Working principle of toothed gasket: How to achieve high-strength sealing?

1. Basic structure and core design

The toothed gasket is a metal or metal composite seal with concentric serrated grooves on its surface. The core design features include:

Serrated structure: The sharp tooth peaks engage with the flange surface to form multiple annular sealing lines.

Material selection: Commonly used 304/316 stainless steel, carbon steel, nickel-based alloys, etc., are resistant to high pressure and high temperature.

Cross-sectional shape: divided into flat tooth type (basic type) and wave tooth type (better elasticity).

2. Sealing mechanism analysis

(1) Mechanical bite effect

When the flange bolts are tightened, the serrations of the toothed gasket are embedded in the micron-level concavities and convexities on the flange surface, forming a mechanical interlock, effectively blocking the medium leakage path.

The plastic deformation of the tooth tip fills the microscopic defects of the flange and reduces the dependence on the flange finish (Ra≤6.3μm).

(2) Line seal to surface seal

When the initial pressurization is applied, only the tooth peak contacts the flange (line contact). As the pressure increases, the tooth valley gradually deforms, and finally forms a continuous annular sealing surface. Typical sealing pressure can reach 42MPa (such as ASME B16.20 standard working conditions).

(3) Rebound compensation capability

The serrated structure can compensate for flange displacement through elastic recovery under thermal cycling or vibration conditions to avoid seal failure (rebound rate ≥ 15%).

3. Precautions for use

Installation requirements: Flange parallelism ≤ 0.1mm, no repeated use (irreversible deformation of the serrated structure).

Failure mode: Excessive wear of the tooth tip (due to flange misalignment) or stress relaxation (high temperature working conditions).

Test standard: Helium mass spectrometry leak detection according to API 6A, the allowable leakage rate ≤ 1×10⁻⁶ atm·cc/s.

4. Serrated Gasket FAQ

How do serrated gaskets achieve sealing?

A: Their sealing principle is based on:

Mechanical engagement: The serrations embed themselves into the flange surface, forming multiple sealing lines.

Elastic deformation: The tooth valleys deform under pressure, forming a continuous sealing surface.

Rebound compensation: The seal remains sealed despite thermal expansion and contraction or vibration.

Can serrated gaskets be reused?

A: Reuse is not recommended!

The serrations undergo plastic deformation after installation, and secondary use may result in seal failure.

If reuse is necessary, inspect the integrity of the tooth profile and re-evaluate the sealing performance according to the ASME PCC-1 standard.

Precautions for installing serrated gaskets

Proper installation steps:

Clean the flange surface (remove oil and rust, Ra ≤ 6.3μm).

Inspect the gasket (no deformation, cracks, and intact tooth profile).

Align the gasket to avoid partial loads that could cause localized leakage.

Tighten the bolts evenly (in a crisscross pattern, achieving the target torque in 2-3 passes). Common mistakes:

Using deformed gaskets

Flange misalignment causing misalignment

Insufficient or excessive bolt preload