NTSB Safety Recommendation Letter P-78-038 through P-78-040

Page 1Official PDF&T& p- ,os NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: .July 1 9 , 1978 Forwarded to: M r . Austin F. P l a t t President Dresser Manufacturing Division Dresser I n d u s t r i e s , Inc. 4 1 Fisher Avenue Bradford, Pennsylvania 16701 SAFETY RECOMMENDAT ION(S) P-78-38 throueh -40 A t 12:50 a.m., c . s . ~ . , on December 15, 1977, a 2-inch p l a s t i c gas main under an a l l e y i n downtown Lawrence, Kansas, pulled out of a compression coupling which joined i t t o a s t e e l gas main. Natural gas escaped from t h e main and migrated through t h e stone foundation walls of two nearby buildings. A t 1:20 a.m., t h e accumulations of gas i n t h e two buildings i g n i t e d . The r e s u l t i n g explosion and f i r e destroyed one building, severely damaged t h e o t h e r building, and broke nearby windows. Two persons were k i l l e d and t h r e e persons were injured. l/ - The 394-foot-long polyethylene p l a s t i c gas main had been i n s e r t e d i n an abandoned 3-inch steel main on June 2, 1975, and connected t o a s t e e l gas main with a Dresser S t y l e 90 short-barrel compression coupling. The 5-inch-long s t e e l s t i f f e n e r used i n s i d e of t h e end of the p l a s t i c pipe was manufactured by Du Pont and was a smooth s t i f f e n e r as opposed t o t h e s e r r a t e d type manufactured by Dresser. Tests a t t h e National Bureau of Standards indicated t h a t t h i s combination of component p a r t s w a s not a s strong a s t h e p l a s t i c pipe being joined. The tests f u r t h e r indicated t h a t t h e r e was an approximate one-third reduction i n t h e pullout r e s i s t a n c e of t h e j o i n t after it had been i n s t a l l e d f o r 2 112 years. Marks on the end of the plastic pipe indicated t h a t it had moved w i t h i n t h e standard S t y l e 90 compression coupling by thermal contraction over three winters. - 1/ For more d e t a i l e d information read "Pipeline Accident Report -- Kansas Public Service Company, I n c . , Explosion and F i r e , Lawrence, Kansas, December 15, 1977 ," (NTSB-PAR-78-4). 2386#

Page 2- 2 - The Dresser i n s t a l l a t i o n i n s t r u c t i o n s f o r S t y l e 90 couplings dated January 1974 s t a t e s t h a t "when pipe movement out of t h e coupling o r f i t t i n g might occur, proper anchorage of the pipe must be provided.'' This message s e n t i n boxes of f i t t i n g s probably w a s overlooked by t h e gas company's f i e l d personnel. Therefore, the Safety Board would l i k e t o see a more strongly worded warning issued with each box of f i t t i n g s s o t h a t f i e l d personnel w i l l not overlook its importance, such as: WARNING! THIS STANDARD 2-INCH STYLE 90 COUPLING I S NOT RECOMXENDED FOR ANCHORING STEEL OR PLASTIC PIPE. THE USE OF A SPECIAL PLASTIC P I P E LOCK INSERT STYLE 90 OR "700" POSI-HOLD TRANSITION COUPLING IS RECOMMENDED FOR J O I N I N G INSERTED PLASTIC PIPELINES MORE THAN 75 FEET I N LENGTH. CONSULT WITH YOUR ENGINEERING DEPARTMENT OR YOUR DRESSER REPRESENTATIVE IF YOU HAVE ANY QUESTIONS. The American Gas Association has been asked t o publish results of tests t o member companies regarding whether t h e j o i n t should be used f o r gastightness only o r a l s o f o r pullout r e s i s t a n c e . The Safety Board recognizes t h e need of the steel s t i f f e n e r t o be compatible with t h e design of t h e compression coupling, and would p r e f e r t h a t a s i n g l e manufacturer produce both components and be responsible f o r t h e e n t i r e j o i n t . However, t h e r e a r e those i n industry and government t h a t w i l l i n s i s t on using products from more than one manufacturer. I f i t is f e a s i b l e t o test various combinations of s t i f f e n e r s and p l a s t i c pipes t h a t a customer may wish t o use with your couplings, it would be preferable f o r a s i n g l e t e s t i n g laboratory t o test t h e entire j o i n t under controlled conditions. Therefore, t h e National Transportation Safety Board recommends t h a t the Dresser Manufacturing Company: Enclose strongly worded warning l i t e r a t u r e i n each box of S t y l e 90 couplings shipped i n d i c a t i n g t h a t t h i s standard compression coupling is NOT recommended f o r connecting long lengths of i n s e r t e d p l a s t i c pipes o r t h e anchoring of p l a s t i c pipe. (Class 11, P r i o r i t y Action)(P-78-38) Provide test data t o t h e American Gas Association and make recommendations t o them as t o what t h e safe a p p l i c a t i o n should be f o r each f i t t i n g t h a t Dresser manufactures t o j o i n p l a s t i c pipe. (Class 111, Longer Term Action) (P-78-39)#

Page 3- 3 - Investigate the possibility of setting up a testing laboratory where customers can send in samples of plastic pipe and inserts to be tested with couplings and then be provided certified results of the tests and application recommendations. (Class 111, Longer Term Action)(P-78-40) KING, Chairman, McADAMS, HOGUE, and DRIVER, Members, concurred in the above recommendations.#