DOT-107A vs ASME Sect VIII

[RPRad]

Have a client who would like to use a vessel constructed to CFR 49-179.5 - DOT-107A (?) for High Pressure Helium Gas Storage (3000 psig)... his will be a static storage application and not for transport purposes. I am not at all familiar with vessels designed to this code, nor do I have a copy of this Code, so with respect to this application a few questions arise

1) The vessels that he has sourced are "used" (not sure how old but probably constructed after 2000), definitely not new construction. They will require a Canadian Registration Number in order to be utilized which means that in our Province, aside from a current nondestructive inspection, they must be evaluated with respect to the current edition of ASME Sect VIII. My recollection is that many of the DOT Codes permit the use of higher allowable stresses in order to reduce wall thickness and overall weight of the vessel.

What are the chances of a vessel constructed to this Code passing an ASME Section VIII design evaluation (min wall, joint config, joint efficiency, opening configuration etc)?

2) At this time I dont know what the vessel materials are, but are the material specifications typically utilized under DOT-107A permissible under ASME Sect VIII?

3) Are there any other issues (including those that might escape NDT) that should also be considered given that vessels could have been regularly used for transportation(I believe they were utilized for Helium gas storage)?

Thks

 

[vpl]

This won't completely answer your questions ... but I happened to have the US Code of Federal Regulations open when I read your post. So it was easy to look up the DOT requirement.

I have the feeling that the applicable section is 49 CFR Subpart F: SPECIFICATION FOR CRYOGENIC LIQUID TANK CAR TANKS AND SEAMLESS STEEL TANKS (CLASSES DOT-113 AND 107A)

Here's the link to CFR page

http://ecfr.gpoaccess.gov/cgi/t/tex...&tpl=/ecfrbrowse/Title49/49cfr179_main_02.tpl

Patricia Lougheed

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[RPRad]

Hi Patricia

Thank you very much for that link, has all the current information in one spot and makes it easier to distinguish between the different DOT constructions. I agree the 113 / 107A spec sounds like the vessels the client has described.

A cursory look appears to indicate that these vessels could be "light" with regard to wall thickness, when compared to ASME, for a given pressure and you would potentially have to pressure derate the vessels in order to use them, which effectively means a decrease in storage volume. It also appears that there could be some issues around end closures and openings, when compared to ASME.

Interesting that there isnt much limitation with regard to materials and for the most part they are specifying a medium plain carbon steel, although I see it does indicate that alloy steels can be utilized upon approval (whose I am not sure).

It also appears that the seller should be able to produce the Inspector form described in 179.500-18, which is essentially the DOT equivalent to an ASME U1A form, however it doesn't look like the vessels are required to have a nameplates, just stampings which correlate with the specification and some of the info in the Inspectors report.

All in all it appears that there could be several stumbling blocks to registering these vessels, although I guess it will depend on how the vessels were constructed and their current condition.

Thanks