We analyze 12”, STD wall, CS liquid line on a pipe rack in seismic zone.

CASE 2 (OPE) W+T1+P1 (with friction) is used for loads on restraints / equipment and OPE displacements per B31.3.

According to ACSE: “The seismic design should not take credit for the friction force between pipe and support, which tends to reduce seismic motion of the pipe”

That means that cases:
CASE 6 (OPE) W+T1+P1+U1+U2
CASE 7 (OPE) W+T1+P1-U1+U2
CASE 8 (OPE) W+T1+P1+U1-U2
CASE 9 (OPE) W+T1+P1-U1-U2
CASE 10 (OPE) W+T1+P1+U3+U2
CASE 11 (OPE) W+T1+P1-U3+U2
CASE 12 (OPE) W+T1+P1+U3-U2
CASE 13 (OPE) W+T1+P1-U3-U2
CASE 14 (OPE) W+D1+T1+P1
CASE 15 (OPE) W-D1+T1+P1
CASE 16 (OPE) W+D2+T1+P1
CASE 17 (OPE) W-D2+T1+P1
Where:
U1 = SEISMIC G LOAD X (EAST)
U2 = SEISMIC G LOAD Z (VERTICAL)
U3 = SEISMIC G LOAD Y (NORTH)
D1 = SEISMIC DISPLACEMENT IN X DIRECTIONS
D2 = SEISMIC DISPLACEMENT IN Y DIRECTIONS
Should be frictionless.

After that, COADE recommends creating load cases to segregate OCC seismic load
CASE 20 (OCC) L6-L2 (CASE NOT ACTIVE) = +U1+U2(*)
CASE 21 (OCC) L7-L2 (CASE NOT ACTIVE) = -U1+U2(*)
CASE 22 (OCC) L8-L2 (CASE NOT ACTIVE) = +U1-U2(*)
CASE 23 (OCC) L9-L2 (CASE NOT ACTIVE) = -U1-U2(*)
CASE 24 (OCC) L10-L2 CASE NOT ACTIVE) = +U3+U2(*)
CASE 25 (OCC) L11-L2 (CASE NOT ACTIVE) = -U3+U2(*)
CASE 26 (OCC) L12-L2 (CASE NOT ACTIVE) = +U3-U2(*)
CASE 27 (OCC) L13-L2 (CASE NOT ACTIVE) = -U3-U2(*)
CASE 28 (OCC) L14-L2 (CASE NOT ACTIVE) = +D1 (*)
CASE 29 (OCC) L15-L2 (CASE NOT ACTIVE) = -D1 (*)
CASE 30 (OCC) L16-L2 (CASE NOT ACTIVE) = +D2 (*)
CASE 31 (OCC) L17-L2 (CASE NOT ACTIVE) = -D2 (*)
(*) - ALGEBRAIC
and combine these loads with SUS for stress check.

Q.1: Do these cases (20-31) have a physical sense as they subtract load WITH friction from loads WITHOUT friction?
Q.2: Do we have to complicate analysis and run 2 systems WITH and WITHOUT friction to obtain a credible result?
Q.3: What load cases would be appropriate to satisfy all requirement in one system?

Thanks a lot for you expertise!
Vikoll

Hi, you can go to the load case editor, create the new operating case, and change the friction multiplier to zero, with this you have both the cases W+P1+T1 (with friction multiplier as 1.0 & without friction with friction multiplier set to as Zero).

I hope this will solve your point no 2,3.

Regards,
R.K.