Rail tanker cars converted to pressure vessels

[Tweetybird]

Have not run across this before. Since the old adage is that there is no stupid question, here goes.
We have a client with several rail car tankers that have been retrofitted or I should say undercarriage removed and are now being used as horizontal pressure vessels. (low pressure 15-20 psi)
They want them inspected but I am not sure what code to use. API 510?

 

[dhengr]

Tweetybird:
They will have been designed and built to Association of American Railroads (AAR) Specs. and Stds. See if you can track down who built them and when they were built, who they were built for, who owned them, this would be a helpful starting point. If they weren’t painted over, most of this info. should be stenciled on the side of the car body. Otherwise, your client’s purchase records of the cars might be helpful. This will pin down what version of the AAR Specs. they were designed under. Then you will need a current conditions inspection, which it sounds like you intend to do. They are designed and built to far more stringent loading conditions, due to the railroad handling environment, than they will ever see sitting on a couple of saddles (foundations) at the locations where the truck center plates and side bearings (truck centers) were located. I wouldn’t put fixed saddles anyplace else. And, they would have been designed to the same environmental conditions (temperature ranges, pressure fluctuations, etc.) as they would see just sitting in place, as storage units.

Fill in a few more of the details, I may be able to be of some help, although I didn’t have that much to do with tank cars. They are pretty much a specialty in terms of design and manufacturing. Certainly, they were designed as pressure vessels, but not likely to today’s ASME Pressure Vessel Stds., some of which you may have to work around today. Off the top of my head I don’t know what pressure ranges were being used. It is pretty impressive to watch one of them implode when they are not vented during unloading.

 

[Tweetybird]

thanks, that at least gives me a starting point

 

[JStephen]

Make sure what they're after with the inspection. Specifically, make sure they're not planning to change a random undocumented tank into an ASME pressure vessel by way of your inspection.

It occurs to me that the normal tank-car configuration would probably handle 15-20 psi whether it was designed for it or not, which would leave the possibility that they weren't designed for pressure, period.

 

[racookpe1978]

Knowing the explicit pressure that these would be "designed" for use as storage vessels is critical: the rules change at 15 psig (one atmosphere) and what might be adequate at 14.5 psig would be illegal, immoral, unethical and fattening at 15.5 psig.

 

[EdStainless]

It may not be in your scope, but the saddles are critical.
They must be at the correct locations, provide uniform well distributed support, allow for some motion, and have protection against external corrosion.
I recall a set of tank cars that were used as a vacuum reservoir (storing vacuum?). One of them rusted significantly because of trapped water at one of the support saddles. It thinned enough that one day it buckled and collapsed, pulling the piping and causing a lot of damage.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[MJCronin]

I think that there may be a local regulation issue here.

Railcar containers must meet DOT standards which may or may not reference/borrow the rules of ASME VIII.

The state regulations I am familiar with for stationary storage tanks and pressure vessels only reference ASME-VIII, API 650/620, UL standards etc.

The state or local regulator may or may not sign off on the acceptability of these tanks based on the letter of the law that he has to work with.

I am not saying that this is a bad idea, nor do I think that this will be unsafe...... however,

You may find yourself in a crack between two sets of rules once the railcar undercarriage ( trucks ?) are removed.....

Anyone else on this issue ?

Does anyone else know of this being done before ?

MJCronin
Sr. Process Engineer

 

[StoneCold]

Tweetybird

My current employer wanted to make used tank cars into flammable liquid storage tanks. We were unable to do so due to the fact that they are built to DOT regulations not ASME regulations and the fire department would not allow the exception. You might have better luck if they are not storing flammable liquid in them.

Regards
StoneCold

 

[JStephen]

What we've run into is that people have some random old undocumented tank, and want to do an API-653 inspection and somehow change it into an API-650 tank to meet fire codes or whatever; my point was to make sure you don't have similar unrealistic expectations there.

 

[dhengr]

A good quality used tank car would seem to be a perfect fit for a storage tank at a wellhead. They can’t be worse than some used vert. tank delivered on a lowboy and standing on an aggregate bed/foundation. They could be delivered on their own truck wheels, with railcar trucks removed. A kingpin/fifth wheel mating system on the front end and a rubber tired wheel set on the rear. With the proper attention to detail, single end crane picks would move the tank from the truck to some flat saddles in the field. The trick is, finding a group of tank cars of a good age which has a good pedigree/historical record, so that the tank cars are not a major issue from the start. I assume this is not a high pressure situation, and their cap’y. and insulation might allow a whole different mode of unloading equipment and time cycle, maybe good, maybe not.