A pressure pipe is a tubular device used to transport gas or liquid under a certain pressure. Its scope is stipulated as the gas, liquefied gas, steam medium with the maximum working pressure greater than or equal to 0.1MPa, or the liquid medium with the highest working temperature higher than or equal to the standard boiling point, which is flammable, explosive, toxic or corrosive,and the pipe with nominal diameter greater than 25mm.

Seamless steel pipe refers to a steel pipe that is made of a single piece of metal and has no seams on the surface. According to the production method, seamless tubes are divided into hot-rolled tubes, cold-rolled tubes, cold drawn seamless tubing, extruded tubes, jacked tubes, etc. The piercing methods of seamless pipe blanks include pressure piercing, push rolling piercing and skew rolling piercing.

The annealed state is a kind of seamless steel pipe delivery state, that is, the steel pipe is annealed and heat-treated before leaving the factory. A metal heat treatment process in which the metal is slowly heated to a certain temperature, maintained for a sufficient time, and then cooled at an appropriate rate (usually slow cooling, sometimes controlled cooling).

Seamless steel pipes have a hollow cross-section and are widely used as pipes for transporting fluids, such as pipes for transporting oil, natural gas, gas, water, and certain solid materials. After the seamless steel pipe is put into use, because external factors will cause the steel pipe to block and produce stains, it is necessary to maintain and clean the steel pipe

The surface heat treatment of seamless steel pipe is a metal heat treatment process that changes the mechanical properties of the surface layer by heating and cooling the surface of the steel pipe. Surface quenching is the main content of surface heat treatment, and its purpose is to obtain a high-hardness surface layer and favorable internal stress distribution to improve the wear resistance and fatigue resistance of steel pipes.

The annealing of seamless steel pipe is a metal heat treatment process, which refers to slowly heating the metal to a certain temperature, keeping it for a sufficient time, and then cooling it at an appropriate speed.