NTSB Safety Recommendation P-84-007

NTSB safety recommendation P-84-007.

THE NTSB RECOMMENDS THAT THE BOSTON GAS COMPANY: INSPECT ALL PRIMARY AND MONITORING REGULATORS IN ITS GAS DISTRIBUTION SYSTEM TO VERIFY THAT THE REGULATOR GASKETS ARE CORRECTLY INSTALLED AND THAT THE VENT PIPING IS WATERTIGHT.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 1984-04-09

Adopted Date: 1984-04-03

Overall Date Closed: 1984-08-01

Synopsis: ON SEPTEMBER 23, 1983, THE BOSTON WATER AND SEWER COMMISSION RECEIVED A TELEPHONE CALL FROM THE BOSTON POLICE DEPARTMENT NOTIFYING IT OF A BROKEN WATER MAIN AND FLOODING AT THE INTERSECTION OF PORTER AND BREMEN STREETS IN EAST BOSTON, MASSACHUSETTS. GAS PRESSURE IN THE BOSTON GAS COMPANY'S (GAS COMPANY) DISTRIBUTION SYSTEM IN EAST BOSTON RAPIDLY INCREASED FROM 7 INCHES WATER COLUMN (W.C.) (ABOUT 0.25 PSIG) TO MORE THAN 16 INCHES W.C. (ABOUT 0.6 PSIG). THE BOSTON FIRE DEPARTMENT BEGAN RECEIVING TELEPHONE CALLS ABOUT GAS ODORS, HIGH PILOT LIGHTS, AND FIRES, AND MORE THAN 200 SIMILAR TELEPHONE CALLS WERE RECORDED BY THE FIRE DEPARTMENT. GAS COMPANY CREWS SEARCHING FOR THE SOURCE OF THE HIGH GAS PRESSURE FOUND THE DISTRICT REGULATOR VAULT AT BREMEN AND PORTER STREETS (ONE OF FOUR DISTRICT REGULATORS IN THE EAST BOSTON AREA) HAD BEEN SUBMERGED IN WATER. AFTER THE VAULT HAD BEEN PUMPED OUT, INSPECTION OF THE PRIMARY REGULATOR AT BREMEN AND PORTER STREETS SHOWED THAT WATER HAD ENTERED THE REGULATOR THROUGH LEAKS IN A GASKET AND THROUGH THE VENT PIPING, THAT WATER HAD FILLED THE AREA ABOVE THE REGULATOR DIAPHRAGM, AND THAT THE WEIGHT OF THIS WATER IN THE DIAPHRAGM HAD HELD THE REGULATOR VALVE OPEN, THEREBY ALLOWING THE GAS PRESSURE TO INCREASE IN THE DISTRIBUTION SYSTEM.

Probable Cause: None

Ntsbnumber: DCA83MP025

Report Number: PAR-84-05

Addressee Name: Boston Gas Company

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 1984-08-01

Addressee Organization Type: P-Private Industry

Communication Date: 1984-05-16

Communication Type: Official Correspondence

Communication Contents: BOSTON GAS LETTER: IN ORDER TO INSURE THAT THE VENT PIPING AND THE DIAPHRAGM CHAMBER SYSTEM OF EACH REGULATOR IS WATER TIGHT, BOSTON GAS HAS REVISED ITS INSPECTION STANDARD AND PROCEDURE TO INCLUDE A MORE RIGOROUS AND FREQUENT LEAK CHECK. AS PART OF ITS SIX MONTH PERIODIC INSPECTION, ALL CONNECTIONS, FITTINGS AND GASKETED SURFACES OF THE VENT PIPING AND DIAPHRAGM CHAMBER SYSTEM OF EACH REGULATOR WILL BE SOAP TESTED FOR THE DETECTION OF LEAKS WHILE A PRESSURE OF 5 PSIG IS BEING APPLIED. SINCE THIS PROCEDURAL REVISION TO OUR OPERATING STANDARD WAS IMPLEMENTED, APPROXIMATELY 15 PERCENT OF THE SUBJECT WEIGHT-LOADED REGULATORS HAVE UNDER GONE THIS TEST. THE TESTING OF THE REMAINING REGULATORS WILL BE COMPLETED BY JULY 1, 1984.

Addressee Organization Type: P-Private Industry

Communication Date: 1984-08-01

Communication Type: Official Correspondence