and RCB721M column a Interpolation and extrapolation are permitted To minimize work hardening a closer fit between tube OD and tube ID as shown in column b may be provided when specified by the purchaser 578 Tubular Exchanger Manufacturers Association Inc wwwtemaorg RCB71252 MINIMUM SPACING BETWEEN TUBESHEETS The minimum spacing g in mm between tubesheets required to avoid overstress of tubes resulting from differential thermal growth of individual tubesheets is given by g d₀ Δr Eₜ 027 Yₜ where d₀ Tube OD between tubesheets in mm Yₜ Yield strength of the tube material at maximum metal temperature psi kPa Δr Differential radial expansion between adjacent tubesheets in mm Measured from center of tubesheet to Dₜₗ where Δr Dₜₗ 2 α₂ΔT₂ α₁ΔT₁ where Dₜₗ Outer tube limit in mm