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Pipes and rolled metal products

19 January 2011
Pipes and rolled metal products

«Our business is a trumpet» — the famous phrase of any cinematic criminal at the appearance of the police and then on the screen there are titles. But for clever people this phrase is just beginning their business because the pipe is a very demanded type of production of metallurgical enterprises.

Everyone is interested in where the hole from the donut goes — it can be turned into a pipe. Do not believe me, let's read the definition of the word pipe in the famous Wikipedia: «The pipe is the wall of a long hole».

Modern metallurgical plants produce many types of pipes intended for use by various industries. Pipe rolling is classified according to a variety of parameters and takes into account the material of manufacture, the method, the field of application of pipes, their corrosion resistance, and so on.

Initially, all tube-rolling is divided according to the type of metal:

  1. Color (copper, aluminum, etc.)
  2. Black (iron and its alloys)

Corrosion resistance

  1. Of metal or steel
  2. Stainless steel
  3. Galvanized
  4. With a coating of polymers (PPU, PPMI, VUS insulation)

According to the type of pipe wall:

  1. Seamless
    • Hot-rolled
    • Cold-rolled
    • Produced by drilling
    • Casting (cast iron pipes)
  2. Welded
    • With straight seam
    • Spiral seam

In section form:

  1. Round or oval
  2. Square
    • Welded or rolled welded seams

On purpose with respect to the pressure to be maintained:

  1. Sewage
  2. Pressure
  3. Water and gas
  4. Special purpose

Pipes are reconditioned — these pipes are widely represented in the market of secondary raw materials. Large firms carry out qualitative technical evaluation and recovery of used pipes, and they can be used for a long time in less aggressive environments. This metal rolling advantageously distinguish the low price of the products.

On the rank of tubular rolled metal the largest share is made of products made of ferrous metal — iron and steel. This is due to such characteristics of steel and iron as good thermal conductivity, strength, corrosion resistance (especially stainless and galvanized) and a relatively low price compared to non-ferrous metallurgy products.

The welded pipe itself is in demand on the market and is often used from all types of pipes. It is produced from sheet rolled metal of various thickness by bending it on a special machine into a circle, square or oval with subsequent welding of the joint. When bending along the length it turns out also by welding a joint in a straight line, a straight-seam pipe is produced, and when spiraling, the spiral is correspondingly.

Seamless pipes are made by drawing a metal workpiece on a special machine, drilling or casting. The first method of production of tubular rolled metal is the most popular. Technologically, it consists of several stages going one after another.

At the beginning of the process of seamless hot rolled metal rolled metal, a special blank in the form of a blank is manufactured by cutting excess metal. The next stage is its heating in a special furnace with simultaneous special processing and giving a round and elongated shape.

In the future, the so-called firmware is produced — after even more heating through a ready blank with a special machine with rollers, a steel rod of the appropriate diameter is dragged. The preheated and pre-heated pipe is additionally rolled on a special mill, forming the walls and giving the products a smooth shape. At the final stage of the tubular rolled metal, the inserted rod is removed.

For the formation of thinner walls and production with more precisely specified parameters, cold-rolled tubular metal is used. With this method, ready-made pipes made with hot rolling are subjected to further machining. In this case, high plasticity of black metal and especially steel is used.

The tube is placed in a special machine which, with the help of rollers, stretches the pipe and at the same time the thickness of the walls decreases to the required parameters, and the exact length of the pipe is formed. The advantages of cold-deformed pipes include the high precision of the shapes, sizes and wall thicknesses. With this method, the tube lumen is modeled — an oval, a square and any other.

The production of cast iron pipes by casting is produced in stationary form and in a rotating form. The first step in both cases is the melting of the metal to the liquid state.

When pouring into the stationary form, a hollow tube sample is formed from the sand first, into which molten iron is poured. After cooling, the sand form is broken and the product comes out of it. In the second case, the molten metal is poured into a spinning shape, and under the influence of gravity forces a pipe is formed on its walls.

In the future, the formed pipes are subjected to hot treatment to achieve more accurate dimensions of the products produced. At the final stage, in order to protect against corrosion, the walls of cast-iron pipes are treated with special mastics. In stationary forms, mainly molded connecting molded products for joining pipes into one system and heating batteries.

Well, with drilling everything is simple and clear. The drilling method is used in the manufacture of products of high accuracy and strength such as guns or artillery trunks.

If necessary, the finished tubular metal is subjected to further anti-corrosion treatment. For these purposes the method of galvanizing is most often used.

Recently, polymer coatings have been used in various combinations or simple coloring. Tubular metal rolling with the use of polymer coatings include — pipes with PPU, PPMI, VUS insulation. This tubular metal has both corrosion protection and thermal protection.

Pipes PPU treated with a heat-insulating layer of polyurethane foam (PPU) with a protective polyethylene sheath. Tubular metal PPU can be laid in the ground without the formation of channels or used in air networks. Pipes PPU have a high degree of both anti-corrosion and thermal protection.

Piping pipes ППМИ (ПЕНОПОЛИМЕРМЕРНЕАЛЬАЛЬНАЯ ИЗОЛЯЦИЯ) represent from themselves a complex monolithic vapor-permeable construction. The protective layer has a variable density over the cross-section.

It is removed from three layers:

  1. Anticorrosive layer, with high adhesion to the pipe wall. The main function is to protect the pipe wall from external influences.
  2. A heat-insulating layer with a porous structure and is formed for each region separately depending on the operating conditions
  3. The mechanical-hygro-protective layer is very dense and is made as a shell with the function of protecting the heat-insulating layer from mechanical damages and excessive blotting.

The VUS pipe (protection of extruded polyethylene of a very reinforced type) refers to the latest developments in the protection of tubular rolled metal products and is a priority in world practice. The VUS coating consists of a layer of extruded polyethylene on a strong adhesion base. Adhesive base creates a high degree of adhesion of the coating to the wall of the pipe, and the outer layer of polyethylene — mechanical protection. Depending on the method of production, the pipes are used in various fields of industry and construction.

In accordance with the needs of the customer, rolled metal products have different names and applications. There are products that are widely in demand in the market, and there are products manufactured for special requirements and specific orders.

The most popular pipe (VGP) is water and gas or water and gas galvanized. They are widely used in construction for the installation of heating systems, gas pipelines and water pipes.

Pipes hot and coldly deformed are used in assembling high pressure heating systems, building gas and oil pipelines, drilling wells for gas, oil, and water. Rectangular pipes are used to create the designs of various communication systems (heating, gas, water, ventilation) in civil and industrial construction, they are particularly in demand on the market.

Oval pipes are used for finishing buildings under various design projects, in the automotive industry. Cast-iron pipes are also quite a popular product on the metal-roll market. They are used to create low-pressure sewage systems. It should be noted that in the last decade, high-quality cast iron pipes have been supplied to the market, which can be used for high-pressure operation.

It becomes especially popular pipe metal rolling with corrosion protection systems such as PPU, PPMI, VUS. Pipes with these protective systems are cheaper than those made of stainless steel, and the service life and protection against aggressive media are not inferior to them and in addition there is additional heat protection.

They are used for installation of heat and high pressure water pipes, oil and gas pipelines. They can be laid in the ground without the creation of special trenches or simply left in the air, tubes coated with VUS can be laid in seawater.

In modern times, the volume of output, and the sale of rolled metal, is constantly growing. It fell slightly against the background of the crisis, but there are undoubtedly prospects for further growth. The technology of production is improved, and consequently the price is reduced.

18 January 2011
20 January 2011