Drain systems PAB 2073

Drain Systems Drain systems are important to allow equipment to be drained, opened, inspected and repaired If else, process fluids would have to be collected in containers to prevent spillage to sea Drain pipings ran throughout the platform and routed to vessels (caissons) on the lowest level of the platform – gravity drainage

2 separate drain systems  Open drain  Closed drain

OPEN DRAIN SYSTEMS Open drain systems deals with drain fluids at atmospheric pressure Open drain lines converge into headers and then flow to Open Drain Caisson Water is then disposed into sea and oil is skimmed off and pumped into Closed Drain Vessel Open Drain Caisson has atmospheric vent to release gas

Example drain lines  Deck drains  Drains under vessels, pumps, equipment skids  Rainwater, chemicals from chemical injection package, spent lube oil from generators, diesel fuel overflow and wash water from decks

CLOSED DRAIN SYSTEM Process drain system Closed drain lines connects to a Closed Drain Header and fluid flows to a Drain Vessel Drain vessel separates oil and water, oil pumped back to oil surge vessel, water disposed to sea via Closed Drain Caissons Closed Drain Caissons has pumps to return skimmed fluids back to Drain Vessel Closed Drain Caisson has atmospheric vent to release gas

Example closed drain lines  Hydrocarbon liquid lines from water treatment tanks, fuel gas filter separators, flare scrubbers  High Pressure Drains from wellheads, hydrocarbon vessels low points and instruments and pipeline pig launchers

Drain Vessel  last separation stage before closed drain fluids go to caissons  Gas line to atmospheric vent  Internals to separate oil and water Oil water separation section Oil boot Water overflow section  Pump to return oil into the main separation process  Water flows into Closed Drain Caisson