Pig Trap Sequence

Pig Launchers

System start condition:

  1. All valves are closed and locked closed.
  2. Vessel door closed and locked closed.
  3. Key 1 is located in the Control Room Key Cabinet.

1. To Load Pigs

  1. Insert Key 1 into V1, unlock and open, lock open by releasing key 2.
  2. Key 2 into V2, unlock and open, lock open by releasing key 3.
  3. Key 3 into door lock. Unlock and open the vessel door, key 3 is retained all the time the door is unlocked and/or opened.

*Load Pigs*

2. To Re-isolate, Pressurise and Launch

  1. Close and lock closed the vessel door, key 3 is released.
  2. Key 3 into V2, unlock and close, lock closed by releasing Key 2.
  3. Key 2 into V1, unlock and close, lock closed by releasing Key 1.
  4. Key into V3, unlock and open, lock open by releasing key 4.
  5. Key 4 into V4, unlock and open.

*Pig(s) Launched*

3. Re-isolate After Launch

  1. Close lock by releasing key 4.
  2. Key 4 into V3, unlock and close, lock closed by releasing key 1.

4. Depressurise Trap

  1. Key 1 into V1, unlock and open, lock open by releasing key 2.
  2. Key 2 into V2, unlock and open, lock open by releasing key 3.
  3. Key 3 into V2, unlock and close, lock closed by releasing key 2.
  4. Key 2 into V1, unlock and close, lock closed by releasing key 1.

5. To Leave Trap In ‘Dormant/Start’ Condition

  1. Key 1 is returned to the Control Room Key Cabinet.

*Proposed Sequence Ends*