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Title 29: Labor
PART
1910—OCCUPATIONAL SAFETY AND HEALTH STANDARDS
Subpart
R—Special Industries

§1910.272   Grain handling
facilities.

(a) Scope. This section
contains requirements for the control of grain dust fires and explosions,
and certain other safety hazards associated with grain handling
facilities. It applies in addition to all other relevant provisions of
part 1910 (or part 1917 at marine terminals).

Note to paragraph
(a):
For grain-handling facilities in the marine-terminal industry only, 29 CFR
1910.272 is to be enforced consistent with the interpretations in OSHA
Compliance Directive 02-00-066, which is available on OSHA's Web page at
www.osha.gov.

(b) Application. (1) Paragraphs
(a) through (n) of this section apply to grain elevators, feed mills,
flour mills, rice mills, dust pelletizing plants, dry corn mills, soybean
flaking operations, and the dry grinding operations of soycake.

(2) Paragraphs (o), (p), and (q) of this section apply only to grain
elevators.

(c) Definitions.

Choked leg means a condition of
material buildup in the bucket elevator that results in the stoppage of
material flow and bucket movement. A bucket elevator is not considered
choked that has the up-leg partially or fully loaded and has the boot and
discharge cleared allowing bucket movement.

Flat storage structure means a
grain storage building or structure that will not empty completely by
gravity, has an unrestricted ground level opening for entry, and must be
entered to reclaim the residual grain using powered equipment or manual
means.

Fugitive grain dust means
combustible dust particles, emitted from the stock handling system, of
such size as will pass through a U.S. Standard 40 mesh sieve (425 microns
or less).

Grain elevator means a facility
engaged in the receipt, handling, storage, and shipment of bulk raw
agricultural commodities such as corn, wheat, oats, barley, sunflower
seeds, and soybeans.

Hot work means work involving
electric or gas welding, cutting, brazing, or similar flame producing
operations.

Inside bucket elevator means a
bucket elevator that has the boot and more than 20 percent of the total
leg height (above grade or ground level) inside the grain elevator
structure. Bucket elevators with leg casings that are inside (and pass
through the roofs) of rail or truck dump sheds with the remainder of the
leg outside of the grain elevator structure, are not considered inside
bucket elevators.

Jogging means repeated starting
and stopping of drive motors in an attempt to clear choked legs.

Lagging means a covering on
drive pulleys used to increase the coefficient of friction between the
pulley and the belt.

Permit means the written
certification by the employer authorizing employees to perform identified
work operations subject to specified precautions.

(d) Emergency action plan. The
employer shall develop and implement an emergency action plan meeting the
requirements contained in 29 CFR 1910.38.

(e)Training. (1) The employer
shall provide training to employees at least annually and when changes in
job assignment will expose them to new hazards. Current employees, and new
employees prior to starting work, shall be trained in at least the
following:

(i) General safety precautions associated with the facility, including
recognition and preventive measures for the hazards related to dust
accumulations and common ignition sources such as smoking; and,

(ii) Specific procedures and safety practices applicable to their job
tasks including but not limited to, cleaning procedures for grinding
equipment, clearing procedures for choked legs, housekeeping procedures,
hot work procedures, preventive maintenance procedures and
lock-out/tag-out procedures.

(2) Employees assigned special tasks, such as bin entry and handling of
flammable or toxic substances, shall be provided training to perform these
tasks safely.

Note to paragraph
(e)(2):
Training for an employee who enters grain storage structures includes
training about engulfment and mechanical hazards and how to avoid
them.

(f) Hot work permit. (1) The
employer shall issue a permit for all hot work, with the following
exceptions:

(i) Where the employer or the employer's representative (who would
otherwise authorize the permit) is present while the hot work is being
performed;

(ii) In welding shops authorized by the employer;

(iii) In hot work areas authorized by the employer which are located
outside of the grain handling structure.

(2) The permit shall certify that the requirements contained in
§1910.252(a) have been implemented prior to beginning the hot work
operations. The permit shall be kept on file until completion of the hot
work operations.

(g) Entry into grain storage
structures. This paragraph applies to employee entry into bins,
silos , tanks, and other grain storage structures. Exception: Entry through unrestricted
ground level openings into flat storage structures in which there are no
toxicity, flammability, oxygen-deficiency, or other atmospheric hazards is
covered by paragraph (h) of this section. For the purposes of this
paragraph (g), the term “grain” includes raw and processed grain and grain
products in facilities within the scope of paragraph (b)(1) of this
section.

(1) The following actions shall be taken before employees enter bins,
silos, or tanks:

(i) The employer shall issue a permit for entering bins, silos, or
tanks unless the employer or the employer's representative (who would
otherwise authorize the permit) is present during the entire operation.
The permit shall certify that the precautions contained in this paragraph
(§1910.272(g)) have been implemented prior to employees entering bins,
silos or tanks. The permit shall be kept on file until completion of the
entry operations.

(ii) All mechanical, electrical, hydraulic, and pneumatic equipment
which presents a danger to employees inside grain storage structures shall
be deenergized and shall be disconnected, locked-out and tagged,
blocked-off, or otherwise prevented from operating by other equally
effective means or methods.

