Dipping and Coating
Operations (Diptanks)
Chapter 296-835, WAC |
Effective
Date: 10/01/02 |
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Your responsibility:
Safeguard employees working with dip tanks
used for specific processes
You must
HARDENING OR TEMPERING
| Meet specific requirements
if you use a hardening or tempering tank |
WAC 296-835-13005 |
|
ELECTROSTATIC EQUIPMENT
FLOW COATING
ROLL COATING
| Take additional
precautions if your roll coating operation uses a
liquid that has a flashpoint below 140°F (60°C) |
WAC 296-835-13020 |
|
VAPOR DEGREASING
SPRAY CLEANING OR DEGREASING
| Control liquid spray
over an open surface cleaning or degreasing tank
|
WAC 296-835-13030 |
|

HARDENING OR TEMPERING
WAC
296-835-13005
Meet specific requirements if you use a hardening
or tempering tank.
You must
(1) Provide an automatic fire extinguishing system or
an automatic dip tank cover for any hardening and tempering tank
that uses flammable or combustible liquids and:
- Holds 500 gallons (1893 L) or more of liquid
OR
- Has 25 square feet (2.37 m 2)
or more of liquid surface area.
(2) Prevent fires.
- Make sure hardening and tempering tanks are:
- - Not located on or near combustible
flooring.
- - Located as far away as practical from
furnaces.
- - Equipped with noncombustible hoods and
vents (or equally effective devices) for venting to the outside.
- Treat vent ducts as flues and keep them away
from combustible material, particularly roofs.
(3) Make sure air under pressure isn't used to:
- Fill the tank
OR
- Agitate the liquid in the tank.
(4) Equip each tank with an alarm that will sound when
the temperature is within 50°F (10°C) of the liquid's flashpoint
(alarm set point).
(5) Make sure a limit switch shuts down conveyors supplying
work to the tank when the temperature reaches the alarm setpoint,
if operationally practical.
(6) Have a circulating cooling system if the temperature
of the liquid can exceed the alarm set point.
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Note:
The bottom drain of the tank may be combined
with the oil circulating system if the requirements for
bottom drains in WAC
296-835-12015 are satisfied.
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ELECTROSTATIC EQUIPMENT
WAC
296-835-13010
Meet specific requirements if you use electrostatic
equipment.
You must
(1) Provide safe electrical equipment.
- Make sure electrodes in your equipment are:
- - Substantial
- - Rigidly supported
- - Permanently located
- - Effectively insulated from ground by insulators
- Make sure the insulators are:
- - Nonporous
- - Noncombustible
- - Kept clean and dry
- Make sure high voltage leads to electrodes
are effectively:
- - Supported on permanent, suitable insulators
- - Guarded against accidental contact or
grounding.
(2) Make sure transformers, powerpacks, control apparatus,
and all other electrical parts of the equipment:
- Are located outside the vapor area
OR
- Meet the requirements of WAC 296-835-12040.
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Exemption:
High voltage grids and their connections
may be located in the vapor area without meeting the requirements
of WAC
296-835-12040. |
(3) Safeguard paint detearing operations.
- Use approved electrostatic equipment in paint
detearing operations.
(4) Make sure goods being paint deteared are:
- Supported on conveyors
- Not manually handled.
(5) Keep a minimum safe distance (twice the sparking distance)
between goods being paint deteared and the electrodes or conductors
of the electrostatic equipment at all times by:
- Arranging the conveyors to provide the necessary
distance
- Supporting the goods to prevent swinging or
movement, if necessary
- Post a sign that shows the minimum safe distance
(twice the sparking distance) near the equipment, where it can
be easily seen.
(6) Keep paint detearing operations separate from storage
areas and people by using fences, rails or guards that are:
- Made of conducting material
- Adequately grounded.
(7) Protect paint detearing operations from fire by installing:
- Automatic sprinklers
OR
- An approved automatic fire extinguishing system.
(8) Collect and remove paint deposits by:
- Providing removable drip plates and screens
- Cleaning these plates and screens in a safe
location.
(9) Make sure electrostatic equipment has automatic controls
that immediately disconnect the power supply to the high-voltage
transformer and signal the operator, if:
FLOW COATING
WAC
296-835-13015
Meet specific requirements if you use a flow
coating process.
You must
(1) Make sure all piping is substantial and rigidly supported.
(2) Make sure the paint is supplied by a:
- Gravity tank that doesn't hold more than 10
gallons (38 L)
- Direct low-pressure pumping system.
(3) Have an approved heat-actuated device that shuts down
the pumping system if there is a fire.
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Note:
The area of the sump, and any areas on
which paint flows, should be included in the area of dip
tank. |
ROLL COATING
WAC
296-835-13020
Take additional precautions if your roll
coating operation uses a liquid that has a flashpoint below 140°F
(60°C).
Important:
This section applies to the processes of roll coating, roll spreading,
or roll impregnating that use a liquid having a flashpoint below
140°F (60°C). Material may be passed directly through a tank or
over the surface of a roller that revolves partially submerged
in the liquid.
You must
- Prevent sparks from static electricity by:
- - Bonding and grounding all metallic parts
(including rotating parts) and installing static collectors
OR
- - Maintaining a conductive atmosphere (one
with a high relative humidity, for example) in the vapor area.
VAPOR DEGREASING
WAC
296-835-13025
Provide additional safeguards for vapor
degreasing tanks.
You must
(1) Make sure, if the tank has a condenser or a vapor-level
thermostat, that it keeps the vapor level at least:
- 36 inches (91 cm) below the top of the tank
if the width of the tank is 72 inches or more
OR
- 1/2 the tank width below the top of the tank
if the tank is less than 72 inches wide.
(2) Make sure, if you use gas as a fuel to heat the tank
liquid, that the combustion chamber is airtight (except for the
flue opening) to prevent solvent vapors from entering the air-fuel
mixture.
(3) Make sure the exhaust flue:
- Is made of corrosion-resistant material
- Extends to the outside
- Has a draft diverter if mechanical exhaust
is used.
(4) Take special precautions to keep solvent vapors from
mixing with the combustion air of the heater if chlorinated or
fluorinated hydrocarbon solvents (for example, trichloroethylene
or freon) are used in the dip tank.
(5) Keep the temperature of the heating element low enough
to keep a solvent or mixture from:
- Decomposing
OR
- Generating excessive vapor.
SPRAY CLEANING OR DEGREASING
WAC
296-835-13030
Control liquid spray over an open surface
cleaning or degreasing tank.
You must
- Control the spray to the greatest extent feasible
by:
- - Enclosing the spraying operation as completely
as possible
- - Using mechanical ventilation to provide
enough inward air velocity to prevent the spray from leaving
the vapor area.
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Note:
Mechanical baffles may be used to help
prevent the discharge of spray. |
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Reference:
Spray painting operations are covered
in Spray Finishing Using Flammable and Combustible Materials,
WAC
296-24-370, and Spray-Finishing Operations, WAC 296-62-11019. |
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