Cryogenic Welding Procedures and Impact Test Requirements per B31.1

[RobsVette]

Good Evening Everyone,

I am embarking upon my first attempt at making welding procedures for cryogenic service piping down to -320F in accordance with b31.3.

I have never done this before and would appreciate some guidance on how to conduct the charpy impact test. The piping to be welded is all 4" to 12" std wall stainless steel. We have prepared a weld coupon of .375" 304L stainless steel welded with GTAW to qualify the procedure. I am going to have a testing company perform the testing but they want to know what they of testing to perform and how to make the notch.

I have thus far found the table 323.3.1, which seems in indicate one round of tests is needed for each welding procedure (ie... GTAW on SS vs. GTAW/SMAW on SS.) It then indicates one test piece where you can make 3 specimens from the weld and 3 specimens for the HAZ.

The thickness is called out as T/2 to T+1/4" which should cover my range.

The plate we welded is 12" long. So making 6 specimens should be fine. Per 323.3.3, it seems that the tests are supposed to use 10mm square bars. However, my .375" plate will be just shy of that.

Also, how deep does the notch need to be? A370 again seems to have some pretty specific notch dimenions, but it is unclear to me where to find any guidance on this?

As I am sure you can tell, I am new to this and trying to get through B31.3 and ASTM A370 and could use some guidinace on how the actual impact testing is conducted.

Thanks for any help.
Rob

 

[weldstan]

You have the wrong test lab. It is clear in B31.3 and ASME IX how impact testing is to be performed and what must be recorded (lateral expansion).

 

[weldstan]

Per B31.3 only the weld metal need be tested with minimum lateral expansion measured and recorded for austenitic stainless steels at -320F

 

[weldstan]

One final thought, qualify your WPS on 3/8" plate welded in the 3G position with upward progression. I've done this for all of our -320F applications using 304(L) and 316(L) stainless steels, most recently for LNG import and export facilities.