(iii) The atmosphere within a bin, silo, or tank shall be tested for
the presence of combustible gases, vapors, and toxic agents when the
employer has reason to believe they may be present. Additionally, the
atmosphere within a bin, silo, or tank shall be tested for oxygen content
unless there is continuous natural air movement or continuous forced-air
ventilation before and during the period employees are inside. If the
oxygen level is less than 19.5%, or if combustible gas or vapor is
detected in excess of 10% of the lower flammable limit, or if toxic agents
are present in excess of the ceiling values listed in subpart Z of 29 CFR
part 1910, or if toxic agents are present in concentrations that will
cause health effects which prevent employees from effecting self-rescue or
communication to obtain assistance, the following provisions apply.

(A) Ventilation shall be provided until the unsafe condition or
conditions are eliminated, and the ventilation shall be continued as long
as there is a possibility of recurrence of the unsafe condition while the
bin, silo, or tank is occupied by employees.

(B) If toxicity or oxygen deficiency cannot be eliminated by
ventilation, employees entering the bin, silo, or tank shall wear an
appropriate respirator. Respirator use shall be in accordance with the
requirements of §1910.134.

(iv) “Walking down grain” and similar practices where an employee walks
on grain to make it flow within or out from a grain storage structure, or
where an employee is on moving grain, are prohibited.

(2) Whenever an employee enters a grain storage structure from a level
at or above the level of the stored grain or grain products, or whenever
an employee walks or stands on or in stored grain of a depth which poses
an engulfment hazard, the employer shall equip the employee with a body
harness with lifeline, or a boatswain's chair that meets the requirements
of subpart D of this part. The lifeline shall be so positioned, and of
sufficient length, to prevent the employee from sinking further than
waist-deep in the grain. Exception: Where the employer can
demonstrate that the protection required by this paragraph is not feasible
or creates a greater hazard, the employer shall provide an alternative
means of protection which is demonstrated to prevent the employee from
sinking further than waist-deep in the grain.

Note to paragraph
(g)(2):
When the employee is standing or walking on a surface which the employer
demonstrates is free from engulfment hazards, the lifeline or alternative
means may be disconnected or removed.

(3) An observer, equipped to provide assistance, shall be stationed
outside the bin, silo, or tank being entered by an employee.
Communications (visual, voice, or signal line) shall be maintained between
the observer and employee entering the bin, silo, or tank.

(4) The employer shall provide equipment for rescue operations which is
specifically suited for the bin, silo, or tank being entered.

(5) The employee acting as observer shall be trained in rescue
procedures, including notification methods for obtaining additional
assistance.

(6) Employees shall not enter bins, silos, or tanks underneath a
bridging condition, or where a buildup of grain products on the sides
could fall and bury them.

(h) Entry into flat storage
structures. For the purposes of this paragraph (h), the term
“grain” means raw and processed grain and grain products in facilities
within the scope of paragraph (b)(1) of this section.

(1) Each employee who walks or stands on or in stored grain, where the
depth of the grain poses an engulfment hazard, shall be equipped with a
lifeline or alternative means which the employer demonstrates will prevent
the employee from sinking further than waist-deep into the grain.

Note to paragraph
(h)(1):
When the employee is standing or walking on a surface which the employer
demonstrates is free from engulfment hazards, the lifeline or alternative
means may be disconnected or removed.

(2)(i) Whenever an employee walks or stands on or in stored grain or
grain products of a depth which poses an engulfment hazard, all equipment
which presents a danger to that employee (such as an auger or other grain
transport equipment) shall be deenergized, and shall be disconnected,
locked-out and tagged, blocked-off, or otherwise prevented from operating
by other equally effective means or methods.

(ii) “Walking down grain” and similar practices where an employee walks
on grain to make it flow within or out from a grain storage structure, or
where an employee is on moving grain, are prohibited.

(3) No employee shall be permitted to be either underneath a bridging
condition, or in any other location where an accumulation of grain on the
sides or elsewhere could fall and engulf that employee.

(i) Contractors. (1) The
employer shall inform contractors performing work at the grain handling
facility of known potential fire and explosion hazards related to the
contractor's work and work area. The employer shall also inform
contractors of the applicable safety rules of the facility.

(2) The employer shall explain the applicable provisions of the
emergency action plan to contractors.

(j) Housekeeping. (1) The
employer shall develop and implement a written housekeeping program that
establishes the frequency and method(s) determined best to reduce
accumulations of fugitive grain dust on ledges, floors, equipment, and
other exposed surfaces.

(2) In addition, the housekeeping program for grain elevators shall address fugitive
grain dust accumulations at priority housekeeping areas.

(i) Priority housekeeping areas shall include at least the following:

(A) Floor areas within 35 feet (10.7 m) of inside bucket elevators;

(B) Floors of enclosed areas containing grinding equipment;

(C) Floors of enclosed areas containing grain dryers located inside the
facility.

(ii) The employer shall immediately remove any fugitive grain dust
accumulations whenever they exceed 1⁄8 inch (.32 cm) at
priority housekeeping areas, pursuant to the housekeeping program, or
shall demonstrate and assure, through the development and implementation
of the housekeeping program, that equivalent protection is provided.

(3) The use of compressed air to blow dust from ledges, walls, and
other areas shall only be permitted when all machinery that presents an
ignition source in the area is shut-down, and all other known potential
ignition sources in the area are removed or controlled.

(4) Grain and product spills shall not be considered fugitive grain
dust accumulations. However, the housekeeping program shall address the
procedures for removing such spills from the work area.

(k) Grate openings.
Receiving-pit feed openings, such as truck or railcar receiving-pits,
shall be covered by grates. The width of openings in the grates shall be a
maximum of 21⁄2 inches (6.35 cm).

