Specification And Steel Grade Strength Of Drill Pipe

Specification classification 
According to the regulations of the American Petroleum Institute (API), drill pipes are divided into three types according to length (L): the first type: 5.486-6.706m (18-22ft); The second type (commonly used): 8.230-9.144m (27-30ft); Class III: 11.582-13.716m (38-45ft). Drill pipes can also be classified according to the outer diameter. Size of common drill pipe (D): 88.9114.3127mm (traditionally expressed in English size: 3 1/2 ″ 4 ½″ 5 ″) three kinds.
Steel grade strength 
The steel grade of drill pipe refers to the grade of drill pipe steel, which is determined by the yield strength of drill pipe steel. API (American Petroleum Institute) classifies drill pipe steel into five grades: D, E, 95 (X), 105 (G), 135 (S). The higher the steel grade of the drill pipe, the greater the yield strength of the pipe, and the greater the various strengths of the drill pipe. In the strength design of drill string, it is recommended to improve the strength of drill string by increasing the steel grade instead of increasing the wall thickness.