§1910.272 Grain handling facilities

[Code of Federal Regulations]
[Title 29, Volume 5]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 29CFR1910.272]

[Page 819-830]

TITLE 29--LABOR

CHAPTER XVII--OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT

OF LABOR

PART 1910_OCCUPATIONAL SAFETY AND HEALTH STANDARDS--Table of Contents

Subpart R_Special Industries

Sec. 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).

(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.

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

[[Page 820]]

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

Sec. 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:

[[Page 821]]

(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 (Sec. 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 Sec. 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),

[[Page 822]]

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;

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 2\1/2\ 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

[[Page 823]]

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

[[Page 824]]

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 Sec. 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 Sec. 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 (Sec. 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,

[[Page 825]]

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 Sec. 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

[[Page 826]]

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

[[Page 827]]

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.

[[Page 828]]

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 Sec. 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 Sec. 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

[[Page 829]]

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

<greek-i>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 Sec. 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 Sec. 1910.272 will be considered in

compliance with the corresponding requirements in Sec. 1910.272.

----------------------------------------------------------------------------------------------------------------

Subject National consensus standards

----------------------------------------------------------------------------------------------------------------

Grain elevators and facilities handling bulk raw ANSI/NFPA 61B

agricultural commodities.

Feed mills................................................. ANSI/NFPA 61C

Facilities handling agricultural commodities for human ANSI/NFPA 61D

consumption.

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 Sec. 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.

[[Page 830]]

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]