1. Basic Understanding of Flanges

In industrial connection systems, flanges are core components that enable detachable connections between pipelines, containers, and equipment, also known as flange discs or flanges. Their typical structure is disc-shaped with evenly distributed bolt holes around the edge. Two flange faces are tightly joined through bolt fastening, and together with the middle sealing gasket, they achieve medium sealing, effectively preventing leakage of liquids, gases, or powders.

Flanges can be divided into various types according to connection scenarios and working condition requirements. Welded flanges are fixed by welding to pipelines or equipment, featuring high connection strength and suitability for high-pressure and high-temperature environments; threaded flanges are connected to pipelines via threads, allowing convenient installation and disassembly, and are mostly used in low-pressure systems; loose flanges are not fixed to pipelines and can move freely with the thermal expansion and contraction of pipelines, making them suitable for occasions with large temperature differences.

Material selection should match the service environment: carbon steel flanges have low cost and are suitable for general working conditions; stainless steel flanges have excellent corrosion resistance and are often used in systems transporting corrosive media such as acids and alkalis; alloy steel flanges can withstand extreme temperatures and pressures and are widely used in high-temperature and high-pressure equipment. From industrial pipeline transportation to petrochemical reaction devices, from power steam turbine systems to municipal water supply projects, flanges are key components for modular assembly and maintenance.

2. Correct Installation Steps for Flanges

1. Pre-installation Preparation

Check whether the specifications and models of flanges, bolts, and gaskets match the design requirements, and ensure there are no cracks, scratches, or other defects on the surface.

Clean oil stains, rust, and debris from the flange sealing surface and bolt holes to ensure the sealing surface is flat and smooth.

Select appropriate gaskets (such as rubber gaskets, metal wound gaskets, etc.) according to the medium characteristics and working conditions to avoid chemical reactions between the gasket material and the medium.

2. Alignment and Fixing

During hoisting or positioning, ensure that the two flange faces are parallel, and the centerline deviation does not exceed the specified range to avoid additional stress caused by forced docking.

Insert some bolts symmetrically for temporary fixing, adjust the flange gap to be uniform, and then install the remaining bolts to ensure the flange faces fit evenly.

3. Gasket Installation and Bolt Fastening

Accurately place the gasket in the center of the flange sealing surface to avoid offset leading to seal failure.

Tighten the bolts in a diagonal and uniform manner, applying torque step by step to prevent deformation of the flange face due to uneven force. The final torque must meet the design standards, ensuring both tight sealing and avoiding damage to bolts or flanges due to over-tightening.

3. Daily Maintenance Points for Flanges

1. Regular Inspection

Visually inspect the flange surface for corrosion, leakage traces, and check if the sealing gasket is aged or damaged.

Use tools to check the tightness of bolts, and retighten them in time if looseness is found to avoid leakage caused by pressure fluctuations.

2. Cleaning and Protection

Regularly clean dirt and debris from the flange surface and bolt holes to keep the sealing surface clean.

For equipment that has been out of service for a long time, rust prevention treatment should be carried out on flanges and bolts, which can be done by applying anti-rust grease or taking covering protection measures.

3. Replacement of Gaskets and Bolts

When the gasket is aged, hardened, or the seal fails, it should be replaced with a new gasket of the same specification in time. The sealing surface must be thoroughly cleaned before replacement.

If bolts are rusted, deformed, or broken, the entire set of bolts must be replaced to avoid inconsistent strength of bolts from different batches affecting connection reliability.

Through standardized installation procedures and scientific maintenance measures, the service life of flanges can be significantly extended, ensuring the safe and stable operation of industrial systems.