Seamless steel pipe refers to round, square, rectangular, and various special-shaped steel pipes made of hot-rolled or cold-rolled (drawn) high-quality carbon structural steel and alloy steel, etc. The pipe material is executed according to the standard.
Seamless steel pipes are divided into hot-rolled (extruded) seamless steel pipes and cold-drawn (rolled) seamless steel pipes. Hot-rolled (extruded) seamless steel pipes are generally produced on automatic and semi-automatic pierced units. The cold-drawn (rolled) seamless steel pipe is formed by Cold Drawn or Cold Rolling processes, and is formed by cold drawing a few times.
The raw material of Seamless steel pipes must have high temperature strength, low temperature toughness, plasticity and good weldability, and some special performance requirements or steel grades. The purpose of raw material inspection is to ensure that the steel pipe is qualified and conforms to the specified chemical composition and mechanical properties.
The outer diameter, wall thickness and internal quality requirements of seamless steel pipes are conducted according to the corresponding standards.
The numerical value and mode of seamless steel pipes size and structure shall be in accordance with the relevant standards. In addition, the structure size tolerance of seamless steel pipes is mainly used for the wall thickness and outer diameter of seamless steel pipes, and the difference in pipe length values.
The inspection of seamless steel pipe standards at the same time should be in line with the study of each process. In the inspection process, the most primary is to guarantee the accuracy of the diameter and wall thickness. Generally speaking, its accuracy should be in accordance with JB/T3050.143 structural steel pipes.
In order to make the connection properly when manufacturing the seamless steel pipes, the manual chamfering of tbe ends of the seamless steel pipes should be carried out in accordance with the applicable national standards.
In addition, the surface quality of seamless steel pipes should also be carried out according to standards. Surface defects such as scratches, cracks, folds, scale, tape, slag inclusions, excess welding and adhesion, etc. are not allowed on the surface of the seamless steel pipe. It is necessary to ensure that the surface quality of the seamless steel pipes is better than the external requirements.
At the same time, the inner and outer surface of the seamless steel pipe should be burrs and burr-free. The burr is obtained through manual filing or mechanical grinding, and its size shall also meet the standard requirements.
Equally important is the mechanical properties of the seamless steel pipe. Tensile strength and impact toughness should meet the standard requirements, and hydrostatic or nondestructive testing should also be performed.
The acceptance inspection is a program of acceptance and delivery. The length of the seamless steel pipe is the length at the end of the fracture, and the prevailing force is not allowed.
In summary, the relevant national standards of seamless steel pipe should be strictly implemented. The quality of raw materials, mechanical properties, size, surface quality and other aspects should also be tested according to the corresponding standards. In addition to maintaining the accuracy of the manufacturing process, it also requires timely inspection during use to ensure the quality of the seamless steel pipe.