(l) Filter collectors. (1) All
fabric dust filter collectors which are a part of a pneumatic dust
collection system shall be equipped with a monitoring device that will
indicate a pressure drop across the surface of the filter.

(2) Filter collectors installed after March 30, 1988 shall be:

(i) Located outside the facility; or

(ii) Located in an area inside the facility protected by an explosion
suppression system; or

(iii) Located in an area inside the facility that is separated from
other areas of the facility by construction having at least a one hour
fire-resistance rating, and which is adjacent to an exterior wall and
vented to the outside. The vent and ductwork shall be designed to resist
rupture due to deflagration.

(m) Preventive maintenance. (1)
The employer shall implement preventive maintenance procedures consisting
of:

(i) Regularly scheduled inspections of at least the mechanical and
safety control equipment associated with dryers, grain stream processing
equipment, dust collection equipment including filter collectors, and
bucket elevators;

(ii) Lubrication and other appropriate maintenance in accordance with
manufacturers' recommendations, or as determined necessary by prior
operating records.

(2) The employer shall promptly correct dust collection systems which
are malfunctioning or which are operating below designed efficiency.
Additionally, the employer shall promptly correct, or remove from service,
overheated bearings and slipping or misaligned belts associated with
inside bucket elevators.

(3) A certification record shall be maintained of each inspection,
performed in accordance with this paragraph (m), containing the date of
the inspection, the name of the person who performed the inspection and
the serial number, or other identifier, of the equipment specified in
paragraph (m)(1)(i) of this section that was inspected.

(4) The employer shall implement procedures for the use of tags and
locks which will prevent the inadvertent application of energy or motion
to equipment being repaired, serviced, or adjusted, which could result in
employee injury. Such locks and tags shall be removed in accordance with
established procedures only by the employee installing them or, if
unavailable, by his or her supervisor.

(n) Grain stream processing
equipment. The employer shall equip grain stream processing
equipment (such as hammer mills, grinders, and pulverizers) with an
effective means of removing ferrous material from the incoming grain
stream.

(o) Emergency escape. (1) The
employer shall provide at least two means of emergency escape from
galleries (bin decks).

(2) The employer shall provide at least one means of emergency escape
in tunnels of existing grain elevators. Tunnels in grain elevators
constructed after the effective date of this standard shall be provided
with at least two means of emergency escape.

(p) Continuous-flow bulk raw grain
dryers. (1) All direct-heat grain dryers shall be equipped with
automatic controls that:

(i) Will shut-off the fuel supply in case of power or flame failure or
interruption of air movement through the exhaust fan; and,

(ii) Will stop the grain from being fed into the dryer if excessive
temperature occurs in the exhaust of the drying section.

(2) Direct-heat grain dryers installed after March 30, 1988 shall
be:

(i) Located outside the grain elevator; or

(ii) Located in an area inside the grain elevator protected by a fire
or explosion suppression system; or

(iii) Located in an area inside the grain elevator which is separated
from other areas of the facility by construction having at least a one
hour fire-resistance rating.

(q) Inside bucket elevators.
(1) Bucket elevators shall not be jogged to free a choked leg.

(2) All belts and lagging purchased after March 30, 1988 shall be
conductive. Such belts shall have a surface electrical resistance not to
exceed 300 megohms.

(3) All bucket elevators shall be equipped with a means of access to
the head pulley section to allow inspection of the head pulley, lagging,
belt, and discharge throat of the elevator head. The boot section shall
also be provided with a means of access for clean-out of the boot and for
inspection of the boot, pulley, and belt.

(4) All the employer shall:

(i) Mount bearings externally to the leg casing; or,

(ii) Provide vibration monitoring, temperature monitoring, or other
means to monitor the condition of those bearings mounted inside or
partially-inside the leg casing.

(5) All the employer shall equip bucket elevators with a motion
detection device which will shut-down the bucket elevator when the belt
speed is reduced by no more than 20% of the normal operating speed.

(6) All the employer shall:

(i) Equip bucket elevators with a belt alignment monitoring device
which will initiate an alarm to employees when the belt is not tracking
properly; or,

(ii) Provide a means to keep the belt tracking properly, such as a
system that provides constant alignment adjustment of belts.

(7) Paragraphs (q)(5) and (q)(6) of this section do not apply to grain
elevators having a permanent storage capacity of less than one million
bushels, provided that daily visual inspection is made of bucket movement
and tracking of the belt.

(8) Paragraphs (q)(4), (q)(5), and (q)(6) of this section do not apply
to the following:

(i) Bucket elevators which are equipped with an operational fire and
explosion suppression system capable of protecting at least the head and
boot section of the bucket elevator; or,

(ii) Bucket elevators which are equipped with pneumatic or other dust
control systems or methods that keep the dust concentration inside the
bucket elevator at least 25% below the lower explosive limit at all times
during operations.

Note: The
following appendices to §1910.272 serve as nonmandatory guidelines to
assist employers and employees in complying with the requirements of this
section, as well as to provide other helpful information.

No additional burdens are imposed through these appendices.

Appendix A to §1910.272 Grain Handling Facilities

Examples presented in this appendix may not be the only means of
achieving the performance goals in the standard.

1. Scope and Application

The provisions of this standard apply in addition to any other
applicable requirements of this part 1910 (or part 1917 at marine
terminals). The standard contains requirements for new and existing grain
handling facilities. The standard does not apply to seed plants which
handle and prepare seeds for planting of future crops, nor to on-farm
storage or feed lots.

