What is Sandblasting?
In the corrosion control, there are some procedures to extend the life of the metal surfaces and to make the desired quality coating. Surface quality is largely dependent on surface preparation before coating.
The most commonly used and most effective method of removing the effects of corrosion is the
coating of the surface with materials resistant to external factors. The surface preparation before of these coatings is the basic of the coating quality.
Sandblasting is a method used to provide the roughness required for the paint to adhere to the surface and to homogenize the surface and to clean rust, lime, oil and paint residue on the metal surface.
As the application, blasting is the process of impacting the granule with high-pressure air. During this impingement, the granule abrades the surface at the micron level and at the same time cleans the surface. Special pressure blasting pots are used for sandblasting application.
The degree of roughness desired on the surface depends on the type, size, shape and application pressure of the abrasive granule used. Blasting process should be done in special facilities suitable for sandblasting and these facilities must be installed in accordance with the Environmental Health Standards and Safety Rules.
Sandblasting Facilities Environmental Health Standards
In order to obtain the work permit, the established sandblasting facilities must be designed in accordance with environmental regulations.
The goal of the Environment Regulation is to ensure that the operations in the facilities do not damage the environment, ensure the emission limit values, control the quality of the air and control the mass flow.
Emission:
By firing of fuel and the similar; with synthesis, decomposition, evaporation and similar processes; states to air pollutants emitted to the atmosphere from a facility as a result of the agglomerate of the material, separation, handling of the material and other mechanical processes.
Dust emission values specified in the regulation of industrial air pollution control should be provided in the sandblasting facilities. In order to obtain emission permits, the dust is sent to the dust collector unit and it is filtered and discharged from the chimney.
The height of the chimneys from the roof is important of fulfilling the emission values and provisions of the regulations. Chimney heights are one of the definitive provisions that must be provided for obtaining the necessary permits. The dust emission limit value specified in the regulation is 20 mg / Nm³.
The dust released during the blasting process is quite intensive. Suitable filtering is very important both in terms of OHS rules in terms of employee health, both in terms of the operating efficiency of the factory environment and in terms of the standards of the Ministry of Environment.
Special filter units are used to provide emission values. Dusty air is brought to the filter by air ducts designed in suitable diameter and thickness.
The air through from the filter is discharged from the chimney by way of a fan. In filter design and fan selection, the facility volume, the quantity of sandblasting operators to operate in the facility and location of dust suction points and similar criteria should be taken into consideration.
Sandblasting Facilities Safety Precautions and Employee Health
Sandblasting in closed areas should be performed in facilities with sufficient lighting system, security measures taken, and enough space for processing.
Lighting: The lighting value should be selected in order to provide the operation quality and the correct angle of view to the operator in the sandblasting facilities. Sandblasting process in darker areas should not only affect the surface quality but also present a danger to the safety of the operator.
Equipment Used and Protective Measures;
Pressure Sandblasting Pot
Sandblasting pots which are used for blasting applications are worked with the high pressure. There is an average of 7.5 bar pressure at the nozzle outlet.
The sandblasting pots to be used must have hydrostatic tests, the test results are documented and they must have a certificate of conformity to the AT Pressure Equipment Directive.
High pressure sandblasted granules contain serious danger in false use. In order to prevent possible accidents, the sandblasting pots should be automatically controlled from the deadman handle.
In the event that the operators fall for any reason or the nozzle get out of their hand, the system automatically stops blasting and this prevents injury.
Blasting Hose:
Sandblasting process is made with special hoses resistant to high pressure. Hoses to be used in the sandblasting process should be certified and in TS 5928 EN ISO 3861 standards. The sandblasting hoses must be fixed with the safety cables.
Blasting Nozzle:
Blasting nozzles are manufactured from various special materials that are explosion-proof. The quality of nozzle and compliance with standards are of major importance in order to prevent occupational accidents.
The Blast Helmet & Blast Suit of the Operator:
The blasting operator must use a protective blast helmet and suit made specifically for sandblasting. Thus, the blast helmet and blast suit prevent the damaging of the operator because of granule which is going out from the pressurized blasting pot during the blasting. The blasting helmet must be certified to EN 14594 standards.
Breathing Air Filter Unit:
One of the most of important factors that threaten the health of personnel in the sandblasting facilities is the dust in the air. In addition to the filtration system located in the sandblasting facilities, the operator must use a fresh air supply unit as long as it is in the facility.
The clean air units are usually supplied from the compressor. The fresh air unit passes the air from the compressor through the activated charcoal filter and gives fresh air to the operator helmet.
Çiğdem Arslan
Project Director
Sandblasting & Painting Systems
Alfatechnic Makina San. ve Dış Tic. Ltd. Şti.
