NTSB Safety Recommendation Letter P-78-033

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: July 10, 1978 ^______-_-_________-____________________- Forwarded t o : M r . L. D. Santman Director Materials Transportation Bureau Department of Transportation Washington, D.C. 20590 SAFETY RECOMMENDATION (S) P-78-33 A t 12:50 a.m., c . s . t . , 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 to a steel gas main. Natural gas escaped from t h e main and migrated through t h e stone foundation w a l l s of two nearby buildings. A t 1:20 a.m., the accumulations of gas i n t h e two buildings ignited. 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 three persons were injured. - 1/ 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. The p l a s t i c main had not been anchored against pullout t h a t could be expected with thermal contraction. The mechanical j o i n t was a standard, short-barrel com- pression coupling w i t h a smooth metal i n s e r t which individually were acceptable under 49 CFR 192.281(e). However, a s the Safety Board recom- mended t o t h e Secretary of Transportation after the similar Fremont, Nebraska, accident, t h e s t i f f e n e r a l s o should have been designed t o be compatible with t h e compression coupling s o t h a t t h e p l a s t i c pipe would n o t p u l l out of the coupling. A t t h e same t i m e , the Safety Board a l s o recommended that the Department of Transportation: “Determine i f t h e r e are l o c a t i o n s o r circumstances where standard compression couplings are unsafe, and amend 49 CFR 1 9 2 accordingly to p r o h i b i t their use f o r such a p p l i c a t i o n s (P-76-45).” I n a response dated March 2, 1977, the Material Transportation Bureau (MTB) s t a t e d : “We b e l i e v e t h a t a properly i n s t a l l e d compression coupling can be u t i l i z e d i n v i r t u a l l y a l l locations o r circumstances. A t t h i s t i m e , w e have no evidence t o i n d i c a t e t h a t t h e use of compression couplings m u s t be predicated on l o c a t i o n o r other circumstances.” - 1/ For more d e t a i l e d information read “Pipeline Accident Report -- Kansas Public Service Company, Inc., Explosion and F i r e , Lawrence, Kansas, December 15, 1977,” (NTSB-PAR-78-4). - 2 / L e t t e r of Recommendation dated September 15, 1976; Safety Recommendation P-76-44. 2386#

Page 2The Safety Board hopes that the MTB will consider the evidence of this and other accidents that have occurred with plastic pipe and standard compression couplings since 1977, and will reconsider its response to these recommendations. Unlike MTB, the Safety Board does not share the opinion that the correction of these safety problems will result in a "comparatively minor improvement in safety." The Safety Board is emphatic in its contention that a standard compression coupling on an unrestrained plastic gas main is unsafe unless the coupling manufacturer also designs the stiffener so that the joint is as strong as the pipes being joined. The location of this standard compression coupling under a narrow paved alley and within 5 feet of a building wall is likewise considered unsafe by the Safety Board. Therefore, the National Transportation Safety Board recommends that the Materials Transportation Bureau of the U.S. Department of Transportation: Reconsider its responses to safety recommendations P-76-44 and P-76-45 in light of this and other accidents that have occurred with plastic pipe and I t standard" compression couplings since 1977. Urgent Action) (P-78-33) (Class I,#