Sealing mechanism and performance advantages of annular joint gaskets under high temperature and high pressure conditions

1. Industrial application background of ring joint gaskets

Ring joint gaskets are key sealing components in the oil industry, drilling platforms and high-pressure pipeline systems, and are designed for extreme working conditions. In oil and gas production equipment, pipelines and containers usually need to withstand pressures above 9.8MPa and temperatures above 700℃. Traditional non-metallic gaskets (such as rubber or asbestos) are prone to creep, aging or chemical corrosion, while metal ring joint gaskets have become a reliable choice under high temperature and high pressure environments through unique self-tightening sealing principles and high-precision structural design.

2. Sealing mechanism of ring joint gaskets

Plastic deformation fills micro defects of flanges

The sealing core of ring joint gaskets lies in the plastic deformation ability of metal materials. When the bolts apply a clamping force, the gasket (usually made of soft metal such as pure iron, copper or silver-plated steel) flows plastically under high pressure and penetrates into the microscopic unevenness of the flange sealing surface, thereby blocking the leakage channel. This "metal-to-metal" sealing method is more resistant to high temperature and pressure shock than non-metallic gaskets.

Solution to interface leakage: Through high bolt preload (usually more than 70% of the material yield strength), ensure that the gasket and flange contact surface are tightly fitted to reduce interface leakage caused by thermal deformation or vibration.

Prevention of penetration leakage: Metal gaskets have a non-porous structure, which avoids the problem of medium penetration caused by loose fibers in non-metallic materials.

Self-tightening design enhances sealing reliability

Some annular gaskets adopt the "Unsupported Area principle" and use the system internal pressure to push the gasket to further press the surface to form a dynamic self-tightening effect. This design improves the sealing performance when the pressure increases, especially for oil and gas pipelines with frequent pressure fluctuations.

3. Performance advantages under high temperature and high pressure conditions

Material resistance to extreme environments

High temperature stability: Gaskets made of nickel-based alloys (such as GH4169) or stainless steel (SUS316L) can maintain strength in the range of -200℃ to +700℃, and the long-term working temperature can reach 538℃ (corresponding to ASME B16.20 standard).

Chemical corrosion resistance: Silver or nickel plating can prevent corrosion from hydrogen sulfide (H₂S) and acidic media, extending the life of the gasket.

Structural design and flange adaptability

High-precision processing requirements: The annular joint gasket must be strictly matched with the annular groove of the flange (such as R type or RX type), and the tolerance must be controlled within ±0.05mm to ensure the initial sealing effect.

Flange strength optimization: Compared with traditional flat gaskets, annular gaskets require lower bolt preload, which can reduce the risk of flange deformation.

4. Key considerations in practical applications

• Installation and maintenance points

Bolt torque management: Bolts must be tightened in stages according to standards to avoid leakage caused by uneven stress.

Surface treatment: The roughness of the flange sealing surface must be controlled at 0.8~1.6μm (Ra value). Too high or too low will affect the sealing.

• Failure mode and solution

Thermal cycle leakage: Sudden temperature changes may cause bolts to loosen, and they need to be re-tightened after shutdown.

Material hardening: Metal may become brittle under long-term high temperature, so it is recommended to replace it regularly (usually every 3-5 years).

5. Comparison with traditional gaskets