Hydrotest API 598 Trim Valves B31.3

[tcbm]

I have a question I am hoping someone can shore up for me.

Under B31.3 is there any way to waive a hydrotest for vessel trim (valve / blind flange) that are attached to vessels. Under B31.3, do we need to hydrotest all valves?

The valves themselves were tested to API 598, however they were not tested to B31.3. If we can waive, what para should I use to submit to the owner. The valves are bolted only, so it would be strictly a test for shell.

 

[Duwe6]

B31.3 only requires the pipewelds to be hydro'ed. Makes no difference if you hydro through a valve or around it to the Code. As discussed elswhere, it is better to hydro around the valves.

 

[lsone]

I feel this is dependent on the client at hand. I am fairly new to the game but have experienced several pneumatic tests with ABSA where every valve in the system was tested against, This is the only way to prove a valve(weld, bonnet weld or bolt up, packing glands, etc. If tightening the packing glands does not stop the bypass, there will be a cut out and replace.

However on a flanged valve, some clients will hydro/pneumatic test them via inhouse or 3rd party and will not require them to be hydro'd a second time, BUT.. the bolt up(both flanges and gasket) have to be proven aswell, thus the valve is included into the hydro/pneumatic test in the end.

 

[Duwe6]

isone, you seem to be mixing up Tightness testing with Hydrostatic and/or Pneumatic testing.

Bringing the system up to operating pressure [plus or minus] and checking for packing, flange, and bonnet leaks is Tightness.

A B31.3 hydro takes the system up to at least 1.5 times Max Allowable Working Pressure. At that pressure, ALL your valve packing should be 'weeping', because the packing was adjusted for 'Normal Operating Pressure'. If you tighten the valve and pump packing to stop the leaks, weeps, & seeps at Hydro pressure, the packing will be so tight that it will take "2 men, a boy, and a dog" to operate each valve. When the pump starts up, the shaft will start overheating due to overtight packing, ruining the shaft.

Thus you hydro around all Control Valves, pumps, and other equipment, and as many shut-off valves as possible. You never adjust packing when the system pressure is above "Normal Operating" pressure.

 

[lsone]

This is how we hydro everything. For Suncor in Fort Mcmurray we always included valves in our hydrotests. Always tested at 1.5 times the operating system limit. Very Rarely have I done any service tests as the process is not human friendly. We will isolate a line to do a carber test before we service test. All of our handles still operate just fine aswell.

The only time we add hoses is if we cannot flip or remove the internals in a check valve, then we will have to put pressure on both sides of the check to accurately proceed with our tests.

Some valves will also be tested against to ensure they can isolate a line in an emergency situation(although not overly common)