National Industrial Chemicals Notification and Assessment Scheme

7.2.1Trichloroethylene

The NICNAS industry survey identified the following industries using trichloroethylene:

Metal forming/Machining (50%)

Powdercoating (10%)

Automotive (10%)

Aerospace (6%)

Electrical (6%)

Chemical Processing (2%)

Rubber products manufacture (2%)

Telecommunications (1%)

Paint (1%)

Oil refining (1%)

Gas production and manufacture (1%)

Locomotive (1%)

Lubricants manufacture (1%)

Manufacture (unspecified) (4%)

Other (4%)

In the final stages of the assessment NICNAS was advised that trichloroethylene is also used in the Textile Clothing and Footwear Industry as a cleaning agent.

Small amounts of trichloroethylene are also used in the asphalt industry to dissolve bitumen in the laboratory analysis of aggregate in asphalt.

Vapour degreasing

Vapour degreasing was the most common use of trichloroethylene among respondents to the NICNAS survey. Seventy seven percent of respondents (89/115) were end users of trichloroethylene, and of these, 75 percent (67/89) used trichloroethylene for vapour degreasing. Overseas studies have also reported that vapour degreasing is the most common use of trichloroethylene (IPCS, 1985; United Kingdom, 1996).

Vapour degreasing is a process used in many industries to clean metal components. Most commonly it is used to remove oil, grease, and/or metallic swarf from metal components prior to surface coating, assembly or repair operations, machining, inspection, or end use of the component. Vapour degreasing is also used to remove polishing compounds, paints, metallic oxides, and mineral soils.

Vapour degreasing involves the heating of a quantity of solvent in a tank to boiling point. Condensing coils located on the inside perimeter of the tank control the height to which the solvent vapours rise, creating a ‘vapour zone’ into which metal components to be degreased are lowered. Vapour condenses on the cold components, dissolving surface oils and greases. The contaminated condensate drains into the boiling liquid below. This cleaning action continues until the temperature of the components being degreased reaches the temperature of the vapour, at which point condensation ceases. The components are then lifted above the vapour zone and held in a freeboard area for cooling and evaporation of any remaining solvent, and then removed from the degreaser at a controlled rate to avoid lifting vapour out of the degreaser. Vapour degreasers can incorporate spraying and/or immersion in boiling solvent as part of the cleaning process.

Trichloroethylene is one of several solvents that can be used for vapour degreasing. Other solvents used include tetrachloroethylene, methylene chloride, and 1,1,2-trichloro-1,2,2-trifluoroethane. The manufacture of 1,1,1-trichloroethane, another solvent commonly used in vapour degreasing, ceased in January 1996 in accordance with the Montreal Protocol, and importation of existing stocks is strictly regulated under the Ozone Protection Act 1989. It is possible that the use of trichloroethylene in vapour degreasing may increase due to the phase out of 1,1,1-trichloroethane.

Cold cleaning

Cold cleaning refers to the process of cleaning by dipping or soaking articles in a cleaning liquid, or spraying, brushing, or wiping the cleaner onto articles at temperatures below boiling point. Twenty nine percent of end users (26/89) of trichloroethylene responding to the NICNAS industry survey reported using trichloroethylene in cold cleaning processes. This proportion of use of trichloroethylene in cold cleaning activities is higher than that reported in overseas studies.

Cold cleaning activities mentioned in the NICNAS survey included immersion in tanks, drums, or other containers, ultrasonic cleaning, and spraying, brushing and wiping. In ultrasonic cleaning, a transducer mounted on the bottom or side of a tank containing solvent creates vibrations which cause the rapid expansion and contraction of microscopic bubbles in the solvent, resulting in a scrubbing action on parts that are immersed in the tank. Ultrasonic agitation can be employed in hot or cold immersion cleaning, and is sometimes incorporated into vapour degreasing systems.

7.2.2Products containing trichloroethylene

adhesives

electrical equipment cleaning solvents

metal degreasing solvents

waterproofing agents

paint strippers

carpet shampoos

tyre cleaning product

Details on the number of products identified in each product category, the range of concentrations of trichloroethylene within each category, and the total estimated amount of trichloroethylene used in the products are summarised in Table 5.

It is expected that there are more products containing trichloroethylene formulated in Australia which have not been identified. Regarding imported products, it is not possible to identify products containing trichloroethylene from customs data, and so it is possible that more products containing trichloroethylene are being imported.

Product Type	Number of products	Percentage TCE (range)	Approx. amount TCE used annually (tonnes)
Adhesives – imported	18	20 - >90	105
Adhesives - formulated in Australia	3	10 - 88	6.5
Electrical equipment cleaning solvents	8	13 - >60	93
Metal degreasing solvents	7	<10 - 65	53
Waterproofing agents –imported	1	90	0.2
Waterproofing agents - formulated in Australia	3	60 - 70	5.4
Paint strippers	3	0.05 - 8	1.5
Carpet shampoos	2	3	0.2
Tyre cleaning product - imported	1	>90	18
TOTAL	46	0.05 - >90	282.9

Solvents are used in adhesives to lower the viscosity and increase the wetting of the adherent/substrate. Many industrial adhesives comprise polymer blends, organic compounds and mineral fillers dissolved in solvent (such as trichloroethylene). They are used in bonding natural and synthetic rubber to metal and other rigid substrates, plastics, and fabrics. Other adhesives bond plastics, rubber and fabric, and bond polyurethane coatings to metal or to natural or synthetic rubber. Some are two-part adhesive systems, which are mixed just prior to use. Further dilution of the mixtures with solvents including trichloroethylene may also occur prior to application. Trichloroethylene is often used where a solvent of low flammability with the desired drying time is required.

The majority of the imported adhesives containing trichloroethylene are used for rubber repair and rubber lining in the mining and automotive industries. Uses include the hot or cold vulcanisation of patches to tyres, and sealing tyre inner linings after buffing; and the lining of tanks with rubber and repair of rubber belting. Two products, used in cold vulcanisation repair of tyres, are available to the public. Approximately 5 tonnes of trichloroethylene per year are used in these two products in total.