Page 433 - Pipelines and Risers

400 Chapter 21

- Temporary condition

1. Normal operating condition

The following conditions (ULS) with riser and floater in the normal intact status should be
checked
- Environmental condition of 100 years wave plus 10 years current
- Floater at the neutral, far, near and transverse positions

2. Abnormal operating condition

The following conditions (PLS) shall be checked
- Riser and floater in intact condition with environmental condition of 10,000 years wave
plus 10 years current.
- Loss of station-keeping ability
One mooring line or tendon failure
Floater is tilt due to damage
Dynamic position failure (drive-off or drift-off)
- Impact of dropped objects
- Partial loss of riser tension or buoyancy
- The probability and consequences of fire, explosion and riser collision should be
evaluated.

3. Temporary condition

The following conditions (ULS) shall be checked
- Transportation condition
Consider loads to be applied during transportation
- Installation/n%-ieval condition
Varying amount of risers deployed
Riser filled with air or water
Environmental condition of 1 year wave (or 10 year) plus 1 year current
- Pressure test
Loads (especially pressure loads) during pressure test shall be considered for riser
system design.
- Riser shut-down and start-up
Loads induced by shut-down and start-up shall be included in the fatigue evaluation.
- Pigging condition