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2 SAFETY AND ENVIRONMENTAL
2.1 Introduction
Surface preparation, thermal spraying, and sealing and painting operations expose workers to
numerous potential health and safety hazards. Common health and safety hazards associated with
the industry include (a) electric shock; (b) flammable and explosive solvents, gases, and fine
particulate dusts and fumes; (c) confined space entry; (d) fall hazards; (e) exposure to high- intensity
noise, ultraviolet light, and toxic materials; and (f) high-velocity particle impingement.
While this guide does not purport to address all of the safety issues regarding TSMCs and their
application, some of the more important safety concerns associated with the process are discussed
below. It is recommended that all personnel involved with the thermal spray process be familiar with
safe working practices and safety regulations in current standards and guides. These standards and
guides include, but are not limited to, documents from the American National Standards Institute
(ANSI), the American Welding Society (AWS), the Coast Guard Academy (CGA), the military, the
National Association of Corrosion Engineers (NACE), the National Fire Protection Association
(NFPA), the Occupational Safety and Health Administration (OSHA), and the Society for Protective
Coatings (SSPC). Also refer to the U.S. Army Corps of Engineers's Manual, Safety--Safety and
Health Requirements, EM 385-1-1, Washington, D.C., November 3, 2003. Some of these standards
are listed in Section 10 of this guide.
2.2 Blast Cleaning
2.2.1 Equipment Maintenance and Use
Maintain abrasive blast machines and equipment in accordance with the manufacturers'
recommendations. Tag and remove from service worn or damaged components pending
replacement or repair.
2.2.1.1 Hose connections. Use hoses and hose connections that do not allow electrostatic discharge.
Use hose couplings and nozzles designed to prevent accidental disconnection. Use a
"deadman" control device that automatically shuts off the flow of air and abrasive when the
hose is dropped. Inspect hoses and fittings used for abrasive blasting frequently to ensure the
timely replacement of worn parts and equipment.
2.2.1.2 Hose use. Blast hoses shall be kept as straight as possible. Use a large radius of curvature
for any bends so as to avoid excessive friction and wear. Store hoses in cool dry areas to
avoid accelerated degradation. Never point the blast nozzle at the body parts of any person.
Relieve air pressure in the blast tank and system before working on the system. Use a "tag-
out" labeling system during system maintenance.
2.2.1.3 Ventilation. Provide mechanical ventilation in blasting operations that are not performed in
the open or in a properly designed and ventilated room.
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2.2.2 Personal Protective Equipment
Wear respiratory protective devices--helmets, hand shields, eye protection (face shields or
goggles), and appropriate protective clothing--during all blasting operations. For blasting in
the open, use a mechanical filter respirator in conjunction with face shields and dust hoods.
Alternatively, an air-line respirator may be used. For blasting in confined or enclosed spaces,
a continuous flow air-line respirator, a full-face piece or helmet, and dust hood are required.
2.2.2.1 Respirators. The guidelines listed below should be followed when using respirators.
· Compressed air should meet at least the requirements of the specification for Type 1,
Grade D breathing air as described in CGA G 7.1 "Commodity Specification for Air."
· Respiratory protection shall be in accordance with ANSI Z88.2.
· All respiratory devices shall comply with the U.S. Bureau of Mines and the National
Institute for Occupational Safety and Health (NIOSH). Respirators selected from those
currently approved and certified by NIOSH/Mine Safety and Health Administration
(MSHA) Section 134 should be used.
· Use NIOSH-certified Type CE respirator and Type CE hood (air-line-supplied air hood
with faceplate and devices to protect the wearer's eyes, face, chin, neck, shoulders, and
upper body from rebounding abrasive blasting media).
· Note: Personnel using/wearing respirators require "fit-testing" before they can legally
work under these conditions. Also, beards can affect the efficacy of respirators.
2.2.2.2 Eye and body protection. The guidelines listed below should be followed when using eye
and body protection.
· Head protection shall be in accordance with ANSI Z89.1. Face shields or helmets shall
be equipped with dust hoods to protect the eyes, face, chin, and neck.
