The technical requirements of stainless steel pipe fittings are clearly defined in various standards or technical agreements. The main contents include the following:
(1) variety specification. Provisions of stainless steel pipe fittings should have the shape, size and its tolerance, the theory of trial, etc.. Round pipe specifications are usually expressed in DxS, such as 50mmx2mm stainless steel pipe diameter of 50mm, wall thickness of 2mm. The precision of the dimension is the thickness of the wall, the precision of the outside diameter and the ellipticity.
(2) surface quality requirements. The internal and external surface condition of stainless steel pipe fittings and the degree of the existence of the allowable surface defects.
(3) chemical properties. The chemical composition of steel and P, the maximum content of S and test methods.
(4) the physical and mechanical properties of the steel structure: the metallurgical structure, mechanical properties and technological properties of the steel.
(5) inspection standards. Requirements for inspection items, sampling locations, sample shapes and dimensions, test conditions and methods, etc.. In the production of stainless steel pipe in addition to conventional test items, and sometimes need to carry out some of the process performance test.
Geometric dimensions include outer diameter, inner diameter and wall thickness. It is also required to control the radius of curvature. If the radius is 1.5d, the radius of curvature must be within the required tolerances. As most of these stainless steel pipe fittings are connected to pipes by welding, in order to improve the quality of welding, the end of the stainless steel pipe fitting should be cut into a groove, leaving a certain angle with a certain edge; this requirement is relatively stringent and there are regulations for edge thickness, angle and range of variation. The surface quality and mechanical properties of pipe fittings are basically the same as those of the tubes. The stainless steel grade of stainless steel pipe fitting is the same as the connected pipe in order to facilitate welding. There should be surface treatment for all stainless steel pipe fittings, removing the inner and outer scales by shot blast and then coating with anti-corrosion paint. This process is not only for exporting to other countries, but also for preventing oxidation rust during domestic transportation. There are also some requirements for packing. For small size stainless steel pipe fittings, we need to make a wooden box which is about 1 cubic meter and the total weight of pipe fittings inside should not exceed one ton; this standard allows a mixed package, that is, putting the small size stainless steel pipe fittings into the big ones, but the total weight can not be over 1 ton. For big size stainless steel pipe fittings, we need to have a single package, for example, stainless steel pipe fittings with size of 24 inch should be packed alone. In addition, the marks on packages, is to indicate the size, steel number, batch number and manufacturer trademark. Stamp the stainless steel pipe fitting with steel seal along with documents of packing list and written warranty.
Source: China Pipe Fitting Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)