OSHA Hazard Information Bulletins
December 15, 1994
| MEMORANDUM FOR: |
REGIONAL ADMINISTRATORS |
| FROM: |
JOHN B. MILES, DIRECTOR
DIRECTORATE OF COMPLIANCE PROGRAMS |
| SUBJECT: |
Hazard Information Bulletin - Suffocation Hazards in
Flat Storage Buildings and Tanks |
The purpose of this Hazard Information Bulletin is to heighten awareness of
the existence of a serious engulfment (suffocation) hazard in grain handling
facilities. Additionally, this bulletin is intended to alert OSHA's field
compliance personnel to such hazards so that the inspection scope in similar
facilities can be expanded to address them.
A serious hazard was reported by the Jacksonville, Florida, Area Office
associated with the cleaning of a large flat bottom grain tank located
at some feed mills or other grain storage facilities. In October 1993, while
"walking" the corn during the cleaning of a tank at a feed mill which
services a Florida poultry processing plant, an employee sank into the corn,
was engulfed and suffocated. These tanks are generally designed with a
single discharge auger that collects and transports grain from the silo to
another destination (the feed mill). In the process of moving the grain from
the tank, a residue will be left behind and some will extend upwards along
the side of the tank. This grain frequently cakes together and must
periodically be moved down to the auger for discharge.
In the Florida case, workers entered the tank from a side access portal
several feet above the floor. While the auger was operating, they walked
around on the corn (knocking it down from the sides of the tank with picks
and poles and pushing it with their feet), causing it to move toward the
center where it was removed by the auger.
A cleaning process similar to that used in Florida is likely to be necessary
in other storage facilities as well. Workers who enter the tank to clear the
grain may be required to "walk" a sizable accumulation of grain. If the
depth of the grain is more than a few feet and, particularly, if the
discharge auger is running while the workers are in the tank, the employees
are exposed to the hazard of suffocation, if the grain shifts and engulfs
them. This hazard is recognized in the industry and is addressed in the
preamble to the grain handling standard, 29 CFR 1910.272.
Hazards in grain storage structures used in agricultural operations covered
by 29 C.F.R. Part 1928 shall be cited under the General Duty Clause. Grain
storage structures used in non-agricultural operations shall generally be
cited under the grain handling standard, 29 C.F.R. 1910.272. The
requirements of 1910.272, however, do not cover structures if the diameter of
the structure is greater then the height, unless entry is made from the top
of the structure. This lack of coverage was based on comments received
during the rulemaking that certain flat storage structures do not present
engulfment hazards.
Because engulfment and mechanical hazards may exist in a grain storage
structure with a diameter greater than its height and not entered from its
top, such a structure can be cited under the Permit-Required Confined Space
and Lock-out/Tag-out Standards (1910.146 and .147).
To reduce or prevent suffocation and mechanical hazards in these structures,
the following guidance is provided:
a. Employers must have written confined space entry and lockout procedures;
b. A procedure for clearing the storage tank without exposure to employees
to an engulfment hazard must be developed and implemented;
c. Or, if the job cannot be done without employee exposure, employees must
wear a harness with a life line for any entry into any tank or structure
where an engulfment hazard is present. The life line shall be of such length
that it would not allow the employees to sink any further than waist deep in
the grain;
d. Employers could use an alternative protective system, e.g., static line
restraint devices in conjunction with the life line and harness;
e. An attendant must be stationed outside of the structure where he/she
can monitor the employees who are inside;
f. During any entry, the discharge auger shall not be running;
g. Wherever practicable, the employer should install horizontal sweep
augers at floor level that move the grain from the periphery of the
structure, where the corn is "bridged" or "hanging on the side" to the center
for discharge. This action removes the requirement (other than for
maintenance purposes) for employees to enter the structure to move the grain
manually.
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