Sometimes, when building temporary metal structures, drainage systems, drains, and other irresponsible structures, old and restored used pipes can be a great alternative new pipe rolling company.
But how to choose a product of this kind? After all, there is always a risk of getting into an unscrupulous seller and, instead of high-quality restored products, getting a pile of scrap metal. The first obvious answer would be to inspect the product before buying. But even in this case, without knowing the specifics, the risk remains quite high.
How to choose a used steel pipe?
There are several parameters that will help you get an idea of a used rental even without inspecting it. And the first of these is his condition. Pipe-roll, which was in use, is divided into restored and stale. The remanufactured steel includes all rolled products that were already in operation, and after dismantling, they went through a cycle of restoration work (removal of old insulation, steaming, sandblasting, applying new chamfers). A stale one is one that has not been used. But it cannot be attributed to new ones either, because due to long storage, it could lose a number of qualities.
The second parameter is the diameter. Conventionally, products can be divided into 3 categories: small (10 - 114 mm), medium (114 - 530 mm) and large (508 - 1420 mm) diameter. Used small diameter products were used in plumbing systems at end points of consumption. Medium-diameter rolled products are often dismantled from industrial collection systems for crude oil, light oil products and municipal water supplies. A used product of large diameter was used in the main oil and gas pipelines. Knowing the diameter and condition of the offered used rolled steel, it is already possible to determine what kind of pipe it is and from which system it was dismantled. This will greatly help in determining its shortcomings and advantages. And here the third parameter comes into force, or rather, the question:
What raw materials were transported along it and how could it affect the quality?
Gas.
Products from under the gas are distinguished by their relative internal cleanliness. Outside, the gas station is often covered with film insulation. But sometimes there is also bituminous. Products in bituminous insulation are a product of increased attention, since corrosion processes under such insulation are far from uncommon. But this is easy enough to check, because the bituminous insulation is easily removed. Removing film insulation is a more laborious process, but the surface quality under the film is usually better than under bitumen.
Gas pipelines operate under high pressure (up to 75 atm.). Therefore, very high quality steel (St10 or St20) is used for their manufacture. Gas stations are produced with resistant protection against external corrosion. Due to this, most of the outer surface is devoid of defects. But local damage still occurs. The cause may be damage to the insulation or cathodic protection. Gas tubes also have defects on the inner surface. It can be called "orange peel" because of the similarity in structure. But, this does not affect the functionality in any way. After processing, it can be used in systems that work under pressure, as well as in the creation of metal structures, chimneys, supports, drains, racks. To improve used rolled products, additional insulation is allowed. The price of such used products is one of the highest, higher than used pipes from under water, oil, and sometimes even higher than some used products. Therefore, a too low cost may well serve as an alarming “bell” that something is wrong with the product.
Oil.
Pipes of medium and large diameter with external insulation, which are dismantled from the main oil pipelines. Such products, before dismantling, are flushed from the remnants of petroleum products. This significantly improves their condition, but you need to understand that it is extremely difficult to achieve perfect cleanliness. In addition, unwashed steel is often on sale. But it is very easy to identify it even from a photograph. Buyers perceive oil-filled rolled products extremely ambiguously due to the fact that it requires more expenses for cleaning work, passing strict radiation control. All this affects the cost. But it would not be superfluous to note that the quality of such a pipe is often much higher than used rolled products after gas or water. This is due to the fact that there are practically no corrosion processes in the oil industry, and the product itself is made of the best steel. Therefore, if you need to get high-quality used rolled products, you can consider oil companies that have undergone a thorough restoration. It is possible that even such a pipe will not be cheaper than a gas pipe or a used pipe from under water.
Water.
Used pipes dismantled from water supply and drainage systems, as well as from irrigation systems, drains. Such systems do not provide for high pressure or temperature, therefore, for you
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