· Personnel in or near blasting operations should wear helmets, handshields, faceshields,
or goggles conforming to ANSI Z87.1 and eye protection conforming to ANSI Z89.1.
· Appropriate protective clothing shall be worn during spray operations. Clothing should
be strapped tightly around wrists and ankles to prevent contact with abrasive dust. Open
shirt collars and unbuttoned pocket flaps are unacceptable. High-top shoes should be
worn and cuff-less trousers should cover the tops.
· Blasting operators should wear heavy canvas or leather gloves and an apron or coveralls.
Approved safety shoes should be worn to protect against foot injury.
2.2.2.3 Hearing protection. Noise levels generated during blasting and thermal spray operations
can cause temporary or permanent hearing loss, damage, and fatigue.
· Wear approved earmuffs and properly fitted approved earplugs when thermal spray
operators and personnel are in the immediate vicinity of thermal spray operations to
reduce the high-intensity noise levels to acceptable conditions.
· All personnel in the vicinity of blasting operations shall be provided with hearing protection
if the noise exposure exceeds the limitations established by OSHA in paragraph 1910.95,
"Occupational Noise Exposure".
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2.2.3 Cleaning with Compressed Air
Cleaning with compressed air should be restricted to systems where the air pressure has been
reduced to 204 kPa (30 psi) or less. Cleaning operators should wear safety goggles or a face
shield, hearing protection, and appropriate body covering. Compressed air or pressurized gas
nozzles should never be pointed at other personnel or at exposed skin.
2.2.4 Cleaning with Solvents
The guidelines listed below should be followed when cleaning with solvents.
· The material safety data sheet (MSDS) for each solvent used must be readily available
and should be consulted for specific solvent information, handling, and storage and
disposal procedures, in addition to those listed here.
· Flammable liquids with a closed-cup test flash point below 100°F (38°C) should not be
used for cleaning purposes.
· Sources of ignition should not be permitted in the vicinity of solvent cleaning if there is
any indication of combustible gas or vapor present.
· Measurements should be made to ensure that solvent vapors are not present during
thermal spray operations, especially in confined spaces. Representative air samples should
be collected from the breathing zone of workers involved in the cleaning process to
determine the specific solvent vapor concentrations.
· Worker exposures should be controlled to levels below the Occupational Safety and
Health Administration (OSHA) Permissible Exposure Limit, as indicated in CFR 29 Part
1910, Section 1000.
2.3 Thermal Spraying
2.3.1 Safety Issues
Airborne metal dusts and fumes, finely divided solids, or other particulate accumulations
should be treated as explosive materials. Proper ventilation, good housekeeping, and safe
working practices should be maintained to prevent the possibility of fire and explosion.
Thermal spray equipment should never be pointed at personnel or flammable materials.
Thermal spraying should not be performed in areas where paper, wood, oily rags, or cleaning
solvents are present. Electrically conductive safety shoes should be worn in any work area
where an explosion is a concern. During thermal spray operations, including the preparation
and finishing processes, employees should wear approved protective coveralls or aprons,
hand protection, eye protection, ear protection, and respiratory protection.
SAFETY PRECAUTION: The fine aluminum and zinc particulates (metal dust and fume) produced
during thermal spraying may be an extreme explosion hazard. Special precaution should be taken
during wire-arc spraying due to the higher amounts of metal dust and fume produced that accompany
higher spray rates, especially if multiple wire-arc spray units are being used in the same work area.
Do not use water to extinguish aluminum or zinc fires. Use dry sand or a Class D extinguisher.
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2.3.2 Personal Protective Equipment
The general requirements for the protection of personnel involved with thermal spraying are
the same as those specified for welders in ANSI/AWS Z49.1, "Safety in Welding and
Cutting." Helmets, hand shields, eye protection (face shields or goggles), hearing protection,
respirators, and appropriate protective clothing shall be worn during all spraying operations.
2.3.2.1 Eye and skin protection. All thermal spray processes introduce particulates and fumes into
the air that may irritate and damage the eyes or skin. The processes also emit hazardous
ultraviolet (UV), infrared (IR) and intense visible light radiation.
