Dear Experts,

I would like to ask for the suggestion about my calculation of riser lines to pig launchers and receivers in offshore platform.

I applied wave loads in to my calculation in X,-X,Z and -Z directions and load cases are following;

CASE 1 (HYD) WW+HP
CASE 2 (OPE) W+T1+P1
CASE 3 (OPE) W+T1+P1+WAV1
CASE 4 (OPE) W+T1+P1+WAV2
CASE 5 (OPE) W+T1+P1+WAV3
CASE 6 (OPE) W+T1+P1+WAV4
CASE 7 (SUS) W+P1
CASE 8 (EXP) L8=L2-L7
CASE 9 (OCC) L9=L3-L2
CASE 10 (OCC) L10=L4-L2
CASE 11 (OCC) L11=L5-L2
CASE 12 (OCC) L12=L6-L2
CASE 13 (OCC) L13=L9+L7
CASE 14 (OCC) L14=L10+L7
CASE 15 (OCC) L15=L11+L7
CASE 16 (OCC) L16=L12+L7

I am using Caesar II version 5.20.03 built . Ambient Temp = 84F, Operating Temp = 250F, Operating Press = 1325 lb/sq.in and HYD Press = 2220 lb/sq.in. Design Code are B31.3 and B31.8. Fluid density are 1.95 - 6.75 lb/cu.ft. And supports stiffness at Launchers/Receivers came from structure department.

As checked, I found pipe supports loading in sustained case are heavier than hydtest case. In my opinion that HYD load should be heavier than sustained load????

Please see in the attachment and help. I will appreciate very much.

Very Best Regards,
Billy

Addition, Pipe supports loading look ok when I turned off wave loads. As per my load case above, does it concern with sustained and hyd loads??

Regards,
Bill

One cause is "marine growth"

Regards,

How did you input your fluid density? The entry should be lbs/in^3 (or you can input a specific gravity value if you append the value with SG)

Hi billy
One thing i wanted to share with you
during hydrotest caesar wont add the insulation density
bcoz of there is no insulation in hydrotest for determining
leakage.In operating condition or sustained insulation plays
major role in calculation.
therefore hydro load become lower than sustained.

Be careful here, the insulation effect is controled by the "configuration". It is up to the user as to whether or not the insulation weight is included in the hydrotest. (By default it is not.)