2. Emergency Action Plan

The standard requires the employer to develop and implement an
emergency action plan. The emergency action plan (§1910.38) covers those
designated actions employers and employees are to take to ensure employee
safety from fire and other emergencies. The plan specifies certain minimum
elements which are to be addressed. These elements include the
establishment of an employee alarm system, the development of evacuation
procedures, and training employees in those actions they are to take
during an emergency.

The standard does not specify a particular method for notifying
employees of an emergency. Public announcement systems, air horns, steam
whistles, a standard fire alarm system, or other types of employee alarm
may be used. However, employers should be aware that employees in a grain
facility may have difficulty hearing an emergency alarm, or distinguishing
an emergency alarm from other audible signals at the facility, or both.
Therefore, it is important that the type of employee alarm used be
distinguishable and distinct.

The use of floor plans or workplace maps which clearly show the
emergency escape routes should be included in the emergency action plan;
color coding will aid employees in determining their route assignments.
The employer should designate a safe area, outside the facility, where
employees can congregate after evacuation, and implement procedures to
account for all employees after emergency evacuation has been
completed.

It is also recommended that employers seek the assistance of the local
fire department for the purpose of preplanning for emergencies.
Preplanning is encouraged to facilitate coordination and cooperation
between facility personnel and those who may be called upon for assistance
during an emergency. It is important for emergency service units to be
aware of the usual work locations of employees at the facility.

3. Training

It is important that employees be trained in the recognition and
prevention of hazards associated with grain facilities, especially those
hazards associated with their own work tasks. Employees should understand
the factors which are necessary to produce a fire or explosion, i.e., fuel
(such as grain dust), oxygen, ignition source, and (in the case of
explosions) confinement. Employees should be made aware that any efforts
they make to keep these factors from occurring simultaneously will be an
important step in reducing the potential for fires and explosions.

The standard provides flexibility for the employer to design a training
program which fulfills the needs of a facility. The type, amount, and
frequency of training will need to reflect the tasks that employees are
expected to perform. Although training is to be provided to employees at
least annually, it is recommended that safety meetings or discussions and
drills be conducted at more frequent intervals.

The training program should include those topics applicable to the
particular facility, as well as topics such as: Hot work procedures;
lock-out/tag-out procedures; bin entry procedures; bin cleaning
procedures; grain dust explosions; fire prevention; procedures for
handling “hot grain”; housekeeping procedures, including methods and
frequency of dust removal; pesticide and fumigant usage; proper use and
maintenance of personal protective equipment; and, preventive maintenance.
The types of work clothing should also be considered in the program at
least to caution against using polyester clothing that easily melts and
increases the severity of burns, as compared to wool or fire retardant
cotton.

In implementing the training program, it is recommended that the
employer utilize films, slide-tape presentations, pamphlets, and other
information which can be obtained from such sources as the Grain Elevator
and Processing Society, the Cooperative Extension Service of the U.S.
Department of Agriculture, Kansas State University's Extension Grain
Science and Industry, and other state agriculture schools, industry
associations, union organizations, and insurance groups.

4. Hot Work Permit

The implementation of a permit system for hot work is intended to
assure that employers maintain control over operations involving hot work
and to assure that employees are aware of and utilize appropriate
safeguards when conducting these activities.

Precautions for hot work operations are specified in 29 CFR
1910.252(a), and include such safeguards as relocating the hot work
operation to a safe location if possible, relocating or covering
combustible material in the vicinity, providing fire extinguishers, and
provisions for establishing a fire watch. Permits are not required for hot
work operations conducted in the presence of the employer or the
employer's authorized representative who would otherwise issue the permit,
or in an employer authorized welding shop or when work is conducted
outside and away from the facility.

It should be noted that the permit is not a record, but is an
authorization of the employer certifying that certain safety precautions
have been implemented prior to the beginning of work operations.

5. Entry Into Bins, Silos, And Tanks

In order to assure that employers maintain control over employee entry
into bins, silos, and tanks, OSHA is requiring that the employer issue a
permit for entry into bins, silos, and tanks unless the employer (or the
employer's representative who would otherwise authorize the permit) is
present at the entry and during the entire operation.

Employees should have a thorough understanding of the hazards
associated with entry into bins, silos, and tanks. Employees are not to be
permitted to enter these spaces from the bottom when grain or other
agricultural products are hung up or sticking to the sides which might
fall and injure or kill an employee. Employees should be made aware that
the atmosphere in bins, silos, and tanks can be oxygen deficient or toxic.
Employees should be trained in the proper methods of testing the
atmosphere, as well as in the appropriate procedures to be taken if the
atmosphere is found to be oxygen deficient or toxic. When a fumigant has
been recently applied in these areas and entry must be made, aeration fans
should be running continuously to assure a safe atmosphere for those
inside. Periodic monitoring of toxic levels shuld be done by direct
reading instruments to measure the levels, and, if there is an increase in
these readings, appropriate actions should be promptly taken.

Employees have been buried and suffocated in grain or other
agricultural products because they sank into the material. Therefore, it
is suggested that employees not be permitted to walk or stand on the grain
or other grain product where the depth is greater than waist high. In this
regard, employees must use a full body harness or boatswain's chair with a
lifeline when entering from the top. A winch system with mechanical
advantage (either powered or manual) would allow better control of the
employee than just using a hand held hoist line, and such a system would
allow the observer to remove the employee easily without having to enter
the space.

