The basic machining process of stainless steel pipe fittings is mainly composed of blanking, forming (welding), heat treatment, surface treatment, cutting processing, nondestructive testing, surface protection and marking.
The processing materials of stainless steel pipe fittings are usually stainless steel tubes, stainless steel plates and stainless steel bars, and the material properties are determined by the material properties and the shape of the blank materials used in the products.There are different processing requirements for the shape, size and processing requirements of billets.
The commonly used stainless steel pipe is used for cutting, gas cutting, plasma cutting, etc.
The commonly used stainless steel sheet material is made of gas cutting, plasma cutting, punch cutting.
The commonly used stainless steel rod feeding method has a sawing machine and a hacksaw machine cutting and cutting cutting.
Forming process is a process that must be made when any stainless steel pipe fittings is made.The final product is different, and the forming process is different, so we will briefly introduce the heating and welding in the forming process.
If the stainless steel pipe fittings is made with a hot forming method, the requirement for the deformation of the material should be met, and the blank should be heated when forming.The heating temperature is determined by the material and process.
When a hot bend or a hot bend is formed, the method of heating is generally a medium or high frequency induction, and a few are heated by flame.This heating method is continuous heating with the bend or pipe forming process. The tube billet is heated in the movement and completed the forming process.
The method of heating is generally used in furnace, flame heating, induction heating or electric furnace heating.The method is to heat the tube first to the desired temperature and then press it into the mould to form it.
Welding with welding of stainless steel pipe fittings, there are two, one is with the welding of pipes, for pipe fittings factory, the forming process of welded pipe and seamless pipe forming process, forming process of stainless steel pipe fittings is no welding processes;Another is done by fitting factory required for welding stainless steel pipe fittings forming process, such as single chip to suppress again after assembling welding elbow, use steel drum welding into the pipe and then to suppress the tee, etc.
The welding methods of stainless steel pipe fittings are manual arc welding, gas shielded welding and automatic welding.
The heat treatment process is an important part of the manufacturing process of stainless steel pipe fittings.After heating, insulation and cooling after heat treatment process, can eliminate the strain hardening of the pipe on the forming process, residual stress, the metal deformation defects, etc., can improve even pipe after forming metal microstructure and properties.
The commonly used heat treatment equipment is the reverberatory furnace, electric furnace and so on;The usual control mode is to connect the thermocouple in the furnace to the control device of the temperature ~ time recorder.
Generally, heat treatment results are tested by hardness test.
The surface of the stainless steel pipe fittings processing method is generally sandblasting, shot blasting, polishing, pickling, etc., used to remove surface rust, scratches, etc., maintain a smooth surface, so as to meet the requirements of processing and inspection.
The cutting process is the process of finishing the welding end, structure dimension and shape tolerances of the stainless steel pipe fittings.Sometimes the machining also includes the inner and outer diameter of the tube.The process is usually done through special machine tools or general, if the pipe size is too big, and no ability to process the existing machine tools, processing can also use other methods, such as large diameter bend after gas cutting grinding methods.The appearance and size of stainless steel pipe fittings are inspected after machining.
Nondestructive testing is an important process for inspection of defects in the machining process of materials and fittings.In addition to meet the requirements of product standards and order for nondestructive testing, some of the more stringent quality control of the factory is according to the material, processing technology and quality of internal control regulation on nondestructive testing requirements, in order to guarantee the quality of products.
In the actual work, the determination of the non-destructive testing of the pipe piece shall be specified in accordance with the requirements or criteria of the order.For fitting surface basically is the original state of pipe, plate, or forging, the surface quality of pipe nondestructive testing (MT, PT), if there is no clear requirement according to Ⅱ level grade, but no matter how qualified level regulation, for sandwich and this is not easy to determine the depth of crack defect shall be considered not qualified.For the nondestructive testing of the internal quality of the tube (RT, UT,), the ultrasonic testing should be graded in class II (such as the weld inspection), and the ultrasonic testing shall be according to level I.
In order to prevent the possible defects of the product during heat treatment, the final nondestructive testing of the pipe shall be carried out after heat treatment.
The JB/T 4730 specification is usually used for nondestructive testing of domestic pipe fittings.Personnel engaged in nondestructive testing shall be entitled to the relevant provisions.
The surface of the stainless steel pipe fittings is generally protected by using the passivation method. If the whole surface of the stainless steel pipe fittings is machined, no passivation is needed.The main purpose of the surface protection of stainless steel pipe fittings is anticorrosion, while the appearance of the fittings is also attractive.Of course, the manufacturer will make a certain surface appearance according to the order.
The sign is an integral part of stainless steel pipe fittings, which is the basis of the traceability requirement.In general, product standards define the content and method of the logo.The contents of the pipe fittings generally include the manufacturer’s trademark or name, material grade, specification and other contents of the order.The method of marking includes permanent mark, such as steel seal, engraving, etching, etc.Non-permanent marker, such as print, label, etc.
Of course, there are other processes besides the above normal process manufacturing process.For example, in order to control the quality of raw materials, the manufacturer shall also conduct the inspection of raw materials to ensure the accuracy of the materials.In order to meet the special requirements of materials or customers, it is necessary to test the metallographic structure and intercrystalline corrosion of the metal to ensure that the finished products can meet the customers’ requirements completely.
Source: China Stainless Steel Pipe Fittings Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)