On the use of raw materials, most of mills are using coils which carbon content is high, nickel and chromium are unstable and the sulfur and phosphorus and other impurity content are also high. These coils are mainly produced by some small factories. The corrosion resistance of tube which made by the those coil will be decrease. Some mills even use 301 and 201 material to palm off 304 material. Most of the mills do not have the strict requirement on the quality standard control and production technique. Some mills even do not know much about the production standard such as GB/T12770 and ASTM A554.
For example, in terms of thickness, the thickness of the manufacturer's products and the actual thickness of the deviation significantly exceeded the relevant standards, if the thickness of 0.6mm, the actual product thickness will only 0.4mm, which led to the thickness of stainless steel welded pipe thinner. At present, the actual thickness is 0.4mm and some mills even make into 0.2mm.