Functional Safety 2016

Riser packing

• On closure of the SDV, pressure increases due to

settle out as a gas cap fills the riser and liquid falls

to the horizontal part of the subsea line

• If Subsea valves are closed, or flow relies on

subsea pumps, the hazard will be the high pressure

gas cap.

Already significant hazard potential!

• If the Subsea valves remains open, the gas cap can

grow and be further pressurised; i.e. it is packed.

• Furthermore, rather than a closed-in riser volume,

the FPSO is connected to an “infinite” oil reservoir.

• Separator relief valves are not sized for riser de-

packing.

• Significant hazard potential due to high pressure

(several hundred bar), and presence of personnel

during hazard zone during this start-up operation.