The quality of pipe flanges is of paramount importance in the PGO (petrochemical, gas and oil) industries. Each application has its own unique demands that must be met to the highest standard possible.

This is why we at ChemiPetro manufacture our pipe flanges in several different alloys. The unique demands of the PGO industries means pipe fittings must be manufactured from alloys with highly specified corrosion, temperature, pressure and impact resistant qualities. Depending on the application, one or more of these qualities must be highlighted.

Stainless steel alloys are graded and named according to their microstructure. They are created by combining ferrite (iron) plus one or more other elements in solution. Each alloy has a resultant unique crystalline structure that enhances resistance or strength.

The two main types of stainless steel alloy used in our pipe flanges are ferritic and austenitic. These are the basis for many other, superior alloys.

The two terms refer to the iron base. Ferritic stainless steel is derived from ferrite (a stable form of iron that is non-receptive to carbon) and chromium. Its body-centred crystalline structure means it is very strong, and thus resistant to stress corrosion. However, it cannot be hardened by heat treatment, and thus is difficult to weld.

Austenitic steel alloys are created by adding nickel (at least 6%) to a phase transition form of ferrite i.e. one created by heating. In this form it is receptive to carbon, creating austenite. This gives the alloy a face-centred crystalline structure, making it more brittle than ferrite alloys, but highly resistant to corrosion.

At ChemiPetro, our pipe flanges are made from specialised alloys that combine the best elements of both ferritic and austenitic steel, in varying amounts. Thus our austenite alloys usually have high levels of chromium. Other elements, such as titanium and molybdenum, may also be present.

Duplex steels are so called because they contain equal amounts of ferrite and austenite, equally composed of ferritic and austenitic alloy, making them immensely strong and corrosion resistant.