Abrasive blast cleaning

SSPC-VIS-1-89, Visual Standardfor Abrasive Blast Cleaned Steel, Steel Stmctures Painting Council, Pittsburgh, Pa., 1989. 

J. L. Goodier, E. Boudreau, G. Coletta, and R. Lueas. Industrial Health and Safety Criteria for Abrasive Blast Cleaning Operations. HEW Publication no. (NIOSH) 75-122. NIOSH (. krthur D. Little), 1974. 

Dry abrasive blast cleaning should be used on new steelwork where the main contaminant is mill scale. For heavily rusted and pitted steelwork, increased durability can be obtained by the use of wet abrasive blasting where this is practicable. The water will be more effective in removing the potentially destructive and corrosive soluble iron-corrosion products that form at the bottom of corrosion pits. 

Very high standards of surface preparation are necessary, e.g. abrasive blast cleaning to Sa2y, BS7079 Part Al, 1989 for steel components... 

Profile - Surface profile is a measure of the roughness of a surface which results from abrasive blast cleaning. The height of the profile produced on the surface is measured from the bottom of the lowest valley to the top of the highest peak. 

BS EN ISO 8504-2 2001, BS 7079-D2 2000 Preparation of steel snbsirates before application of paints and related prodncts. Surface preparation methods. Abrasive blast cleaning. 

Method for the Grading of Surface Profile of Abrasively Blast Cleaned Steel using a Comparator, BS 7079 Part C2 1989, British Standards Institution, London (1989)... 

ISO 8503-2 1988 Preparation of Steel Substrates before Application of Paints and Related Products— Method for Grading of Surface Profile of Abrasive Blast cleaned Steel... 

Abrasive blasting cleaning is in wide use in many industries and presents both a physical hazard due to the force of particles being propelled, and a health hazard depending npon what material (e.g., silica) is used to abrade the article. 

When compressed air is used with abrasive blast cleaning equipment, the operating valve must be held open manually. As compressed air is used to inflate auto tires, a clip-on chuck and an inline regulator preset to 40 psi are required. It should be prohibited to use compressed air to clean up or move combustible dust because such action could cause the dust to be suspended in the air and cause a fire or explosion hazard. 

Abrasive blast cleaning nozzles. The blast cleaning nozzles shall be equipped with an operating valve which must be held open manually. A support shall be provided on which the nozzle may be mounted when it is not in use. 

Field Measurement of Surface Profile of Abrasive Blast Cleaned Steel Surfaces Using a Replica Tape... 

When compressed air is used with abrasive blast cleaning equipment, is the operating valve a type... 

Wet abrasive blast cleaning Compressed air propels abrasive against the surface. Water is injected into the abrasive stream either before or after the abrasive exits the nozzle. The abrasive, paint debris, and water are collected for disposal. 

For smaller items, or for touch-up, venturi-abrasive blast cleaning cup guns may be used. The abrasive in this equipment is stored in a small container fastened beneath the blasting gun and ejected into the air stream. This equipment is used by hobbyists, by automotive repainting shops, and for small areas or inside shops for work on small pieces. 

Wet abrasive blast cleaning systems commonly encountered include air, water, or abrasive blast cleaning, which uses compressed air to propel the abrasive pressurized water or abrasive blast cleaning, which uses water to propel the abrasive and a combination of pressurized water or pressurized air with abrasives. The abrasive defines the profile. 

Fusion Bonded Epoxy (F.B.E.). The steel is decontaminated, abrasive blast cleaned and heated by electrical induction heaters to the prescribed temperatures, before uniformly applying epoxy powder. Another example is the use of hot applied coal tar enamels used mainly as pipeline coatings. 

All blast cleaning nozzles are to be equipped with an operating valve that must be held open manually and should operate as a deadman or positive-pressure control. A support should be provided upon which the nozzle may be mounted when not in use. All abrasive blasting cleaning enclosures need to be exhaust ventilated in such a way that a continuous inward flow of air will be maintained at all openings in the enclosure during the blasting operation. 

Guide to SSPC-VIS 1-89 Visual Standard for Abrasive Blast Cleaned Steel (Standard Reference Photographs)... 

This specification covers the requirements for cleanliness of recycled ferrous metallic blast cleaning abrasives used for the removal of coatings, paints, scales, rust, and other foreign matter from steel or other surfaces. Requirements are given for lab and field testing of recycled ferrous metalhc abrasives work mix. Recycled ferrous metallic abrasives are intended for use in field or shop abrasive blast cleaning of steel or other surfaces. 

This guide covers those shop primers used in today s modem commercial shipyards for preconstmction and prefabrication priming of abrasive blast cleaned stmctural steel and steel plates, lb maximize efficiency in new construction, aU ships steel plates, shapes, and angles are abrasive blast cleaned, shop primed, and stored for future use in preparation of sections of ships, called modules or units. Shop primers are covered by generic classification. 

A typical system using this formulation would be over abrasive blast cleaned steel (SIS 05 59 00 Sa2 /2 or SSPC-SPIO) which has been primed with 1 x 30 microns dft (dry film thickness) zinc rich epoxy primer. The topcoat may be 2 x 150 microns dft white Eggshell acrylic topcoat. 

For better anti-corrosive protection in Marine and Off-shore environments a zinc-rich or epoxy primer would normally be used over abrasive blast cleaned steel. Acrylic/chloro-mbber based formulations are favoured for these thermoplastic applications rather than acrylic/vinyl based systems. 

---