maximum amount of time to complete a weld 4

[Downhand]

Do any of the North American codes state the minimum amount of weld that needs to be deposited on a pipe joint before it can be left overnight? As well, do any of the North American codes state a maximum amount of time that a weld can be left without being fully completed? Let's say a welder is eighty percent complete and an emergency comes up, can the weld be left for a few weeks before it is completed or is there a maximum amount of time that it can be left uncompleted before it must be cut out?

 

[racookpe1978]

If the pipe and joint and status are DOCUMENTED (no weld assumed complete that isn't) and if it is left in a safe condition) then no.

But a purge cannot be left running(for practical reasons) for even a few hours. Preheat cannot be left "on." Weld rods (GTAW) wires or FCAW spools cannot be unattended (rust and accountability.)

7018 SMAW wires cannot be left out of the oven for more than 4 hours.

There are many reasons you need to finish welds - some related to time. Most for practical reasons of construction ans accountability.

 

[stanweld]

Refer to ASME B31.1, 131.6 Interuption of Welding.

 

[ornerynorsk]

Rods and other coated fillers that are staged in the oven for use should also be consumed within a specified period. Overbaking degrades some fluxes and causes big problems.

 

[Downhand]

B31.3 330.2.4 states,"If welding is interrupted, the rate of cooling should be controlled or other means shall be used to prevent detrimental effects in the piping. The preheat specified in the welding procedure shall be applied before welding is resumed." Would it be correct to interpret this to mean a partially completed weld can be left for any amount of time as long as it is preheated to the appropriate temperature before welding is resumed?

What code states that rods in the oven should be consumed within a specified period?

 

[gtaw]

My experience has been that if the welder cannot complete at least 1/3 of the joint thickness before ceasing operations, it is best to wait until the next shift or consider double shifts. That isn't a code requirement, it is based on practical experience when welding heavy structural sections where preheat is required and the joint offers considerable restraint.

Best regards - Al

 

[Mr168]

Material type is also going to come into play. CSEF's should not be cooled and allowed to stand for prolonged periods of time prior to PWHT due to the risks of hydrogen embrittlement/cracking.

Downhand: AWS is one of them. It's not necessarily that they should be consumed within a window, but rather that they should be consumed or returned to the rod oven within that window, 4 hours being typical.

 

[Ron]

If preheat and post-heat are required, interruption is a problem. Otherwise, typically not.

 

[ornerynorsk]

Some rods cannot or should not be reconditioned once they have been out of the oven, as well.

 

[Downhand]

Which rods cannot be reconditioned once they have been out of the oven?

 

[ornerynorsk]

I'm thinking tropical where flux actually picks up dampness. E7018 is one of them, if the the flux has actually gotten wet or picked up dampness, they should not be used. I've been in climates where the welders should have been pulling the rods one at a time from the oven just prior to use because of the oppressive humidity. The 4 hour standard will absolutely not apply in situations like this. Think 100 degress F, 100% humidity, quick monsoon rain every morning and afternoon, no breeze or wind whatsoever. Sweating bullets with or without the helmet. We had rods shipped in the small cans and they did not get opened until just before use and right into the oven.