CONSUMERS ENERGY CO — Gas transmission and gathering — incident on 2016-09-15

Gas transmission and gathering incident in MANCHESTER, WASHTENAW County, MI. Reported cause: INCORRECT OPERATION. Reported consequences: 0 fatalities, 0 injuries, 3484 NATURAL GAS released, $0 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20160084.

Operator ID: 2748.

Reported incident date: 9/15/2016 8:16.

Location detail: FREEDOM CS

Cause detail: VALVE LEFT OR PLACED IN WRONG POSITION, BUT NOT RESULTING IN AN OVERPRESSURE

Cause detail: AT 0816 HOURS ON THURSDAY, SEPTEMBER 15, 2016, TWO EMPLOYEES WERE FOLLOWING A PROCEDURE TO REPLACE A SECTION OF PIPE AT FIREGATE BOX 2-4 AT FREEDOM COMPRESSOR STATION. TO ISOLATE THE LINE TO BE WORKED ON, THE PILOT GAS LINES BETWEEN THE PILOT ISOLATION VALVE AND PILOT GAS SOLENOID WERE REQUIRED TO BE VENTED. IN ORDER TO PERFORM THIS TASK, THE FIREGATE VENT VALVES NEEDED TO BE IMMOBILIZED, TO PREVENT THE UNINTENDED RELEASE OF GAS. THE NORMAL PROCEDURE TO COMPLETE THIS TASK IS TO ISOLATE THE LOCAL POWER GAS AT THE ACTUATOR, AND VENT THE LINE BETWEEN THE ISOLATION VALVE AND THE ACTUATOR, THEN ISOLATE THE PILOT GAS AT THE ACTUATOR, AND VENT THE LINE BETWEEN THE ISOLATION VALVE AND THE ACTUATOR. ALL POWER GAS LINES AND PILOT GAS LINES TO THE EMERGENCY SHUTDOWN VALVE ACTUATORS WERE ISOLATED, AND THE CREW BEGAN TO VENT THE PILOT LINES ON TWO OF THE VALVES, VALVE 612 AND VALVE 614. THIS RESULTED (AS DESIGNED) IN TWO FIREGATE VALVES (612 AND 614) TRAVELING TO 100% OPEN AND VENTING 3.484 MMCF OF NATURAL GAS FROM A 620 PSI LINE TO ATMOSPHERE THROUGH THE 16-FOOT VENT STACK, FROM 0816 HOURS TO 0825 HOURS. THE OPENED VALVES WERE MANUALLY CLOSED BY STATION PERSONNEL. AFTER RE-ASSESSMENT OF THE PROCEDURE AND SITUATION, STATION PERSONNEL RELIEVED PRESSURE OFF OF THE POWER GAS BETWEEN THE ISOLATION VALVE AND FIREGATE VENT VALVE ACTUATORS, AND THEN RELIEVED PRESSURE OFF THE PILOT GAS. THE REQUIRED SEQUENCE TO ISOLATE FIREGATE VALVES IS TO ISOLATE POWER GAS AND THEN PILOT GAS. THIS SEQUENCE WAS NOT OUTLINED IN THE PROCEDURE PROVIDED. A DETAILED REVIEW OF THE PROCEDURE WAS NOT COMPLETED BY ADDITIONAL ENGINEERING REPRESENTATION FROM GAS COMPRESSION OPERATIONS, AND A PHYSICAL WALK-DOWN OF THE EQUIPMENT WAS NOT PERFORMED BY THE SITE FIELD LEADER, PRINCIPAL FIELD LEADER, OR BY ASSIGNED CREW PRIOR TO PROCEDURE APPROVAL OR WORK PERFORMANCE.

PHMSA trend classification: not significant, not serious.

PHMSA standardized cause: INCORRECT OPERATION — INCORRECT VALVE POSITION.

PHMSA indexed costs: $10,068 reported total cost, $10,719.299 in 1984 dollars, $13,161.671 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.