NTSB Safety Recommendation P-82-033

NTSB safety recommendation P-82-033.

THE NTSB RECOMMENDS THAT THE MISSOURI POWER AND LIGHT COMPANY: CONDUCT AN INSPECTION OF ALL OF ITS DISTRICT REGULATOR STATIONS SYSTEMWIDE TO DETERMINE IF ALL RELIEF VALVES AND CONTROL SENSING LINE VALVES ARE IN THEIR CORRECT POSITIONS AND IF THE REGULATOR STATION CONTROL LINES ARE ADEQUATELY PROTECTED AGAINST EXCAVATION DAMAGE AND TAKE CORRECTIVE ACTION AS NECESSARY.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 1982-09-08

Adopted Date: 1982-08-24

Overall Date Closed: 1983-02-16

Synopsis: ON JANUARY 28, 1982, AT CENTRALIA, MISSOURI, NATURAL GAS AT 47 PSIG ENTERED A LOW PRESSURE DISTRIBUTION SYSTEM WHICH NORMALLY OPERATED AT 11 INCHES WATER COLUMN (0.40 PSIG) AFTER A BACKHOE BUCKET SNAGGED, RUPTURED, AND SEPARATED THE 3/4-INCH-DIAMETER STEEL PRESSURE REGULATOR CONTROL LINE AT THE MISSOURI POWER AND LIGHT COMPANY'S DISTRICT REGULATOR STATION NO. 1. THE BACKHOE, WHICH WAS OWNED AND OPERATED BY THE CITY OF CENTRALIA, WAS BEING USED TO CLEAN A DITCH LOCATED ADJACENT TO THE PRESSURE REGULATOR STATION. THE HIGH PRESSURE GAS ENTERING CUSTOMER PIPING SYSTEMS IN SOME CASES RESULTED IN HIGH PILOT LIGHT FLAMES WHICH INITIATED FIRES IN BUILDINGS; WHILE IN OTHER CASES, THE PILOT LIGHT FLAMES WERE BLOWN OUT, ALLOWING GAS TO ESCAPE WITHIN THE BUILDINGS. OF THE 167 BUILDINGS AFFECTED BY THE OVER PRESSURE, 12 WERE DESTROYED AND 32 SUSTAINED MODERATE TO HEAVY DAMAGES. FIVE PERSONS RECEIVED MINOR INJURIES.

Probable Cause: None

Ntsbnumber: DCA82MP010

Report Number: PAR-82-03

Addressee Name: Missouri Power and Light Company

Addressee Status: Closed--No Longer Applicable

Addressee Date Closed: 1983-02-16

Addressee Organization Type: P-Private Industry

Communication Date: 1982-10-07

Communication Type: Official Correspondence

Communication Contents: MISSOURI POWER AND LIGHT COMPANY LETTER: WE HAVE ALREADY INSPECTED EACH DISTRICT REGULATOR STATION AND REVIEWED CONTROL LINE LOCATIONS. WHERE THERE WAS A QUESTION ABOUT THE SECURITY OF A CONTROL LINE, WE HAVE MADE MODIFICATIONS.

Addressee Organization Type: P-Private Industry

Communication Date: 1983-02-16

Communication Type: Official Correspondence

Communication Contents: The actions you have described concerning appropriate inspections and reviews with associated corrective actions are satisfactory in fulfilling these recommendations. We have placed P-82-33 and -34 in a “Closed--Acceptable Action” status.