ASME B31.3 and Impact Testing for welds on A333 Grade 6

[Blizzardo]

Good Afternoon All,

I am posting this query as I'm struggling with determining impact test requirements for welds on A333 Grade 6 piping under the ASME B31.3 code of construction. The client has noted the design code of B31.3 and has specified that A333 Grade 6 piping is to be used. Minimum design temperature is listed as -46.5 deg C (-51.7 deg F). They have also noted that impact testing is required to -50 deg C (-58 deg F).

Questions;
Does the B31.3 Code demand weld impact tests at the above noted temperatures?

For the A333 steel, does this material fall under line #2 of column B within Table 323.2.2, or does this material fall under "other carbon steels" on line #3 of column B?

Considering the details provided by the client in so far as design temperature and material, is there a bonafide requirement to perform impact testing?

Thank you all for your assistance.

 

[mmmiscs]

you could refer to this thread hereby is its link

http://www.eng-tips.com/viewthread.cfm?qid=400384

 

[Blizzardo]

Thank you kindly for your response.

I did research all previous posts prior to posting my query. Though I did see this post, what I was looking for was something in the Code that would allow for the avoidance of impact testing. There is a notation in Column A of Table 323.2.2 - Section A-3 relating to the weld metal and HAZ which references Note (3) and (5) as exceptions. For Note (3) I recognize that I can defer impact testing where the design minimum temp is -29C (-20F) but at or above -104C (-155F) and the stress ratio defined in Fig. 323.2.2B does not exceed 0.3.

It would appear that the piping in question falls into the temperature range, though I am unclear in so far as how to calculate the stress ratio for the pipe in question. Is there anyone that could assist with pointing me in the right direction? My preference is to qualify that impact testing is not required by the Code if this is possible.

Thank you.

 

[DVWE]

Since your client has specified the minimum design temperature, as well as the temperature to which impact testing is to be performed, is there a reason you are working so diligently to get around the requirement?

A333 Gr 6 is commonly welded with WPSs qualified with impact testing. Given the minimum temperature listed in Table A-1 for this material, to me it would just be easier to proceed with impact testing.

 

[Blizzardo]

Understood.

There was an error made on our behalf whereby we proceeded with the work WITHOUT impact testing for the WPS. Essentially, the piping was welded-out with 6010/7018-1 in SMAW. We have since impact tested the piping in question and it does meet the minimum requirements of the Code for toughness values at the specified minimum design temperature. So, I now have a proven WPS complete with impact test results for 6010/7018-1 in SMAW, however...I am looking at all avenues to be able to support that the welds in question should be left as-is and avoid any rework, hence my queries above.

 

[DVWE]

I see. We've all been there, trust me.

I can't provide you with any insight on the stress ratio subject, and I don't know if this will help you out or not, but I'll throw it out there anyway.

If you performed welding with a WPS that was not qualified with impact testing, ASME Section IX allows you to add the supplementary essential variables per QW-401.1

Without knowing the full history of your predicament, with the above and the fact that you've already done the impact testing gives you a pretty strong position with your client in my opinion.

 

[Blizzardo]

Thank you kindly DVWE.

The impact testing came back sound and my welding engineer endorsed the new WPS...I was simply looking for anything additional that would support our position. I've even gone as far as looking at meta data for the region of installation to identify any periods of extreme cold that may have a negative impact on the installation. Looking back since 1965...the lowest recorded temp was -40C. The piping in question is also heat traced and insulated, so really it's way over-engineered. I'm not even certain why they have the -50C requirement, but it's there and we need to address the error.

Again, thank you for your assistance. I'll post the results of the outcome when the issue has been resolved.

 

[CWEng]

The problem with after-the-fact impact testing, is that presumably the heat input was not controlled during production, but with impact testing, keeping the heat input below that qualified is required. How can you verify he production heat input complied after the welding has already been completed? That is usually the biggest hurdle in these type of cases.

 

[metengr]

In some cases if the welder or welders that performed the original production welding with the original WPS can qualify with impact using the original WPS, I don't see a technical issue.

 

[Duwe6]

concur with metengr

 

[DekDee]

I agree with CWEng.
Very hard to confirm what has gone on in production in the field or workshop and then compare with a "staged" mock up in a controlled environment after the fact.
As an example, I caught a couple of welders(as the cients rep) "blocking out" (excessive weaving to fill the prep in one run) on large bore super duplex piping.
They were then running stringers on the capping run so the whole joint looked as if it had been welded as per the WPS (100% stringers).
Obviously heat input was blown out of the water but if they had not been "caught in the act" nobody would have been any the wiser.
Letting the client choose one random joint to be cut out and impact tested would be my preferred option (as a client).
Then it would be a case of cross your fingers and hope for the best,
Cheers,
DD

 

[metengr]

Even a single weld joint out of many may not prove anything simply because good welders followed an WPS that resulted in acceptable impact results after a second weld coupon qualification. I thought about destructive testing but having been in this situation before as a client, I went the way of a mock-up under controlled conditions and it worked. This is really a case-by-case situation based on design review and analysis. If by contract or specification the work required or specified impact qualification, cut them all out and do it again.