As there are many steel tubes suppliers
in the market, you must master the ability of telling from quality steel tubes from others. Folding refers to all sorts of line formed on the surface of steel tube, this defect often exist throughout the entire product vertically. The reason of folding is that some manufacturers overly pursuit the high efficiency, set high reduction which leads to folding in the next rolling procedure and fold products will crack after bending and the strength of steel tubes declines greatly. Pits surface means irregular and uneven surface which is a defect due to serious wear of steel rolling slot. As the pursuit of profit, pits surface steel tubes is a common defect produced by some shoddy steel tube manufacturers.
Unqualified steel tube surface is easily scarring. There are two reasons for this. Material used for steel tube manufacturing is not even and contains numbers of impurities. And the equipment the manufacturer used is simple and crude which is not able to manufacture quality steel tubes. Surface of some steel tubes are easy to crack, that is because the manufacture used polyporous adobe block as blank, cracks are formed in the process of cooling due to thermal stress after rolling. Easy to scratch is another defect of unqualified steel tubes, the reason is tatty equipment is easy to produce burr that will scratch steel surfaces. Deep scratch may reduce the strength of steel tube
Some steel tubes don’t luster as metal but as pink or pig iron, and this is caused by adobe block and nonstandard rolling temperature, they estimate the temperature through visual observation and that makes it unable to rolling in the stipulated area of austenite, steel tubes performance cannot reach the standards. And the inner diameter of the steel tube undulates greatly, unstable temperature, uneven composition of the steel and the tatty equipment are the reasons for this problem. There will be larger changes in the same circle, the steel tubes are easy to fracture when under stress non-uniform.
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If you find some steel tube cross-section is oval, the reason is that in order to save material, manufacture finish product before the second rolling of reduction too large, the strength of the rebar drops substantially and does not conform to the rebar appearance standard size. High quality steel tubes components uniform, cold cutting machine has high tonnage, the section is smooth and neat, and because of poor material, the section is uneven, and no metal luster. When looking for steel tubes, make sure the specifications of the tubes are specified so that you can check them one by one, no one wants to waste his money even spend some time on checking.
When there is no vernier caliper, you can check the quality of steel tube by weighing, because unqualified steel tubes contain much impurity material, the density and the oversize are not normative. It is recommended that buy steel tubes from experienced and reputable manufacture and you can enjoy quality service.