NTSB Safety Recommendation P-98-018

NTSB safety recommendation P-98-018.

THE NTSB RECOMMENDS THAT THE DRESSER INDUSTRIES, INC.: DEVELOP & PUBLISH RECOMMENDATIONS & INSTRUCTIONS FOR LIMITING SHEAR & BENDING FORCES AT LOCATIONS WHERE YOUR STEEL TAPPING TEES ARE USED TO CONNECT PLASTIC SERVICE PIPE TO STEEL MAINS.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 1998-04-30

Adopted Date: 1998-04-23

Overall Date Closed: 1999-02-08

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: Dresser Industries, Inc.

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 1999-02-08

Addressee Organization Type: P-Private Industry

Communication Date: 1998-12-02

Communication Type: Official Correspondence

Communication Contents: Letter Mail Controlled 12/4/98 1:59:01 PM MC# 981434 WE HAVE PUBLISHED RECOMMENDATIONS THAT APPLY TO GAS UTILITY ENGINEERING PERSONNEL AS WELL AS THE GAS UTILITY TECHNICIANS WHO INSTALL OUR PRODUCTS. 1. GAS UTILITY ENGINEERING PERSONNEL- WE HAVE PUBLISHED TWO DOCUMENTS, THE FIRST IS AN ADDITION TO OUR 'GAS PRODUCTS INSTALLATION MANUAL' (EXHIBIT 1). THESE INSTRUCTIONS SPECIFICALLY ADDRESS RECOMMENDATIONS ON HOW TO MINIMIZE SHEAR AND BENDING FORCES ON THE PIPE, WHICH INCLUDES A MINIMUM BEND RADIUS RECOMMENDATION FOR THE PLASTIC PIPE AS WELL AS DESIGN AND INSTALLATION OF SUPPORT SLEEVES. THIS MANUAL REPRESENTS THE SPECIFICATION TO WHICH DRESSER PRODUCTS ARE PRODUCED INCLUDING INSTALLATION INSTRUCTIONS FOR ALL PRODUCTS, PRODUCT MARKING, MANUFACTURING STANDARDS, PRESSURE RATINGS AND OTHER DATA. WHEN THE MANUAL IS ISSUED IT COMES WITH A REGISTRATION CARD FOR THE HOLDER TO FILL OUT AND RETURN TO DRESSER'S ADVERTISING DEPT. A DATABASE OF ALL REGISTERED HOLDERS OF THIS MANUAL IS MAINTAINED SO THAT WHEN CHANGES OR ADDITIONS ARE MADE, A DIRECT MAILING CAN UPDATE MANUALS. WE HAVE ALSO PUBLISHED AN INFORMATION LEAFLET ENTITLED, 'YOU SHOULD KNOW' (SEE EXHIBIT 2). THIS IS A MORE GENERAL NEWSLETTER TYPE DOCUMENT THAT WILL BE MAILED TO ALL CURRENT GAS UTILITY CUSTOMERS ALERTING THEM TO THE ISSUE OF PIPE BENDING/SHEARING AND HOW TO REDUCE STRESS IN PIPING. 2. GAS UTILITY TECHNICIANS - TO ALERT THE PERSON INSTALLING OUR PRODUCT TO THE ISSUE OF MINIMIZING SHEAR AND BENDING FORCES ON PIPING, WE HAVE DESIGNED A WARNING TAG (SEE EXHIBIT 3) WHICH WILL BE ATTACHED TO EACH OF OUR STEEL TAPPING TEES WHEN THEY ARE SHIPPED. THE ENCLOSED DOCUMENTS ADDRESS P-98-18, HOWEVER, WE ARE RECEPTIVE TO ANY FUTURE RECOMMENDATIONS THAT THE NTSB MAY HAVE, THAT IMPROVES THE SAFETY OF OUR PRODUCTS AND HOW THEY INTERFACE WITH NATURAL GAS DISTRIBUTION SYSTEMS. WE ARE CONTINUING OUR EFFORTS (AS WE HAVE DONE FOR MANY YEARS) AS PARTICIPANTS ON VARIOUS STANDARDS COMMITTEES INCLUDING ASTM, PPI, AND AGA, TO MAKE APPROPRIATE IMPROVEMENTS TO STANDARDS WHICH DEAL WITH PIPING INSTALLATIONS.

