NTSB Safety Recommendation Letter P-76-067 through P-76-072

Page 1Official PDFI/ 7' :. / i i { i ATIONAL T ~ A ~ S P O ~ T A T I O ~ SAFETY WASHINGTON, D.C. BOA 1SSUED:October 2 , 197G Forwarded to: Honorable Frank Roberts Mayor, Phenix C i t y , Alabama P. 0 . Box 1207 Phenix C i t y , Alabama 36867 i S A F E T Y R E C O W M E N D A T l O N ( S ) P-76-67 through P-76-72 A t 7 a.m. on March 2 7 , 1 9 7 6 , a two-story b u i l d i n g t h a t housed Phenix Cutting and Sewing, I n c . , i n Phenix C i t y , Alabama, exploded and burned. The explosion and f i r e k i l l e d t h e s i x persons i n the b u i l d i n g . - 1/ The National Transportation Safety Board's i n v e s t i - g a t i o n of t h e accident d i s c l o s e d t h a t n a t u r a l gas a t 20-psig p r e s s u r e had leaked from a cracked, 3-inch c a s t i r o n main, which was l o c a t e d 1 2 f e e t from t h e b u i l d i n g under concrete s t e p s which l e d from t h e s t r e e t up t o t h e sidewalk. The 3-inch p i p e was cracked c i r c u m f e r e n t i a l l y and gas which leaked from t h i s crack was trapped from above by t h e concrete s t e p s . Consequently gas seeped i n t o a v a u l t e d a r e a under t h e sidewalk and i n t o t h e base- ment of t h e b u i l d i n g through h o l e s i n t h e w a l l , where it w a s i g n i t e d by an unknown source. The 3-inch c a s t i r o n p i p e was l o c a t e d under, and a t p o i n t s touching, t h e concrete s t e p s , a t about t h e same e l e v a t i o n as t h e s t r e e t . A l s o i n s t a l l e d under t h e s t e p s were a 6-inch c a s t i r o n gas main and a 24-inch storm sewer l i n e a t depths of 2 f e e t and 4 f e e t , r e s p e c t i v e l y . From an i n s p e c t i o n made by t h e Phenix City Building Department on March 1 3 , 1975, t h e City was aware t h a t during heavy r a i n s , water e n t e r e d t h e b u i l d i n g e i t h e r from t h e storm sewer or from cracks i n t h e sidewalk. Water from e i t h e r source had t h e p o t e n t i a l t o undermine the p i p e ' s founda- t i o n and thus enable the v i b r a t i o n s from t r a f f i c on t h i s - 1/ The National Transportation Safety Board w i l l n o t i s s u e a f u l l r e p o r t of t h i s a c c i d e n t . 1898#

