Transitions are widely used in water supply and drainage systems, pipelines of steam and hot water, main and field oil and gas pipelines, process pipelines in the oil, gas, chemical and petrochemical industriesFor their production is used carbon and alloy steel of ordinary quality, high quality, that have cold-resistant and heat-resistant properties, as well as the resistance to aggressive media.
The shape and the technical requirements for the production are regulated by corresponding GOST, OST and Technical specifications.
According to the shape there are concentric and eccentric transitions. The most widely used are concentric transitions because they are flexible and relatively easy to manufacture.
According to the method of manufacturing there are following types of transitions:
- Stamped seamless transitions
Produced by deforming the blank in a die of the corresponding size. Seamless tubes are used as blanks.
- Welded transitions
They are made by rolling of sheet metal on special equipment with subsequent longitudinal welding. Used in systems with operating pressures up to 4 MPa
- Stamp welded transitions
They are made from a blank by hot stamping method. Metal sheets and electric-welded tubes are used as blanks. They are widely spread in main and field pipelines with diameter up to 1420mm and operating pressure up to 9.8 MPa.
- Turned transitions
This type is produced by machine processing of the blank. Bar sections or forging (with normalized mechanical properties) are used as blank. This type is widely used in high pressure pipeline systems up to 100MPa.