Sealing Principle of Flange Connections
Publication Date:
Jul 30,2026
Author:
Dacheng Jiaye
Sealing performance determines the safety and stability of flange pipe fitting systems, and the core sealing mechanism relies on coordinated compression of flange faces
Sealing performance determines the safety and stability of flange pipe fitting systems, and the core sealing mechanism relies on coordinated compression of flange faces, elastic gaskets and fastening bolts. After technicians tighten flange bolts, axial pressure is generated between two paired flange surfaces. The pressure squeezes the intermediate sealing gasket to produce elastic and plastic deformation, filling tiny gaps existing on flange contact surfaces. These micro gaps are the main channels for gas or liquid medium leakage. Without effective compression, medium will penetrate outward along the gaps, forming pipeline leakage accidents. Multiple types of flange sealing surfaces are designed to match different working environments, including flat face, raised face, tongue and groove face, ring joint face and male female face. Flat face flanges are mostly used for low-pressure, non-toxic medium pipelines; raised face flanges occupy the largest market share and apply to most conventional industrial pipelines. Tongue and groove structures lock gaskets inside grooves to prevent gasket displacement under fluid impact, suitable for flammable, toxic and high-pressure media. Ring joint faces adopt metal ring gaskets, achieving reliable sealing under extreme temperature and pressure conditions. Sealing gaskets are categorized into non-metallic gaskets, semi-metallic composite gaskets and all-metal gaskets. Rubber and asbestos-free fiber gaskets belong to non-metallic types, suitable for low-temperature and low-pressure environments. Spiral wound gaskets, the typical semi-metallic products, combine metal strips and flexible filling materials, balancing elasticity and pressure resistance for medium temperature and pressure pipelines. Metal ring gaskets and metal flat gaskets bear ultra-high pressure and high temperature working loads. Many pipeline leakage failures stem from improper gasket selection rather than flange quality defects. Gasket material must resist corrosion by transported media and maintain stable elasticity within the full operating temperature range. In addition to material matching, bolt tightening process directly affects sealing effects. Uneven bolt torque leads to uneven gasket compression, resulting in partial insufficient sealing and leakage. Standard construction requires cross symmetrical bolt tightening in multiple steps to guarantee uniform pressure distribution on the entire sealing surface. Long-term operation will cause gasket aging, bolt stress relaxation and flange surface scratch abrasion. Enterprises should establish regular maintenance cycles to replace aging gaskets and repair damaged flange surfaces to sustain long-term sealing reliability.
TAG:
Next:
Related Blog
Contact Us
E-mail:
Phone:
Whatsapp:
Add:
Yanglongtan Village, Bianwu Town, Yanshan County, Cangzhou City, Hebei Province, China
CANGZHOU LONGGUAN PIPE INDUSTRY
We manufacture various flanges and pipe fittings in carbon steel, stainless steel and alloy steel, supplying standard and custom pipeline components for global industrial projects.
Contact Us
E-mail: sales@lgpipefittings.com
Phone: +86 19333059881
Whatsapp: 8619333059881
Add: Yanglongtan Village, Bianwu Town, Yanshan County, Cangzhou City, Hebei Province, China
