If you use flammable or combustible liquids, you must comply with the requirements of this section as well as the requirements of sections 1910.123, 1910.124, and 1910.126, as applicable.

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     You must comply with        |             And:
        this section if:         |                               
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* The flashpoint of the          |    * The liquid is heated as 
  flammable or combustible       |      part of the operation; or
  liquid is 200 deg. F           |    * A heated object is placed 
  (93.3 deg. C) or above...      |      in the liquid.
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1910.125(a)

What type of construction material must be used in making my dip tank? Your dip tank must be made of noncombustible material.

1910.125(b)

When must I provide overflow piping?

1910.125(b)(1)

You must provide properly trapped overflow piping that discharges to a safe location for any dip tank having:

1910.125(b)(1)(i)

A capacity greater than 150 gallons (568 L); or

1910.125(b)(1)(ii)

A liquid surface area greater than 10 feet² (0.95 m²).

1910.125(b)(2)

You must also ensure that:

1910.125(b)(2)(i)

Any overflow piping is at least 3 inches (7.6 cm) in diameter and has sufficient capacity to prevent the dip tank from overflowing;

1910.125(b)(2)(ii)

Piping connections on drains and overflow pipes allow ready access to the interior of the pipe for inspection and cleaning; and

1910.125(b)(2)(iii)

The bottom of the overflow connection is at least 6 inches (15.2 cm) below the top of the dip tank.

1910.125(c)

When must I provide a bottom drain?

1910.125(c)(1)

You must provide a bottom drain for dip tanks that contain more than 500 gallons (1893 L) of liquid, unless:

1910.125(c)(1)(i)

The dip tank is equipped with an automatic closing cover meeting the requirements of paragraph (f)(3) of this section; or

1910.125(c)(1)(ii)

The viscosity of the liquid at normal atmospheric temperature does not allow the liquid to flow or be pumped easily.

1910.125(c)(2)

You must ensure that the bottom drain required by this section:

1910.125(c)(2)(i)

Will empty the dip tank during a fire;

1910.125(c)(2)(ii)

Is properly trapped;

1910.125(c)(2)(iii)

Has pipes that permit the dip tank's contents to be removed within five minutes after a fire begins; and

1910.125(c)(2)(iv)

Discharges to a safe location.

1910.125(c)(3)

Any bottom drain you provide must be capable of manual and automatic operation, and manual operation must be from a safe and accessible location.

1910.125(c)(4)

You must ensure that automatic pumps are used when gravity flow from the bottom drain is impractical.

1910.125(d)

When must my conveyor system shut down automatically? If your conveyor system is used with a dip tank, the system must shut down automatically:

1910.125(d)(1)

If there is a fire; or

1910.125(d)(2)

If the ventilation rate drops below what is required by paragraph (b) of §1910.124.

1910.125(e)

What ignition and fuel sources must be controlled?

1910.125(e)(1)

In each vapor area and any adjacent area, you must ensure that:

1910.125(e)(1)(i)

All electrical wiring and equipment conform to the applicable hazardous (classified)-area requirements of subpart S of this part (except as specifically permitted in paragraph (g) of §1910.126); and

1910.125(e)(1)(ii)

There are no flames, spark-producing devices, or other surfaces that are hot enough to ignite vapors.

1910.125(e)(2)

You must ensure that any portable container used to add liquid to the tank is electrically bonded to the dip tank and positively grounded to prevent static electrical sparks or arcs.

1910.125(e)(3)

You must ensure that a heating system that is used in a drying operation and could cause ignition:

1910.125(e)(3)(i)

Is installed in accordance with NFPA 86A-1969, Standard for Ovens and Furnaces (which is incorporated by reference in §1910.6 of this part);

1910.125(e)(3)(ii)

Has adequate mechanical ventilation that operates before and during the drying operation; and

1910.125(e)(3)(iii)

Shuts down automatically if any ventilating fan fails to maintain adequate ventilation.

1910.125(e)(4)

You also must ensure that:

1910.125(e)(4)(i)

All vapor areas are free of combustible debris and as free as practicable of combustible stock;

1910.125(e)(4)(ii)

Rags and other material contaminated with liquids from dipping or coating operations are placed in approved waste cans immediately after use; and

1910.125(e)(4)(iii)

Waste can contents are properly disposed of at the end of each shift.

1910.125(e)(5)

You must prohibit smoking in a vapor area and must post a readily visible "No Smoking" sign near each dip tank.

1910.125(f)

What fire protection must I provide?

1910.125(f)(1)

You must provide the fire protection required by this paragraph (f) for:

1910.125(f)(1)(i)

Any dip tank having a capacity of at least 150 gallons (568 L) or a liquid surface area of at least 4 feet² (0.38 m¹); and

1910.125(f)(1)(ii)

Any hardening or tempering tank having a capacity of at least 500 gallons (1893 L) or a liquid surface area of at least 25 feet² (2.37 m²).

1910.125(f)(2)

For every vapor area, you must provide:

1910.125(f)(2)(i)

Manual fire extinguishers that are suitable for flammable and combustible liquid fires and that conform to the requirements of §1910.157; and

1910.125(f)(2)(ii)

An automatic fire-extinguishing system that conforms to the requirements of subpart L of this part.

1910.125(f)(3)

You may substitute a cover that is closed by an approved automatic device for the automatic fire-extinguishing system if the cover:

1910.125(f)(3)(i)

Can also be activated manually;

1910.125(f)(3)(ii)

Is noncombustible or tin-clad, with the enclosing metal applied with locked joints; and

1910.125(f)(3)(iii)

Is kept closed when the dip tank is not in use.

1910.125(g)

To what temperature may I heat a liquid in a dip tank? You must maintain the temperature of the liquid in a dip tank:

1910.125(g)(1)

Below the liquid's boiling point; and

1910.125(g)(2)

At least 100 deg. F (37.8° C) below the liquid's autoignition temperature.

[64 FR 13909, March 23, 1999]