What are the types and scope of use of flange fittings?

Ⅰ. Types of flange fittings

1. The types of flanged pipe fittings are divided into national standards: integral flange, threaded flange, butt welding flange, flat neck flange, socket welding flange with neck, butt welding ring with neck loose flange, plate type Flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flanging ring plate loose flange, flange cover.

2. The different types of flanges pipe fittings are divided into chemical industry standards: integral flange, threaded flange, plate flat welding flange, butt welding flange with diameter, flat welding flange with neck, socket welding flange, butt welding ring loose Sleeve flange, flat welding ring loose sleeve flange, lining flange cover, flange cover.

3. The types of flanged pipe fittings are divided into petrochemical industry standards: threaded flange, butt welding flange, flat welding flange, socket welding flange, loose flange, flange cover.

4. Flange pipe fittings are divided into mechanical industry standards: integral flange, butt welding flange, plate flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flanging ring plate Loose flange, flange cover.

Ⅱ. Precautions for the use of stainless steel stamping elbow fittings

1. The electrode should be kept dry when used. The titanium calcium type should be dried at 150 °C for 1 hour, and the low hydrogen type should be dried at 200 °C-250 °C for 1 hour to prevent the electrode coating from sticking to oil and other dirt, so as not to increase the weld. Carbon content and influence on weldment quality.

2. In order to prevent intergranular corrosion due to heating, the welding current should not be too large, about 20% less than that of carbon steel welding rods and fittings, the arc should not be too long, and the layers are cooled quickly, and a narrow weld bead is appropriate.

3. For stainless steel stamping elbows, appropriate amount of stability elements ti, nb, mo, etc. are appropriately added to improve corrosion resistance and weldability. The weldability is better than that of stainless steel stamping elbows.

When using the same type of chromium stainless steel electrode, it should be preheated above 200°C and tempered at about 800°C after welding. If the weldment cannot be heat treated, chrome-nickel stainless steel electrode fittings should be used.

4. The coating of stainless steel stamping elbow has titanium calcium type and low hydrogen type. Titanium calcium type can be used for AC and DC, but the penetration depth is shallow during AC welding, and it is easy to become red, so DC power is used as much as possible.

5. When the stainless steel stamping elbow is welded, it is repeatedly heated to precipitate carbide, which reduces the corrosion resistance and mechanical properties.

6. Stainless steel stamping elbow electrodes have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.

7. Stainless steel stamping elbow fittings have certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance and wear resistance. Usually used in power station, chemical, petroleum and other equipment materials. The weldability of stainless steel stamping elbows is poor, and attention should be paid to the welding process, heat treatment conditions and the selection of appropriate electrodes.

8. The stainless steel stamping elbow has a large hardening after welding and is prone to cracks. If the same type of stainless steel stamping elbow is used for welding, it must be preheated above 300°C and slowly cooled at about 700°C after welding.

If the weldment cannot be subjected to post-weld heat treatment, stainless steel stamping elbow welding rod pipe fittings should be used.