Stainless Steel Seamless Tube

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Stainless Steel Seamless Tube

The thicker the wall thickness of the Stainless Steel Seamless Tube, the more economical and practical it is, and the thinner the wall thickness, its processing cost will rise substantially.

Description of Stainless Steel Seamless Tube

The thicker the wall thickness of the Stainless Steel Seamless Tube, the more economical and practical it is, and the thinner the wall thickness, its processing cost will rise substantially.

stainless steel seamless tube, stainless steel seamless pipes

Produce of  Stainless Steel Seamless Pipes
Process flow of Stainless Steel Seamless Tube

Tube Billet-Inspection-Peeling-Inspection-Heating-Piercing-Pickling-Grinding-Lubrication and Air Drying-Welding Head-Cold Drawing-Solution Treatment-Pickling-Pickling Passivation-Inspection-Cold Rolling-Degreasing-Cutting Head -Air drying-internal polishing-external polishing-inspection-marking-finished product packaging

Manufacturing Process of Stainless Steel Seamless Tube

Hot rolled, cold drawn, hot expanded

According to different production methods, it can be divided into hot rolled tubes, cold rolled tubes, cold drawn tubes, extruded tubes, etc.

  1. Hot-rolled seamless tubes are generally produced on automatic tube rolling mills. The solid tube is inspected and cleaned of surface defects, cut to the required length, centered on the perforated end of the tube, and then sent to the heating furnace for heating and piercing on the punching machine. When the perforation continues to rotate and advance at the same time, under the action of the roller and the plug, a cavity is gradually formed inside the tube blank, which is called a capillary tube. And then sent to the automatic rolling mill to continue rolling.
  2. If you want to obtain a stainless steel seamless pipe with a 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.
  3. The extrusion method is to put the heated tube blank in a closed extrusion cylinder, and the perforated rod and the extrusion rod move together to make the extruded part extrude from the smaller die hole. This method can produce steel pipes with smaller diameters.
How to distinguish between stainless steel welded tube and stainless steel seamless pipe?
  • First, check whether there are welds on the inner and outer surfaces and whether there are protrusions.

If you encounter a steel pipe that has not been surface-coated, you should first look at the inner and outer surfaces of the steel pipe.

If you look at the inner and outer surfaces of the steel pipe, you can clearly see the weld, you can directly determine it is a welded pipe. The specific weld appearance generally has two categories: straight seam and spiral. Among them, there are two common types of straight welding seams: resistance welding and submerged arc welding. There are also single seam and double seam welding for straight seam welding. With the development of technology, the general double seam welding products are basically invisible on the market.

  • Look at the color and strip of the stainless steel seamless pipe

Due to high-temperature heating and deburring in the production process of high-frequency welded pipes, the color of the weld and its heat-affected zone is generally different from other parts. Generally, it is blue or the color is obviously darker, which is obviously different from the surrounding color, which is a longitudinal strip.

The bands are distributed, the width is basically the same, and there is no obvious depth change. However, seamless steel generally does not have such long strip-like traces. Sometimes rolling underfilling defects (referring to allowable defects) will also show a similar all-directional appearance, but underfilling is generally difficult to distribute over long. And there is no guarantee that the width and depth are consistent. It is also easier to distinguish.

  • Three looks at the wall thickness tolerance level and ovality

Most stainless steel seamless tubes are directly pierced and rolled from a tube blank. From tube blank to steel tube forming, it is a three-dimensional complex deformation. Compared with two-dimensional plate rolling, its wall thickness precision control is much more difficult.

The wall thickness tolerance level of general stainless steel seamless pipes is about ±12.5%, some of the higher levels can reach ±8-10%, and very few can reach about ±5%, and most of these stainless steel seamless tubes are thick-walled pipes. The welded pipe is welded directly from the steel plate or coil made of hot-rolled/thick plate, and its wall thickness quality depends on the thickness control accuracy of the steel plate, which can generally reach within ±0.10mm. Therefore, pipes with high wall thickness accuracy are generally more likely to be stainless steel welded pipes.

Package of Stainless Steel Seamless Tube

stainless steel seamless tubes package stainless steel seamless tubes package stainless steel seamless tubes package stainless steel seamless tubes package

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