A Blog on Categorizing, Assembling, and Joining Flanges - Wholesale Titanium Flanges - Titanium Flange Manufacturers in China

The term "flange" is derived from the word "flange," originally introduced by Richard in 1809. He also proposed the casting technique for flanges; however, it was not widely adopted for quite some time. It wasn't until the early 20th century that flanges became extensively utilized in various mechanical equipment and pipe connections.

Classification of flanges

1. Following the chemical (Hg) industry standard:

Integral flange (IF), threaded flange (TH), plate-type flat weld flange (PL), neck butt weld flange (WN), neck flat weld flange (SO), socket weld flange (SW), butt weld ring loose flange (PJ/SE), flat weld ring loose flange (PJ/RJ), lined flange cover (BL (S)), and flange cover (BL). 

2. As per the petrochemical (SH) industry standard: 

Threaded flange (PT), butt weld flange (WN), flat weld flange (SO), socket weld flange (SW), slip-on flange (LJ), and flange cover (unspecified). 

3. As per the machinery (JB) industry standard:

Integral flange, butt weld flange, plate-type flat weld flange, butt weld ring plate loose flange, flat weld ring plate loose flange, flanged ring plate loose flange, flange cover.

4. Following national (GB) standards:

Integral flange, threaded flange, butt weld flange, necked flat weld flange, necked socket weld flange, necked flat weld ring loose flange, plate-type flat weld flange, flat weld ring plate loose flange, flat weld ring plate loose flange, flanged ring plate loose flange, flange cover.

Flange assembly.

The flange surface, particularly the sealing surface, should be thoroughly cleaned before assembly. 

1. When installing the flat weld flange, insert the pipe end into the flange with an inner diameter thickness of 2 ≤ 3, and then spot weld the flange onto the pipe. If it's a horizontal pipe, spot-weld the flange from above. Next, verify and adjust the flange position from various directions using a 90° angle ruler to ensure its sealing surface is perpendicular to the pipe's centerline. Finally, confirm the correctness of the second spot welding point. 
2. Utilize a 90° angle ruler to verify and adjust the flange's position from both left and right directions. Once aligned, complete the spot welding and fixation of the flange by spot welding the third and fourth points. 
3. During the assembly of flange pairs, ensure that the bolt holes on the mounting flange are aligned with the corresponding bolt holes on the fixed flange and are parallel to it. The deviation should be within 1.5% of the outer diameter of each thousand flanges but not exceeding 2mm. 
4. When choosing the appropriate flange for equipment or valve components, it's essential to verify if the flange size of the original equipment or valve components matches the flange connection size used in the pipeline. 

Common gasket materials

Rubber and asbestos sheets are the most commonly used flange gasket materials. 

1. Industrial rubber plate

Rubber gaskets are often called industrial rubber sheets, industrial vulcanized rubber sheets, or simply rubber sheets. 

2. Rubber cotton board

Rubber fiber or asbestos rubber sheets are used as gaskets to seal equipment and pipeline flanges. These gaskets can seal various media such as water, steam, air, gases, ammonia, alkalis, oils, and more. 

Flange connection.

1. The flange connection must remain on the same axis, with the center deviation of the bolt holes not exceeding 5% of the hole diameter. Bolts should be able to pass through freely. Flange connecting bolts should match precisely in specifications, with consistent installation direction, and be tightened symmetrically and evenly. 
2. Do not utilize inclined washers of varying thicknesses to compensate for the lack of parallelism between flanges. Avoid using double washers. When joining large-diameter washers, they should not be placed flat against each other but in a diagonal or labyrinth configuration。
3. To simplify the installation and removal of flanges, the distance between the fastening bolts and the flange face should be at least 200mm. 
4. the bolts should be evenly and symmetrically tightened in a crossed pattern to ensure uniform stress distribution across the washer. 
5. Bolts and nuts should be coated with molybdenum disulfide, graphite oil, or graphite powder for easy removal in the following situations: stainless steel and alloy steel bolts and nuts; pipeline design temperature is below 100 ℃ or 0 ℃; outdoor installations exposed to atmospheric corrosion or corrosive media. 
6. Metal gaskets like copper, aluminum, and mild steel should undergo annealing before installation. 
7. Direct burial of flange connections is prohibited. Flange connections for buried pipelines must include inspection wells. If burial is necessary, anti-corrosion measures must be implemented...

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