Stainless steel is a widely used material in industry due to its physical properties. Being made of an alloy between steel and other special metals such as: Chromium, Nickel or Manganese, stainless steel has a high corrosion resistance, being an ideal material for a wide range of products and applications: complex pipe and pipeline works, fittings for pipes, hoses, food tanks and taps, cabinets and locks with keys, screws and nuts, mainly used in industry.
Garnet and Electro-corundum: Most Effective Materials for Blasting Stainless Steel Surfaces
Blasting inner walls of the pipes allows a smooth and rapid flow of liquids and gases through pipelines, thus increasing their efficiency and operation. A number of studies shows that corroded inner walls present a lower transport capacity than inner walls regularly cleaned using blasting operations. Even a small increase in pipelines' efficiency mean an increase in the financial figures and the company's profitability.
The Chromium alloy in stainless steel reacts with the Oxygen in the air, forming a layer of Chromium oxide that protect the stainless steel surface from the negative effect of climatic factors: rust and corrosion. If the stainless steel parts are not periodically cleaned, therefore being covered with various deposits of impurities and dirt, the oxidation process does not take place, and the steel starts to rust and corrode. In his paper "Now is the time," George F. Hays, CEO, World Corrosion Organization, estimates that global corrosion has an annual cost of about $ 2.2 billion, accounting for nearly 3% of the global Gross Domestic Product. However, several studies show that these costs can be reduced by up to 30%, in case of conducting an efficient corrosion management with optimal maintenance and periodic cleaning actions.
Blasting is of major importance in cleaning and maintaining the properties of stainless steel elements. Special blasting materials that do not contaminate the surface with ferrous particles are generally used: red garnet and white or brown fused aluminium oxide (white or brown electro-corundum).
Totally natural almandine rock, red garnet is characterized by high chemical stability where low or no transfer of grit into the substrate can be tolerated. Red garnet has superior hardness (8 on Mohs scale), and does not produce significant blasting dust. It is a non-toxic material (silicate content <0.1%), an environmentally friendly abrasive, being also very effective in blasting and cleaning stainless steel parts. Garnet blasting ensures an optimal cleaning of the stainless steel surfaces, without ferrous contamination, in order to prepare the area for subsequent anti-corrosion treatments. Red garnet can be used both for wet blasting and dry blasting. Further, garnet can be used for cutting metals or surface patterning with water jet cutting machines. Stainless steel pipes and pipelines in oil and gas industry are effectively maintained when blasted with red garnet. Also, garnet is used in food industry for blasting food tanks, stainless steel tubs, in hospitals and other companies: water treatment plants, water pipes.
White or brown fused aluminium oxide (brown or white electro-corundum) is a very pure abrasive material with superior hardness (9 on Mohs scale) that does not contaminate the blasted surfaces. This material ensures a fast and aggressive blasting, being especially used in blast chambers, due to its possibility of multiple re-use. This abrasive is manufactured from artificial corundum by fusion operations. Aluminium oxide particles are extremely harsh and sharp, with high cutting and cleaning speeds. Being an ecological material, it is successfully used in the blasting of stainless steel parts in shipbuilding, oil and gas industry, food industry, as well as in other companies, especially for pipe and pipelines infrastructure, food tanks, stainless steel tubs.
The total cost of blast cleaning an area is obtained by summing up the cost of material acquisition, disposal & neutralisation cost of waste and labour & equipment costs. Divide this amount by the cleaning speed (the number of square feet blasted in one hour) and you will get the real blasting cost. Unlike other materials, the real cost of blasting with garnet and electro-corundum is much lower than other blasting materials (blasting sand, slag) due to a higher cleaning speed of these materials and also, due to the efficiency of such materials that allows significant less consumption of material. Lower cost of blasting also involves a lower cost of neutralizing waste, therefore, increasing the efficiency of the entire blasting process.