It is important that employees be trained in the proper selection and
use of any personal protective equipment which is to be worn. Equally
important is the training of employees in the planned emergency rescue
procedures. Employers should carefully read §1910.134(e)(3) and assure
that their procedures follow these requirements. The employee acting as
observer is to be equipped to provide assistance and is to know procedures
for obtaining additional assistance. The observer should not enter a space
until adequate assistance is available. It is recommended that an employee
trained in CPR be readily available to provide assistance to those
employees entering bins, silos, or tanks.

6.  Contractors

These provisions of the standard are intended to ensure that outside
contractors are cognizant of the hazards associated with grain handling
facilities, particularly in relation to the work they are to perform for
the employer. Also, in the event of an emergency, contractors should be
able to take appropriate action as a part of the overall facility
emergency action plan. Contractors should also be aware of the employer's
permit systems. Contractors should develop specified procedures for
performing hot work and for entry into bins, silos, and tanks and these
activities should be coordinated with the employer. Contractors are
responsible for informing their own employees.

This coordination will help to ensure that employers know what work is
being performed at the facility by contractors; where it is being
performed; and, that it is being performed in a manner that will not
endanger employees.

7.  Housekeeping.

The housekeeping program is to be designed to keep dust accumulations
and emissions under control inside grain facilities. The housekeeping
program, which is to be written, is to specify the frequency and method(s)
used to best reduce dust accumulations.

Ship, barge, and rail loadout and receiving areas which are located
outside the facility need not be addressed in the housekeeping program.
Additionally, truck dumps which are open on two or more sides need not be
addressed by the housekeeping program. Other truck dumps should be
addressed in the housekeeping program to provide for regular cleaning
during periods of receiving grain or agricultural products. The
housekeeping program should provide coverage for all workspaces in the
facility and include walls, beams, etc., especially in relation to the
extent that dust could accumulate.

Dust Accumulations

Almost all facilities will require some level of manual housekeeping.
Manual housekeeping methods, such as vacuuming or sweeping with soft
bristle brooms, should be used which will minimize the possibility of
layered dust being suspended in the air when it is being removed.

The housekeeping program should include a contingency plan to respond
to situations where dust accumulates rapidly due to a failure of a dust
enclosure hood, an unexpected breakdown of the dust control system, a
dust-tight connection inadvertently knocked open, etc.

The housekeeping program should also specify the manner of handling
spills. Grain spills are not considered to be dust accumulations.

A fully enclosed horizontal belt conveying system where the return belt
is inside the enclosure should have inspection access such as sliding
panels or doors to permit checking of equipment, checking for dust
accumulations and facilitate cleaning if needed.

Dust Emissions

Employers should analyze the entire stock handling system to determine
the location of dust emissions and effective methods to control or to
eliminate them. The employer should make sure that holes in spouting,
casings of bucket elevators, pneumatic conveying pipes, screw augers, or
drag conveyor casings, are patched or otherwise properly repaired to
prevent leakage. Minimizing free falls of grain or grain products by using
choke feeding techniques, and utilization of dust-tight enclosures at
transfer points, can be effective in reducing dust emissions.

Each housekeeping program should specify the schedules and control
measures which will be used to control dust emitted from the stock
handling system. The housekeeping program should address the schedules to
be used for cleaning dust accumulations from motors, critical bearings and
other potential ignition sources in the working areas. Also, the areas
around bucket elevator legs, milling machinery and similar equipment
should be given priority in the cleaning schedule. The method of disposal
of the dust which is swept or vacuumed should also be planned.

Dust may accumulate in somewhat inaccessible areas, such as those areas
where ladders or scaffolds might be necessary to reach them. The employer
may want to consider the use of compressed air and long lances to blow
down these areas frequently. The employer may also want to consider the
periodic use of water and hoselines to wash down these areas. If these
methods are used, they are to be specified in the housekeeping program
along with the appropriate safety precautions, including the use of
personal protective equipment such as eyewear and dust respirators.

Several methods have been effective in controlling dust emissions. A
frequently used method of controlling dust emissions is a pneumatic dust
collection system. However, the installation of a poorly designed
pneumatic dust collection system has fostered a false sense of security
and has often led to an inappropriate reduction in manual housekeeping.
Therefore, it is imperative that the system be designed properly and
installed by a competent contractor. Those employers who have a pneumatic
dust control system that is not working according to expectations should
request the engineering design firm, or the manufacturer of the filter and
related equipment, to conduct an evaluation of the system to determine the
corrections necessary for proper operation of the system. If the design
firm or manufacturer of the equipment is not known, employers should
contact their trade association for recommendations of competent designers
of pneumatic dust control systems who could provide assistance.

When installing a new or upgraded pneumatic control system, the
employer should insist on an acceptance test period of 30 to 45 days of
operation to ensure that the system is operating as intended and designed.
The employer should also obtain maintenance, testing, and inspection
information from the manufacturer to ensure that the system will continue
to operate as designed.

Aspiration of the leg, as part of a pneumatic dust collection system,
is another effective method of controlling dust emissions. Aspiration of
the leg consists of a flow of air across the entire boot, which entrains
the liberated dust and carries it up the up-leg to take-off points. With
proper aspiration, dust concentrations in the leg can be lowered below the
lower explosive limit. Where a prototype leg installation has been
instrumented and shown to be effective in keeping the dust level 25% below
the lower explosive limit during normal operations for the various
products handled, then other legs of similar size, capacity and products
being handled which have the same design criteria for the air aspiration
would be acceptable to OSHA, provided the prototype test report is
available on site.

