Pressure Testing

[Bottle]

Possibly a very stupid question, but I am looling for some opinions.

A section of pipework is due to be pressure tested according to ASME B31.1, and there are 2 flanged valves not yet installed as they have not been delivered.

How would one define the limits of the pressure test for the above example. Is it of the piping only, or should it include all equipment which would be normally installed (other than those which may be damaged by the pressure test)? What section of B31.1 defines the scope?

If 2 dummy/spacers were installed for the test would this suffice?

Should the contractor wait for the valves to be installed before carrying out the test?

Thanks in advance for any opinions offered.

 

[metengr]

Bottle;
You have two options that I see;

1). Blank off the existing piping, perform a pressure test and after delivery of the valve bodies weld them in and perform a volumetric examination (RT or UT) of the connecting welds only.

2) Wait until the valve bodies are delivered and perform a pressure test on the completed assembly.

 

[Mr168]

You don't mention material type. If any PWHT is required, you'd have to wait until the valves are installed as per 137.1.5.

It can be done as metengr mentioned. However, it is highly preferred to be done after the valves are installed. I just asked one of our senior QC guys, and he mentioned that the installation of the valves after testing would typically have to have both client and engineering approval in order to take place.

 

[Bottle]

Thanks for the responses.

The piping is GRP, however we have agreed that for pressure testing that we will go along with B31.1. So no PWHT required.

 

[StressGuy]

Why would PWHT be an issue? He said the valves are flanged.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[moltenmetal]

Test the flanged piping. When the valves come, open them, flange them together and test them, then do your final assembly. No different than partial testing of various pieces of piping that are connected by flanges only, or say the piping which is connected to a nozzle on a vessel (both tested separately prior to installation). Piping connnected by welding of course needs to be tested after the last weld is done.

The flanged joints between the valves and the piping can be tested for leakage in service, with the owners' permission of course.