NTSB Safety Recommendation P-91-015

NTSB safety recommendation P-91-015.

THE NTSB RECOMMENDS THAT THE UGI CORPORATION: IMPLEMENT A CAST-IRON PIPE REPLACEMENT PROGRAM, BASED ON FACTORS SUCH AS AGE, PIPE DIAMETER, OPERATING PRESSURE, SOIL CORROSIVENESS, EXISTING GRAPHITIC DAMAGE, LEAK HISTORY, BURIAL DEPTH, AND EXTERNAL LOADING, TO IDENTIFY & REPLACE IN A PLANNED, TIMELY MANNER CAST-IRON PIPING SYSTEMS THAT MAY THREATEN PUBLIC SAFETY.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 1991-08-06

Adopted Date: 1991-07-23

Overall Date Closed: 1997-03-12

Synopsis: ON 8/29/90, A NATURAL GAS EXPLOSION & FIRE DESTROYED TWO ROW HOUSES AT 421-423 NORTH FIFTH STREET & DAMAGED TWO ADJACENT HOUSES & THREE PARKED CARS IN ALLENTOWN, PA. ONE PERSON WAS KILLED, & NINE PEOPLE, INCLUDING TWO FIREFIGHTERS, WERE INJURED. THE NTSB'S INVESTIGATION DISCLOSED THAT WATER LEAKING FROM A CIRCUMFERENTIAL CRACK IN A 6-INCH CAST-IRON MUNICIPAL WATER MAIN BENEATH NORTH FIFTH STREET'S EAST SIDE HAD ERODED THE SOIL FOUNDATION OF A LOW PRESSURE (9 INCHES WATER COLUMN PRESSURE) 4-INCH CAST-IRON UGI CORPORATION (UGI) GAS MAIN BENEATH THE WEST SIDE OF NORTH FIFTH STREET. THE GAS MAIN SUBSEQUENTLY CRACKED CIRCUMFERENTIALLY AND NATURAL GAS FILLED THE VOID BENEATH THE PAVEMENT. NATURAL GAS THEN MIGRATED THROUGH THE SOIL & INTO THE BASEMENT OF 423 NORTH FIFTH STREET, WHERE IT IGNITED, EXPLODED, & BURNED. SUBSEQUENT METALLURGICAL EXAMINATIONS REVEALED THAT BOTH CAST-IRON MAINS WERE SIGNIFICANTLY WEAKENED BY GRAPHITIC CORROSION. THE WATER MAIN WAS INSTALLED IN THE LATE 1800S & THE GAS MAIN WAS INSTALLED IN 1903.

Probable Cause: Undermined and weakened segment of cast-iron gas main

Ntsbnumber: DCA90FP011

Report Number: PAB-91-01

Addressee Name: UGI Corporation

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 1997-03-12

Addressee Organization Type: P-Private Industry

Communication Date: 1991-10-17

Communication Type: Official Correspondence

Communication Contents: P-91-15---UGI BELIEVES THAT OUR CURRENT PROGRAMS FOR INDENTIFYING CAST IRON MAIN REPLACEMENT CANDIDATES HAS BEEN EFFECTIVE AND HAS RESULTED IN THE NUMBER OF MAIN BREAKS OCCURRING ON OUR SYSTEM.

Addressee Organization Type: P-Private Industry

Communication Date: 1992-10-07

Communication Type: Official Correspondence

Communication Contents: WHILE WE FEEL OUR CURRENT PROGRAMS ARE SUFFICIENT TO SATISFY THE BOARD'S CONCERN, WE ARE UNDERTAKING A REVIEW OF AVAILABLE ANALYTICAL PROGRAMS, SUCH AS CIMOS, WHICH ARE DESIGNED TO IDENTIFY AND PRIORITIZE POTENTIAL CAST IRON REPLACEMENT CANDIDATES.