Another method of controlling dust emissions is enclosing the conveying
system, pressurizing the general work area, and providing a lower pressure
inside the enclosed conveying system. Although this method is effective in
controlling dust emissions from the conveying system, adequate access to
the inside of the enclosure is necessary to facilitate frequent removal of
dust accumulations. This is also necessary for those systems called
“self-cleaning.”

The use of edible oil sprayed on or into a moving stream of grain is
another method which has been used to control dust emissions. Tests
performed using this method have shown that the oil treatment can reduce
dust emissions. Repeated handling of the grain may necessitate additional
oil treatment to prevent liberation of dust. However, before using this
method, operators of grain handling facilities should be aware that the
Food and Drug Administration must approve the specific oil treatment used
on products for food or feed.

As a part of the housekeeping program, grain elevators are required to
address accumulations of dust at priority areas using the action level.
The standard specifies a maximum accumulation of 1⁄8 inch dust, measurable
by a ruler or other measuring device, anywhere within a priority area as
the upper limit at which time employers must initiate action to remove the
accumulations using designated means or methods. Any accumulation in
excess of this amount and where no action has been initiated to implement
cleaning would constitute a violation of the standard, unless the employer
can demonstrate equivalent protection. Employers should make every effort
to minimize dust accumulations on exposed surfaces since dust is the fuel
for a fire or explosion, and it is recognized that a 1⁄8 inch dust
accumulation is more than enough to fuel such occurrences.

8. Filter Collectors

Proper sizing of filter collectors for the pneumatic dust control
system they serve is very important for the overall effectiveness of the
system. The air to cloth ratio of the system should be in accordance with
the manufacturer's recommendations. If higher ratios are used, they can
result in more maintenance on the filter, shorter bag or sock life,
increased differential pressure resulting in higher energy costs, and an
increase in operational problems.

A photohelic gauge, magnehelic gauge, or manometer, may be used to
indicate the pressure rise across the inlet and outlet of the filter. When
the pressure exceeds the design value for the filter, the air volume will
start to drop, and maintenance will be required. Any of these three
monitoring devices is acceptable as meeting paragraph (l)(1) of the
standard.

The employer should establish a level or target reading on the
instrument which is consistent with the manufacturer's recommendations
that will indicate when the filter should be serviced. This target reading
on the instrument and the accompanying procedures should be in the
preventive maintenance program. These efforts would minimize the blinding
of the filter and the subsequent failure of the pneumatic dust control
system.

There are other instruments that the employer may want to consider
using to monitor the operation of the filter. One instrument is a zero
motion switch for detecting a failure of motion by the rotary discharge
valve on the hopper. If the rotary discharge valve stops turning, the dust
released by the bag or sock will accumulate in the filter hopper until the
filter becomes clogged. Another instrument is a level indicator which is
installed in the hopper of the filter to detect the buildup of dust that
would otherwise cause the filter hopper to be plugged. The installation of
these instruments should be in accordance with manufacturer's
recommendations.

All of these monitoring devices and instruments are to be capable of
being read at an accessible location and checked as frequently as
specified in the preventive maintenance program.

Filter collectors on portable vacuum cleaners, and those used where
fans are not part of the system, are not covered by requirements of
paragraph (l) of the standard.

9. Preventive Maintenance

The control of dust and the control of ignition sources are the most
effective means for reducing explosion hazards. Preventive maintenance is
related to ignition sources in the same manner as housekeeping is related
to dust control and should be treated as a major function in a facility.
Equipment such as critical bearings, belts, buckets, pulleys, and milling
machinery are potential ignition sources, and periodic inspection and
lubrication of such equipment through a scheduled preventive maintenance
program is an effective method for keeping equipment functioning properly
and safely. The use of vibration detection methods, heat sensitive tape or
other heat detection methods that can be seen by the inspector or
maintenance person will allow for a quick, accurate, and consistent
evaluation of bearings and will help in the implementation of the
program.

The standard does not require a specific frequency for preventive
maintenance. The employer is permitted flexibility in determining the
appropriate interval for maintenance provided that the effectiveness of
the maintenance program can be demonstrated. Scheduling of preventive
maintenance should be based on manufacturer's recommendations for
effective operation, as well as from the employer's previous experience
with the equipment. However, the employer's schedule for preventive
maintenance should be frequent enough to allow for both prompt
identification and correction of any problems concerning the failure or
malfunction of the mechanical and safety control equipment associated with
bucket elevators, dryers, filter collectors and magnets. The pressure-drop
monitoring device for a filter collector, and the condition of the lagging
on the head pulley, are examples of items that require regularly scheduled
inspections. A system of identifying the date, the equipment inspected and
the maintenance performed, if any, will assist employers in continually
refining their preventive maintenance schedules and identifying equipment
problem areas. Open work orders where repair work or replacement is to be
done at a designated future date as scheduled, would be an indication of
an effective preventive maintenance program.

It is imperative that the prearranged schedule of maintenance be
adhered to regardless of other facility constraints. The employer should
give priority to the maintenance or repair work associated with safety
control equipment, such as that on dryers, magnets, alarm and shut-down
systems on bucket elevators, bearings on bucket elevators, and the filter
collectors in the dust control system. Benefits of a strict preventive
maintenance program can be a reduction of unplanned downtime, improved
equipment performance, planned use of resources, more efficient
operations, and, most importantly, safer operations.

