During periods when horizontal pipelines are partially filled with LNG during filling or draining operations,
temperature differentials between top and bottom of the pipe up to 60°C may occur. This will then lead to “Cryogenic bending” with consequently extra stresses, support loads and angular deflections and rotations,particularly at the elbows of the pipeline.

Stresses due to this cryogenic bending or bowing are to be classified as displacement stresses. In the calculation, the temperature differential will be assumed to be linearly distributed from top to bottom.

Temperature differentials for the various parts of the system shall be considered.

However, the design shall allow for a temperature differential of 60°C.

Weight has a hold down effect on the cryogenic bending. In evaluating the cryogenic bending, the line shall be considered to be filled only half full with LNG.

Supports uplift during cryogenic bending shall be limited to 50mmn and will be controlled with 100mm high guide thrusts

B31.3 CRYOGENIC BENDING LOAD CASES (LNG LINES)
EXECUTION CONTROL PARAMETERS (CAESAR II File)
Rigid/ExpJt Print Flag ..... 1.000
Bourdon Option ............. 1.000 (Translation only)
Loop Closure Flag .......... 1.000
Thermal Bowing Delta Temp +60.000 C
Liberal Allowable Flag ..... 1.000 (yes, if needed)
Uniform Load Option ........ 1.000 (g)
Ambient Temperature ........ 25.000 C