NTSB Safety Recommendation P-98-009

NTSB safety recommendation P-98-009.

THE NTSB RECOMMENDS THAT THE PLASTICS PIPE INSTITUTE: ADVISE YOUR PLASTIC PIPE MANUFACTURING MEMBERS TO REVISE THEIR PIPELINE BEND RADIUS RECOMMENDATIONS AS NECESSARY TO TAKE INTO ACCOUNT THE EFFECTS OF RESIDUAL COIL BENDS INPLASTIC PIPING.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 1998-04-30

Adopted Date: 1998-04-23

Overall Date Closed: 1998-10-19

Synopsis: DESPITE THE GENERAL ACCEPTANCE OF PLASTIC PIPING AS A SAFE & ECONOMICAL ALTERNATIVE TO PIPING MADE OF STEEL OR OTHER MATERIALS, THE BOARD NOTES THAT A NUMBER OF PIPELINE ACCIDENTS IT HAS INVESTIGATED HAVE INVOLVED PLASTIC PIPING THAT CRACKED IN A BRITTLE-LIKE MANNER. FOR EXAMPLE, ON 10/17/94, AN EXPLOSION & FIRE IN WATERLOO, IOWA, DESTROYED A BUILDING & DAMAGED OTHER PROPERTY. SIX PERSONS DIED & SEVEN WERE INJURED IN THE ACCIDENT. THE BOARD INVESTIGATION DETERMINED THAT NATURAL GAS HAS BEEN RELEASED FROM A PLASTIC SERVICE PIPE THAT HAD FAILED IN A BRITTLE-LIKE MANNER AT A CONNECTION TO A STEEL MAIN.

Probable Cause: None

Ntsbnumber: DCA95MP001

Report Number: SIR-98-01

Addressee Name: Plastics Pipe Institute

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 1998-10-19

Addressee Acronym: PPI

Addressee Organization Type: A-Associations

Communication Date: 1998-06-30

Communication Type: Official Correspondence

Communication Contents: (Letter Mail Controlled 7/9/98 2:51:30 PM MC# 980864) BY COPY OF YOUR LETTER WE ADVISED OUR MEMBERS TO ADDRESS MINIMUM BEND RADIUS RECOMMENDATIONS FOR PE FUEL GAS PIPING AS NECESSARY. AGAIN MOST OF OUR MEMBER COMPANIES ALREADY HAVE MINIMUM BEND RADIUS RECOMMENDATIONS IN THEIR TECHNICAL & INSTALLATION LITERATURE. THESE RECOMMENDATIONS ARE, IN MOST CASES, BASED ON SOUND ENGINEERING DATA & CALCULATIONS. FOR EXAMPLE WHEN PE PIPING IS USED IN PRE-BENT ANODELESS RISERS, MOST, IF NOT ALL, MANUFACTURERS MAKE SURE THAT THE RESIDUAL COIL CURVATURE MATCHES THE DIRECTION OF THE BEND OF THE STEEL RISER CASING.

Addressee Acronym: PPI

Addressee Organization Type: A-Associations

Communication Date: 1998-10-19

Communication Type: Official Correspondence

Communication Contents: THE SCOPE BOARD'S REPORT WAS LIMITED TO FIELD BENDS FOR UNCASED DIRECT BURIAL APPLICATIONS. THE REPORT NOTED THAT PLASTIC PIPING IS OFTEN DELIVERED TO JOB SITES IN BANDED COILS SOME RESIDUAL BENDING IN THE PIPING REMAINS AFTER THE BANDS ARE REMOVED. THE REPORT STATED THAT THE "GAS INDUSTRY FIELD (EMPHASIS ADDED) BEND RESIDUAL RECOMMENDATIONS DO NOT ADDRESS RESIDUAL COIL BENDING P-98-9 WAS ISSUED TO THE PPI TO ENCOURAGE THE PLASTIC PIPING MANUFACTURERS TO REVISE THEIR PIPELINE BEND RADIUS RECOMMENDATIONS TO TAKE INTO ACCOUNT THE EFFECTS OF RESIDUAL COIL BENDS INPLASTIC PIPING. THE BOARD UNDERSTANDS THAT SOME GAS SYSTEM OPERATORS ARE AWARE OF OLDER PLASTIC PIPING MATERIALS HAVING A SUSCEPTIBILITY TO PREMATURE BRITTLE-LIKE CRACKING & ARE MONITORING THEIR PLASTIC PIPELINE SYSTEMS. THE BOARD'S REPORT CONCLUDED THAT THE GAS PIPELINE SYSTEM OPERATORS HAVE HAD INSUFFICIENT NOTIFICATION THAT MUCH OF THE PLASTIC PIPE MANUFACTURED FROM THE 1960S THROUGH THE MID-1980S MAY BE SUSCEPTIBLE TO BRITTLE-LIKE CRACKING &, THEREFORE, MAY NOT HAVE IMPLEMENTED ADEQUATE PIPELINE SURVEILLANCE & REPLACEMENT PROGRAMS FOR THEIR OLDER PIPING. AS THE BOARD'S REPORT NOTES, PLASTIC PIPE'S ECONOMY, OUTSTANDING CORROSION RESISTANCE, LIGHT WEIGHT, EASE OF INSTALLING & JOINING, & DUCTILITY HAVE ALL CONTRIBUTED TO MAKE PLASTIC PIPING THE MATERIAL OF CHOICE FOR NATURAL GAS DISTRIBUTION SYSTEMS. THE BOARD DOES NOT PROPOSE TO DISCOURGE PIPELINE SYSTEM OPERATORS FROM USING PLASTIC PIPE; HOWEVER, THIS IMPORTANT ISSUE NEEDS THE ATTENTION OF ALL GAS PIPELINE OPERATORS HAVING OLDER PLASTIC PIPING IN SERVICE. BECAUSE THE PPI PROVIDED COPIES OF THE BOARD'S 4/30/98, LETTER & ADVISED ITS MEMBERS AS REQUESTED, P-98-7 THROUGH -9 HAVE BEEN CLASSIFIED "CLOSED--ACCEPTABLE ACTION."