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Up Topic Welding Industry / Inspection & Qualification / Time Between Passes
- - By Joey (***) Date 05-12-2016 07:58
Hi, need you opinion on welding procedure qualification test.

A CWI was called to conduct the welding procedure qualification test based on D1.1 or ASME IX for SMAW process & A36 material.
The entire welding of test coupon is estimated to complete in less than 3hrs without break time.
If the welder wanted to stop in the mid of welding for an hour lunch break before completing the entire welding, my questions are:-

1. Will you allow the welding to stop? If Yes, will you ask the contractor to revise the WPS and indicate the maximum time between completion of weld bead and the start of the next beads? Again if Yes, what the welder must do on uncompleted weld before and after taking his break?

2. If you will not allow the break time, why?

3. Why increase in maximum time between passes constitute essential variable in some code?

Thank you
Parent - - By jarsanb (***) Date 05-13-2016 12:35
1. Depends on whether it's an essential variable or not - codes/standards differ on this issue. Essential then no. Non-essential, with appropriate people involved, documentation of deviation, revision at least in process if approved and communicated. What must the welder do? Often this is covered in the procedure or specification. Requirements may include that the welder must reheat the joint to a specified minimum temp. Were there any preheat requirements to begin with? Those may be applicable as well. How much thickness to be deposited before welding is delayed may also be an issue. Joint restraint, alignment stresses may be factors - material type and welding process/electrode selection as well.

2. Production welding or during the WPS qualification? Assuming there is documented instruction such as in the written WPS, from an inspectors perspective I would follow what the requirements are, if any. During qualification, this may be an opportunity to document the delay in weld passes and include that into the WPS if all factors are weighed and are deemed reasonable.

3. Cracking. It's one way to prevent cracking. When all the factors are considered for certain joints, conditions, welding variables ect...strict criteria may not be necessary for every situation. In either case, strict criteria or not, this should addressed during the qualification process when required. If you say for example, time between this pass and that pass can be 72 hrs or unlimited but the PQR has documented only a couple of minutes, how would you know this delay is adequate? We're talking multi-pass welds here. So, probably some things > than .500 wall. Accelerated cooling and other issues come into the picture. Have you increased the chances for hydrogen cracking? What about stresses? If welding was delayed, was NDT involved to verify quality before welding resumes? Not all situations have high risk factors. But some do. Address those.
Parent - - By Joey (***) Date 05-16-2016 00:39
Totally agree:smile: thanks
Parent - - By js55 (*****) Date 05-16-2016 12:30
API 1104 is the only Standard/Code I know of that has the time limitation as a variable. And this only applies between the first and second pass. The logic is clear when one understands how pipelines work; the progression of the welders along the line.
Parent - - By jarsanb (***) Date 05-16-2016 17:23
Time between root bead and start of the second bead is an essential variable. Maximum time between the second bead and the start of  other beads is non-essential. But SHALL be designated per Procedures missing this information are often issued a notice of probable violation. This I have first hand knowledge of. I missed this on some contractor submitted procedures recently where there were mandatory preheat requirements anyway. They had the root to hot, just nothing for subsequent passes. They do now...
Parent - - By js55 (*****) Date 05-16-2016 19:09
However, being a nonessential variable you can essentially establish this maximum as you wish.
Parent - By Joey (***) Date 05-17-2016 03:59
Hi js, the CWI is charging based on hourly rate, the longer he stay in the workshop, the more $$$ he get:lol:
But if the CWI is not paid during the welder's break time, he will not allow the break and welding must continue till completion:lol:

I remeber an Inspector representing the owner who came to witness the welding procedure test, he sarcastically argued with the fabricator....he said if you're saying that it is non essential variable to have a break time, then after the hot pass, you can take a long break and continue tomorrow...I will go back to hotel and come back tomorrow:twisted::twisted::yell:
Up Topic Welding Industry / Inspection & Qualification / Time Between Passes

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