Dipping and coating requirements

Any container you use as a dip tank must be strong enough to withstand any load you expect it to carry. See the requirement in 1910.124(a) for the exact language.

You must provide ventilation that keeps the airborne concentration of any substance in the vapor area below 25% of its lower flammable limit (LFL). This is stated in 1910.124(b)(1).

When a liquid in a dip tank creates an exposure hazard covered by a standard listed in subpart Z, you must control worker exposure as required by that specific subpart Z standard. See 1910.124(b)(2).

Yes — you may use a tank cover or a material that floats on the liquid surface to replace or supplement ventilation, provided the method keeps airborne concentrations and worker exposures within the limits in 1910.124(b)(1) and 1910.124(b)(2).

When you use mechanical ventilation it must conform to one of the listed consensus standards incorporated by reference in 1910.124(b)(4), such as [ANSI Z9.2-1979] (via the paragraph 1910.124(b)(4)(i), [NFPA 34-1995] (via 1910.124(b)(4)(ii)), ACGIH's Industrial Ventilation manual (via 1910.124(b)(4)(iii)), or the older ANSI/NFPA standards in 1910.124(b)(4)(iv).

Mechanical ventilation must draw the flow of air into a hood or exhaust duct; the system must capture vapors and carry them into a hood or duct as required by 1910.124(b)(5).

Yes—each dip tank must have an independent exhaust system unless the combination of substances being removed will not cause a fire, explosion, or chemical reaction, as specified in 1910.124(b)(6) and its subparagraphs (1910.124(b)(6)(i), 1910.124(b)(6)(ii), 1910.124(b)(6)(iii).

You may not recirculate exhaust air when any substance in that air poses a health hazard to employees or exceeds 25% of its LFL, as stated in 1910.124(c)(1).

If you recirculate exhaust air from dipping or coating operations using flammable liquids or liquids with flashpoints greater than 199.4 °F (93 °C), the air must be free of solid particulates that pose hazards and must be monitored by approved equipment, as required in 1910.124(c)(2) and its subparagraphs (1910.124(c)(2)(i), 1910.124(c)(2)(ii).

You must have a system that sounds an alarm and automatically shuts down the operation when the vapor concentration for any substance in the exhaust airstream exceeds 25% of its LFL, as required by 1910.124(c)(3).

Each room with exhaust hoods must receive a volume of outside air that is at least 90 percent of the volume of the exhaust air, according to 1910.124(d)(1).

You must ensure the outside air supply does not damage the exhaust hoods, as required by 1910.124(d)(2).

Before an employee enters a dip tank you must meet the entry requirements of OSHA's Permit-Required Confined Spaces standard, [1910.146], as applicable; see 1910.124(e) and 1910.146.

Employees must know the first-aid procedures appropriate to the dipping or coating hazards they face, as required by 1910.124(f). You should train workers in the specific first-aid steps for exposures they may encounter.

You must provide locker or storage space to prevent contamination of street clothes, an emergency shower and eyewash station (or an approved hose alternative), and at least one basin with a hot-water faucet for every 10 employees working with such liquids, as detailed in 1910.124(g) and its subparagraphs (1910.124(g)(1), 1910.124(g)(2), 1910.124(g)(3).

You may substitute a water hose at least 4 feet (1.22 m) long and at least 3/4 inch (18 mm) thick with a quick-opening valve and carrying a pressure of 25 psi (1.62 k/cm2) or less instead of an emergency shower and eyewash, per 1910.124(g)(2).

You must get a physician's approval before an employee with a sore, burn, or other lesion that requires medical treatment works in a vapor area; ensure small skin injuries are treated by a properly designated person; and provide appropriate first-aid supplies near the operation, as required by 1910.124(h) and its subparagraphs (1910.124(h)(1), 1910.124(h)(2), 1910.124(h)(3).

Employees who work with chromic acid must receive periodic examinations of their exposed body parts, especially their nostrils, as required in 1910.124(h)(4).

Before permitting an employee to clean the interior of a dip tank you must drain the tank and open the cleanout doors, and ventilate and clear any pockets where hazardous vapors may have accumulated, as required by 1910.124(i) and its subparagraphs (1910.124(i)(1), 1910.124(i)(2).

You must inspect hoods and ductwork for corrosion or damage at least quarterly during operation and prior to operation after a prolonged shutdown, and you must ensure airflow is adequate at least quarterly during operation and prior to operation after a prolonged shutdown, per 1910.124(j)(1) and 1910.124(j)(2) with their subparagraphs (1910.124(j)(1)(i), 1910.124(j)(1)(ii), 1910.124(j)(2)(i), 1910.124(j)(2)(ii).

You must periodically inspect all dipping and coating equipment (covers, drains, overflow piping, electrical and fire-extinguishing systems) and promptly correct deficiencies; provide mechanical ventilation or properly selected respirators when welding, burning, or open-flame work releases toxic substances into the vapor area; and have dip tanks thoroughly cleaned of solvents and vapors before permitting welding, burning, or open-flame work, as required by 1910.124(j)(3), 1910.124(j)(4) (see also 1910.134 for respirator selection), and 1910.124(j)(5).

If you recirculate exhaust air you must monitor the exhaust airstream with approved equipment and have an alarm and automatic shutdown when vapor concentration exceeds 25% of LFL, as required by 1910.124(c)(2)(ii) and 1910.124(c)(3).