Dip tank rule applicability

Under 1910.123(a)(1), this rule applies whenever you use a dip tank that contains a liquid other than water and you use that liquid or its vapor to clean, coat, alter the surface of, or change the character of an object. See the coverage language in 1910.123(a)(1).

• Examples include immersing parts in solvents to degrease, suspending parts in solvent vapors to remove contaminants, or using a chemical bath to change a surface.
• If the tank only contains water, this particular dip-tank rule does not apply; other OSHA standards might still apply.

Under 1910.123(a)(2), yes — the rule also applies to the draining or drying of an object that has been dipped or coated. See 1910.123(a)(2).

• That means safety requirements that apply to the dipping stage also extend to associated drain boards, drying conveyors, and similar operations where residues or vapors may create hazards.

Under 1910.123(b), typical covered operations include paint dipping, electroplating, pickling, quenching, tanning, degreasing, stripping, cleaning, roll coating, flow coating, and curtain coating. See 1910.123(b).

• If your process is one of these or similar uses of a liquid other than water (or its vapor) to treat objects, the dip-tank rules apply.

Under 1910.123(c), no — the dip-tank rules do not apply if the operation only uses a molten material (for example, a molten metal, alloy, or salt). See 1910.123(c).

• If your operation involves molten baths only, consult other applicable standards for molten materials and thermal hazards.

Under 1910.123(d), a "dip tank" means a container holding a liquid other than water that is used for dipping or coating; an object may be immersed (partially or fully) or suspended in the vapor above the tank. See the definition in 1910.123(d).

• This definition covers both liquid immersion and vapor-phase processing over the tank.

Under 1910.123(d), a "vapor area" means any space containing a dip tank (including drain boards and drying or conveying equipment) and any surrounding area where the vapor concentration exceeds 25% of the liquid's lower flammable limit (LFL). See 1910.123(d).

• You determine whether an area is a vapor area by measuring vapor concentrations and comparing them to 25% of the LFL for the liquid involved.
• If concentrations exceed that threshold, the area is treated as a vapor area for purposes of the dip tank rules.

Under 1910.123(d), an "adjacent area" is any area within 20 feet (6.1 m) of a vapor area that is not separated from the vapor area by tight partitions. See 1910.123(d).

• If the space within 20 feet of the vapor area is open to it (no tight partitions), treat that space as an adjacent area and consider appropriate controls and protections for employees there.

Under 1910.123(d), "Lower flammable limit (LFL)" means the lowest concentration of a material that will propagate a flame and is usually expressed as percent by volume in air; guidance on flashpoint and related test methods appears in Appendix B to 1910.1200. See the LFL definition in 1910.123(d) and testing reference in 1910.1200.

• Use material data (manufacturer or test data) to find LFL values, or perform appropriate measurements per recognized test methods referenced in the Hazard Communication standard.

Under 1910.123(a), no — the rule applies when you use a dip tank containing a liquid other than water. If the tank holds only water, this specific dip-tank standard does not apply. See 1910.123(a).

• Note: operations using only water may still be covered by other OSHA standards depending on hazards present.

Under 1910.123(a)(1)(i)-(iv), yes — the rule applies when you use the liquid in the tank or its vapor to clean, coat, alter the surface of, or change the character of an object. See 1910.123(a)(1).

• Vapor-phase degreasing or vapor deposition over a dip tank is covered if the tank contains a liquid other than water and the vapor is used for the operation.

Under 1910.123(d), "approved" means the equipment so designated is listed or approved by a nationally recognized testing laboratory as defined by [1910.7]. See 1910.123(d) and the definition in 1910.7.

• Use equipment certified by a recognized lab (for example, UL or similar) when the standard requires "approved" devices.

Under 1910.123(d), "flashpoint" means the minimum temperature at which a liquid gives off a vapor in sufficient concentration to ignite, and the test methods referenced are in Appendix B to [1910.1200]. See the flashpoint definition in 1910.123(d) and test-method reference in 1910.1200.

• Use recognized test methods (per Appendix B) or manufacturer data to determine flashpoint for your liquid.

Under 1910.123(d), "autoignition temperature" means the minimum temperature required to cause self-sustained combustion without any other source of ignition. See the definition in 1910.123(d).

• Knowing the autoignition temperature helps you evaluate fire risk from heated tanks and process equipment and select appropriate controls to prevent spontaneous ignition.

Under 1910.123(d), yes — a vapor area includes any space containing a dip tank, its drain boards, and associated drying or conveying equipment. See 1910.123(d).

• When planning controls, include these associated pieces of equipment because they can accumulate liquid residues and emit vapors.

Under 1910.123(d), no — an "adjacent area" is any area within 20 feet of a vapor area that is not separated from the vapor area by tight partitions. If a tight partition isolates that space, it would not be an "adjacent area" under the standard. See 1910.123(d).

• Use engineering judgment and measurements to confirm whether partitions are adequate to separate areas and prevent vapor migration.

Under 1910.123 and 1910.1200, you should consult the Hazard Communication standard whenever you use hazardous chemicals in dip tanks to determine their hazards (flammability, LFL, flashpoint) and label/manage them appropriately. See 1910.123(d) and 1910.1200.

• Hazard communication data sheets will provide the LFL, flashpoint, and other properties you need for compliance with dip-tank rules.

Under 1910.123(c), yes — the molten-materials exception covers only operations that use a molten material (like molten metal, alloy, or salt). A hot but non‑molten liquid (for example, hot solvent) is still a liquid other than water and remains subject to the dip-tank rules. See 1910.123(c) and the general coverage in 1910.123(a).

• Treat hot non‑molten liquids the same as other dip-tank liquids for safety controls.

Under 1910.123(d), no — a space is a "vapor area" only where the vapor concentration exceeds 25% of the LFL of the liquid in the tank. If concentrations are below that threshold, the space is not a "vapor area" under this definition. See 1910.123(d).

• However, continue to monitor and control vapor sources; concentrations can change with process conditions, temperature, or ventilation.

Under 1910.123(d), "you" means the employer as defined by the Occupational Safety and Health Act. See the definition in 1910.123(d) and broader employer responsibilities in 1910.

• Employers are responsible for determining coverage, assessing hazards, and implementing required protections for dip-tank operations.

Under 1910.123(b), electroplating is listed as an example of a covered operation; whether it remains covered when conducted in a fume hood depends on whether the dip-tank liquids or vapors meet the criteria for coverage (liquid other than water and used to treat objects) and whether vapor areas/adjacent areas exist. See 1910.123(b) and the definitions in 1910.123(d).

• Containment and effective ventilation (e.g., a properly designed fume hood) can control vapor dispersion, but you must verify concentrations and maintain required protections for employees.