SPECIFICATION FOR STUD BOLTS AND TAP END STUDS

SPECIFICATION FOR STUD BOLTSAND TAP END STUDSTECHNICAL REPORT TR9501Revision AAWHEM publications may be used by anyone desiring to do so. Every effort has been made by theAssociation to assure the accuracy and reliability of the data contained in them; however, the Associationmakes no representation, warranty, or guarantee in connection with this publication and hereby expresslydisclaims any liability or responsibility for loss or damage resulting from its use or for the violation of anyfederal, state or municipal regulation with which this publication may conflict.Association of Well HeadEquipment ManufacturersPost Office Box 1166Bellaire, Texas 77401

Issue Date:June 6, 1995Revision AJune 11, 2002AWHEMRECOMMENDATION FOR INTERCHANGEABLESTUD BOLTS AND TAP END STUDSFOR API SPEC 6A FLANGESISSUED BY:ASSOCIATION OF WELL HEADEQUIPMENT MANUFACTURERSPOST OFFICE BOX 1166@BELLAIRE, TEXAS 77401This document submitted for industry acceptance. We solicit any corrections, revisions and comments that you may offer.

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A2TABLE OF CONTENTSSection1.0 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.2 Reference Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.4 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.0 Method of calculating stud bolt lengths for type 6B and 6BX flanges . . . . . . . . . . . . . . . . . . . . . . 42.1 Stud bolt length table for 6B flange connections with "R" and "RX" gaskets . . . . . . . . . . . . . . . . . 52.2 Stud bolt length table for 6BX flange connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.0 Method of calculating tap end stud lengths for type 6B and 6BX flanges . . . . . . . . . . . . . . . . . . . . 73.1 Tap end stud length table for 6B studded flange connections with "R" and "RX" gaskets . . . . . . . . . 83.2 Tap end stud length table for 6BX studded flange connections . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Appendix A - Stud bolt length table for 6B flange connections with "R" gaskets . . . . . . . . . . . . . . . . . . . . . . . . . 10Appendix B - Tap end stud length table for 6B studded flange connections with "R" gaskets . . . . . . . . . . . . . . . . 11

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A1.0 GENERALThis AWHEM Recommendation compliments andextends but does not conflict with API Spec 6A.1.1 PURPOSEThis AWHEM Recommendation establishes definitedimensions for stud bolts and tap end studs for usewith API Spec 6A flanges/studded flangeconnections and provides for dimensionallyinterchangeable stud bolts and tap end studs for APISpec 6A flanges/studded flange connections. Studbolts and tap end studs that may have other lengthsetc. for special purposes, and comply with therequirements of API Spec 6A, are beyond the scopeof this document.1.2 REFERENCE DOCUMENTAPI Spec 6A.Note: This AWHEM Recommendation derives itsbasis from API Spec 6A and those standardsreferenced therein.Any subsequentsupplements to API Spec 6A, 17th Edition, orsubsequent editions issued, shall requirereview and revision of this AWHEMRecommendation to assure its application.3achieve one (1) diameter of engagement with therespective tapped holes.Point End portion of the stud that features incompletethreads to facilitate thread engagement. Themaximum length of the point shall equal 1.5times the pitch of the thread.Stud Bolts (For Through Bolt Flanges) Studs that have threads over their full length ormay have an unthreaded portion on the centralarea of the body diameter.Tap End Studs (For Studded Flanges) Studs threaded on each end with an unthreadedportion on the body diameter. The thread lengthdimension on one end controls the depth thatthat end will engage into a tapped hole, and alsocontrols the extension length of the stud beyonda studded flange.Threads All studs and bolts shall have Class 2A unifiedinch screw threads per ASME B1.1-1989(Revision of ANSI B1.1-1982) Standard.1.3 DEFINITIONS:Size 1" and below shall have UNC threads.Length, (Tap End Stud or Stud Bolt) Measurement end to end, including points.Length, Nut End Thread 2-1/2 x Diameter Minimum thread length offull threads measured from the end of the stud.Length, Tap End Thread One diameter maximum point minimumthread length, measured from the end of the studto the end of thread run out (to the last scratchon cut threads, or to the last impression ofthreads made by other means).NOTE: The manufacturer shall have and use ameans to demonstrate that his threading processproduces sufficient full threads on the stud toSize 1-1/8" and above shall have 8 threads perinch.1.4 APPLICATIONAPI Spec 6A, "6B" flanges, may use "R" or "RX"gaskets, "RX" gaskets producing greater standoffbetween flanges. Tables for "6B" flanges in thisdocument show stud bolt and tap end stud lengthsthat will accommodate both "R" and "RX" gaskets.Some equipment designs provide very little nut andwrench clearance, so occasions may arise whenmanufacturers or users must install shorter stud boltsor tap end studs when using the "R" gaskets. For thisreason, Appendices A and B follow in this documentto provide lengths for "R" gaskets only.

