The Manufacturing of Welding Flanges

The welding process of the flange
The welding process of the flange is to fix two pipes, pipe fittings or equipment on a welding first. Put a gasket between the two welds, and then use bolts to complete the connection. Welding is an important connection for the construction of high-pressure pipelines. The welded flange is easy to use and can withstand greater pressure. Welded flanges are widely used in petroleum, chemical, natural gas, power stations, metallurgical pipelines and other fields.
 
There are two main systems for international pipeline flange standards, namely the European pipeline flange system represented by German DIN (including the former Soviet Union) and the American pipeline flange system represented by American ANSI pipeline flanges. In addition, there are Japanese JIS pipe flanges, but they are usually only used for public works in petrochemical plants and have little international impact. The pipe flanges in various countries are introduced as follows: 
 
The assembly cone and the large flange are assembled according to the requirements of the drawings, and the large flange is divided into 8 equal parts. Because the flange is thick and the groove is large, segment symmetry and multi-layer welding are used. The welding is required to have the strength of the base metal at least. The surface of the weld should be flat and smooth, and there are no defects such as gas holes, lack of welding, slag inclusion, undercut, etc. The residual height is less than 2 mm.
 
When the bottom is reached, make sure to use J506 electrodes for manual surfacing and low current welding. Welding should be carried out in strict accordance with the welding process. After each welding position, a level gauge must be used to clamp the deformation of the flange plane, and the welding seam must be hammered with an air hammer in the welding process to achieve the effect of eliminating stress.
 
The technical requirements for welding flanges 
The inclination on both sides of the head and neck of the butt welding flange shall not exceed 7°. The performance parameters of butt welding flanges should be strictly controlled in the manufacturing and welding process.
 
When manufacturing welded flanges, certain performance parameters and regulations must be selected to ensure that certain methods and basic principles can be applied and promoted.  
 
Butt welding flanges are not easy to deform and have good sealing performance; there are requirements for relative rigidity and ductility; the welding seam is far away from the welding surface, and there is no deformation caused by the welding temperature on the welding surface. Butt welding flanges are applied to many fields. The horn shaped main structure is suitable for pipelines with great working pressure, great temperature fluctuations, high-temperature, high-pressure and ultra-low temperature pipelines. It is usually used to connect pipelines and gate valves with PN exceeding 2.5MPa; it is also used for pipelines containing flammable, flammable and explosive substances.
 
Does the annealing temperature reach the required temperature? Butt welding flanges are usually treated by heat treatment, tempering and quenching. The temperature range is from 1040 to 1120°C (Japanese standards). You can also observe according to the inspection of the quenching furnace. The flanged tube in the quenching zone should be an incandescent lamp, but there is no softening and relaxation.
 
The butt welding flange generates water vapor in the forging furnace. On the one hand, check whether the raw materials on the furnace wall are dry. When the furnace is installed for the first time, the raw materials on the furnace wall must be air-dried. On the other hand, if there are holes on the flange pipe, check whether or not there are excessive water marks on the flange pipe when entering the furnace. There should be no water. Otherwise, it will destroy the atmosphere of the furnace.
 
What are the technical requirements for manufacturing butt welding flanges? The air tightness of the furnace wall should be paid attention to. The bright quenching furnace of the butt welding flange should be closed and isolated from the outside air. Use the soap liquid on the gaps of the joints of the quenching furnace to see if it works. The easiest area to exhaust is the area of the inlet and outlet pipe of the quenching furnace. The sealing ring at this position is very easy to damage, so it should be checked and replaced frequently.
 
The applications of butt welding flanges
Butt welding flanges are widely used in natural gas, power engineering, crude oil, chemical plants, industrial production, pharmaceuticals, etc. The price of the butt welding flange is reasonable and the quality is good. The stainless steel butt welding flange is heat-resistant, high-pressure and corrosion resistant. Carbon steel butt welding flanges are inexpensive and have low requirements for the natural environment.