D1.1 Minimum Preheat and Interpass Temperature Requirements

By ESell Date 12-04-2013 15:01

MTR for base metal is a dual cert for API-5L-X42/X52. 1" wall thickness

X42 in table 3.2 is a category B.
X52 in table 3.2 is a category C.
Each having different preheat requirements

3.5.1 Base Metal/Thickness combinations. The minimum preheat or interpass temperature applied to a joint composed of base metals with different minimum preheats from Table 3.2 (based on Category and thickness) shall be the highest of these minimum preheats.

Because the material is dual certified, would I use Category B or Category C preheat requirements?

By jarsanb (***)

Date 12-04-2013 19:33

Little confused. Not sure if you are using API 5L materials for API work, and since API offers nil in supporting information you are looking to AWS D1.1 for preheat/interpass temp guidance OR if you are using API 5L materials for AWS D1.1 requirements. Probably the latter. API has addressed this issue through the inquiries section and also through "Guidleines for interpretation and Application of API 1104". The dual graded materials do confuse many inspectors/engineers. Not only are they in separate catagories as you mention within AWS but they are also in different groups in API 1104 requiring separate qualification testing for pocedures (the groups that is).

"For pipe that meets the requirements of more than one grade (i.e. pipe that is multi-graded or dual stenciled) it is not necessary to use a welding procedure that is qualified to the highest grade to which the pipe is certified. It is only necessary to use a welding procedure qualified for use on the grade for which the material will be used".

Basically, if your using it as X42 you can/should forget that it is also rated at X52 and Vise Versa.

By Milton Gravitt (***)

Date 12-04-2013 20:21

D1.1 says you go to the base metal with the highest preheat which one is the highest preheat B or C. But you might have deferent preheat in another welding code.

M.G.

By jarsanb (***)

Date 12-04-2013 20:52

slightly different issue. If you were welding an X42 to an X52, you'd be correct. This issue is something different if I understand the O.P. correctly. If you are welding this multiple grade pipe to the same multiple grade pipe...what do you treat the material as - X42 or X52? It meets both criteria. It may not be as simple as just saying - hey, why not just specify it as X52 and call it good. That could lead to unnecessary added expense.

By 803056

Date 12-04-2013 23:16 Edited 12-05-2013 01:19

D1.1 lists the minimum preheat temperature requirements.

I would favor the higher preheat requirements if it further mitigates the chance of delayed hydrogen cracking. To that end, the welding process and electrode can play a part in determining the preheat requirements. Regardless of the contractor's wishes, the Owner has the last say in whether the WPS is accepted or not.

Al