high pressure testing query

[alrsmith]

Hi,
I have recently begun to work for a company which overhauls parts from oil exploration/drilling rigs.

As well as many other things this involves pressure up to 23,000psi. Water is used in the testing procedures. Obviously with such high pressures safety is a big concern. Some of the volumes being pressurized tend to be large therefore if something goes wrong then parts tend to be blown off at high speed. We already use a pit for testing purposes but thick + heavy safety shielding may be introduced in the near future.

It has been suggested that the volume being pressurized be reduced by inserting something within the cavity. This would reduce the ‘explosive’ power of any fittings blown off from a failure and hence the thickness of any extra shielding needed.
Instead of using solid metal cylinders my boss has asked me if it would be feasible to use pipes filled with concrete as a cheap alternative.

I’m not sure if there any quick calculations which would let me know if concrete would be viable. If there are any other factors that should be taken into consideration I would be interested to know.

Any help/suggestions would be greatly appreciated.

dave

 

[unclesyd]

I have to agree with you that you can generate a missile at this pressure. Been there and done that.

I have never seen concrete used for this pressure range. I have seen brick used at around 15,000 psig and they fractured.

What are the volumes you are concerned with?
Is this the design pressure or testing pressure?
What is the test fluid?

If the volume isn't excessive I would use Al solid cylinders.

 

[alrsmith]

1) off the top of my head, I'm not entirely sure of the exact volumes being tested (I will find out though). As equipment from several different companies is tested and there is a wide variety it does change from case to case (which would of course mean that if solid metal was being used we would probably need many different sizes adding to costs).
However, of some of the bigger parts, such as blow out preventers (BOP's), I would estimate in the region of 1 m^2 give or take. (Another reason for introducing these measures is that the (oldish) pumps tend to take a while to pressurize these volumes fully, there are usually several similar tests conducted, thus having less volume would reduce time costs).

2) These are the testing pressures, they are in the region of 1.5 times the working pressure.

3) The test fluid is water.


thanks again for your time.
dave

Ps - Before my time, there were failures which caused parts weighing more than a tonne to be ejected through walls/roof and land some distance away. Hence the test pit and now the extra safety measures.

 

[zdas04]

airsmith,
I think you are on the right track. While bricks would crumble, steel pipe filled with concrete (and vented) should stand up very well. I would get the biggest pipe that I could fit into the vessel, put on and end cap, fill it with concrete, and put a vented cap on the other end. Make sure you have a retreival loop on both ends so that you can fish it out.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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