Replace of boiler's pressure relief valves

[wayuu1981]

Hello,

We need to contract a company to remove three (3) old safety valves, and install new valves on a 150 MW coal fired boiler (the valves have been previously purchased with V stamp, and they are stored in the plant ready to be installed).

What kind of stamp is required for the company that will remove the old valves and will intall the new ones? each valve have to be butt welded to a 4" diameter pipe sch 160.

In my country ASME and NB are not mandatory, but the insurance company requires us to follow those codes.

As the company will only do the welds (with the required NDE tests and thermal reliefs if required) with no disassembly, assembly, inspection, calibration or test of the valves; is an "R" stamp enough for that company to perform this work according to the code? what other stamps or recommendation do we have to consider when contracting a company for this work?

Thanks for you help.

Javier Guevara E.
Projects, Mechanical Engineer

 

[billMcL]

I think you are outside the National Board "R" Stamp (Repair to boiler and pressure vessels) boundry and replacing pressure piping might require a "PP" stamp

 

[puigi]

Javier:

An organizatrion with an R stamp should be capable of performing the welding required to install the new valves in place, but not any adjustments or calibration of the new valves, this would require VR certification. I recommend you consult with the valve manufacturer, they may recommend disassembly of the valve before welding the bodies onto the drum nozzels. Reassembly, adjustments and calibration should be done by the VR stamp holder.
If your are unclear as to what the insurance company's contractor qualification requirements are, I recommend you ask again.
Are there are particular reasons why you are considering replacing the valves rather than just repairing or overhauling in place?