Blast resistant wall design 3

[GerhardSA]

Hi All,

I have to design a 4m high blast wall to resist the explosion of 3- 2m dia. x 4m high hydrogen storage silos. The wall is about 4m from the silos.

I am finding it difficult to determine the blast pressure on the wall. It is not possible for me to obtain the relevant design loads (the code we use does not provide for this and it is hard to obtain american military codes).

Can anyone give me a ballpark figure? (8KN/m2 ??)
From what I can gather it is not an exact science with many variables.

Alternatively I have gotten hold of actual test data that I will scale. I am just not sure of the relationship between volume of gas and blast pressure. Does it increase linearly or exponentially?

Any guidance appreciated.

 

[dik]

I'm not the expert in this area, but the blast pressure from three tanks that size would be substantial. 8 kN/m2 is too low a value; this is less than 200 psf. I would expect pressures 5 times this magnitude... You might be able to browse the FEMA documents or similar. Is it possible to relocate the tanks? Sorry I can't be more helpful.

Dik

 

[steellion]

TM5-1300 is the old standard for blast resistance. I believe it is still publicly available. If you are recognized as a government contractor performing military design work, you can get blast design software and FOUO UFC's. If you're not a govt. contractor, I think the TM5 is your best bet.

 

[GerhardSA]

thanks guys,

FEMA documents had nothing relative. But I downloaded the TM5-1300, very helpful in general terms, but still not real in depth about gas explosions and specifically hydrogen explosions, as I read it is not advisable to equate gas explosions to equivalent TNT explosions, the general design procedure in the TM5-1300.

dik, not possible to relocate the tanks they are part of a small hydrogen plant on a big coal power plant. Relocating my building is also not possible due to financial constraints of extending some expensive pipes.

 

[JLNJ]

Hire a specialist to determine the pressure and time components. They can also probably help you with the dynamic design.

 

[JStephen]

By explosion, do you just mean the tanks rupturing, as from overfill condition?

The maximum force on the wall could be due to pieces of tank hitting it, rather than gas pressure.

 

[beton1]

Try

http://www.wbdg.org/resources/env_blast.php.

It will give you a basic understanding and links to other resources, among them (I believe)TM5-1300, mentioned in another reply.

Tricky subject. We used explosion panels (pop off at 20 psf if I remember correctly) to 'channel/control' explosion from within a mill with fine dust (produced from milling wheat). Walls were obviously stiffened & reinforced, the panels allowed a pressure relief system.
Just another perspective.You can't always contain it, so this is one alternate: don't know if you can apply it here.

Hope some of this helps.

 

[msquared48]

Evefr see a toilet interact with an M100?

Mike McCann
MMC Engineering

 

[GerhardSA]

Afraid there is not too many specialists here, so that might take too much time.

Jstephen: The wall will be 14m long and 6m high and the tanks is only about 4m away so I think the worst case is the actual explosion of the hydrogen tanks. The problem is also explosion not rupture as we are bringing a lot of new electrical work, including transforer, into the proximity of the tanks.

beton1: helpful site. I suggested containing the plant and silos but this was deemed too expensive so I am only protecting the new building.

Am building a retaining wall type structure between the new building and the hydrogen towers.

 

[JStephen]

I was curious about the design condition because hydrogen in a pressure vessel isn't going to explode by itself. The condition with sparks outside a tank is a concern with atmospheric tanks storing flammable liquids, where you can then have a fuel-air mixture in the vapor space at the top of the tank, but that's not how you normally store hydrogen.

 

[GerhardSA]

JStephen,

I know almost nothing about hydrogen storage. It would be very helpful if you could enlighten me a bit.

There are hydrogen storage on site and the client requested that a blast resistant wall be constructed to minimise damage if an explosion occurs.
The hydrogen Silos were constructed around 1980.

I attach a foto of the tanks.

 

[lsmfse]

Gerhard, we are always given the pressure and duration of blast by the client. Attached is a page from "Design of Blast Resistant Buildings in Petrochemical Facilities".
As you can read, there are no specific industry standards.

 

[bmagdalena]

here is more literature for blast design:

Mays, G. C. and Smith, P. D., Eds. Blast Effects on Buildings: Design of Buildings to Optimize Resistance
to Blast Loading. Reston, VA: American Society of Civil Engineers (ASCE), 1995.

Task Committee on Blast Resistant Design, Petrochemical Committee of the Energy Division. Design of
Blast Resistant Buildings in Petrochemical Facilities. Reston, VA: American Society of Civil Engineers
(ASCE), 1997.

Design of Structures to Resist Nuclear Weapons Effects. ASCE Manuals and Reports, No. 42. Reston, VA:
American Society of Civil Engineers (ASCE), 1985.

Conrath, E. J., Krauthammer, T., Marchand, K. A. and Mlakar, P.F., Eds. Structural Design for Physical
Security: State of the Practice, Committee Report. Reston, VA: American Society of Civil Engineers
(ASCE), 1999.

Cooper, P. W. Explosives Engineering. Wiley-VCH, 1997.
Baker, W. E., Cox, P. A., Westine, P. S., Kulesz, J. J. and Strelow, R. A. Explosion Hazards and Evaluation.
Elsevier Scientific Publishing Co., 1983.

Smith, P. D. and Hetherington, J.G. Blast and Ballistic Loading of Structures. Butterworth-Heinemann
Ltd, 1994.

Protective Technology Center,

http://www.ptc.psu.edu

 

[JStephen]

I thought I'd wait and see what else showed up on this thread. (And I'm not an expert on hydrogen storage, either.)

It seems to me that you have two issues here: First, to find the effects of an explosion; secondly, to design the structure or wall to resist it. The problem is that you don't have the first part, which leaves you without a basis for the design in the second part.

Some of the responses above indicate that the owners have furnished the information for the first part, and perhaps that comes out of the chemistry or chemical engineering end of things.

 

[JLNJ]

Firms such as Baker and ABS take the data from the blast source and give you things such as side-on pressure and duration on which to base your design. Seek out their help.