Special material

The chemical process industry calls titanium, zirconium, tantalum and niobium special materials. They are extremely resistant to acids and alkaline media. Also, many nickel and nickel-chrome-based alloys are classified as special materials due to their high resistance, corrosion-resistance and their suitability for use in aggressive environments in combination with reducing media such as acids.

Special materials are used in a number of areas: titanium is suitable for use in seawater-cooled heat exchangers and systems that come into contact with bleaching lyes, chrome and nitric acid. In addition, titanium is also used in the aerospace industry and in medical equipment. Amongst other things, zirconium is used in apparatuses used to produce acetic and hydrochloric acid or urea, and also in medical and nuclear equipment. Special materials are also used in the aerospace industry, to build power plants, in the petrochemical industry and in high-performance components in the automobile industry. Nickel alloys are used for instance to build machines and in the chemical industry.

In-depth expertise in the field of materials science and welding processes is essential, if special materials are to be joined correctly. For instance, nickel, nickel-based alloys, and titanium and its alloys are often welded in the MIG or TIG welding procedure using DC current with a negative electrode. As far as titanium is concerned, it is also important to protect the part with shielding gas even at a distance from the welding point to prevent discoloration and oxygen enrichment. Zirconium and zirconium alloys are usually easy to weld. To ensure that all material properties remain intact, very precise shielding with shielding gas is required and the inert gas situation also needs to be monitored carefully. Copper can be processed in a TIG or plasma welding procedure and is often used for example to produce boilers for water tanks.