Hydrotesting of open end valves

[MannyPM]

Hi All,

We have got 4 off cast valves (ASTM A216 WCC) as per attached drawing which require hydrotesting (pressure: 11,000 kPa and hold time: 30 minutes).

As you can see from drawing, valve has 3 ends, 2nd end is proper flange with gramophone finish, one end is flat face with tapped holes and 3rd end is just an open end.

We can make a recessed blind flange from a thick plate to suit flat dace end, for the open end we explored hydrotest plug option but the length from end is not long enough for a plug to grip.

I was wondering if anyone has come across this and what solutions did they come up with?

Feel free to ask me more questions.

Regards,
Manny

 

[3DDave]

It looks like it's going to be welded to attach it. If so, wait until after welding when the weld will also be tested.

You can do radiographic inspection for inclusions or internal tears.

They could have added extra length to allow welding on a cover plate and, after it passes, do the final machining to length outside the heat affected zone.

 

[MannyPM]

Hi 3DDave,

Good suggestions, but this has come from Valve manufacturer to use for hydrotesting it and then it get welded to a live plant which doesn't get hydrotested, only NDT tested.

I agree that there should have been an extra length to weld a plate, but this is what I have got and now I have to come up with a way to make it work.

 

[3DDave]

Not going to happen. Part of the pressure test should exert tension on the valve body. There is no way to do that without a welded attachment. Seems like someone failed to plan this properly. Consult the designers of this mess.

For example - take a large threaded rod through the center that takes 90% of the diameter and put a cover plate and a nut on both ends. Great = that tests the side port and doesn't test anything else. So, if failing to perform a reasonable test is the goal and it's ok for it to fail later, then do that.

 

[LittleInch]

very odd but only thiong I can suggust is that you make a T shaped plug approx 240mm diam with inside say 195 or 200mm diam and lower it inside from the top end with some sort of suitable seal.

Only gives you 15mm of bearing inside the valve body, so you might break the valve body, but at least most of the body will see pressure in the way it is intended.

The problem with simply putting sealing forces between the top and bottom holes is the thinness of the weld end prep section may become overstressed when you tighten up the flanges to prevent leakage at 110 bar test pressure.

But yes, the vendor should have though of how to pressure test the casting.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[btrueblood]

What LI said, a t-shaped or possibly conical plug can be machined, possibly with an o-ring to seal on the 6.3 micrometer finished tapered surface, and installed prior to closure of the top flange/plate. To me, it appears that the conical surface is meant to bear a tapered plug anyway, although not perhaps at full hydro-test pressure. But consultation with the manufacturer should be done before taking that approach.

As 3DDave says, the above approach does not test the tensile load that the valve would experience with the port in question open, and piping attached. Dunno how you would do that, except by hydrotesting the installed/welded valve.

 

[MannyPM]

Thanks everyone for your advice.