# NTSB Safety Recommendation Letter P-78-056

**Citation:** P-78-056  
**Type / status:** guidance / guidance  
**Agency:** National Transportation Safety Board  
**Effective:** 1978-08-28  
**Published:** 1978-08-28

Official NTSB transmittal letter for safety recommendation P-78-056, issued 1978-08-28.

## Document text

Page 1
NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: August 28, 1978 Mr. L.D. Santman Director Materials Transportation Bureau Department o f Transportation Washington, D.C. 20590 SAFETY RECOMMENDAT I ON (S) P-78-56 On March 29, 1978, the Oklahoma Natural Gas Company ( O N G ) dispatched a crew to shut off gas service t o a shopping center i n Oklahoma cit.y a t a regulator vault so that customer service lines could be repaired. The crew was unable t o close a valve, inside the vault, that was under water upstream of the regulator, so the,y disconnected the l i n e on the low-pressure side of the regulator a t a 2-inch union and plugged the line without f i r s t stopping the flow of gas. There was another valve outside the vault; however, i t was paved over with asphalt, and the crew did not attempt to uncover i t . On April 24, 1978, ONG assigned a different crew t o restore gas service to the shopping center. A t 3:50 p.m., c.s.t., two employees were overcome by gas while attempting t o reconnect the 2-inch union without f i r s t stopping the flow of gas inside the vault. This crew also had not been able t o close the valve inside the vault upstream of the regulator, and the,y did not try t o uncover the valve outside the vault. Instead, the men had removed the p l u g and stuffed the l i n e with a rag. When the rag was pulled out, however, the,y were unable t o align the union properly t o s t a r t the threads. The escaping gas f i l l e d the 3- by 4- by 6-foot vault within minutes and the men were overcome. Three other ONG employees entered the vault t h r o u g h the 19-inch opening t o rescue the men and were also overcome; the crew d i d n o t have a respirator a t the job s i t e . One man was pulled out of the vault by other ONG workers and was revived a t the scene; however, the other four men died of asphyxiation. A mainline valve f i n a l l y was turned off, and rescue personnel with a i r packs arrived and removed the asphyxiated men from the vault. The five men involved i n connecting the l i n e in the vault had each been employed by ONG an average of 20 years, and three of them were supervisors. A l t h o u g h ONG has trained i t s men on the use of air-breathing masks, ventilators, and l i f e b e l t s , the company does not have written instructions about where t h i s safety equipment shall be used. 2422

Page 2
-2- The Safety Board concludes that if the ONG workmen had pumped the water out of the vault and mad? the valve operable, or i f they had uncovered the valve outside the v a u l t so t h a t i t could be used t o stop the flow of gas before reconnecting the 2-inch union, this accident would not have occurred. On December 22, 1975, the Office of Pipeline Safety Operations (OPSO) issued an Advance F!otice of Proposed Rulemaking i n Uocket No. This notice proposed development of additional safety and health regulations f o r gas system employees and pointed out the need t o better define applicability of Occupational Safety and Health Administration (OSHA) and OPSO regulations as they r e l a t e t o gas system operations. The Safety Board investigated an accident, which occurred on March 26, 1977, i n Buffalo, New York, that resulted in the deaths o f two gas company employees who were performing repairs in a manhole. During i t s investiga- t i o n , the Safety Board learned t h a t neither OSHA nor OPSO has adequate standards governing employee safety while working in manholes or vaults. Therefore, the National Transportation Safety Board recommends t h a t the Materials Transportation Bureau of the U.S. Department of Transpor- t a t i on : Expedite i t s role in setting standards f o r gas company safety and health, promulgate necessary regulations, and coordinate a l l actions with the Occupational Safety and Health Administration t o assure t h a t regulations developed are compatible. (Class I , Urgent Action) (P-78-56). KING, Chairman, kAUAMS, HOGUE, and URIVER, Members, concurred i n the above recommendation.

## Provenance

- Official: Yes
- Source: <https://www.ntsb.gov/safety/safety-recs/recletters/P78_56.pdf>
- Source ID: `ntsb-transmittal-letters`
- SHA-256: `6b13399135c8a5b509cc8dd22cda12aaeb44f7b35b4f42137917db88eb205837`
- Retrieved: 2026-08-20T04:55:47.446Z
- Exported: 2026-08-27T09:02:59.442Z
- Document slug: `ntsb-transmittal-letter-p78-56`

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