Rapid Pressurization of Pressure Vessel

[WorkerB]

I'm evaluating the rapid pressurization of an ASME section VIII pressure vessel (Division 1) from a vacuum to about 700 psig in under one second. The code maximum allowable working pressure (MAWP) is 750 psig. I'm concerned that this rapid pressurization may cause micro-crack propagation and eventual failure, even though the MAWP isn't exceeded.

Any thoughts on this?

The gas is hydrogen.

Thanks.

 

[JoeTank]

You have not mentioned temperature, but with the storage of hydrogen gas I would always be concerved about hydogen blistering and embrittlement.

Regarding the short time over which this vessel is pressurized, I am assuming that you are concerned about fatique and possibly dynamics.

The fatigue issue will depend on the magnitude of stress per cycle and the number of cycles. It looks to me like you have essential a full stress cycle (700psi vs MAWP of 750psi). ASME VIII, Div 2 has provisions for the analysis.

The dynamic issue will be influenced by the frequency of vibration of the vessel vs. the speed over which the load is applied. I suspect that you will find that the one second ramp-up of pressure is actually quite long compared to the vessel's first period of vibration. As such, dynamics of the load may not have a great influence on the vessel shell. However, that does not mean that some other components such a piping might not be a problem. I may have greatly simplfied your problem here, but there is very little info provided to work with in your post.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[prex]

Adding to SteveBraunes's comments, I would also worry about temperatures: gas temperature will go down in the capacity that is feeding it, and will go up in your vessel. As you don't give the volume of your vessel, I can't guess whether your 1 sec transient is fast or not, but please check this issue: there have been people died in accidents when they tried to transfer gas from one bottle to another.

prex

http://www.xcalcs.com

Online tools for structural design

 

[jay165]

Check this post on H2 service considerations:

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http://www.tipmaster.com/includes/refinfo.cfm?w=450&h=350')

I'm curious as to what your application is. Sounds almost like a detonation.

 

[zdas04]

The size of the vessel only affects the distance that the shards could be spread if you make a little mistake (it also affects the BTU's available to transfer heat to the vessel). This application is over 45 compression ratios (at 0 psig, it wouldn't take much vacuum to make it 60 ratios). Heat of compression of taking 60F gas from an absolute pressure of 22 in-Hg to 700 psig results in gas temperatures over 1,200F (using k=1.4 for hydrogen).

Since people have been keeping statistics on industrial accidents (early 1920's) the Oil & Gas industry has averaged one fatality per month due to activities like this. If there is any chance of there being air in the vessel and you're injecting hydrogen at that rate, then you've created a really effective bomb.

Even with zero chance of air, the materials issues of temperature transients of this magnitude are a pretty big thing.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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