Impregnation Of High Pressure Castings

Does anyone have any experience with impregnating steel castings used in high pressure applications?

I have a cast steel housing that is used in the transportation of natural gas and every 4th or 5th housing leaks when we do a pneumatic test. We close the housing place it under water and apply compressed air into the system to look for leaks. The MAOP of this part is 3000 psi.

We also have aluminum versions of this product whose MAOP is 300 PSI. We do impregnate these with a vacuum system. Because of the elevated pressures on the steel version, our company is a bit cincerned about using the impregnated housings.

I have impregnated a steel housing that leaked and when retested, th eleak was no longer observed. To see where the impregnation mght fail, I pressure tested the housing to 10,000 psi. There was no change. My equipment (10000 psi hydrostatic test) couldnt go any higher so I had to stop.

Im confident that the impregnation will do what we need it to do, but I cannot get the manufacturer to say that the resin will work for our application. They say we have to test it for ourselves and then make a decision. I just wanted to know if anyone else is doing something like this?

Would love to hear your thoughts and replies!

Thanks,

Adam

What exactly do you mean by "impregnating steel castings", never heard of that before..

When I read your testing description, it sounds like casting porosity testing.

See: [url]http://www.rastgar.com/rec/papers/Porosity%20in%20Castings.pdf[/url]

Adam see PM...

Hi Kelly,

Thanks for the link. Thats a good paper.


We are testing for porosity and any other leak that might be in the system (failed o-ring, bad plugs, improperly assembled NPT fittings, ....etc.) but most (95%) of our failures on this product are coming from porosity in the actual casting which causes champagne-like bubbles to form when we pressure test it. We use a sealant from loctite and our impregnation system to fill in this porosity and seal the leaks. I was just wondering if anyone else does this? I have a fairly high confidence it would work, but I just wanted to know if anyone else in the manufacturing world does this as a standard practice?

Thanks,

Adam

Adam,

We impregnate some of out pressure regulator castings. Our casting house in Taiwan does it. Not sure what the process is.

I would recommend x-raying your casting....that'll tell you if there are problems internally.