What should be paid attention to when using stainless steel flanges?

What should be paid attention to when using stainless steel flanges?

Precautions before using stainless steel flanges

 1. In order to prevent the corrosion between the eyes due to the heating of the flange cover, the welding current should not be too large, about 20% less than the carbon steel electrode, the arc should not be too long, the interlayer cooling is fast, and the narrow welding bead is better.
2. The electrode should be kept dry during use. The calcium-titanium type should be dried at 150°C for 1 hour, and the low-a hydrogen type should be dried at 200-250°C for 1 hour (do not repeat the drying multiple times, otherwise the coating will easily crack and peel) to prevent The electrode coating sticks to oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the weldment.
3. When stainless steel flange pipe fittings are welded, carbides are precipitated after repeated heating, which reduces corrosion resistance and mechanical properties.
4. Chromium stainless steel flange pipe fittings have larger hardenability American standard flanges after welding, which is prone to cracks. If the same type of chromium stainless steel electrode (G202, G207) is used for welding, preheating above 300°C and slow cooling treatment at about 700°C after welding must be carried out. If the weldment cannot be subjected to post-weld heat treatment, stainless steel flange pipe welding rods (A107, A207) should be used.
5. For stainless steel flanges, appropriate amount of stability elements Ti, Nb, Mo, etc. are added to improve corrosion resistance and weldability. The weldability is better than that of chrome stainless steel flanges. When using the same type of chromium stainless steel flange electrode (G302, G307), it should be preheated above 200℃ and tempered at about 800℃ after welding. If the weldment cannot be heat treated, stainless steel flange pipe welding rods (A107, A207) should be used.
6. Stainless steel flange pipe fittings and butt welding flange electrodes have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.

What is a flange?

Flange, also known as flange flange or flange. Flanges are the interconnected parts between shafts and are used for the connection between pipe ends; they are also used as flanges on the inlet and outlet of equipment for the connection between two equipment, such as reducer flanges. Flange connection or flange joint refers to a detachable connection in which flanges, gaskets and bolts are connected to each other as a set of combined sealing structures. Pipe flange refers to the flange used for piping in the pipeline installation, and used on equipment refers to the inlet and outlet flanges of the equipment. There are holes on the flanges, and bolts make the two flanges tightly connected. The flanges are sealed with gaskets. Flange is divided into threaded connection (thread connection) flange, welding flange and clip flange. Flanges are used in pairs, wire flanges can be used for low-pressure pipelines, and welded flanges can be used for pressures above four kilograms.

 

What are the commonly used flange materials?

WCB, LCB, CF8M (316), CF8C (347), CF8 (304), CF3 (304L), CF3M (316L), etc.;

 

What are the common flange connection methods?

 

According to the connection method, the flange connection type can be divided into: plate flat welding flange, flat welding flange with neck, butt welding flange with neck, socket welding flange, threaded flange, flange cover, butt welding ring with neck Loose flanges, flat welding ring loose flanges, ring groove face flanges and flange covers, large diameter flat flanges, large diameter high neck flanges, eight-character blind plates, butt welding ring loose flanges, etc;

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