OSHA Hazard Information Bulletins
July 3, 1996
| MEMORANDUM FOR: |
REGIONAL ADMINISTRATORS |
| FROM: |
STEPHEN MALLINGER
Acting Director
Directorate of Technical Support |
| SUBJECT: |
Hazard Information Bulletin(1): Water-Reactive
Chemicals, Hazardous Materials Not Covered Under
29 CFR 1910.119 |
________
FOOTNOTE(1)The Directorate of Technical Support issues Hazard Information
Bulletins (HIBs) in accordance with OSHA Instruction CPL 2.65 to provide
relevant information regarding unrecognized of misunderstood health hazards,
inadequacies of materials, devices, techniques, and engineering safety
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
through evaluation of available facts, literature and in coordination with
appropriate parties.
This HIB highlights a potentially serious hazard regarding materials not
covered by the Process Safety Management Standard, 29 CFR 1910.119.
Recently, the Hasbrouck Heights Area Office investigated an explosion and
fire which occurred at a custom chemical blending ("toll blending") facility,
resulting in the deaths of five employees and the destruction of the
facility. The employees were in the process of making "Gold Precipitating
Agent" by blending 5,400 lbs. of sodium hydrosulfite, 1,800 lbs. of aluminum
powder, 900 lbs. of potassium carbonate, and 8 liters of benzaldehyde.
Sodium hydrosulfite and aluminum powder are highly water reactive and
aluminum powder in this quantity has catastrophic potential. Neither of
these materials are covered by 29 CFR 1910.119.
The employer's representatives stated that they relied on the information in
the material safety data sheets (MSDSs) to perform a brief hazard review.
This review failed to identify the hazards of that mixture. The mixing was
done in a 125 cubic foot blender that had a water-cooled mechanical seal. It
is very likely that water inadvertently entered the blend. Mechanical seals
are known throughout the industry to be prone to this type of failure.
Symptoms of a leak were noted and reported, but only to employees who did not
know that water reactive chemicals were to be blended. A mechanical problem
developed with the liquid feed system, which had not been checked prior to
the addition of the dry ingredients. This caused a deviation from the
standard operating procedures and the dry ingredients remained in the blender
for a much longer period than originally anticipated. Water entering the
subsurface caused the sodium hydrosulfite and possibly the aluminum powder to
react, slowly at first. The large volume of powder did not conduct heat
readily and the exothermic reaction intensified. In response to noxious
gases being released, the employer decided to unload the blender, based upon
the information in the MSDS for the finished blend. During the unloading
process, an ignition and explosion occurred, propelling the vessel and its
concrete supports approximately 48 feet. The pressure wave destroyed part of
the facility and caused four of the five deaths; the fifth employee was
killed by the ensuing fire, which destroyed most of the plant.
As a result of this accident, the following recommendations are made:
* A process safety analysis should be done for all materials with a
catastrophic potential, even if they are not covered by the Process Safety
Standard. This should include a careful review of chemical hazards,
incompatibilities, and a thorough check of all mechanical equipment.
Standard operating procedures should be developed and the consequences of
deviation should be identified.
* Employers that rely on MSDSs created by other entities must be
aware that the MSDSs for raw materials may not identify all hazards which may
be encountered when mixing or blending them with other materials. This may
be true even if there is no reaction anticipated or apparent. MSDSs for the
final mixture may specifically address the hazards of shipping container
quantities, but may not apply to the hazards of the larger quantities
necessary to make the mixture.
* Many types of industrial vessels use mechanical seals to permit
external drive of internal equipment such as agitators. In certain
applications, mechanical seals must be liquid cooled. While regular
maintenance may help to prevent failure and leakage, the possibility of a
malfunction always exists. Employers should assure that materials processed
in these vessels are not incompatible with liquids used to cool the seals.
Please distribute this bulletin to all Area Offices, State Plan States,
Consultation Projects and appropriate local labor and industry associations.
Copies of this HIB may be used for outreach purposes.
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