Pipe Pressure Testing with Control Devices in Place

[ChEMatt]

Question has come up now and again and I don't have a really good answer for it. If this is the wrong forum, please direct me to the correct place to post this. Thanks.

Let's say I have a system that is designed for 300 psig maximum operating pressure. I ensure that all my instrumentation is designed to handle up to MAOP (or MAWP, if you like) pressure. The pipe was assembled with the control valve, pressure, temperature, and flow instrumentation.

The pressure test calls for 1.5x maximum allowable pressure. The control valve has 300# ANSI flanges on it, but as designed it says it's only good to 300 psig. Do you leave it in the line? Do you leave all the other instruments in the line and expose them to 450 psig? Should they be capable of handling that pressure if the system is designed only for 300 psig?

Sorry if the question isn't clear or lacks details. Thank you for your help.

-m

 

[danw2]

What temperature is the testing at? Check the table at the link.

 

[MikeHalloran]

You would typically mount instruments on the distal side of barstock plug valves, so that you can change the instruments without shutting down the process.

So, close the valves and open the associated bleeds.


Mike Halloran
Pembroke Pines, FL, USA

 

[ChEMatt]

The testing parameters would keep the temperature within typical expected operating conditions. Generally you fill these pipes in water at 40 to 60 degrees (just whatever the temperature is of the tank truck that brought the water to the site) and then start to increase the pressure.

The question is, do you leave the control devices and instrumentation in place, or do you remove them while you knowingly exceed the MAOP of the pipe?

-m