OSHA Hazard Information Bulletins
March 5, 1990
| MEMORANDUM FOR: |
REGIONAL ADMINISTRATORS |
| THRU: |
LEO CAREY
Director
Office of Field Programs |
| FROM: |
THOMAS J. SHEPICH
Director
Directorate of Technical Support |
| SUBJECT: |
Hazard Information Bulletin Anaerobic Decomposition in
Cooling Water Systems |
The Directorate of Technical Support issues Hazard information
Bulletins (HIB) as needed to provide relevant information regarding
unrecognized or misunderstood safety and health hazards, inadequacies of
materials, devices, techniques, and engineering controls. HIBs are initiated
based on information provided by the field staff, studies, reports and
concerns expressed by safety and health professionals, employers, and the
public. Information is compiled based on a comprehensive evaluation of
available facts, literature, and in coordination with appropriate parties.
HIBs do not necessarily reflect an OSHA policy.
Recently information from the Department of Energy indicated that a health
and safety risk could exist while cutting and salvaging abandoned cooling
water systems.
In 1989, a fireball developed when a pipefitter used a cutting torch on a
cooling water system pipe. The piping connected a heat exchanger used to
cool wall panels in a room housing a nuclear reactor. The system had been
abandoned for 19 years. The water in the cooling system pipes contained
untreated tap water supplied from the building main. The pipes for this
system had been left charged with water. The water in the pipes was drained
several months before the cutting and salvaging operation. While cutting
these pipes, a fireball suddenly developed and lasted for a short time.
Fortunately, the pipefitter was not hurt.
Upon investigation, a hydrogen sulfide odor was present in parts of the pipe
which had been previously cut open. Apparently explosive gases were
generated within the piping system. The gases were ignited by the cutting
torch.
Anaerobic decomposition is the probable causative agent for the production
of the explosive gases. Anaerobic decomposition can occur under certain
conditions, when microorganisms or bacteria (capable of existing without
oxygen) and organic materials are brought together. Flammable gases such as
hydrogen sulfide and methane may be produced. This reaction is not unusual in
waste processing facilities; it is, however, unusual to find hazardous
quantities of such gases in water cooling systems. Precautions to be taken
when cutting into water cooling system include:
a. Before cutting open any water line flush the system with fresh
water.
b. Drain the system, allowing for proper disposal of contents,
after assuring that the area is appropriately ventilated.
c. Open valves
d. Ventilate the area before cutting to permit the safe
dissipation of hazardous vapors and gases.
Please distribute this bulletin to all area offices, state plan states, and
consultation project officers.
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