Addressee Organization Type: P-Private Industry

Communication Date: 1998-05-27

Communication Type: Official Correspondence

Communication Contents: (etter Mail Controlled 5/29/98 3:17:19 PM MC# 980692) WE ARE CURRENTLY REVIEWING THE INFO THAT YOUR FORWARDED WITH THE GAS INDUSTRY GROUPS IN WHICH WE PARTICIPATE, INCLUDING AMERICAN GAS ASSOCIATION, PLASTIC PIPE INSTITUTE, & AMERICAN SOCIETY FOR TESTING MATERIALS. WE ARE AWARE OF THE CURRENT INDUSTRY RECOMMENDATIONS PUBLISHED FOR LIMITING SHEAR AT MAIN CONNECTION WHICH ARE FOLLOWS: 1. THE AGA PLASTIC PIPE MANUAL, CHAPTER 4, UNDR GENERAL REQUIREMENTS, CONTAINS, A RECOMMENDATION FOR PROTECTING INSTALLATIONS FROM EXTERNAL LOADING. 2. THE GUIDANCE MANUAL FOR OPERATORS OF SMALL GAS SYSTEMS PUBLISHED BY THE DOT ALSO CONTAINS RECOMMENDATIONS ON THE USE OF PROTECTIVE SLEEVES FOR LIMITING LOADING ON THE PLASTIC PIPE AT SERVICE CONNECTIONS. 3. GPTC GUIDE FOR GAS TRANSMISSION & DISTRIBUTION PIPING SYSTEMS 1995-98 (ANSI Z380-1995). 4. ASTM D2774-94 REF. PARAGRAPH 7.4.3.3. 5. CODE OF FEDERAL REGULATIONS, TITLE 49,TRANSPORTATION, PART 192 PARAGRAPH 192.321 (C). OUR PRODUCTS HAVE BEEN DESIGNED IN KEEPING WITH THE REQUIREMENTS REFERENCED IN THE ABOVE DOCUMENTS. IN AN EFFORT TO HELP NTSB ACHIEVE A MEANINGFUL SOLUTION FOR THE PROBLEM, WE NEED SOME TIME TO CONSULT WITH THE ABOVE SOCIETIES, OUR CUSTOMERS & PIPE MANUFACTURERS. ANY ADDITIONAL INFO THAT YOU MAY HAVE REGARDING THE LOADING & SOIL CONDITIONS AROUND THE FAILED PIPED INSTALLATION WOULD BE HELPFUL. WE WANT TO ASSURE TYOU THAT SAFETY IS A MATTER OF PRIME CONCERN FOR US AT DMD & THAT WE WILL DO WHATEVER SHOULD BE DONE ASSIST IN ACHIEVING THAT GOAL. THE PROBLEMS SEEMS TO LIE IN THE CHARACTERISTICS OF DIFFERING PLASTIC PIPING & IMPROPER INSTALLATION TECHNIQUES BY THE INSTALLERS, WHETHER THAT BE UTILITY CREWS OR INDEPENDENT CONTRACTORS ENGAGED BY THE UTILITIS. THUS, IT APPEARS THE PROBLEM CAN BE MOST MEANIGFULLY ADDRESSED BY THE PIPING MANUFACTURERS, WHO BEST KNOW THE CHARACTERISTICS & TRAITS OF THEIR OWN PRODUCTS, & THE INSTALLERS OF THE SYSTEM.

Addressee Organization Type: P-Private Industry

Communication Date: 1998-07-07

Communication Type: Official Correspondence

Communication Contents: THE BOARD IS PLEASED THAT DRESSER IS DISCUSSING THE RECOMMENDATION WITH INDUSTRY GROUPS, SUCH AS THE AMERICAN GAS ASSOCIATION, THE PLASTICS PIPE INSTITUTE, AND THE AMERICAN SOCIETY FOR TESTING MATERIALS; DRESSER CUSTOMERS; & PIPING MANUFACTURERS TO ACHIEVE A MEANINGFUL SOLUTION FOR THE PROBLEM IDENTIFIED IN THE BOARD'S REPORT. THE BOARD ENCOURAGE DRESSER TO DEVELOP & PUBLISH RECOMMENDATION FOR LIMITING SHEAR & BENDING FORCES WHEN ITS STEEL PIPING TEES ARE USED TO CONNECT PLASTIC SERVICES TO MORE RIGID STEEL MAINS. WE WOULD APPRECIATE BEING KEEP INFORMED OF DRESSER'S PROGRESS IN IMPLEMENTING THIS RECOMMENDATION. PENDING FURTHER RESPONSE FROM DRESSER, P-98-18 HAS BEEN CLASSIFIED "OPEN--ACCEPTABLE RESPONSE."

Addressee Organization Type: P-Private Industry

Communication Date: 1999-02-08

Communication Type: Official Correspondence

Communication Contents: THE BOARD IS PLEASED THAT DRESSER, AFTER DISCUSSING THE RECOMMENDATION WITH INDUSTRY GROUPS, SUCH AS THE AMERICAN GAS ASSOCIATION, THE PLASTICS PIPE INSTITUTE, AND THE AMERICAN SOCIETY FOR TESTING MATERIALS, WITH DRESSER CUSTOMERS, AND WITH PIPING MANUFACTURERS, DEVELOPED AND PUBLISHED RECOMMENDATIONS THAT APPLY TO UTILITY ENGINEERING PERSONNEL AS WELL AS TO GAS UTILITY TECHNICIANS WHO INSTALL DRESSER STEEL TAPPING TEES. ACCORDINGLY, P-98-18 HAS BEEN CLASSIFIED "CLOSED--ACCEPTABLE ACTION."