316 stainless steel pipe has good corrosion resistance and high temperature resistance, and is commonly used in chemical industry, food, light industry, machinery and instrumentation and other industrial transportation pipelines and mechanical structure parts. Do you know how 316 stainless steel pipe is produced? The following will take you to understand one by one.
How is 316 stainless steel pipe produced?
Author: Robby
316 stainless steel pipe has good corrosion resistance and high temperature resistance, and is commonly used in chemical industry, food, light industry, machinery and instrumentation and other industrial transportation pipelines and mechanical structure parts. Do you know how 316 stainless steel pipe is produced? The following will take you to understand one by one.
1, material selection
Cold rolled stainless steel strip is used as raw material, surface condition BA grade. Before the steel strip is used in the factory, the steel strip must be inspected in detail. Inspection items include: thickness, width, edge quality status, appearance, and physical property inspection. If necessary, the grain size of the raw material should be checked, and it can be used for production only after passing the inspection.
2, uncoiling
Steel strip before entering the welded pipe unit, you need to use the steel strip uncoiler to unfold the steel strip, compared with the steel strip, you need to increase the leveling mechanism to level the steel strip to ensure that the steel strip in a straight state into the molding part of the welded pipe unit, the successful completion of the bending of the steel strip molding.
3, billet forming
Using continuous roll forming equipment, the steel strip is continuously rolled and deformed to make an open pipe billet. Steel strip through the welded pipe unit of the import module, rough rolling module, the closing module of several functional modules, each module was used in different types of rolls to achieve different parts of the steel strip bending molding, and ultimately the steel strip from the plane of the gradual bending, the formation of the open billet, ready to be welded into the 304 stainless steel pipe preparation.
4, continuous welding
Steel strip after continuous roll bending forming unit, made of open pipe blanks. Using TIG welding equipment, continuous welding, made of round pipe. Welding process using argon as a protective gas to prevent oxidation of the weld before solidification and cooling in contact with oxygen. The argon gas is passed into the tube to protect the internal weld, and the argon gas passed into the welding torch is used to protect the tungsten electrode. In the molten pool around the formation of argon protective layer, to protect the molten pool and the weld does not oxidize.
5, weld leveling
Due to the impact of the welding current and the influence of gravity, resulting in stainless steel products tube internal weld protrusion, external weld will also appear depression, these problems if used in the ordinary low-pressure fluid environment, will not have an impact. If used in high temperature, high pressure, high speed fluid environment, will cause the use of problems. Special weld leveling equipment must be used to eliminate this defect.
6, online heat treatment
Steel strip for roll forming process, will produce work hardening, is not conducive to the later processing of the pipe, especially for pipe bending process. Welding process, there will be welding stress in the weld, will cause cracking in the later use of the process, which requires heat treatment.
At present, the commonly used heat treatment process for the bright solution treatment in a hydrogen-protected atmosphere, the 304 stainless steel pipe heated to more than 1050 °, after a period of heat preservation, is the internal organization of the morphology of the transformation, the formation of a homogeneous austenitic organization, under the protection of the hydrogen atmosphere, does not occur oxidation.
7, sizing and finishing
Welded pipe outer diameter size, welded pipe in the welding and heat treatment process will occur deformation, resulting in the outer diameter size can not meet the use of requirements, the need for calibrated finishing. Usually use the sizing and finishing unit consists of 4 groups of flat rollers and 4 groups of side rollers, flat rollers are designed as flat oval (or round), side rollers are designed as a set of oval (or round). The sizing amount is based on the different outer diameter and wall thickness of the tube, generally within the range of 0.20-0.50mm. After calibrating and finishing, the tolerance of the outer diameter of the tube can be controlled within ±0.05mm, which can fully meet the requirements of the use of precision.
8、On-line Flaw Detection
Due to a certain pressure, and the need for a certain degree of reliability, the weld only rely on pressure detection is difficult to detect internal defects in the weld, you can use online eddy current flaw detection or ultrasonic flaw detection, real-time online 100% detection. The welding status can be corrected at any time according to the alarm information to reduce the production of nonconforming products.
9, Cut-to-length
The use of online cut-to-length equipment, according to the length of the customer's requirements, cut to length, you can use the rotary cutting (chipless) technology, compared with chip cutting, chipless cutting has no cutting burrs, in the later stages can not be deburred port.
10, straightening
Roll forming unit production of welded pipe straightness can not meet the requirements of the use of such welded pipe generally need to control the straightness of 0.10/100mm. need to use the straightening machine to straighten the welded pipe, to achieve the required product requirements.
11、Pressure test
The use of automatic static hydraulic testing machine, 304 stainless steel pipe pressure test, loading, flushing, pressure testing, discharging all automatically completed, holding pressure for a certain period of time through the differential pressure method to sort out unqualified welded pipe.
12、Cleaning and drying
Welded pipe in the completion of mechanical processing, the need for final cleaning and drying, remove the pipe wall or the outer wall of the residual coolant, oil and other pollutants, and then use the hot air drying, to prevent rust during transportation and storage. Finally, the stainless steel welded pipe for finished product inspection and packaging, you can leave the factory.
The above is the production process of 316 stainless steel pipe, the production process includes material selection, uncoiling, billet molding, continuous welding, seam straightening and a series of processes.