Surface treatment technology of flat welding flange

Slip on flanges are generally suitable for connection of carbon steel pipes with nominal pressure not exceeding 2.5 MPa. Flat-welded flanges can also be made into smooth, concave-convex and mortise-groove types. Flat-welded flanges are the most widely used in mild medium conditions, such as low pressure, non-purified compressed air and low pressure. Circulating water, its advantage is that the price is cheaper.
 
Flat welding and butt welding are the welding methods when flange and pipeline are connected. Slip on flange only needs one-sided welding and does not need internal opening of flange connection. Flange welding and installation of butt welding flange needs double-sided welding of flange. Flat welding flange is generally used for low and medium pressure pipelines, butt welding flange is used for connection of medium and high pressure pipelines. The butt-welding flange is usually at least PN2.5Ppa. The butt-welding is used to reduce stress concentration. The common butt-welding flange is necked flange or nipple flange. Therefore, the installation cost, labor cost and auxiliary material cost of butt-welding flange should be high. The flange manufacturer has more than one process.

The main functions of Slip on flanges are divided into the following categories:

1. pipeline failure, easy to disassemble and detect.
2. Connect the pipeline and maintain good sealing performance of the pipeline.
3. If a section of pipeline problems, easy to replace a certain pipeline.

Slip on flange has certain technical requirements and technical parameters in production and use. It is manufactured and processed in accordance with certain ways and methods:
1. The butt weld of the ring should be heat treated after welding, and 100% ray or ultrasonic flaw detection should be done. The radiographic flaw detection meets the grade II requirements of JB4730, the ultrasonic flaw detection meets the grade I requirements of JB4730, and the welding flange should be manufactured with certain welding standards and technology, which meets the corresponding production standards and requirements of the country.
2. The steel plate for flat-welded flange shall be inspected by ultrasonic wave without delamination defect to ensure good quality and performance. It shall be produced and inspected in accordance with certain quality requirements to ensure that the steel plate for production and use has no quality problems.
3. It should be cut into strips along the rolling direction of steel, welded into circular rings by bending and butt welding, and made the surface of steel to form a ring cylinder. In the production of Harbin flange, the flange plate with neck can not be directly machined by steel fixed Xiang flange plate, and a certain process is adopted to make and process it.
4. The butt welding of flange needs to adopt certain welding technology, and the butt welding of ring should adopt full penetration weld.
 
Flange products should be sprayed with paint when they are out of the factory. If customers do not have special requirements, what color the factory paints is what color. The effect is not to rust, to prevent rust during transportation or storage. If users have special requirements, such as processing into yellow, or black, etc. When the color is used, the factory will do it according to the requirements of users.
 
After the product is produced, there will be some welding nodules, and there will be some areas with spurs that are not processed well, that is to say, further topics need to be repaired. The factory will first use grinding wheels to do some rough processing, which looks fairly flat, and then a more detailed processing, with some sandpaper to do it. Some polishing and polishing, the whole flange products are polished with sandpaper, and then carefully wiped with fine cloth, the last is the link of color, may be sprayed with spray gun, can also be painted with brush, the role is the same, but the sprayed flange products give people the feeling. It is uniform in color and beautiful in color. If you sell a piece of leather, it will add a lot of color to the flange products.