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test coupon wall thickness and bevel preparation

test coupon wall thickness and bevel preparation

test coupon wall thickness and bevel preparation

I am working on WPS and PQR for canister lid welding and have some questions about the test coupon preparation. The wall thickness of the canister structure lid is 3" wall thickness (which will weld to the outer shell of the canister) and have a 30° bevel angle with 1.25" deep. But the weld penetration requirement is 1". My questions are:

1. Base on ASME IX,QW-451, I will need a 1.5" test coupon to qualify the 3" thickness base metal, is that right? or the base metal thickness can be treated as 1.25" and I can use an 5/8" thick test coupon?

2. If I use 1.5" thick test coupon, should I prepare the bevel as deep as 1.5" or I can make 1.25" deep bevel?

I really hope I can get some help on this and your reply is highly appreciated.

RE: test coupon wall thickness and bevel preparation

You don't mention the base metals for the canister and lid or welding process. However, I would use the 1.5" thick base metal coupon and run a groove weld 1.5" in depth.

Why? Two reasons, the first is you need the 1.5" coupon thickness to take credit for the 3" base metal thickness for procedure qualification. Using that 1.5" thickness coupon takes you all the way to 8" thickness.

Second comment, is the weld joint and simulating the groove depth for this type of job is important in going to 1.5" groove depth, despite the fact you only need 1.25" in groove depth. I know this is added welding, but again going the route of 1.5" groove depth affords maximum flexibility for other jobs using this procedure. Do you need to run impacts if this is carbon steel or is this stainless steel?

RE: test coupon wall thickness and bevel preparation

Thanks for your time and comments, Metengr. I am new for using the code and I really appreciate your help.

The process is automatic TIG welding. Material for the canister is 304 stainless steel and impact test is not required. The production parts for the canister lid has 45° and 30° compound bevel angle (totally 1.25" deep). The weld is 1G circular weld.I have more questions on the tested coupon:

1. If I also use the same setup as the production weld and weld two tested plates in a circular(65" diameter)in 1G. Will this work for tension test and bend test? since the centerline of the weld is not completely vertical to the test coupon. I hope I can be understood about this question.
2. May I just use feather edge and put a backing bar with 1/8 root open for the test coupon?

Thanks in advance.

RE: test coupon wall thickness and bevel preparation

I would obtain a section of 16" Sch 160 (1.593" wall), TP 304 stainless steel pipe and machine a coupon for groove weld procedure qualification in the 1G rotated position (see Qw-461.3) in accordance with ASME Section IX. Make sure you purchase this pipe to an ASME SA specification because you need traceability for all welding procedure qualification.

You can machine the compound bevel and insert a backing bar for this coupon, which would be welding with backing. Once completed, you will have the material necessary to perform bend and tensile testing using this pipe coupon versus trying to weld a production piece and going the route you mentioned above.

Do you know how to generate a WPS and PQR?

RE: test coupon wall thickness and bevel preparation

Thanks again for your time and reply.
I do not have positioner to rotate the pipe for 1G welding on pipe. And the equipment I have for doing the test is the one will be used on production.

We have some standard format for WPS and PQR, but for this job, we also need to provide welding technical data sheet. Does that mean I have to use the same joint design as in production weld?

RE: test coupon wall thickness and bevel preparation

No. I would recommend you review Section IX, Article 2, QW-256 that lists all of the essential welding variables for procedure qualification using the GTAW process. These variables must be addressed to qualify this procedure, AND any change in the variables would require re-qualification of this welding procedure.

Do you have any welding engineers or QC or ANI personnel experienced in reviewing welding procedures in your organization or at your facility that could help you? This looks to me to be an important job.

RE: test coupon wall thickness and bevel preparation

Thanks for all your information, metengr.

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