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ASME B31.3-2016
<br /> Table 302.3.5 Weld Joint Strength Reduction Factor, W
<br /> Component Temperature, Ti, °C( F)
<br /> 427 454 482 510 538 566 593 621 649 677 704 732 760 788 816
<br /> Steel Group (800) (850) (900) (950) (1,000) (1,050)(1,100) (1,150)(1,200) (1,250) (1,300)(1,350) (1,400)(1,450) (1,500)
<br /> CrMo 1 0.95 0.91 0.86 0.82 0.77 0.73 0.68 0.64 ... ... ... ... ... ...
<br /> [Notes (1)—(3)]
<br /> CSEF(N+T) ... ... ... 1 0.95 0.91 0.86 0.82 0.77 ... ... ... ... ... ...
<br /> [Notes (3)—(5)]
<br /> CSEF ... ... 1 0.5 0.5 0.5 0.5 0.5 0.5 ... ... ... ... ... ...
<br /> [Notes (3) and (4)]
<br /> (Subcritical PWHT)
<br /> Autogenous welds in aus. ... ... ... 1 1 1 1 1 1 1 1 1 1 1 1
<br /> tenitic stainless grade
<br /> 3xx, and N088xx and
<br /> N066xx nickel alloys
<br /> [Note (6)]
<br /> Austenitic stainless grade ... ... ... 1 0.95 0.91 0.86 0.82 0.77 0.73 0.68 0.64 0.59 0.55 0.5
<br /> 3xx and N088xx nickel
<br /> alloys [Notes (7) and
<br /> (8)]
<br /> Other materials [Note (9)] ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
<br /> GENERAL NOTES:
<br /> (a) Weld joint strength reduction factors at temperatures above the upper temperature limit listed in Appendix A for the base metal or out-
<br /> side of the applicable range in Table 302.3.5 are the responsibility of the designer.At temperatures below those where weld joint
<br /> strength reduction factors are tabulated, a value of 1.0 shall be used for the factor Wwhere required; however,the additional rules of
<br /> this Table and Notes do not apply.
<br /> (b) Tr = temperature 25°C (50°F) below the temperature identifying the start of time-dependent properties listed under
<br /> "NOTES—TIME-DEPENDENT PROPERTIES" (Txx) in the Notes to Tables 1A and 1B of the BPV Code Section 11, Part D for the base metals
<br /> joined by welding. For materials not listed in the BPV Code Section 11, Part D, Tr shall be the temperature where the creep rate or
<br /> stress rupture criteria in paras. 302.3.2(d)(4), (5), and (6) governs the basic allowable stress value of the metals joined by welding.
<br /> When the base metals differ, the lower value of Tr shall be used for the weld joint.
<br /> (c) Ti = temperature,°C ff), of the component for the coincident operating pressure—temperature condition,i, under consideration.
<br /> (d) CAUTIONARY NOTE: There are many factors that may affect the life of a welded joint at elevated temperature and all of those factors
<br /> cannot be addressed in a table of weld strength reduction factors. For example,fabrication issues such as the deviation from a true cir-
<br /> cular form in pipe (e.g., "peaking" at longitudinal weld seams) or offset at the weld joint can cause an increase in stress that may
<br /> result in reduced service life and control of these deviations is recommended.
<br /> (e) The weld joint strength reduction factor, W, may be determined using linear interpolation for intermediate temperature values.
<br /> NOTES:
<br /> (1) The Cr—Mo Steels include: '/2Cr—'/zMo, 1Cr—'/2Mo, 11/4Cr—'/2Mo—Si, 2'/4Cr-1Mo, 3Cr-1Mo, 5Cr—'/2Mo, 9Cr-1Mo. Longitudinal and spiral
<br /> (helical seam) welds shall be normalized, normalized and tempered, or subjected to proper subcritical postweld heat treatment (PWHT)
<br /> for the alloy. Required examination is in accordance with para. 341.4.4 or 305.2.4.
<br /> (2) Longitudinal and spiral (helical seam) seam fusion welded construction is not permitted for C—'/ZMo steel above 850°F.
<br /> (3) The required carbon content of the weld filler metal shall be>-0.05 C wt.%. See para. 341.4.4(b) for examination requirements.
<br /> Basicity index of SAW flux>!1.0.
<br /> (4) The CSEF(Creep Strength Enhanced Ferritic) steels include grades 91, 92, 911, 122, and 23.
<br /> (5) N+T = Normalizing+Tempering PWHT.
<br /> (6) Autogenous welds without filler metal in austenitic stainless steel (grade 3xx) and austenitic nickel alloys UNS Nos. N066xx and
<br /> N088xx.A solution anneal after welding is required for use of the factors in the Table. See para. 341.4.3(b) for examination
<br /> requirements.
<br /> (7) Alternatively, the 100,000 hr Stress Rupture Factors listed in ASME Section III, Division 1, Subsection NH, Tables 1-14.10 A-xx, B-xx,
<br /> and C-xx may be used as the weld joint strength reduction factor for the materials and welding consumables specified.
<br /> (8) Certain heats of the austenitic stainless steels, particularly for those grades whose creep strength is enhanced by the precipitation of
<br /> temper-resistant carbides and carbonitrides, can suffer from an embrittlement condition in the weld heat affected zone that can lead to
<br /> premature failure of welded components operating at elevated temperatures.A solution annealing heat treatment of the weld area miti-
<br /> gates this susceptibility.
<br /> (9) For carbon steel, W = 1.0 for all temperatures. For materials other than carbon steel, CrMo, CSEF, and the austenitic alloys listed in
<br /> Table 302.3.5, W shall be as follows: For Ti 5 Tr, W= 1.0. For Tcr< T,5 1,500°F, W= 1 —0.000909(T,—Tyr). If Ti exceeds the upper
<br /> temperature for which an allowable stress value is listed in Appendix A for the base metal,the value for W is the responsibility of the
<br /> designer.
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