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A42.0METHOD OF CALCULATING STUD BOLT LENGTHS FOR TYPE 6B AND 6BX FLANGES2.0aCALCULATION. The following formula wasused in establishing stud bolt lengths listed inthe tables and is included here for theconvenience of industry. Length shown intables results from rounding as specified inparagraph 2.0b.L2.0bROUNDING OFF PROCEDURE. If L is0.010 inch (or more) greater than any 1/4 inchincrement, round off upward to the next 1/4 inchincrement; if less than 0.010 inch, round offdownward to the next 1/4 inch increment.2.0cEND POINT-HEIGHT OF STUD BOLTS.The end point is the end portion of a stud boltbeyond the complete thread; and may bechamfered, rounded, or sheared. The maximumheight of each end point shall be 1.5 x pitch ofthread.2.0dFLANGE FACE STANDOFF VALUES, S.The approximate distance between faces ofmade-up flanges, S is given in API Spec 6A forR and RX ring gaskets. 2(T t d) S 2(P)Where:L Calculated stud bolt length.T Total flange thickness.t Plus tolerance for flange thickness.d Heavy hex nut thickness (equals nominal boltdiameter; see ANSI B 18.2.2: Square andHex Nuts).S Flange face standoff. S 0 for BXassemblies. See Figure 2.0-1.P Maximum end point height (1.5 x Pitch ofthread).Figure 2.0-1LSAPI TYPE 6B FLANGEWITH R GASKETLSAPI TYPE 6B FLANGEWITH RX GASKETLPOINT HEIGHTSTUD BOLT WITH NUTSLNO STANDOFFAPI TYPE 6BX FLANGE

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A52.1 STUD BOLT LENGTH TABLE FOR 6B FLANGE CONNECTIONS WITH "R" AND "RX" GASKETSACCOMMODATES"R" AND "RX" TYPE GASKETSLENGTHLENGTHDIAPOINTLENGTH 2( T t d ) S 2( P )TtdSTotal flange thickness.Plus tolerence for flange thickness.Heavy hex nut thickness.Flange face standoff. (with "RX" gasket )PPoint Max. (1.5 X .50010.50020-3/43M2.00015.000tolerance on bolt length: 1/8 , - 0 inch for lengths up to 12 inches. 1/4 , - 0 inch for lengths over 12 inches.

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A2.26STUD BOLT LENGTH TABLE FOR 6BX FLANGE CONNECTIONS"BX" TYPE GASKETLENGTHLENGTHNO STANDOFFDIAPOINTLENGTH *2( T t d ) S 2( P )TtdSTotal flange thickness.Plus tolerence for flange thickness.Heavy hex nut thickness.Flange face standoff.PPoint Max. (1.5 X .87516.000920M2.50021.750tolerance on bolt length: 1/8 , - 0 inch for lengths up to 12 inches. 1/4 , - 0 inch for lengths over 12 inches.