Addressee Organization Type: P-Private Industry

Communication Date: 1994-01-14

Communication Type: Official Correspondence

Communication Contents: ON OCTOBER 21, 1993, UGI SIGNED A LICENSE AGREEMENT WITH WOODWARD-CLYDE CONSULTANTS, INC. TO PURCHASE THE CIMOS SOFTWARE PACKAGE. INITIAL MEETINGS HAE BEEN HELD BETWEEN THE PARTIES & WE HAVE BEGUN TO GATHER THE NECESSARY DATA TO DEVELOP THE CIMOS MODEL FOR UGI. IT IS ANTICIPATED THAT THE MODEL WILL BE COMPLETED BY MID-1994 & THAT THE CIMOS PRIORITIZATION WILL BE USED TO IDENTIFY CAST IRON REPLACEMENTS IN 1995.

Addressee Organization Type: P-Private Industry

Communication Date: 1996-11-20

Communication Type: Official Correspondence

Communication Contents: UGI'S LETTER STATED THAT THEY HAVE COMPLETED ANALYSIS OF PAST INCIDENTS & FOUND COMMON ATTRIBUTES, LEADING TO THE IDENTIFICATION OF CAST IRON MAINS PRESENTING THE GREATEST POTENTIAL THREAT TO THE PUBLIC. APPLYING THESE RISK FACTORS TO THEIR CAST IRON PIPING SYSTEM, UGI ESTIMATES THAT THERE ARE APPROXIMATELY FORTY-THREE MILES OF MAIN OF THE TOTAL CAST IRON IN UGI'S SYSTEM HAVING A REPLACEMENT PRIORITY. THESE LINE SECTIONS HAVE BEEN IDENTIFIED & THEN RANKED USING THE CAST IRON MAIN OPTIMIZATION SYSTEM (CIMOS). SYSTEMATIC REPLACEMENT OF THESE PRIORITY SECTIONS IS UNDERWAY.

Addressee Organization Type: P-Private Industry

Communication Date: 1992-11-23

Communication Type: Official Correspondence

Communication Contents: THE BOARD UNDERSTANDS THAT THE UGI IS REVIEWING AVAILABLE ANALYTICAL PROGRAMS, SUCH AS THE CAST IRON MAINTENANCE OPTIMIZING SYSTEM, THAT ARE DESIGNED TO IDENTIFY & PRIORITIZE POTENTIAL CAST-IRON REPLACEMENT CANDIDATES. WE WOULD APPRECIATE RECEIVING THE RESULTS OF THE REVIEW & THE UGI PLANS TO IMPROVE ITS CAST-IRON REPLACEMENT PROGRAM. PENDING FURTHER RESPONSE, RECOMMENDATION P-91-15 HAS BEEN CLASSIFIED AS "OPEN--ACCEPTABLE RESPONSE."

Addressee Organization Type: P-Private Industry

Communication Date: 1997-03-12

Communication Type: Official Correspondence

Communication Contents: THE BOARD NOTES THAT UGI HAS ANALYZED PAST INCIDENT & HAS IDENTIFIED THOSE CAST-IRON PIPELINES PRESENTING THE GREATEST POTENTIAL THREAT TO THE PUBLIC. THE BOARD UNDERSTANDS THAT APPROXIMATELY 43 MILES OF MAIN HAVE BEEN IDENTIFIED AS HAVING A REPLACEMENT PRIORITY & THAT THE SYSTEMATIC REPLACEMENT OF THESE PRIORITY SECTIONS IS UNDERWAY. THEREFORE, P-91-15 HAS BEEN CLASSIFIED "CLOSED--ACCEPTABLE ACTION."

Addressee Organization Type: P-Private Industry

Communication Date: 1994-04-22

Communication Type: Official Correspondence

Communication Contents: THE BOARD UNDERSTANDS THAT UGI HAS RECENTLY SIGNED A LICENSE AGREEMENT WITH WOODWARD-CLYDE CONSULTANT, INC., TO PURCHASE THE CAST IRON MAINTENANCE OPTIMIZATION SYSTEM (CIMOS). IT IS ANTICIPATED THAT THE MODEL WILL BE COMPLETED LATER THIS YEAR & THAT THE CIMOS PRIORITIZATION WILL BE USED TO IDENTIFY CAST-IRON MAIN REPLACEMENTS IN 1995. PENDING THE ACTUAL APPLICATION OF CIMOS, P-91-15 WILL REMAIN CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."

Addressee Organization Type: P-Private Industry

Communication Date: 1992-01-28

Communication Type: Official Correspondence