American pipe tongs, also known as gravity tongs, pipe tongs, pipe tongs are mainly used for clamping and rotating round steel pipe or other cylindrical workpieces, for the installation and repair of pipelines in common use. Its structure is composed of movable jaw, handle body, fixed jaw, adjusting nut and leaf spring. Its kind can be divided into American, British, heavy three kinds, specifications are: 200mm, 250mm, 300mm, 350mm, 450mm, 600mm, 900mm and so on.
The hardness of each part of the pipe clamp after heat treatment shall be 47HRC at the jaw, 30HRC at the thread and adjusting nut at the jaw, and 71HRA at the spring.
Surface quality inspection: pipe tongs shall be free from striations, burrs, obvious surface defects such as oxide scale, sand holes and air holes. The surface roughness Ra value of the machined surfaces on both sides of the jaws shall not be greater than 3.2 m, and the roughness Ra value of the machined surfaces on the other parts shall not be greater than 12.5 m. The surface coating of the clamp handle body should be uniform, color and luster, without obvious flow mark, delamination and other defects.
Precautions for use of pipe tongs:
(1) to choose the appropriate specifications;
(2) the opening of the clamp head shall be equal to the diameter of the workpiece;
(3) clamp the workpiece tightly before pulling it hard to prevent it from slipping and hurting people;
(4) when using the force bar, the length should be appropriate. When lifting the handle, pay attention to the bearing torque, do not use too much force to prevent overload damage;
(5) pipe clamp teeth and adjusting ring should be kept clean;
(6) generally pipe tongs cannot be used as hammer head;
(7) can not clamping workpiece temperature over 300 ℃.