Elements Responsible for Formation of and Influence by Surface Scale of Oil Well Pipe during Quenching & Tempering

Investigated are elements responsible for formation and peeling of surface scale of the oil well pipe during quenching & tempering treatment. It is identified that for oil well pipes of high grades like N80Q, provided relevant elements such as combustion atmosphere, heating temperature and time as well as the chemical composition of the steel are relatively consistent, the amount of the said surface residual scale is mainly related to the surface roughness of the pre-heat treatment pipe, and much less influenced by the combustion atmosphere. Accordingly, it is recommended that the surface finish of the tube as being rolled has to be as improved as possible, and that the roughness of the tube should be under 3.2;in case of storing the tube in open air, anti-corrosion treatment needs to be made so as to prolong the normal surface condition;and at last the surface residual scale amount needs to be as reduced as possible to ensure good adhesion of the anti-corrosion coating of the oil well pipe.