Manufacturing process of stainless steel seamless pipe

Seamless stainless steel pipe, also known as stainless steel seamless pipe, is made of steel ingots or solid tube blanks through perforation to make capillaries, and then hot-rolled, cold-rolled or cold-drawn.

1. Hot-rolled stainless steel seamless pipes are generally produced on automatic rolling mills. After inspection and removal of surface defects, the solid tube blank is cut into required lengths, centered on the end face of the perforated end of the tube blank, then sent to a heating furnace for heating, and perforated on a punching machine. During the continuous rotation and advancement of the perforation at the same time, under the action of the roll and the plug, a cavity is gradually formed inside the tube blank, which is called a capillary. And then sent to the automatic rolling mill to continue rolling. Finally, the wall thickness of the whole machine is averaged, and the diameter is sizing by a sizing machine to meet the specification requirements. It is a relatively advanced method to produce hot-rolled seamless steel pipes with continuous pipe rolling mills.

2. In order to obtain seamless pipes with smaller size and better quality, cold rolling, cold drawing or a combination of the two methods must be used. Cold rolling is usually carried out on a two-roll mill, and the steel pipe is rolled in an annular pass composed of a variable-section circular hole groove and a stationary conical head. Cold drawing is usually carried out on a single-chain or double-chain cold drawing machine of 0.5 to 100T.

3. The extrusion method is to place the heated tube blank in a closed extrusion cylinder, and the perforated rod and the extrusion rod move together to extrude the extrusion part from the smaller die hole. This method can produce steel pipes with smaller diameters.

This kind of steel pipe can be divided into two categories: stainless steel seamless steel pipe and stainless steel welded steel pipe (seamed pipe). The shape can be divided into round pipe and special-shaped pipe. The widely used is round steel pipe, but there are also some square, rectangular, semi-circular, hexagonal, equilateral triangle, octagonal and other special-shaped stainless steel pipes.

For steel pipes under fluid pressure, hydraulic tests should be carried out to check their pressure resistance and quality. It is qualified if no leakage, wetting or expansion occurs under the specified pressure. , flaring test, flattening test.