ACCIDENT
INVESTIGATION REPORT – OIL RELEASE FROM HEATER-TREATER BY FAILING TO
DEPRESSURIZE THE VESSEL
On June 23, 2014, an incident occurred at approximately 10:30 A.M. on the
Arena Offshore East Cameron 328 B facility which resulted in a pollution event
and injury to an operator (injured person or IP). The
IP was also the platform's Person in Charge (PIC). At the time of the incident, the IP was
attempting to replace the pneumatic temperature controller (TC) on Heater
Treater #2 NBK-2770 (vessel). The TC was
threaded directly into a thread-o-let within the liquid medium of the vessel
instead of being installed inside a thermo-well as recommended by the
manufacturer. The vessel normally operates
at approximately 40 pounds per square inch (psi) and 150 degrees Fahrenheit. There were six persons on board the facility,
including one Field Foreman, four Operators, and one Electrician.
On June 24, 2014, the BSEE Lake Charles District conducted an onsite
accident investigation and learned that operations personnel experienced
problems with the vessel's TC maintaining a stabilized temperature on June 22,
2014. As a result of the temperature
instability, the vessel's liquid medium temperature safety high (TSH) sensor
activated a shut-in action of fuel and inflow of fluids. Again on June 23, 2014, the vessel's TSH
activated due to temperature instability and operations personnel deemed it
necessary to replace the faulty TC. Approximately two hours after the TSH
activated, with the vessel's heat source shutdown and the liquid inlets and
outlets blocked off, the IP began removing the TC.
However, the vessel was not depressurized and the hot oil was not drained
to a safe level below the TC. Once the TC was completely removed from the
thread-o-let, hot pressurized oil blew out of the one inch opening in the
vessel, striking and burning the IP on his left bicep. Operations personnel
then shut-in the rest of the facility by manually actuating an emergency
shut-down station. Oil continued to flow
out of the one inch thread-o-let, striking the line heater approximately 20 ft across the
deck. In an effort to direct the oil
into the containment skid beneath the vessel, operations personnel positioned a
sheet of plywood in front of the oil stream. Once the pressurized flow of oil
declined, operations personnel installed a one inch nipple and ball valve into the
open thread-o-let, isolating the leak. After regaining control of the vessel, operations
personnel reported the pollution event (National Response Center Incident Report
# 1086799) and made arrangements for the injured operator to be evacuated.
Personnel then cleaned themselves up due to being covered in oil, and
then began cleaning the facility. A Spill Report Form was submitted showing
that 12 gallons of crude oil were discharged into offshore waters and one
person sustained a burn injury to his arm due to the incident.
The BSEE investigation findings revealed that the operations personnel
took the following precautionary measures in preparation for replacement of the
TC: manually blocked the boarding valve on the Vermillion 342 A incoming
pipeline, isolated the vessel's liquid dump lines, and isolated the make-up gas
to the vessel. The Job Safety Analysis (JSA) for this task identified hazards,
including: pressure, temperature, and liquid release; however, the JSA failed
to specifically identify the primary potential threat which was the TC not
being installed inside a thermo-well.
As a result, critical mitigations were not executed prior to removing the
TC from the vessel which jeopardized the safety of personnel, production
equipment, and the environment. These
critical mitigations included: depressurizing the vessel, lowering the liquid
levels within the vessel, and allowing sufficient time for cooling.
LIST THE PROBABLE CAUSE(S) OF ACCIDENT:
The IP removed the TC prior to depressurizing and lowering the oil level
within the vessel.
LIST THE CONTRIBUTING CAUSE(S) OF ACCIDENT:
Operations personnel failed to recognize the potential hazards associated
with the TC being installed directly into the vessel instead of inside a
thermo-well; therefore adequate mitigations were not identified on the JSA and
implemented prior to performing the TC replacement.
SPECIFY VIOLATIONS DIRECTLY OR INDIRECTLY CONTRIBUTING. NARRATIVE:
E-100 A pollution event occurred on June 23, 2014, discharging 12.3
gallons of crude oil into the Gulf of Mexico, during an incident involving the
NBK-2770 Heater Treater.
G-110 Operations personnel failed to conduct operations in a safe and
workmanlike manner which resulted in injury to the PIC and uncontrolled flow of
oil into offshore waters on June 23, 2014.
