Views: 3 Author: Site Editor Publish Time: 2025-11-21 Origin: Site
Shanghai Zhucheng Pipe Fitting Manufacturing Co Ltd. as a professional supplier of ASME B16.5 forged flanges in China. We can provide various sizes, types, and materials of forged flange for customers. Slip on flange and socket weld flange are two common types of forged flanges in ASME B16.5. This article introduces the appearance, purpose, and characteristics of the two types of flanges, and provides reference for pipeline engineering selection by analyzing their relationship and differences.
Slip on flange has a simple structure, with a disc-shaped main body and a flow hole diameter at the center that matches the size of the pipeline. Multiple bolt holes are evenly distributed on the flange, which are used in conjunction with bolts, nuts, and washers for connection.
Slip on flanges include plate flanges(PL) and slip on flanges(SO). The appearance of the plate type PL flange is a flat disk shape with a weak pressure bearing capacity; The SO flange adds a shorter neck design at the connection between the flange and the pipeline, which improves the stiffness and load-bearing capacity of the flange. Its sealing surface is often in the form of flat (FF), protruding (RF) and other common forms. The flange neck is relatively short, and when welding with the pipeline, the pipeline port is flush with the flange sealing surface, and the welding point is located on the outside of the flange.
Slip On Flange (SO flange) is one of the most commonly used flange types in pipeline systems. Its core features are simple structure, easy installation, and low cost. By fitting the gap between the flange inner hole and the pipeline outer wall, the pipeline connection and sealing are achieved after welding. It is widely used in fluid transportation scenarios at medium and low pressure, room temperature, or low temperature.
Easy installation
cost-effective
Widely applicable
Weak pressure bearing capacity
The appearance of the socket flange is similar to that of the flat welding flange, but the difference in detail is that the center hole diameter of the socket welding flange is slightly larger than the outer diameter of the pipeline, forming a circular groove, which facilitates the insertion of the pipeline into the groove for welding. The flange also has bolt holes, and the sealing surface type is similar to that of flat welding flanges (such as RF, FF, RTJ).
Socket flanges are designed specifically for small diameter (≤ DN80) pipeline systems with high pressure and high sealing requirements. They are commonly used in instrument pipelines, sampling systems, and situations that require compact installation space.
Strong Sealing Performance
High Compressive Strength
High Installation Requirements
Relatively High Cost
Comparison Item | SO Flange | SW Flange |
Structure | Align welding | Socket Weld |
Pressure | Class 150/300/600/900/1500/2500 | Class 150/300/600/1500 |
Size | 1/2"-24"（DN15-DN600） | 1/2"-3"(DN15-DN80) |
Installation Difficulty | Simple | Complex |
Cost | high Cost-Effectiveness | Suitable for high demand scenarios |
Medium | water, steam, air | High pressure, Flammable, Explosive, Toxic |
Welding Process | Simple Process | Complex process |
Although there is a significant difference between slip on flanges and socket weld flange, as an important member of the flange family, there are commonalities that cannot be ignored:
Consistent core functions: Both are used for connecting pipelines to pipelines and pipelines to equipment.
Standard interoperability: All must comply with flange standards such as ASME B16.5, and key parameters such as bolt hole quantity, center distance, and sealing surface size must meet the standard requirements;
Wide range of material selection: commonly used materials include carbon steel (ASTM A105), stainless steel (ASTM A182 F304, F316L), alloy steel (ASTM A182 F11, F22), etc., which can be flexibly selected according to the corrosiveness and temperature requirements of the medium;
Complementary application scenarios: In the same pipeline system, it can be combined according to different pressure requirements.
ASME B16.5 is a globally recognized forging flange standard, covering various types of flanges such as SO flange, SW flange, WN flange,TH flange, LAPJ flange, blind flange, etc. Its forging process gives flanges higher strength and toughness, and is widely used in various industries
Petrochemical industry: used for connecting high-pressure reaction towers and heat exchange, resistant to acid and alkali corrosion and high temperature and pressure;
Natural gas: Long distance pipelines are connected to urban pipeline networks to ensure leak free transportation of gas;
Power industry: High temperature steam pipeline connection for power plant boilers, capable of withstanding frequent temperature fluctuations;
Water treatment: High pressure dosing pipelines in municipal sewage treatment plants, corrosion-resistant and easy to maintain;
Food and medicine: Stainless steel flanges are used for sterile pipelines and meet hygiene requirements;
Shipbuilding industry: Pipeline connections for ship power systems, resistant to vibration and seawater corrosion;
Mechanical manufacturing: Connect high-pressure oil pipes of hydraulic equipment to ensure that there is no leakage of hydraulic oil.
