Any metallurgist in the group?

Odawgp

Been awhile since my last post, I don't spend much time in the office these days.

We have been contracted to weld some well casing 24" dia. Some of it is 316ss. A common question that comes up every time we get ready to drop classing is weather or not quenching will cause the weld to fracture.

MudderChuck

Take two lengths of pipe, lay them on four saw horses with the weld in the middle, weld and quench, watch the far end of the pipe.

IMO they have been trying to scientifically gauge stress for ever, while stress relief seems to be more art than science.

Quenching is a bad idea, not so much because it makes SS brittle, it doesn't like it does steel. But it has to cause stress as the heated area is unevenly cooled.

Slowly cooling, as evenly as possible, is likely the better technique.

Most stainless, other than the special blends, bleed heat away from the weld quickly anyway and along the entire length of the pipe.

The failure rate for patch welds is above 50%, IMO due to heat induced stress and uneven cooling.

The trick is to weld at the lowest practical temperature, less heat stress, less chance of changing the properties of the SS and making it prone to oxidation.

I'm not a metallurgist, other than what I learned in school decades ago, just some old fart who has welded a lot of pipe.

Warbirds

If its important get a certified weld engineer from the AWS to stamp off on that drawing before you do anything.

I brought one to England for 2 weeks once and he turned a $60 part into a $600 part but the reliability in the material was worth it.

woodhog

I haven't welded much, butI have laid a lot of pipe.

MG1890

Quenching from what temperature? That pipe is going to suck the heat out of the weld very fast. Weld it & wait 2 minutes... you will be cool enough that quenching won't bother it.

Odawgp

after welding it we be 300+ 20 mins with ambient temps being in the 40's it will drop to 160-200 deg. we start out dunking them at 200 and as the weight starts to add up we wait until it is below 160. the last 10 joints will be holding 100k plus so we wait a little longer for it to cool. The drill solution is probably about air temp as it is being circulated from the ground to the surface and back while we case the well. (As with anything everyone wants it done faster but we cant find anyone that can say one way or the other)

here are a few pics from the last casing run. 1500+ ft 130,000lbs. The screen manufacture says that these water wells are the largest ever cased with this type of stainless steel screen in the world.







It was a gusher at 1800gpm


custom fabricated cap that allowed them to pull off of it