Semi Lugged Butterfly Valve

Semi-lug butterfly valve is a butterfly valve that connects the pipe flange through stud bolts. The valve body is designed with lug structures (through holes or through hole internal threads) on both sides, which is convenient for installation and fixing and suitable for clamp-type connection. It is widely used in fluid control under medium and low pressure conditions.

‌Structural characteristics‌:
‌Lug design‌: Strengthen the valve body structure, reduce the influence of pipeline stress on the valve sealing performance, and is suitable for frequent opening and closing scenarios;
‌Butterfly plate structure‌: Adopt three-layer composite structure (such as alloy steel + insulation layer + stainless steel) to improve temperature resistance and deformation resistance;
‌Sealing type‌: Optional soft seal (rubber/PTFE) or hard seal (metal cladding), the leakage level can reach up to ANSI V level.

Working principle and performance advantages ‌ ‌Opening and closing mechanism‌

The butterfly plate can achieve 90° rotation through the ‌lever principle‌ or ‌drive device‌, and quickly control the medium on and off (opening and closing time ≤3 seconds);

Double eccentric or triple eccentric structure design reduces sealing surface friction and extends service life.
‌Core Advantages‌

‌Pressure and temperature resistance‌: Applicable pressure range is up to PN10~PN16 (Class 150~300), temperature coverage is -20℃~250℃ (hard seal can be extended to 600℃);
‌Low flow resistance and high efficiency‌: The thickness of the butterfly plate is optimized, and the pressure loss is ≤0.05MPa when fully open, which is suitable for large flow pipelines;
‌Easy maintenance‌: The lug structure simplifies the disassembly and assembly process and supports online replacement of the sealing ring.

 

semi lugged butterfly valve

 

Applications
Chemical industry: For the transportation of corrosive media such as sulfuric acid and liquid alkali, PTFE valve seats and stainless steel valve bodies are required;
Water treatment system: DN50~DN2000 water supply network regulation, soft seals (EPDM/NBR) are suitable for leakage prevention;
Ships and energy: Marine fuel systems and power plant cooling water control must comply with JIS/ANSI standards.
Selection and maintenance points
Selection parameters
Seal type: Hard seals (tungsten carbide spraying) are preferred for particle-containing media, and soft seals are optional for clean fluids;
Drive mode: Worm gear or pneumatic drive is recommended for DN≥300, and manual lever operation is optional for DN＜300;
Material adaptation: 316L valve body + Hastelloy seals are selected for corrosive environments, and WCB + hard alloy is used for high-temperature steam.
‌Maintenance Specifications‌

Check the lug bolt preload every quarter to prevent loosening and flange leakage;
The valve cavity should be cleaned every six months for medium containing particles to avoid butterfly plate jam;
Lubrication cycle: Add high-temperature grease to the valve stem bearing every 12 months (applicable to ≥150℃ working conditions).

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