In the oil and gas transmission industry, several materials are specified to be zinc-coated to provide superior corrosion protection.There are three common methods of galvanization which include: hot-dip galvanizing, pre-galvanizing and electro-galvanizing. The choice in method will depend on the application of the end product as well as the environment it will be applied in
Hot dip galvanizing pipe is that a Pipe was dipped into the bath after fabrication.Thickness by this method will reach minimum up to 45 µm and the thickness of the zinc coating is influenced by a number of factors, including the surface of the steel, the time the steel is dipped in the bath, the composition of the steel as well as the steel's size and thickness.
One advantage of hot dip galvanizing is that the entire part is covered including the edges, welds, etc. giving it an all-round corrosion protection. The end product can be used outdoors in all different weather conditions. It is the most popular galvanizing method and is widely used in the construction industry.
Pre-galvanizing pipe,also known as mill galvanized pipe, hot dip mill galvanized or continuous hot dip galvanized.Pre-galvanized steel pipe refers to pipe which was galvanized while in sheet format, thus prior to further manufacturing. After the sheet is sent through the mill to be galvanized it is cut to size and recoiled.the pipe thickness will be minimum 12 µm.
One of the advantages which pre-galvanized steel has over hot dip galvanized steel is that it has a better appearance.pre-galvanized materials are used for a wide variety of products including conduit, lip and open channels.
Different lifespan in various atmospheric environment:
ASTM A 123 is the specification for Hot Dip Galvanizing. This specification covers the standard requirements for hot-dip galvanized zinc coatings on iron and steel products made from rolled pressed and forged shapes, castings, plates, bars, and strips. This specification deals with unfabricated products and fabricated products, for example, assembled steel products, structural steel fabrications, large tubes already bent or welded before galvanizing, and wire work fabricated from uncoated steel wire.