Effect of Hot Fills on Tanks

[Curly]

I'm wondering if there are any tank gurus, technicians, or metalurgists out there who can comment on the impact of multiple "hot" fills on a steel tank. Seems to me that, over time, such fills could impact the structural integrity of a tank.

Has anyone seen any studies or articles? Had any personal experiences?

Thanks.

 

[parrothead600]

I'm not a metalurgist or technician, but I would think that in order to affect the tank's integrity the tank would have to be so hot that you wouldn't be able to handle it.

 

[pescador775]

"Hot"? What is that? If you mean "heat" then the Parrot man is correct. Figure about 800F sustained to damage the metal. If by "hot" you mean "fast", it could be a possible problem if you are over filling and fast filling in extreme low temps, 40 below zero F, especially if you strike the tank with a hammer. Otherwise, no problem, IMO. Why don't you send letters to PST, Worthington and Norris? You could end up being our resident expert.

 

[jimclarke]

When the tank cools its pressure will have dropped.
If it is at 60C when filled 200 bar and it cools off to 20C, the pressure will drop to 176 bar. There is a temptation to overfill to compensate!

 

[Curly]

I'm talking about the heat resulting from filling too fast -- it's become an issue at a local facility for some folks. I was wondering about the cumulative effect of hot fills on a tank over time. Granted, the hot fill cools and results in less air -- that's an inconvenience (and a ripoff). But do these fast, hot fills have an impact on the tank itself?

Maybe an e-mail to Worthington is in order. Thanks for the suggestion.

 

[knotical]

Here's one article:
http://www.psicylinders.com/library/Current/Fast Fill.htm

 

[CompuDude]

Here's one article:
http://www.psicylinders.com/library/Current/Fast Fill.htm

Holy cow, a 45 second fill to 4500 psi?!?! We should be so lucky! (If we have disposable tanks, that is...)

If I recall correctly, someone in the know on this board wrote that the fill pressures are designed to accomodate a 10% overfill, roughly, to allow for hot fills that cool to the proper pressure. (I also recall that the figure assumed 70 degree ambient temp... it could be lower hot weather) So a 3500 psi tank could be hot filled to 3850, and once it cools, it should settle down to the correct 3500 psi.

 

[Curly]

Here's one article:
http://www.psicylinders.com/library/Current/Fast Fill.htm

Excellent. Many thanks.

I've also submitted a query to Worthington, and will post whatever I hear back from them. My guess is that product liability concerns would prod them in the direction of conservatism. There is a sticker on the new tank that says it should not be stored above 125 F -- which is much cooler than most cars in the summer. But I'm talking about hot fills.

 

[Curly]

Okay -- within 30 minutes of posting a questions re: hot fills to the Worthington Industries site, I was called by an engineering manager.

Talk about customer service.

The bottom line: Hot fills do not jeopardize the structural integrity of a steel cylinder. They will, of course, result in a higher initial pressure that will drop when the tank cools, but they do not harm the tank itself. The Worthingtons are hydrostatically tested at 5250 psi, so even an overfill is well within the test pressure.

The cylinders are treated at 1180-1200 degrees F when produced, so a 150 degree temp from a fill is nothing to worry about.

Oh -- and the best part -- the engineer who designs and builds these tanks indicated that he's interested in getting certified. I encouraged him to do so ASAP and to grab a few of this own products.

 

[jeraldjcook]

Great info. I'm in the market for a couple of tanks and this might influence my decision. I wonder if the same is true of aluminum tanks as well.