What’s the seamless steel pipes made

How to seamless steel pipes made? Before answer this question we should answer anther question firstly. Is the seamless steel pipe normalization products? What’s the standard of steel pipes? Steel tube is a normalization products which containing Chinese Standard GB/T 3639-2008, GB/T 1862, GB/T 1863 etc, Germany Standard DIN2391, DIN17175 etc, European Standard EN10305-1, EN10305-3, Japanese Standard JIS G3445, JIS G3441 etc. And other standards for producing steel pipes.

So before making steel pipes we must know what the standard of steel tubes should to be complied with. For example 2000m seamless steel tubes with an outside diameter of φ32mm and an inside diameter of 30mm in according . Made of grade E355 in BK condition, delivered in random length. It is used in gas spring of adjustable tables and chairs. So the precision cold rolled seamless steel pipes are required . That must be the standard EN10305，equal to GB/T 3639, or DIN2391. Then we think about how to make this size of steel pipes?

Firstly we get the outside diameter 50mm raw steel bar. The material is E355 for reference as below.

After preparing the steel bar it is hot pierced. Which is like as ear piercing. There are no any quantities lost. Just change the density and volume. After pickling and phosphating it should to be made by the first cold drawn. After then get annealing treatment and straightening. Till now it is finished a small circulation. After three times circulation like this the size will become approaching to 32*29mm. It will go to another process. Cold rolled. After the cold rolling the seamless steel pipes will become precision steel pipe within 0.05mm tolerance. Which has bright and mirror-like surface. After inspection these steel pipes can be packed and delivery to customers.      

That’s the total process of how to made seamless steel pipes. This steel pipes are widely used in gas spring of furniture, motorcycle and auto mobile shock absorber, shock reducer and others.