Safe use manual
8. Installation and maintenance of Chrysotile-Cement Products
Page 18
Precautions must be taken when installing chrysotile-cement sheet and pipe in the field, i.e when using sheet in construction and when laying pipe into the ground. This is necessary because both sheet and pipe are often cut, sawed, drilled or bored during the installation process. All these actions can produce a considerable amount of dust if proper tools are not used. However, if the appropriate control practices are followed, studies have shown that exposure levels can be kept well below the 1 f/ml level.
8.1 Tools and techniques
Because of the potential hazards involved, manufacturers recommend that high-speed tools never be used when cutting or drilling chrysotile-cement products. Indeed, in order to avoid cutting at construction sites, most manufacturers are pre-cutting or pre-drilling products prior to their leaving the factory. For certain chrysotile-cement products, it is also possible to use installation techniques, such as the offsetting system, where little or no onsite cutting is necessary.
Where cutting must be carried out at the construction site, hand tools should be used as much as possible. For example, mitring can be done by using shears that break the asbestos-cement into chips. Alternatively, simple hand saws with large teeth that produce a very coarse dust can be used. Also, the drilling of holes (when punching is not possible) can be performed by hand drill that produce coarse shavings because of the low speed. These materials can be cleaned-up by wet sweeping and require no special precautions.
If disc grinders, hand-held power saws are used in the field, a centrally located, separate building should be provided. Each piece of equipment should be fitted with a properly designed hood that is connected to an HEPA vacuum system. Clean-up of the interior of the building can be accomplished by using the HEPA vacuum system. In general, abrasive or masonry disc grinders should never be used, unless equipped with a HEPA vacuum system. If highspeed drilling is used, the drill must have a vacuum attachment to collect dust, and the drill should run at low speed. Another method is to puncture holes with a sharply pointed hammer, such as the so-called roofers hammer. Applications of simple work practices, which do not generate dust, will protect worker during removal of chrysotile cement products.
|