The standard also requires the employer to develop and implement
procedures consisting of locking out and tagging equipment to prevent the
inadvertent application of energy or motion to equipment being repaired,
serviced, or adjusted, which could result in employee injury. All
employees who have responsibility for repairing or servicing equipment, as
well as those who operate the equipment, are to be familiar with the
employer's lock and tag procedures. A lock is to be used as the positive
means to prevent operation of the disconnected equipment. Tags are to be
used to inform employees why equipment is locked out. Tags are to meet
requirements in §1910.145(f). Locks and tags may only be removed by
employees that placed them, or by their supervisor, to ensure the safety
of the operation.

10. Grain Stream Processing Equipment

The standard requires an effective means of removing ferrous material
from grain streams so that such material does not enter equipment such as
hammer mills, grinders and pulverizers. Large foreign objects, such as
stones, should have been removed at the receiving pit. Introduction of
foreign objects and ferrous material into such equipment can produce
sparks which can create an explosion hazard. Acceptable means for removal
of ferrous materials include the use of permanent or electromagnets. Means
used to separate foreign objects and ferrous material should be cleaned
regularly and kept in good repair as part of the preventive maintenance
program in order to maximize their effectiveness.

11. Emergency Escape

The standard specifies that at least two means of escape must be
provided from galleries (bin decks). Means of emergency escape may include
any available means of egress (consisting of three components, exit
access, exit, and exit discharge as defined in §1910.35), the use of
controlled descent devices with landing velocities not to exceed 15
ft/sec., or emergency escape ladders from galleries. Importantly, the
means of emergency escape are to be addressed in the facility emergency
action plan. Employees are to know the location of the nearest means of
emergency escape and the action they must take during an emergency.

12. Dryers

Liquefied petroleum gas fired dryers should have the vaporizers
installed at least ten feet from the dryer. The gas piping system should
be protected from mechanical damage. The employer should establish
procedures for locating and repairing leaks when there is a strong odor of
gas or other signs of a leak.

13. Inside Bucket Elevators

Hazards associated with inside bucket elevator legs are the source of
many grain elevator fires and explosions. Therefore, to mitigate these
hazards, the standard requires the implementation of special safety
precautions and procedures, as well as the installation of safety control
devices. The standard provides for a phase-in period for many of the
requirements to provide the employer time for planning the implementation
of the requirements. Additionally, for elevators with a permanent storage
capacity of less than one million bushels, daily visual inspection of belt
alignment and bucket movement can be substituted for alignment monitoring
devices and motion detection devices.

The standard requires that belts (purchased after the effective date of
the standard) have surface electrical resistance not to exceed 300
megohms. Test methods available regarding electrical resistance of belts
are: The American Society for Testing and Materials D257-76, “Standard
Test Methods for D-C Resistance or Conductance of Insulating Materials”;
and, the International Standards Organization's #284, “Conveyor
Belts-Electrical Conductivity-Specification and Method of Test.” When an
employer has a written certification from the manufacturer that a belt has
been tested using one of the above test methods, and meets the 300 megohm
criteria, the belt is acceptable as meeting this standard. When using
conductive belts, the employer should make certain that the head pulley
and shaft are grounded through the drive motor ground or by some other
equally effective means. When V-type belts are used to transmit power to
the head pulley assembly from the motor drive shaft, it will be necessary
to provide electrical continuity from the head pulley assembly to ground,
e.g., motor grounds.

Employers should also consider purchasing new belts that are flame
retardant or fire resistive. A flame resistance test for belts is
contained in 30 CFR 18.65.

Appendix B to §1910.272 Grain Handling Facilities

National Consensus Standards

The following table contains a cross-reference listing of current
national consensus standards which provide information that may be of
assistance to grain handling operations. Employers who comply with
provisions in these national consensus standards that provide equal or
greater protection than those in §1910.272 will be considered in
compliance with the corresponding requirements in §1910.272.

Subject

National consensus standards

Grain elevators and
facilities handling bulk raw agricultural commodities

ANSI/NFPA 61B

Feed mills

ANSI/NFPA 61C

Facilities handling
agricultural commodities for human consumption

ANSI/NFPA 61D

Pneumatic conveying
systems for agricultural commodities

ANSI/NFPA 66

Guide for explosion
venting

ANSI/NFPA 68

Explosion prevention
systems

ANSI/NFPA 69

Dust removal and exhaust
systems

ANSI/NFPA
91

Appendix C to §1910.272 Grain handling facilities

References for Further Information

The following references provide information which can be helpful in
understanding the requirements contained in various provisions of the
standard, as well as provide other helpful information.

1. Accident Prevention Manual for
Industrial Operations; National Safety Council, 425 North Michigan
Avenue, Chicago, Illinois 60611.

2. Practical Guide to Elevator
Design; National Grain and Feed Association, P.O. Box 28328,
Washington, DC 20005.

3. Dust Control for Grain
Elevators; National Grain and Feed Association, P.O. Box 28328,
Washington, DC 20005.

4. Prevention of Grain Elevator and
Mill Explosions; National Academy of Sciences, Washington, DC.
(Available from National Technical Information Service, Springfield,
Virginia 22151.)

5. Standard for the Prevention of
Fires and Explosions in Grain Elevators and Facilities Handling Bulk Raw
Agricultural Commodities, NFPA 61B; National Fire Protection
Association, Batterymarch Park, Quincy, Massachusetts 02269.

6. Standard for the Prevention of Fire
and Dust Explosions in Feed Mills, NFPA 61C; National Fire
Protection Association, Batterymarch Park, Quincy, Massachusetts
02269.

