11.Should the oil casing coupling be heat treated?
Oil casing coupling needs heat treatment, and different materials need different heat treatment processes. For example, N80Q steel needs quenching and tempering heat treatment. Quenching and tempering treatment: the heat treatment method of high temperature tempering after quenching is called quenching and tempering treatment. High temperature tempering refers to tempering at 500-650℃. Quenching and tempering can adjust the properties and materials of steel to a great extent, with good strength, plasticity and toughness and good comprehensive mechanical properties. tempered sorbite is formed when martensite is tempered. It can be distinguished by magnification above 500~600 times under optical metallographic microscope that it is a composite structure with carbide (including cementite) spheres distributed in ferrite matrix. It is also a tempered structure of martensite and a mixture of ferrite and granular carbide. At this time, ferrite has basically no carbon supersaturation, and carbide is also stable carbide. It is a balanced structure at normal temperature.
22.Is the oil casing coupling a positive and negative thread?
The positive thread is not the reverse thread, and the structure of the oil pipe coupling is that the end of the oil pipe is connected with the inner wall of the coupling body in a tapered thread manner, and the end of the coupling body is connected with the oil pipe in a flat thread manner with the same thread and the same pitch. It has the characteristics of relieving stress concentration at the root of the external thread of the oil pipe connected by single taper thread, and is not easy to produce fatigue fracture, and has good connection effect. Effectively prevent the occurrence of oil well string breaking accident.
33.Can oil casing coupling be marked?
Oil casing couplings shall not be marked (i.e. stamped with steel) unless negotiated with customers. According to API Spec 5CT standard, it can only spray the label (i.e. spray printing)