Heavy weight drill pipe was developed to provid a gradual transition from the heavy weight drill collars to the relatively light weight drill pipe. This intermediate weight pipe has a wall thickness of approximately, and it helps prevent stress concentration at the top of the drill collars. It also allows you to drill at higher pms, reducing torque and differential pressure sticking. It is intended primarily for directional drilling. Because it bends easily, it simplifies directional control and minimizes connection fatigue problems common to high angle or horizontal drilling. The reduced number of pipe failures and increased drill stem service also make it appropriate for some straight hole applications. Assembled heavyweight drill pipes are made of AISI 4142H - 4145H alloy structural steel. Production complies with the provisions under the Standard SY/T 5146-1997. Connector screws comply with the provisions of the Standard API SPEC 7. Heavyweight drill pipe is a kind of drilling tool of medium weight which is similar to the drilling rod. Its wall thickness is greater than that of the drill rod but smaller than that of the drill collar. The prolonged tool joint is linked to the pipe with thick walls. Generally, it is placed between the drill rod and the drill collar during the formation of the drilling string to prevent the unexpected change in the section of the drill string and reduce fatigue of the drill rod. It can be used for directional well drilling, to work quickly when the torque is rather low in order to cut wear and damage of drilling string. As its steel performance is lower than that of the drill collar and the contact area on the well wall is small, differential pressure jamming is rare.