7. Standard for the Prevention of Fire
and Dust Explosions in the Milling of Agricultural Commodities for Human
Consumption, NFPA 61D; National Fire Protection Association,
Batterymarch Park, Quincy, Massachusetts 02269.

8. Standard for Pneumatic Conveying
Systems for Handling Feed, Flour, Grain and Other Agricultural
Dusts, NFPA 66; National Fire Protection Association, Batterymarch
Park, Quincy, Massachusetts 02269.

9. Guide for Explosion Venting,
NFPA 68; National Fire Protection Association, Batterymarch Park, Quincy,
Massachusetts 02269.

10. Standard on Explosion Prevention
Systems, NFPA 69; National Fire Protection Association,
Batterymarch Park, Quincy, Massachusetts 02269.

11. Safety-Operations Plans;
U.S. Department of Agriculture, Washington, DC 20250.

12. Inplant Fire Prevention Control
Programs; Mill Mutual Fire Prevention Mutual Fire Prevention
Bureau, 1 Pierce Place, Suite 1260 West, Itasca, Illinois 60143-1269.

13. Guidelines for Terminal
Elevators; Mill Mutual Fire Prevention Bureau, 1 Pierce Place,
Suite 1260 West, Itasca, Illinois 60143-1269.

14. Standards for Preventing the
Horizontal and Vertical Spread of Fires in Grain Handling
Properties; Mill Mutual Fire Mutual Fire Prevention Bureau, 1
Pierce Place, Suite 1260 West, Itasca, Illinois 60143-1269.

15. Belt Conveyors for Bulk
Materials, Part I and Part II, Data Sheet 570, Revision A; National
Safety Council, 425 North Michigan Avenue, Chicago, Illinois 60611.

16. Suggestions for Precautions and
Safety Practices in Welding and Cutting; Mill Mutual Fire
Prevention Bureau, 1 Pierce Place, Suite 1260 West, Itasca, Illinois
60143-1269.

17. Food Bins and Tanks, Data
Sheet 524; National Safety Council, 425 North Michigan Avenue, Chicago,
Illinois 60611.

18. Pneumatic Dust Control in Grain
Elevators; National Academy of Sciences, Washington, DC. (Available
from National Technical Information Service, Springfield, Virginia
22151.)

19. Dust Control Analysis and Layout
Procedures for Grain Storage and Processing Plants; Mill Mutual
Fire Prevention Bureau, 1 Pierce Place, Suite 1260 West, Itasca, Illinois
60143-1269.

20. Standard for the Installation of
Blower and Exhaust Systems for Dust, Stock and Vapor Removal, NFPA
91; National Fire Protection Association, Batterymarch Park, Quincy,
Massachusetts 02269.

21. Standards for the Installation of
Direct Heat Grain Driers in Grain and Milling Properties; Mill
Mutual Fire Prevention Bureau, 1 Pierce Place, Suite 1260 West, Itasca,
Illinois 60143-1269.

22. Guidelines for Lubrication and
Bearing Maintenance; Mill Mutual Fire Prevention Bureau, 1 Pierce
Place, Suite 1260 West, Itasca, Illinois 60143-1269.

23. Organized Maintenance in Grain and
Milling Properties; Mill Mutual Fire Prevention Bureau, 1 Pierce
Place, Suite 1260 West, Itasca, Illinois 60143-1269.

24. Safe and Efficient Elevator Legs
for Grain and Milling Properties; Mill Mutual Fire Prevention
Bureau, 1 Pierce Place, Suite 1260 West, Itasca, Illinois 60143-1269.

25. Explosion Venting and Supression
of Bucket Elevators; National Grain and Feed Association, P.O. Box
28328, Washington, DC 20005.

26. Lightning Protection Code,
NFPA 78; National Fire Protection Association, Batterymarch Park, Quincy,
Massachusetts 02269.

27. Occupational Safety in Grain
Elevators, DHHS (NIOSH) Publication No. 83-126); National Institute
for Occupational Safety and Health, Morgantown, West Virginia 26505.

28. Retrofitting and Constructing
Grain Elevators; National Grain and Feed Association, P.O. Box
28328, Washington, DC 20005.

29. Grain Industry Safety and Health
Center—Training Series (Preventing grain dust explosions,
operations maintenance safety, transportation safety, occupational safety
and health); Grain Elevator and Processing Society, P.O. Box 15026,
Commerce Station, Minneapolis, Minnesota 55415-0026.

30. Suggestions for Organized
Maintenance; The Mill Mutuals Loss Control Department, 1 Pierce
Place, Suite 1260 West, Itasca, Illinois 60143-1269.

31. Safety—The First Step to
Success; The Mill Mutual Loss Control Department, 1 Pierce Place,
Suite 1260 West, Itasca, Illinois 60143-1269.

32. Emergency Plan Notebook;
Schoeff, Robert W. and James L. Balding, Kansas State University,
Cooperative Extension Service, Extension Grain Science and Industry,
Shellenberger Hall, Manhattan, Kansas 66506.

[52 FR 49625, Dec. 31, 1987, as amended at 53 FR 17696, May
18, 1988; 54 FR 24334, June 7, 1989; 55 FR 25094, June 20, 1990; 61 FR
9242, Mar. 7, 1996; 61 FR 9584, Mar. 8, 1996; 67 FR 67965, Nov. 7, 2002;
76 FR 80740, Dec. 27, 2011]

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