Seismic Coefficient Rp for piping and its supports 2

[ellas1]

For ASME piping with joints made by welding or brazing Table 13.6.1 of ASCE 7-10 (Seismic Coefficient for Mechanical & Electrical Components) shows an Rp=12. However, section 13.4.1 of ASCE 7-10 Design Force in the Attachment) indicates that Rp shall not be larger than 6. Is the code expecting the analysis and the design of the piping for Rp=12 and the supports and restraints as Nonstructural Components with Rp=6 or the entire piping and pipe support system can be treated the same with Rp=12?

Please advise

Thank you

 

[RVAmeche]

For piping, stress analysis experts recommend an Rp = 3.5 since a higher Rp results in a lower seismic force. The analysis of the support structure may very well require a different Rp since it's a different system.

 

[KevinNZ]

Piping and Civil codes do not calculate seismic stresses the same way so you end up with difference loads to use in the code stress/capacity calculations.

Even B31.1/3 and B31E require different Rp values. This because the allowable stress in seismic/occasional cases is different.

It gets worse when you are using American pipe codes and local country civil design codes.