Northern End of Pipeline Idled Briefly
The northern end of the pipeline was
idled for approximately twenty minutes on Friday afternoon, March 20, when the operating
two pumps at Pump Station 4 unexpectedly idled. Preventive maintenance work was being
performed at a flow transmitter of a third pump that was shutdown. A controller which
monitors this flow transmitter sensed a change in the flow volume and reacted, idling the
two operating pumps. The northern end of the pipeline was returned to normal operation at
4:30 p.m.
The procedure for this preventive
maintenance task has been corrected to ensure this situation does not reoccur.
Short Section of
Pump Station Piping Possibly Over pressured at Pump Station 1
A segment of the Pump Station 1
metering system was potentially Over pressured on March 18. The pressures in DOT piping
systems are allowed to go up to 110% of rated pressure during surges and other variations
from normal operation. On March 18, the pressure is known to have reached 110% of the
rated pressure in the metering system. The pressure data is currently being analyzed.
The pipe has been inspected and no damage
was found. Approximately three gallons of crude oil were spilled on a floor in the meter
building from a flow strainer installed in one of the incoming meter runs. A complete
investigation of the incident is underway.
As oil enters Pump Station 1, it is
measured (or metered). Normally several meters are online at a time. Each night the
accuracy of each meter is double checked using a meter proving system. On March 18, due to
low flow rates from one producer, only one set of meters was operating. To test the
meters, the flow was diverted from the meter into the prover. The system is designed to
maintain a steady flow rate into the prover during the test. In the middle of the proving
process, flow from the producer into Pump Station 1 increased. A valve began to close to
maintain the steady flow rate into the prover. If another meter run would have been
online, the increased flow would have been diverted through it and no flow blockage would
have occurred. The procedures have changed to ensure that meter testing is performed with
no less than two meters online at a time.
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