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How to make steel seamless pipes?

Steel pipes are made by two different processes. The overall production method for both processes involves three steps. First, raw steel is converted into a more workable form. Next, the pipe is formed on a continuous or semicontinuous production line. Finally, the pipe is cut and modified to meet the customer's needs.

The advent of rolling mill technology and its development during the first half of the nineteenth century also heralded in the industrial manufacture of tube and pipe. Initially, rolled strips of sheet were formed into a circular cross section by funnel arrangements or rolls, and then butt or lap welded in the same heat (forge welding process).

Toward the end of the century, various processes became available for the manufacture of seamless steel pipe, with production volumes rapidly increasing over a relatively short period. In spite of the application of other welding processes, the ongoing development and further improvement of the seamless techniques led to welded pipe being almost completely pushed out of the market, with the result that seamless tube and pipe dominated until the Second World War.

Cold Drawn Seamless Steel Pipe Process
round tube → heating → perforation → Heading → annealing → pickling → oiled (copper) → multi-pass cold drawn (cold rolled) → blank tube → heat treatment → straightening →hydrostatic testing (testing) → mark → storage.



The general cold strip mills, volume should go through continuous annealing (CAPL unit) to eliminate cold hardening and rolling stress, or batch annealing reach the mechanical properties of the corresponding standard specifies. Cold rolled steel surface quality, appearance, dimensional accuracy better than hot-rolled plate, and right-rolled thin product thickness is about 0.18mm, so the majority of users favor.

Cold rolled steel coil substrate products deep processing of high value-added products. Such as electro-galvanized, hot dip galvanized, electro-galvanized fingerprint resistant, painted steel roll damping composite steel, PVC laminating steel plates, etc., so that the excellent quality of these products has a beautiful, high resistance to corrosion, has been widely used.

Cold rolled steel coil finishing after annealing, cut the head, tail, trimming, flattening, smooth, heavy volume, or longitudinal clipboard. Cold-rolled products are widely used in automobile manufacturing, household electrical appliances, instruments, switches, buildings, office furniture and other industries. Steel plate strapping package weight of 3 to 5 tons. Flat sub-volume typically 3 to 10 tons / volume. Coil diameter 6m.

Cold drawn steel tube is with hot-rolled steel coil as raw material, and tandem cold rolling pickled to remove oxide scale, its finished rolling hard roll, rolling hard volumes due to the continuous cold deformation caused by cold hardening strength, hardness increased indicators declined tough plastic, stamping performance will deteriorate, which can only be used for simple deformation of the parts.

Hot Rolled Seamless Steel Pipe Deformed Process
Hot-rolled seamless steel pipe production base deformation process can be summarized as three stages: perforation, extension and finishing.
round tube → heating → perforation →  three-roll rolling, rolling or extrusion → detached → sizing (or reducing) → cooling → straightening hydraulic test (orflaw) → tag → storage.



Billet is fed into the heating furnace, the temperature is about 1200 degrees Celsius. Fuel for a hydrogen or acetylene. The furnace temperature control is critical to wear air tube round, after the release of pressure puncher. which are generally more common puncher tapered roller punch this punch, high production efficiency, product quality, perforated expanding volume, wearing a variety of steels. After perforation, round tube has been three-roll cross rolling, rolling or extrusion.

After extrusion off pipe sizing. Sizing mill by the high-speed rotation of the cone drill into the Billet punch to form a steel pipe. The steel pipe inner diameter is determined by the length of the outer diameter of the sizing mill drill. After sizing, the steel pipe to enter the cooling tower by the water spray cooling, the steel pipe after cooling, it is necessary to be straightening. Sent by conveyor pipe by straightening the metal detection machine (or hydrostatic test) to conduct an internal flaw. Steel pipe internal issues such as cracks, bubbles will be detected.

Steel pipe quality inspection but also through a rigorous manual selection. Steel pipe of Quality Supervision, Inspection, use spray paint on the number, size, production batch. By a cable car hanging into the warehouse.

Quality Control
A variety of measures are taken to ensure that the finished steel pipe meets specifications. For example, x-ray gauges are used to regulate the thickness of the steel. The gauges work by utilizing two x rays. One ray is directed at a steel of known thickness. The other is directed at the passing steel on the production line. If there is any variance between the two rays, the gauge will automatically trigger a resizing of the rollers to compensate.

Pipes are also inspected for defects at the end of the process. One method of testing a pipe is by using a special machine. This machine fills the pipe with water and then increases the pressure to see if it holds. Defective pipes are returned for scrap.

Seamless Pipes Execution Standard
There are probably hundreds of different methods for packing a steel pipe, and most of them have merit, but there are two principles that are vital for any method to work prevent rusting and Sea transportation security.

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