Our pmc wants us to apply 100 % spectrum in every direction and go for SRSS. He says that 100,30,30 rule is applied only to structures. As per nuclear code NC div III, 100 % in each direction and then SRSS for Piping analysis
any opinions?

B31E says:
"The seismic design should be based on either a three-directional excitation, east–west plus north–south plus vertical, combined by square-root sum of the squares (SRSS), or a two-directional design approach based on the envelope of the SRSS of the east–west plus vertical and north–south plus vertical seismic loading."

Nureg calls for 100, 40,40 rule