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A73.0METHOD OF CALCULATING TAP END STUD LENGTHS FOR TYPE 6B AND 6BX FLANGES3.0aCALCULATION. The following formula wasused in establishing tap end stud lengths listed inthe tables and is included here for convenience ofindustry. Length shown in tables results fromrounding as specified in paragraph 3.0b.3.0bROUNDING OFF PROCEDURE. Add1/16 inch to the calculated length and thenround up to the next 1/8 inch increment afterthis addition. This rounding procedureallows for variation in stud installationmethods and assures sufficient extension forfull nut engagement. T t d S P TL RF3.0cEND POINT-HEIGHT OF TAP ENDSTUDS. The end point is the end portion ofa stud bolt beyond the complete thread andmay be chamfered, rounded, or sheared. Themaximum height of each end point shall be1.5 x pitch of thread.3.0dTAP END THREAD LENGTH. Onediameter of tap end stud 1.5 pitch of thread, 1/16 -0 maximum (this includes pointheight).3.0eNUT END THREAD LENGTH. 2.5 xdiameter of tap end stud minimum. Howeverif necessary, this length shall be limited toprovide minimum unthreaded portion equalto one thread pitch between the tap endthreads and nut end threads.3.0fFLANGE FACE STANDOFF VALUES,S. The approximate distance between facesof made-up flanges, S is given in API Spec6A for R and RX ring gaskets.LWhere:LTtd Calculated tap end stud length. Total flange thickness. Plus tolerance for flange thickness. Heavy hex nut thickness (equals nominal boltdiameter; see ANSI B 18.2.2: Square and HexNuts).S Flange face standoff. S 0 for BX assemblies.See Figure 3.0-1.P Maximum end point height (1.5 x Pitch ofthread).TL Tap end thread length, maximum [(one diameter 1.5 pitch) 1/16 - 0].RF Add amount of raised face present on studdedflanges, if not omitted, to the length of studs intable.Figure 3.0-1LLSAPI TYPE 6B FLANGEWITH R GASKETSAPI TYPE 6B FLANGEWITH RX GASKETLPOINT HEIGHTTAP END STUD WITH NUTLNO STANDOFFAPI TYPE 6BX FLANGE

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A3.18TAP END STUD LENGTH TABLE FOR 6B STUDDED FLANGE CONNECTIONS WITH "R" AND "RX GASKETSACCOMMODATES"R" AND "RX" TYPE GASKETSLENGTHLENGTHTAP END THREAD 1/16LENGTH-0(D 1.5 PITCH)MINIMUMUNTHREADEDPORTION SHALLBE EQUAL TO1 THREAD PITCHNUT END THREADLENGTH(2-1/2 D)FULL THREAD MIN.POINTPOINTLENGTH T t d S P TL RFTtdSTotal flange thickness.Plus tolerance for flange thickness.Heavy hex nut thickness.Flange face standoff. (with "RX" gasket)PTLPoint, maximum (1.5 X Pitch)Tap end thread length, maximum .[(one diameter 1.5 Pitch) 1/16 - 0]Add amount of raised face present onstudded flanges, if not omitted, to thelength of studs in table.RFSTUDDIA.FLANGESIZETAP END * NUT ENDLENGTHLENGTH**STUDDIA.FLANGESIZELENGTHTAP END * NUT 7520-3/43M2.0002.1885.00010.125*tolerance on tap end thread length: 1/16 , - 0 inch**tolerance on tap end stud length 1/8 , - 0 inch

AWHEM Recommendation For Stud Bolts and Tap End Studs For API Spec 6A3.29TAP END STUD LENGTH TABLE FOR 6BX STUDDED FLANGE CONNECTIONS"BX" TYPE GASKETLENGTHLENGTHTAP END THREAD 1/16LENGTHNO STANDOFF-0(D 1.5 PITCH)MINIMUMUNTHREADEDPORTION SHALLBE EQUAL TO1 THREAD PITCHNUT END THREADLENGTH(2-1/2 D)FULL THREAD MIN.POINTPOINTLENGTH TtdSPT t d S P TL RFTotal flange thickness.Plus tolerance for flange thickness.Heavy hex nut thickness.Flange face standoff.Point, maximum (1.5 X Pitch)FLANGESIZESTUDDIA.TLTap end thread length, maximum[ (one diameter 1.5 Pitch) 1/16 - 0]Add amount of raised face present onstudded flanges, if not omitted, to thelength of studs in table.RFTAP END * NUT ENDLENGTHLENGTHFLANGESIZE**LENGTHSTUDDIA.TAP END * NUT 4.68810.125920M2.5002.6886.25013.750*tolerance on tap end thread length: 1/16 , - 0 inch**tolerance on tap end stud length 1/8 , - 0 inch