What is Super Piping? ASME B&PV Code Section III Subsection NB

[Muti]

The pipe portion from top of steam generator up to containment isolation valve once I heard is called super piping due to number of penetrations in the pipe for safety and relief valves. Is this term correct? Class 1 piping are constructed according to ASME B&PV code section iii, subsection NB. Can I found such terminology (and rules for construction) in subsection NB or somewhere else (if this terminology exist)?

 

[gmax137]

I have heard the pipe run between the containment penetration and the main steam isolation valves called super pipe. My understanding was the pipe material certs and fabrication procedures and inspections were such that a pipe break need not be postulated in the section of pipe. I'm not real sure about this though. It seems to me that you could have a break downstream of the MSIV, with failure of MSIV to close as a single failure, and have the same effects as a break in the super pipe. So, what's the point of the super pipe? dynamic effects in the safety valve / MSIV room??

Maybe get more answers in the nuclear engineering section?

 

[Muti]

Thanks gmax so now I know at least this word is said sometimes but not a popular term. From you description it come to my mind piping from SG to MSIV is usually design for full primary pressure because of SGTR. May be due to this connection the pipe length you described might be called super pipe.

 

[gmax137]

No, the steam piping design pressure matches the design of the SG secondary, typically 1000 to 1200 psi, depending on the plant.

 

[Muti]

No, the steam piping design pressure matches the design of the SG secondary, typically 1000 to 1200 psi, depending on the plant.

Thanks gmax, you are right. The pipe portion between containment penetration and MSIV is thickened and reinforced in design. Pipe portion up to MSIV is Class 2, while rest is non safety class.I was wrong in previous post because I forgot safety valves in SGTR case. Due to safety valves steam line pressure can not rise above design pressure of about 7.5 MPa.