Advantages and disadvantages of 5 common pipe flanges

Flange connection is widely used in engineering design. It is an important part of pipeline design, pipe fittings and valves. In addition, flange connection is often used in industrial furnaces, thermal engineering, drainage, HVAC, automatic control and other professions. The following introduces the advantages and disadvantages of the five most commonly used pipe flanges.

1. Flat welding flange

Advantages: Raw materials are easy to obtain, simple to manufacture, low cost, and widely used.

Disadvantages: Due to poor rigidity, it is flammable and explosive, has high vacuum requirements, and has high risks.

2. Neck welding flange

Advantages: Convenient on-site installation, eliminating the line clearing process.
Disadvantages: The neck height of the neck welding flange is low, which improves the rigidity and bearing capacity of the flange. Compared with the butt welding flange, the welding workload is large and cannot withstand high temperature and high pressure, repeated bending and temperature fluctuations.

3. Butt welding flange

Advantages: The joint is not easy to deform, has good sealing effect, and is widely used.
Disadvantages: The neck welding flange is large in size, heavy in weight, expensive, and difficult to install and position. Therefore, it is more likely to collide during transportation.

4. Flat-welded ring flange

Advantages: convenient welding and processing or high strength requirements.
Easy to construct, such as corresponding flange bolt holes during connection or preventing changes in flange bolt holes when replacing equipment later. When the pipeline is special, the welding cost of flanges of the same material is high.

Disadvantages:
‌a. Limited pressure resistance: The structural characteristics of the flat-welded flange determine that its pressure resistance is relatively weak. Due to the use of single-sided welding, the strength of the weld is relatively low, and it is easy to leak when subjected to high pressure.

b. Relatively poor sealing performance: The sealing surface of the flat-welded flange is generally flat, and the sealing performance is relatively poor. In some occasions with high sealing requirements, such as pipeline connections of high temperature, high pressure, flammable and explosive media, the flat sealing surface is prone to leakage. In addition, the selection of gaskets is limited, and it is difficult to find suitable gaskets to improve the sealing performance.

‌c. High requirements for welding technology: The welding quality of the flat-welded flange directly affects its sealing performance. If welding defects occur during welding, such as pores, slag inclusions, and incomplete penetration, the connection strength and sealing performance of the flange will be reduced, leading to leakage problems. Therefore, professional welding technicians are required to operate to ensure the quality of welding.

d. Applicable pressure range is narrow: Flat welding flanges are generally suitable for pipeline systems with a nominal pressure not exceeding 2.5MPa. For high-pressure pipeline connections, flat welding flanges cannot meet the requirements, and a connection method with stronger pressure resistance such as butt welding flanges is required.

5. Butt welding ring loose flange

Advantages: Save costs. When the pipeline is special and expensive, the welding cost of flanges of the same material is high.
Not convenient for welding, processing or high strength requirements. Such as plastic pipes, glass pipes, etc.
Convenient construction, the flange bolt hole is not easy to change during the connection process.

Disadvantages:
a. Low pressure bearing capacity: The pressure bearing capacity of the butt welding ring loose flange is relatively low, especially in high-pressure environments, it needs to be used with caution.
b. Low strength at the welding ring: Especially when the welding ring is thin (such as less than 3mm), the strength of the welding ring is low, which may affect its durability and safety.

Read more: How to choose pipe flange material? or Pipe flange size specifications and classification