PWHT Exemptions on A335 P9 attachment welds
PWHT Exemptions on A335 P9 attachment welds
(OP)
My vendor wants to claim an exemption to PWHT of some attachment clips to A335 P9 (P5C piping). (8-10% Cr) He is saying B31.3, Para 331.1.3 tells you what thicknesses to use with Table 331.1.1 with the end of that Para ending with "...except as follows:" where Para (b) states "...for attachment of external non-pressure parts such as lugs or other pipe supporting elements...heat treatment is required...except as follows: Para (2) "not required for P-No. 3,4,5, or 10A materials when weld throat thickness is ½ in. or less, regardless of base metal thickness..." Since these are lugs and since the pipe material is P-No. 5 it appears that heat treatment is not required per ASME B31.3.
What is confusing the issue -for me- is Table 331.1.1 "Requirements for Heat Treatment" indicates that for P5C (base material in question) ALL thickness require heat Treatment. Does anyone have a definitive explanation for this?
What is confusing the issue -for me- is Table 331.1.1 "Requirements for Heat Treatment" indicates that for P5C (base material in question) ALL thickness require heat Treatment. Does anyone have a definitive explanation for this?





RE: PWHT Exemptions on A335 P9 attachment welds
RE: PWHT Exemptions on A335 P9 attachment welds
RE: PWHT Exemptions on A335 P9 attachment welds
RE: PWHT Exemptions on A335 P9 attachment welds
The exception is not in conflict with Table 331.1.1.
I agree with your vendor. Your engineering dept's argument seems to be based on 331.1.3(b)(3), which is also OK.
RE: PWHT Exemptions on A335 P9 attachment welds
RE: PWHT Exemptions on A335 P9 attachment welds
Does this help ?
1•39. 1-40 B31.3 Interpretations No. I
Interpretation: 1•39
Subject:
Date Issued:
File:
331.3.6. Thickness Effect on Heat Treatment Requirements
April 24, 1981
1517
Question (1): In ANSI/ASME B31.3, is postweld heat treatment required for an NPS 2 or smaller
socket or seal weld if the fitting is A 182•F5, the pipe is A 335•P5, a 350°F preheat is used, and the fillet
weld size is less than 1/2: in.?
Reply (I): No, if the provisions of 331.3.6(b) (2) are met.
Question (2): Same, except the fitting is A 182•F5a?
Reply (2): Postweld heat treatment is required by 331.3.6(b) (2). Exceptions to this requirement are
in 331.1.1 and 331.3.6(b) (3).
Question (3): In ANSI/ASME B31.3, is postweld heat treatment required for an NPS 2 or smaller
socket or seal weld if the fitting is A 182•F5 or A 182•F5a, the pipe is A 335•P5, and the weld is made with
metal that is not air hardening?
Reply (3): No, provided the requirements of 331.3.6(b) (3) are met.
Regards,
Kiwi