Bunker Steel Corporation, along with API certified processing facilities, has the ability to upgrade both ERW and SMLS carbon-grade tubing and casing through heat treatment processes. These processes for steel pipe include quenching, tempering, and normalizing to obtain desired API OCTG grades. In addition to the heat-treating processes, our tubing can also be hot forged on both ends to increase the wall thickness, allowing the pipe to maintain consistent strength throughout the tube and to be threaded with either API 8rd EUE or premium threads.

Quenching
Heating the steel pipe material to critical temperature, until microstructure transformation is done, and cooling it at a rapid rate. Quenching can eliminate and improve thermal and tissue stress of the product. The combination of quenching and tempering can make the comprehensive performance needed for API 5CT latest edition OCTG products.

Tempering
The purpose of tempering is to increase the toughness of steel and alloy steel pipe. Before tempering, quenched steel pipe is very hard but too brittle for the most application. Tempering can improve the plasticity and toughness of steel pipe, reduce, or eliminate the residual stress and stabilize the steel pipe’s size, resulting in quality API comprehensive mechanical properties.

Normalizing
Heating the steel pipe above the critical temperature and cooled in the air. Through this normalizing process, the entire tube is changed to the same grain structure; the material stress can be relieved, reducing the brittleness, improving the ductility, strength and toughness of the tubing or casing.