· Eye and face protection must be worn to protect against particulate impingement. Hoods
or face shields conforming to ANSI Z87.1 and ANSI Z89.1 with filter lenses should be
worn to protect the face and eyes. Various shades of lens filters are recommended based
on the type of thermal spray process being used:
For wire-flame spray, use lens shades 2 to 4.
For wire-arc spray, use lens shades 9 to12.
Shades 3 to 6 can be used for wire-arc spray if the gun is equipped with an arc shield.
The shield encloses the arc and reduces the operator's exposure to the high-intensity
light radiation.
· Other workers in the vicinity of the thermal spray applicator should also use proper eye
protection.
· Flame-resistant clothing should be worn to protect the skin. Clothing should be strapped
tightly around the wrists and ankles to prevent contact with sprayed materials. Open shirt
collars and unbuttoned pocket flaps are unacceptable. High-top shoes should be worn,
and cuff-less trousers should cover the shoe tops. Protection against radiation from the
spray process is detailed in ANSI/AWS Z49.1.
· Aluminized clothing may be used with the following precautions:
IR and UV radiation are not to be reflected onto unprotected skin.
Provide suitable protection against electric shock.
2.3.2.2 Hearing protection. Thermal spray produces very high noise levels (up to 130 dBA) that
can rapidly cause permanent hearing loss.
· Thermal spray operators and other workers in the vicinity of the thermal spray operation
should wear approved hearing protection at all times.
· Protection against the effects of noise exposure should be provided in accordance with the
requirements of EM 385-1-1, Section 5, "Personal Protective and Safety Equipment,"
Subsection 05.C, "Hearing Protection and Noise Control," and CFR 29 Part 1910,
Section 95.
· Insert earplugs should be used during wire or powder flame spray. Insert earplugs should
be worn as a minimum protection during wire-arc spraying. Insert earplugs and approved
earmuffs are recommended for use with wire-arc, plasma, and high-velocity oxygen fuel
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(HVOF) spray. Table 1 lists the minimum recommended hearing protection devices for
various thermal spray application methods.
2.3.2.3 Respiratory protection. Thermal spray generates toxic dusts and fumes. Thermal spray
operators and personnel in the general vicinity of the spraying operation should wear
appropriate approved respirators. Overexposure to zinc fume is known to produce flu-like
symptoms, often called "metal fume fever."
· An approved mechanical filter type respirator shall be used when spraying nontoxic
materials with dust and metal-fume exposure. When spraying in confined spaces, an air-
line respirator shall be used. When spraying highly toxic materials, the air-line respirator
shall be equipped with an emergency auxiliary cylinder of respirable air. Respiratory
protection shall be in accordance with ANSI Z88.2.
· All respiratory devices used shall comply with the U.S. Bureau of Mines and the National
Institute for Occupational Safety and Health (NIOSH).
2.3.3 Wire-Arc Spray
2.3.3.1 Electrical shock prevention. High DC voltages and amperages (currents) inherent to the
wire-arc spray process pose severe electrical hazards. The operator shall be thoroughly
trained in the safe operation of the wire-arc spray equipment prior to its use.
· The manufacturer's safe operating procedures should always be followed.
· Ground protection for equipment and cords should be present, in good condition, and
tested regularly for correct operation.
· Electrical outlets should have ground fault circuit interrupters (GFCIs) in addition to
appropriate over-current protection (e.g., fuses and circuit breakers). Electrical circuit
grounds and GFCIs should be tested before work begins and tagged, reported, and not
used if found to be faulty.
· Switches and receptacles should have proper covers.
· Buttons, lights, plugs, and cables shall be in compliance with ANSI/NFPA 70, "National
Electrical Code." Periodic inspections of cables, insulation, and hoses shall be performed.
Damaged components shall be tagged, removed from service, and immediately repaired
or replaced.
· Cords should be approved for outdoor or wet or damp locations. The cords should be
hard usage or extra hard usage as specified in ANSI/NFPA 70 "National Electrical
Code." Cords should not be spliced.
