Document ID: chunk:federal_register_of_legislation:F2016L00417:body:0:p15
Version: federal_register_of_legislation:F2016L00417
Segment Type: other
Provision Reference: 
Character Range: 37154–40116

jetting systems Part 1:– Guidelines for safe operation and maintenance and AS/NZS 4233.2: High pressure water (hydro) jetting systems Part 2:- Construction and performance.

Centrifugal wheel blasting
Centrifugal wheel blasting involves a rotating wheel assembly, either air or electrically driven, inside an enclosure fitted with a dust collector. Abrasive is propelled outwards from the spinning wheel by centrifugal force, striking the surface to be cleaned and removing rust, paint and
mill scale.
Abrasives used include steel shot, steel grit, cut wire and chilled iron grit. They are recyclable
and are continuously recovered, cleaned and returned for re-use.

Centrifugal wheel blasting is normally used where the work is of a consistent size, (e.g. pipes, valves, or steel sections). Normally, the rotating wheel assembly remains fixed and the surface to be cleaned is passed through the enclosure, but centrifugal wheel blasting can also be used on-site, (e.g. on a tank), with special adaptors where the wheel assembly moves across a stationary work surface.

Because all blasting takes place within an enclosure, there is no contact with airborne dust or high velocity particles. This minimises the risk to operators. However, attention should be paid to seals on wheel abrading equipment to ensure that toxic dusts cannot escape into the workplace during operation and that sufficient extraction clearance time is allowed before access doors are opened.

Vacuum blasting
Vacuum blast cleaning uses a standard abrasive blast nozzle, operating inside a shroud which is in close contact with the work surface, forming a tight seal. As the abrasive impinges on the surface, a vacuum is applied inside the shroud, removing the debris. The abrasive material, which typically can be steel shot, steel grit, chilled iron grit, aluminium oxide or garnet, is separated, and returned for re-use.

A variety of heads may be used to achieve a tight seal for inside corners, outside corners, and flat surfaces. In practice, however, operators tend not to change heads, lifting the assembly from the surface to clean odd shapes and inaccessible surfaces. While this may save time, it breaks the seal, defeating the purpose of the vacuum and exposing workers and the environment to hazards. This practice should be avoided where possible.
When used properly, vacuum blast cleaning can clean effectively with minimal dust generation.

Other removal methods
There are many emerging techniques and equipment that may minimise airborne dust levels. These include:
    * sodium bicarbonate blasting
    * blast cleaning with reusable sponge abrasives
    * carbon dioxide (dry ice) blast cleaning.
You should also consider cleaning techniques that do not involve blasting, particularly for smaller jobs. These include:
    * chemical strippers
    * heat guns
    * power tools with dust collection systems
    * manual sanding
    * scraping.
Although these techniques