Long runs purging advice

Date 09-29-2010 17:59

We are putting the final touches on about 2000' of 6" stainless schedule 40 open butt, fuel carrier line (JP8 Jet Fuel) anyway this is 100% X-RAY job we have shot 100% to date, the purging time is killing us.

We used Dams for the fabrication of the straights etc, I hate to use Solarflux but won't rule that out not sure that would work on open butt, We haven't used that product before any advice on this product would be appreciated.

Something we are considering but I want advice from the experts first is doing a pre-purge first blowing it out using Nitrogen once we get the oxygen out then before welding drop the CFH and introduce the Argon.

Thanks,

PI

By 3.2 Inspector (***)

Date 09-30-2010 13:43

Good question.

If you purge with Nitrogen first and later replace it with Argon, how would you know that all the Nitrogen has been replaced with pure Argon?
Since you mention Argon, I guess your WPS has that listed as purge gas.

I would experiment with rice paper as already mentioned in this thread.

Not to sound rude, but this should had been considered at an early stage of construction. (maybe you did and this is the only option)

3.2

By andrewsullivan9 (*)

Date 09-29-2010 22:57

I am no expert on this subject however there is a purge which works more quickly than pure argon if i remember correctly it is a 5 percent hydrogen purge,someone correct me if im wrong, the theory is tht when you start welding the hydrogen burns away all the oxygen therefore getting you the required oxygen level more quickly, all butts ive done in the past have been with 99.9 percent argon so im not familar with this method personally but i have heard about this other mix before

By JeremyW83 (***)

Date 09-30-2010 01:09

I've done long runs purging completely with nitrogen. I have also done butt welds with solarflux.

By scrappywelds (***)

Date 09-30-2010 01:25 Edited 09-30-2010 01:28

Well there is using purge dams on both sides of the joint and purging through the fit. Put all the root in except for a small hole for a football needle to purge through. Puy in most of the hotpass, then pull ouot the needle fill in the hole then imedately back up and do the rest of the hotpass. There is the solarflux option ofcourse. There is also flux coated filler rod and flux cored filler rod. I have had passed x-ray with all of them. probably best bet is to bring in a tanker truck with nitrogen and one of those super flowmeter like pushing 200 or 300 psi. This is the option we used on a big natural gas line system with good success. Best advice for solarflux is not to mix with water use denatured alcohol. Mix it in two different batches, one thin and one thick. Apply thin layer to both insides of joint, then the thick layer on top of that. Good luck.

By PipeIt

Date 09-30-2010 10:14

Did they pass X-ray?