· Arc guns and power supplies should be cleaned frequently, as per the manufacturer's
recommendations, to remove build-ups of metallic dusts, which may cause short circuits.
TABLE 1 Typical noise levels and hearing protection requirements
Thermal Spray Process Noise Level, dB(A) Minimum Recommended Protection
Wire-flame spraying 114 Earplugs
Wire-arc 111116 Earplugs and earmuffs
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2.3.4 Flame Spray
2.3.4.1 Gas cylinder safety. To ensure gas cylinder safety, the guidelines listed below should be
followed.
· Compressed gas cylinders should be handled in accordance with ANSI Z49.1 and with
CGA P-1.
· Only special oxidation-resistant lubricants should be used with oxygen equipment;
grease or oil should not be used.
· Manifolds, pressure-reducing regulators, flow meters, hoses, and hose connections
should be installed in accordance with ANSI Z49.1.
· A protective shield should be used to shield glass tube flowmeters from the spray gun.
· Pressure connecting nuts should be tight, but not overly tight. Fittings that cannot be
sealed without excessive force should be tagged and replaced.
· Compressed air for thermal spraying or blasting operations should only be used at
pressures recommended by the equipment manufacturers. The air-line should be free
from oil and moisture.
· Compressed air, oxygen, or fuel gas should never be used to clean clothing.
· Cylinders should be handled, stored, and secured in accordance with established
regulations and safe working practices.
· Hoses used with flammable gases shall be fitted with approved "flash-back" arrestors to
prevent any flame burning back along the hoses from reaching the cylinders.
2.3.4.2 Flame spray safety. To ensure flame spray safety, the guidelines listed below should be
followed.
· Flame spray equipment should always be maintained and operated according to the
manufacturer's instructions. Thermal spray operators should be trained and familiar with
their equipment before starting an operation.
· Valves should be properly sealed and lubricated.
· Friction lighters, pilot lights, or arc ignition methods of lighting flame spray guns should
be used.
· If the flame spray gun backfires, it should be extinguished immediately. Re-ignition of
a gun that has backfired or blown out should not be attempted until the cause of the
trouble has been determined and remedied.
· Flame spray guns or hoses should not be hung on regulators or cylinder valves. Gas
pressure should be released from the hoses after the equipment is shut down or when
equipment will be left unattended.
· Lubricating oil should not be allowed to enter the gas mixing chambers when cleaning
flame spray guns.
· Do not light wire-flame and rod guns without wire or rod in the nozzle as flames may
burn back into the gun, causing operator injury and equipment damage.
2.3.5 Ventilation
Thermal spraying should only be performed by operators using appropriate respiratory
protection and in locations with adequate ventilation.
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· Local exhaust or general ventilation systems should be used to control toxic fumes, gases,
or dusts in any operations not performed in the open. Thermal spraying in an enclosed
space should be performed with general mechanical ventilation, air-line respirators, or local
exhaust ventilation sufficient to reduce the fumes to safe limits specified by ACGIH-02.
· Personnel exposures should be controlled to the safe levels recommended by ACGIH-02
or prescribed by CFR 29 Part 1910, whichever is the more stringent.
· Air sampling should be performed before entry of personnel into a confined space, during
confined-space entry that involves contaminant-generating operations such as flame
spraying, and in areas where ventilation is inadequate to ensure that air contaminants will
not accumulate.
· Engineering controls (enclosures and/or hoods with ducted, mechanical ventilation of
sufficient volume to remove contaminants from the work space) are the most desired
methods of preventing job-related illness resulting from breathing air contaminated with
harmful dusts, mists, fumes, vapors, and/or gases.
· Treat airborne metal dusts, finely divided solids, or their accumulations, as explosives.
Use adequate ventilation in the thermal spray work area and collect overspray to
minimize the danger of dust explosions and fires. In shop environments, wet, bag, and
dry filter-cartridge type collectors may be used to collect the fine overspray particles,
thus minimizing the explosion and fire hazard and release of controlled and/or hazardous
materials. Keep bag- and filter-cartridge collector units at least 50 ft (15 m) away from
the spraying area to preclude ignition from the flame or heat of the thermal spray process.
· Thermally sprayed aluminum and zinc powders, nominally 40 to 110 µm (0.0016 to
0.0044 in.) in diameter, are not a combustion or explosive hazard when handled and used
in accordance with a powder manufacturer's instructions. Refer to the Aluminum
Association's recommendations for the safe storage and handling of aluminum powders.
· All fans, pipes, dust arrestors, and motors should be properly grounded. Ground to piping
that carries fuel gases or oxygen should not be used. Ventilating fans should be kept
running when cleaning out spray booths, pipes, etc., to prevent the accumulation of dust
or fumes in the system. Aluminum and magnesium dusts present an explosive hazard
that requires special attention. Adequate wet collector systems should be used with either
of these metals. Care should be exercised, since these metallic dusts may generate
hydrogen gas on contact with water. These systems should be designed to prevent
hydrogen accumulation. Frequent, scheduled, cleanout operations should be performed
to reduce residues. Residues should be handled and disposed of in accordance with
OSHA and EPA regulations.
2.4 Housekeeping
2.4.1 Thermal Spraying Area
Remove paper, wood, oily rags, cleaning solvents, sealers, and paints from the thermal
spraying area.
2.4.2 Shop and Field Work Areas
Good housekeeping in the shop and field work areas should always be maintained to ensure
proper storage of hazardous materials and to avoid accumulation of combustible or
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potentially explosive materials and metal dusts, and particular attention should be given to
inspecting for dust build-ups on beams, rafters, booth tops, and in floor cracks.
2.5 Sealers and Topcoats
2.5.1 Solvents
Solvents used for cleaning or to apply sealers or topcoats (e.g., acetone, xylene, or alcohol)
emit vapors that are harmful and can be fatal.
· Use only with adequate ventilation or proper respiratory protection and other protective
clothing as needed.
· Avoid breathing solvent vapors and skin contact with solvents.
· Most solvents are also flammable liquids. All solvent tanks must have lids and be covered
when not in use. Take proper safety precautions.
· Keep all solvents and flammable materials at least 50 ft (15.2 m) away from welding,
oxyfuel cutting and heating, and thermal spraying operations.
2.5.2 Spray Application
Sealers and paint coats are typically applied by spray application. Spray application is a high-
production rate process that may rapidly introduce very large quantities of toxic solvents and
vapors into the air.
· Airless spray systems operate at very high pressures. Very high fluid pressures can result
in penetration of the skin on contact with exposed flesh.
· Tip guards and trigger locks should be used on all airless spray guns. The operator should
never point the spray gun at any part of the body.
· Pressure remains in the system even after the pump is turned off and can only be relieved
by discharging or "blow-down" through the gun.
2.6 Material Safety Data Sheets (MSDSs)
The contractor should maintain current MSDSs for all materials used on the job. These
materials include cleaning solvents, compressed gases, thermal spray wires or powders,
sealers, thinners, and paints or any other materials required to have an MSDS as specified in
CFR 29 Part 1910, Section 1200. The MSDSs should be readily available to all personnel
on the job site in a clearly labeled folder.
2.7 Environmental
2.7.1 Regulations
Federal, state, and local regulations may be applicable with regard to containment, storage, and
disposal of blasting debris and metallizing emissions. This may include partial or complete
containment of the work site for surface preparation and thermal spraying and the collection
and safe disposal of used blasting media and thermal spray overspray. Ensure compliance
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with the purchaser's requirements and all pertinent government agency requirements and
regulations for air-quality and hazardous-materials control.
2.7.2 Handling Debris
The applicator and the purchaser should coordinate the specific requirements, responsibilities,
and actions for the containment, storage, collection, removal, and disposal of the debris
produced by the TSMC operations.
2.7.3 Lead in Coating
The removal of old coating containing lead requires special treatment. Further information
is available in Chapter 11 of the U.S. Army Corps of Engineers Engineering and Design
Manual, Painting: New Construction and Maintenance, EM 1110-2-3400, Washington,
D.C., April 30, 1995.
