• Silicone seals

    This VMQ elastomer is the only one that, under certain conditions, can be used at both low and high temperatures: this is the one characteristic that determines its main use. It can also carry hydrogen peroxide and certain acids.

    It is not recommended for steam because this would significantly reduce its working life.
    FMQ fluorosilicone compounds offer greater resistance to fuel. This is silicone with a trifluoride propyl group in each siloxane unit. Good resistance to heat and to most solvents. Good characteristics at low temperatures.

  • Stainless steel AISI 304

    Austenitic stainless steel is non-magnetic and cannot be hardened by heat treatment. It is very ductile and is excellent for use in welding. The most popular austenitic stainless steel is Type 304, which basically contains 18% chromium and 8% nickel, with a carbon content limited to a maximum of 0.08%.

    It is widely used in chemical, pharmaceutical, alcohol and aeronautics industries and in architecture, food-related sectors and transport. It is also used in cutlery, crockery, sinks, lift linings and endless other applications. In certain environments, especially in those containing chloride ions, stainless steel 304 shows a propensity to form a type of corrosion known as pitting.

    This is an extremely localised type of corrosion in the aggressive environment is able to break the passive film on certain points of the surface of the material before progressing deeper. The growth of pitting arises in an auto-cathodic process and, although the loss of mass may sometimes be insignificant, its form of corrosion is extremely deceptive and pitting is often enough to render equipment useless.

  • Stainless steel AISI 316

    Molybdenum is introduced as an alloy element in stainless steel to decrease the likelihood of this type of corrosion forming. The presence of molybdenum allows for the formation of a more resistant passive layer and, in cases where stainless steel 304 is unable to withstand the action of certain environments, leading to pitting or crevice corrosion, stainless steel 316 and 317 is an excellent solution.

    This steel is widely used in the chemical, alcohol, petrochemical, paper and cellulose, oil, textile and pharmaceutical industries. When exposed to temperatures of between 450 and 850 ºC for some time, austenitic stainless steel is subject to chromium carbide precipitation at its grain boundaries, thus sensitising it.

    This abundant carbide precipitation and sensitisation leads to a decrease in the chromium content in areas adjacent to the edges, which drastically jeopardises their resistance to corrosion, making the material susceptible to intergranular corrosion in certain environments. Areas affected by heat due to welding operations are especially sensitive to this type of corrosion, as part of the material is maintained within the critical temperature range during the heat cycle involved in welding. This phenomenon led to the development of extra low carbon austenitic stainless steel, 304L, 316L and 317L, in which the carbon content is controlled at a maximum of 0.03%, thus keeping the possibility of sensitisation extremely low.