Page 2- 2 - P-76-67 t h r o u g h P-76-72 major a r t e r y between Columbus, Georgia, and Phenix C i t y t o s t r e s s t h e p i p e Neither t h e C i t y ' s Building O f f i c i a l ' s Office nor t h e Public Works Department n o t i f i e d t h e U t i l i t i e s Department of t h e problem s i n c e they d i d n o t r e a l i z e t h a t t h e water flow could undermine t h e gas main. On numerous occasions, t h e Alabama P u b l i c Service Co has i d e n t i f i e d o p e r a t i o n s of t h e Phenix City U t i l i t i e s Bo t h a t do n o t conform t o 49 CFR 192 and has r e q u i r e d a c t i o n Although t h e U t i l i t i e s Board c o r r e c t e d t h e d e f i c i e n t h e c o r r e c t i o n s were s h o r t - l i v e d because management of t h e g operations changed f r e q u e n t l y . The d e f i c i e n c i e s included i n frequent and inadequate leak surveys, inadequate response t o r e p a i r l e a k s found, i n a b i l i t y of t h e gas system's personnel t o f i n d l e a k s found by t h e surveys, and inadequate r e p a i r of l e a k s The most r e c e n t l e a k survey ( A p r i l 1975) d e t e c t e d a Class I11 l e a k over a 2-inch c a s t i r o n main a c r o s s t h e stree from t h e accident s i t e Although gas system personnel r e c o r on December 1 2 , 1975, t h a t no leak could be found, t h e Alabama Public Service Commission l o c a t e d a leak on March 28, 1 9 7 6 , i n t h e a r e a of t h e o r i g i n a l r e p o r t which appeared t o be t h e Class I11 l e a k o r i g i n a l l y d e t e c t e d . Un K ~ L L L 1, 1975, a flame i o n i z a t i o n l e a k sur formed i n f r o n t of t h e Phenix Cutting and Sewing Co d e t e c t e d gas under t h e e a s t e r n p o r t i o n of t h e s t e p s . Gas s y records show t h a t a leak a t a j o i n t on t h e 3-inch main w a s recaulked east of the s t e p s (no leak clamp was i n s t a l l e d 2/ There i s no record t h a t a leak check was performed a f t e r f h j o i n t was recaulked t o a s s u r e t h a t t h e source of t h e gas wh w a s d e t e c t e d under t h e s t e p s had been eliminated by r e p a i r . A f t e r t h e explosion, f o u r breaks were found i n t h e c a s t i r o n mains; a l l b u t one were caused when t h e b u i l d i The S a f e t y Board submitted t h e broken s e c t i o n s of p i p e t o an independent m e t a l l u r g i c a l l a b o r a t o r y (Anderson and Associates Inc of Houston, Texas) The t e s t s and a n a l y s i s de 1 , a crack had been p r e s e n t f o r some p e r i o d of ti p r i o r t o t h e accident . . The crack was caused by bending s t r e s s e s from e x t e r n a l loading or p o s s i b l y c y c l i c v i b r a t i o n loading. The s t r e s s w a s a p p l i e d t o a pipe w a l l d r a s t i c a l l y r duced by g r a p h i t i c c o r r o s i o n . The marginal q u a l i t y of t h e p i was a c o n t r i b u t i n g f a c t o r . Other c o n t r i b u t i n g f a c t type and f i l l i n g c o n d i t i o n s and proximity t o an a r e a c y c l i c load. I ' Therefore, t h e National Transportation S a f e t y mends t h a t t h e U t i l i t i e s Board of Phenix C i t y : Inspect i t s c a s t i r o n p i p i n g system throu a random sampling program t o determine i f - 2/ Leak clamp r e q u i r e d by 49 CFR 192.753(b).#

Page 3- 3 - P-76-67 through P-76-72 o t h e r a r e a s a r e covered s u f f i c i e n t l y t o pre- vent damage from e x t e r n a l l o a d s , i f piping i n o t h e r a r e a s i s g r a p h i t i z e d t o a degree t h a t it should be removed from s e r v i c e , and t o r e c t i f y any p o t e n t i a l l y hazardous conditions found. (P-76-67) (Class I , IJrgent Followup) Perform tests a f t e r a leak has been r e p a i r e d t o a s s u r e t h e adequacy of r e p a i r s and t o assure t h a t no o t h e r source of gas was c o n t r i b u t i n g t o t h e leak a r e a . (P-76-68) (Class I, IJrgent Fo 11 owup ) Assure t h a t when a c a s t i r o n caulked b e l l and s p i g o t j o i n t i s exposed, a leak clamp i s i n - s t a l l e d a s required by 49 CFR 192.753(b). (P-76-69) (Class I , Urgent Followup) Train gas system personnel i n t h e use of a v a i l a b l e leak d e t e c t i o n equipment t o l o c a t e a r e a s of gas leakage and t o pinpoint t h e source of the leakage. (P-76-70) (Class I, Urgent Followup) Test leak d e t e c t i o n equipment and, i f necessary, r e c a l i b r a t e i t p e r i o d i c a l l y a s s u r e i t s proper operation. (P-76-71) (Class I , Urgent Followup) t o Correct promptly a l l outstanding d i f f i c i e n c i e s which have been documented by the Alabama Public Service Commission (P-76-72) (Class I , Urgent Followup. ) TODD, Chairman, BAILEY, Vice and HALEY, Members, concurred i n man, McADAMS, HOGUE, ove recommendations. , By: Webster B . Todd, J'I. Chairman#