Referee Standards in ASTM A691 & B31.1 1

[ravera]

We've recently purchased 30" X .812" A691 1/1/4 Crome pipe from a European producer. We're now finding that the pipe should have been manufacturered to the B31.1 requirements which have a slightly higher tempering temperature than is required by the ASTM spec--details as follows:

Post weld temp requirements:
B31.3 requires: 704-746 deg C
A691 requires: 590-745 deg C
The actual HT applied to the pipe was 650 Deg C

We've simulated the post weld re-heattreatment of pipe samples within the required HT range in a lab furnace at 715 degrees C with the following results:

UTS:

Sample 1-Transverse Weld: 540 MPA (515 MPA min required- for "Normalized" Plate)
Sample 2- " 536 "

Base Metal:
Sample 1- 504 "
Sample 2- 507 "
Sample 3- 497 "
Sample 4- 506 "

YS:
Base Metal:
Sample 1- 304 (310 MPA Min required)
Sample 2- 306 "

etc. etc.

QUESTION:
1) Is there a referee standard in B31.3 or A691 (A387 for 1 1/4% Cr plate) that would provide some allowance on the UTS and YS?

2) Is there a referee standard on the temperatures required by B31.1?

Thanks for your help--


Regards
RAvera

 

[metengr]

ravera;
ASME B31 Pressure Piping Codes do not provide specific material fabrication tempering requirements, when material is furnished under a recognized international material standard specification like ASTM or ASME.

Second, I reviewed ASME SA-691, the 1.25% Cr- 1/2% Mo alloy steel plate is supplied under SA-387. SA-387 Grade 11 plate after austenitizing is tempered at 620 deg C-745 deg C. The recommended PWHT for welded plate fabrication under SA-691 is 540 deg C - 745 deg C. The required mechanical properties have to meet the SA-387 plate specification.

For butt welding in the field, ASME B31.3 recommends a PWHT temperature range of 704 deg C to 746 deg C for P-No 4 material.

 

[ravera]

Thanks metengr. Upon further research I see that the B31.3 HT requirements have specifically been imposed for the longitudinal weld seam by the E&C---KBR. Don't guess I have a way to circumvent the issue since it's imposed by the client.

 

[metengr]

ravera;
This raises an even more interesting issue regarding seam welded piping and PWHT. Your client should be aware that a N&T (normalize and temper) heat treatment is the best approach for any Cr-Mo long seam welded piping in elevated temperature service.

 

[ravera]

Metengr,
The pipe will be provided in the N&T condition. The issue specifically relates to the tempering temp--B31.3 (704-746) VS A691 (590-745). The 650 that has been applied to the tube is not acceptable.


Pls Also note: the 540 mentioned in the orignal post was a typo!

Tks,