1. Structural design differences
Lug distribution characteristics
Semi-lug butterfly valve: Only part of the two sides of the valve body are provided with lug structures (usually single or multiple lugs distributed symmetrically), and pipeline connection is achieved through local reinforcement.
Full-lug butterfly valve: The lugs are covered all around the valve body to form a continuous annular flange support structure with stronger overall rigidity.
Connection mechanical characteristics
The bolts of the semi-lug only pass through part of the valve body area, and only short bolts are required for fixing during installation, reducing the risk of flange extrusion and deformation of the valve body;
Full-lug requires long bolts that run through the entire circumference of the valve body, forming a uniform load after installation, which is suitable for high-pressure or frequently vibrating pipeline environments.
2. Installation and sealing performance
Easy installation
The semi-lug butterfly valve can be quickly positioned through the lug on one side, especially for scenes with limited space or frequent disassembly and maintenance;
The full-lug butterfly valve needs to align all lug holes, and the installation accuracy requirements are higher, but the overall stability after connection is better.
Sealing reliability
The load of flange bolts in the semi-lug structure is concentrated locally. Long-term use may cause micro-deformation of the sealing surface due to stress concentration (compensation with elastic sealing ring is required);
The uniform load distribution of the full lug can reduce local stress. With the metal hard seal design, it is more suitable for high temperature and high pressure conditions.
3. Typical application scenarios
Semi-lug butterfly valve:
Low-pressure and normal temperature water supply and drainage system (such as the end of the fire protection pipe network);
Corrosive medium pipeline (short bolts reduce the contact area with the medium).
Full lug butterfly valve:
Oil and gas transmission high-pressure pipeline (need to withstand pulsation impact);
Chemical high-temperature reaction device (requires zero leakage and structural durability).
4. Maintenance and compatibility
Maintenance cost:
When replacing the sealing ring of the semi-lug valve, only the local bolts need to be removed, and the maintenance time is shorter; the disassembly and assembly of the full lug requires the handling of all bolts, and the labor cost is higher.
Pipeline network compatibility:
The semi-lug can be adapted to non-standard flange spacing (by adjusting the lug position), and the full lug must strictly match the standard flange size.
