Seamless steel pipes
also play a non-negligible role in the construction industry. Steel pipe is not only a raw material for construction, but also a very important construction tool in the construction industry.
Due to the relationship between space and profit, the floor is getting higher and higher, which brings certain difficulties to the construction of high-rise buildings. Without relatively safe construction tools, high-rise buildings cannot be carried out in an orderly manner. Here, the role of seamless steel pipe is reflected. Ordinary steel pipe because his toughness is not very good, it requires a lot of procedures when building steel scaffolding, which increases the construction time. Unlike seamless steel pipes, this pipe uses a cold-drawn hot-rolling process, which makes the steel pipe very good in toughness. In the process of processing these steel pipes, processing can be carried out without adding some measures to protect the steel pipes. This can save a lot of time by installing and disassembling steel scaffolding.
The seamless steel pipe is a long strip of steel with a hollow section
and no seams around it. The length of the seamless tube is 3000~12000mm, including 6 meters.The seamless pipes on the market are generally not fixed, and most of them are 6, 9 and 12 meters. The normal length of steel pipe is as follows: hot-rolled steel pipe 3000~12000mm, cold drawn steel pipe 3000~10500mm; in double-length rolling (processing) steel pipe can reach 80m or longer, but in actual production, the general finished seamless steel pipe is Less than twelve meters, this is mainly for the convenience of shipping.
Seamless steel pipes are divided into hot-rolled (extruded) seamless steel tubes and cold drawn (rolled) seamless steel tubes due to their different manufacturing processes. Cold drawn seamless steel pipe is a product that has appeared in recent years, mainly with strict tolerances and roughness of inner and outer wall dimensions.
1. The outer diameter is smaller.
2. High precision can be produced in small batches.
3. Cold drawn (rolled) seamless steel pipe with high precision and good surface quality.
4. The cross-sectional area of cold drawn seamless steel pipes is more complicated.
5. Cold drawn seamless steel pipe has superior performance and seamless steel pipe is relatively dense.
6. The cold-drawn seamless steel pipe is relieved, and the inner and outer diameters can be controlled within 10 wires according to customer requirements.
The rolling method of cold drawn (rolled) seamless steel pipe is more complicated than hot rolling (extrusion seamless steel pipe). The first three steps of their production process are basically the same. The difference begins with the fourth step. After the round billet is hollowed out, it is required to start and anneal. After annealing, it is acid washed with a special acidic liquid. After pickling, apply oil. This is followed by a multi-pass cold drawing (cold rolling) of the blank tube, followed by a special heat treatment. After heat treatment, it is straightened. After the steel pipe is straightened, it is sent to a metal flaw detector (or water pressure test) by a conveyor belt for internal flaw detection. If there are cracks inside the steel pipe, bubbles and other problems will be detected. After the quality inspection of the steel pipe, it must be carefully selected by hand. After the quality inspection of the steel pipe, the paint is sprayed with the number, specification, production batch number, etc.