Heat treated welds

bigtiller · Mar 2, 2016

Why would that be advantageous on an anhydrous tank? What does post-heating a weld do?

I ask because the Iowa legislature is considering a bill to require it on all anhydrous tanks made in the future.

Gary Fowler · Mar 2, 2016

Heat treating allows all the molecules to realign after welding which removes stress so it makes the steel stronger. In some steels heat treating makes the steel more resistant to corrosion also. This may not be just for the welds either, it could mean a furnace heat treatment for the whole vessel which is going to add a lot of cost to the vessels in the future if that is the case.

bigtiller · Mar 2, 2016

Thanks Gary, I've had enough high school science to understand that. These tanks are 1000 gallons so I am guessing it would be spot treated. Would there be an obvious sign of heat treating or do you think it be simply a certificate of some sort of proof of heat treatment?

bamboozled · Mar 2, 2016

Follow the money, I would assume that some senator's getting a kickback from a manufacturing facility that already is capable of such a procedure. Thus tossing it into the amendment...

Porkman · Mar 2, 2016

Exactly what I was thinking.

bamboozled said:
Follow the money, I would assume that some senator's getting a kickback from a manufacturing facility that already is capable of such a procedure. Thus tossing it into the amendment...

Arc weld · Mar 2, 2016

Usually only the really critical vessels get stress relieved and they do the whole vessel in large heat treating furnaces. They heat the vessel up around 1600 deg's if I recall and hold it at that temperature for a specified length of time and then slow cool it. Sometimes companies goof and after heat treating a vessel weld ladder clips or name plates on which negates the stress relieving. With have shop in Edmonton, Dacro Industries that has the largest heat treating furnace in N America. I imagine it's not cheap to heat it up. There's some pics in the link below. Some thick vessels can take more than 24 hours to cool off.

Dacro - Heat Treating Equipment

LD1 · Mar 3, 2016

bamboozled said:
Follow the money, I would assume that some senator's getting a kickback from a manufacturing facility that already is capable of such a procedure. Thus tossing it into the amendment...

That or in response to a recent incident.

Was there a recent accident involving weld failure on one of them tanks in Iowa?

bigtiller · Mar 3, 2016

LD1 said:
That or in response to a recent incident.

Was there a recent accident involving weld failure on one of them tanks in Iowa?

I don't think so, I think I probably would of read or heard about any accident of substance.

I am guessing the reason for the change is because they are probably made to the same specs. as a propane tank. Compared to a propane tank, anhydrous tanks get the "snot" beat out of them.

bamboozled · Mar 3, 2016

LD1 said:
That or in response to a recent incident.

Was there a recent accident involving weld failure on one of them tanks in Iowa?

I suppose this could also be possible. I don't know a whole lot about them but I assume they are not under high pressure, perhaps mounting tabs for the road chassis' are being ripped off during transport and thus causing spills or something...

aczlan · Mar 3, 2016

bamboozled said:
I suppose this could also be possible. I don't know a whole lot about them but I assume they are not under high pressure, perhaps mounting tabs for the road chassis' are being ripped off during transport and thus causing spills or something...

Ammonia is generally under 300PSI, but its as nasty as propane for cold burns (will cause frostbite) and a good lungful will kill you (or at least burn your lungs badly). Here is an example: