«Minnesota Department of Labor and Industry Occupational Safety and Health Division Adapted from Fiberglass Layup and Sprayup – Good Practices for ...»
Hazards of fiberglass layup and sprayup
Minnesota Department of Labor and Industry
Occupational Safety and Health Division
Adapted from Fiberglass Layup and Sprayup – Good Practices for Employees (DHHS (NIOSH)
publication number 76-148), by National Institute for Occupational Safety and Health. (1976).
Cincinnati, OH: Author.
Minnesota OSHA (MNOSHA) experience shows employees in fiberglass resin plastics
manufacturing are exposed to multiple hazards – high levels of styrene in lamination operations, noise in spray booths and grinding areas, and dust from grinding operations. In addition to chemical vapor and noise hazards, employees may be exposed to burns from eye or skin contact with catalysts used to initiate resin curing. Carpal tunnel injuries can occur among employees using rollers. This booklet outlines some recommended work practices, presents case studies from several plants and provides information about OSHA standards that apply to these industries.
1 Working with epoxies Special precautions and work practices are required when working with epoxies.
Read the labels on all containers and the material safety data sheets (MSDS) for information about health or fire hazards. If you have any questions about the kinds of chemicals you use, ask your supervisor.
Always mix components in hoods that draw the vapors away from you.
Protect your skin and eyes from any contact with epoxies during hand layup. Wear proper gloves, face shields, chemical goggles and coveralls. You may have to wear special rubber clothing when working with some epoxies.
Remove any splashed epoxy from your skin immediately. Use mild soap or waterless cleansers, but do not use solvents because they can cause skin rash.
Remove contaminated clothing immediately and do not reuse it until it has been cleaned.
Epoxies can be removed from rubber clothing and gloves with a solvent, followed by a soap and water washing.
Keep work areas clean. Use disposable cloth rags or paper towels to clean up any spills. In many plants, heavy paper is used to cover work areas and floors at the beginning of each shift; during cleanup or after a spill, the covering is replaced.
Keep tools free of epoxy. Disposable tools like wooden stirrers, plastic or paper containers, and throwaway rollers are best because this avoids additional contact with the chemicals when cleaning.
Shower after each shift to remove any traces of the chemicals from your body.
2 Resin, solvents and styrene Resin arrives at a plant in a liquid form, a polyester thinned with styrene monomer, and mixed with chemical inhibitors to prevent a spontaneous crosslinking reaction. Controlling the polymerization reaction requires the use of catalysts, promoters, temperature and time.
Styrene and many other different kinds of solvents are often used. Accidents and health problems may occur from misuses or improper handling of these solvents, as well as from exposure to styrene. If you are handling styrene or solvents and experience any eye discomfort, breathing difficulty or other type of symptom, tell your supervisor. Permissible exposure limits (PELs) have been set by OSHA and they establish the amounts of different chemicals you can be exposed to in an eight-hour work shift. The MNOSHA PEL for styrene is 50 parts per million (ppm).
Styrene monomer and most of the commonly used solvents, such as acetone and methyl ethyl ketone (MEK), can form flammable or explosive vapor concentrations under normal room temperatures.
Good work practices to follow when working with solvents and styrene Ventilation: Always work with adequate ventilation.
Fire protection: Exclude all possible sources of ignition for areas where solvents are used or stored. This means there must be no smoking, open flame, welding, burning, hot machinery or electrical equipment not designed for this special use in any areas where flammables are used or stored.
Use a ground and bond when transferring flammable liquids.
Dispensing: Prevent static electricity build-up when transferring solvent from a drum to a container by grounding the drum and the container to form an electrical bond. (Just as static builds up when you run a comb through your hair, a similar charge can build up when the molecules of a solvent rub together as the fluid is being poured. This is why the drum must be grounded and the receiving container bonded to the drum.) A metallic cable is usually used for
Handling: Carry solvents in safety cans and dispense from them. Take only the amount of solvent to be used during a shift into the work area. Unused solvent must be returned to approved storage at the end of the shift.
Cleanup: All solvent and styrene spills must be cleaned up immediately. There are special compounds, such as vermiculite, perlite, clay and dry sand, that will absorb spilled solvents.
Cleanup of large spills (spills requiring the efforts of more than one person or as defined by your employer) may be considered emergency response operations. In these instances, employees must not respond unless the appropriate training and protective equipment are provided. Follow the specific spill cleanup instructions provided by your employer.
Case history: The not-so-empty drum
A supervisor wanted an old drum to use as a garbage can at home. He went to the shipping and receiving clerk, who let him pick out an empty 20-gallon solvent drum despite a company rule that no drums be reused without decontamination. The supervisor asked a welder to cut the top off. The welder removed the bung and was adjusting his torch to begin the cut when the drum blew apart. A fragment partially severed the welder’s jugular vein but prompt first aid by a coworker saved his life.
What went wrong? The drum apparently contained a small amount of solvent and the heat from the torch caused it to explode. The drum had not been cleaned thoroughly enough and there remained flammable solvent vapors creating an explosive atmosphere when exposed to heat.
Case history: Static charge triggers fire Two workers were using a hand pump to empty a small amount of solvent that remained in one drum and transfer it into a second drum. While one worker was turning the hand crank on the pump, the second was aiming the pump spout into the bung, but the spout was not touching the drum. The drums exploded. Both men and a fellow employee were severely burned in the fire that followed.
What went wrong? A static charge buildup as the free falling solvent was being transferred and ignited the flammable vapors. Bonding straps were not used to prevent buildup of static charges.
Organic peroxides The basic rule for handling organic peroxides is follow the manufacturer’s directions carefully!
Organic peroxides are used as catalysts and can be dangerous. Handle with care. The various peroxides differ considerably in their chemical properties, but can all be unstable and require special handling, storage and mixing procedures. They may explode from friction, static electricity charges, 4 contamination with other materials, improper mixing procedures or from charges brought about by freezing, evaporation or aging. In addition to the dangers of fire and explosion, skin or eye contact can produce severe irritation or chemical burns. There are special guidelines to follow for mixing and dispensing, spraying, storing and disposing of organic peroxides.
Remember to follow all of the manufacturer’s directions.
Mixing and dispensing organic peroxides Users and handlers should have special training about mixing and dispensing.
Always wear chemical splash goggles and protective gloves. A good practice is to work behind safety shields or in hoods with safety glass fronts. Ventilated hoods or respirators approved for organic vapors are necessary for some formulations because of the solvents they contain.
Never mix peroxides directly with accelerators or promoters. A violent explosion can result.
Keep all work areas, tools and containers clean. Avoid mixing contaminated peroxides with any other substance.
Weigh and mix in a special room or area apart from other plant operations. Never use a storage area containing other peroxides. The mix area should be well-ventilated and have sprinklers.
Know the location of the nearest emergency shower and eye wash in the mix areas.
Adding peroxides to hot resins is dangerous. Be extremely careful during this operation.
Never dilute peroxide solutions. Using the wrong solvent or a contaminated solvent can cause a violent reaction.
Mixing and dispensing containers should be polyethylene, Teflon, glass or stainless steel 304 or 316. (Brass, copper, zinc, galvanized finishes, and some steels and aluminum alloys are corroded by peroxides and this corrosion can trigger a peroxide fire or explosion. Paper containers and wooden stirrers are good for one-time use.) Never return excess peroxides to storage containers. Do not use glass for storage, because any pressure buildup can shatter the container.
Use an electrical ground and bonding strap with any processing equipment.
Do not use acetone to dilute peroxide solutions or to clean containers or tools. Acetone reacts with some peroxides to form explosive compounds.
Spraying with organic peroxides Keep your equipment clean and properly maintained with covers in place.
Avoid contaminating the organic peroxide when filling dispensing containers. Sanding dust and resin over spray are serious sources of contamination.
Never smoke in a spray area.
Keep dispensing containers away from any sources of fire or heat.
Be sure the vents of all pressure pots are free of over spray. Vents that are too small or closed because of over spray buildup cannot work properly.
Wear eye protection.
Avoid breathing overspray – always use the ventilation system and, if necessary, wear your respirator.
Never test-spray peroxide solutions into the air or onto resin overspray. Make all test shots into water.
Be sure all spray gun parts that come in contact with peroxides are stainless steel 316.
Use only original replacement parts. Replacing screens or other parts with copper or other metals that are corroded by peroxide can result in fires or explosions.
Never point a spray gun at yourself or anyone else.
Store in the manufacturer’s shipping containers. Repackaging is dangerous.
Be sure containers are completely emptied and cleaned before disposal.
Destroy empty containers. Do not reuse.
Keep only the quantity that will be used during the shift in the plant.
Store organic peroxides apart from all other materials.
Keep all containers labeled and tightly closed to avoid contamination.
Disposal of organic peroxides Waste, spilled and expired peroxides should be disposed of in accordance with local hazardous waste laws.
Case history: Sprayup operator loses leg A sprayup plant was diluting MEK peroxide catalyst using reclaimed acetone. A two-gallon pressure pot exploded and the operator lost a leg.
What went wrong? Three different safe-handling rules were violated in this accident. First, manufacturers strongly warn against users doing their own dilution. Secondly, acetone must never be used with MEK peroxide. And lastly, use of a reclaimed solvent that could have contained contaminants increased the hazard. All pressure pots must be equipped with a good vent and kept clean.
Case history: Fire sweeps plant
At a plant manufacturing fiberglass-reinforced plastic products, a special room was used for all mixing. Mixing was done at a long bench with a liquid peroxide catalyst station at one end and the accelerator dispenser located at the other end of the bench. The man in charge of the mixing was usually careful about his housekeeping, but on one summer’s day, he used the same cotton rag to clean up spilled catalyst and accelerator. The rag spontaneously caught fire, the flames spread rapidly and the plant was destroyed.
What went wrong? The mix man knew the danger of mixing organic peroxides and promoters or accelerators, but carelessly combined them on his cleanup rag. Never mix peroxides directly with accelerators or promoters because fire or explosion can result. The accident could have been avoided if rags were only used once or if rags were color-coded to help prevent accidental contact of the chemicals.
7 Dusts Dust from flashing removal, finishing operations, sanding joints or repairing defects can irritate your skin, nose, throat and lungs. Workers in finishing areas should work in booths with mechanical exhaust ventilation or use tools that collect the dust as it is generated. If this is not feasible, they should wear dust respirators. Wearing long-sleeved shirts is also recommended to keep the dust off the skin. If high dust levels are expected, employees should wear protective clothing over their street clothes. Never use compressed air to remove dust from your clothing.
This practice contaminates the air with dust and presents an eye injury hazard.
Even when heat treated, epoxy resins are often not completely cured when you start finishing operations. These uncured resin dusts can give you allergic reactions and asthma-like problems.
Some people may develop skin reactions.
Ventilation Proper ventilation in conjunction with good work practices is the most important key to preventing airborne hazards from reaching you. There are some standard variations of the two basic types of ventilation – general dilution and local exhaust systems.
General dilution ventilation uses fans to exhaust air from a room or building and to keep air contaminants at a low level by diluting contaminated room air.
Local exhaust systems are the most effective. They move the air toward a hood, pulling contaminants along before they reach the breathing zone of the operator. But the effectiveness of local exhaust systems is greatly reduced as you move the work away from the hood. A hood 12 inches from the sources of the contaminant is only about one-fourth as effective as a hood six inches away.