How to Determine if a Corrugated Metal Gasket Needs Replacement？

1. Standards for immediate replacement of corrugated metal gaskets

(1). Sealing failure

Visible leakage: Leakage of medium (oil, gas, water, etc.) occurs at the pipe or flange connection, and cannot be eliminated after tightening the bolts.
Detection method: Apply soapy water to check for bubbles, or use an infrared leak detector.
Failure of pressure test:
During the system pressure test, the pressure drop exceeds the standard (such as a drop of >10% within 15 minutes).

(2). Physical damage

Permanent deformation or cracks: The gasket surface appears crushed, wavy warping, or radial cracks (especially common in high temperature and high pressure conditions).
Metal corrugation fracture: The corrugated structure is partially broken or separated between layers (common in multi-layer metal gaskets).

(3). Corrosion or material deterioration

Severe rust/chemical corrosion: The metal layer is corroded with an area of ​​>30%, or the non-metallic filling layer (such as graphite, PTFE) is powdered and falls off. High-risk scenarios: acidic environment (pH < 4), hydrogen sulfide (H₂S) environment. High-temperature ablation: oxidation and discoloration of the gasket surface (such as blueing of stainless steel), carbonization (graphite gasket) or metal creep.

2. Preventive standards for recommended replacement

(1). Service time and working condition changes

Exceeded service life: Continuous use exceeds the manufacturer's recommended life (usually 3 to 5 years, shortened to 1 to 2 years under high temperature conditions). Working condition upgrade: System pressure and temperature exceed the gasket rating (such as the original design of 1.6 MPa, now requires 2.5 MPa).

(2). Decreased sealing performance

Repeated tightening requirements: The same gasket needs to be tightened multiple times due to poor sealing (such as tightening > 3 times within 1 year). Insufficient compression rebound rate: The rebound rate of the gasket after compression is < 40% (new gaskets are usually > 60%), resulting in a decrease in sealing force.

(3) Matching problem

Flange surface or bolt changes: Change flange material/surface treatment (e.g., flat FF to convex RF), or adjust bolt preload.

3. Inspection and diagnosis methods

Visual inspection: After disassembly, observe whether the gasket has uneven indentations, cracks, or corrosion (see Figure 1).
Dimension measurement: Use a caliper to check thickness wear (if the thickness reduction is greater than 15%, it needs to be replaced).
Sealing test: After reinstallation, perform airtightness/hydraulic test and record the leakage rate.
Material analysis: Take samples of severely corroded gaskets and perform EDS energy spectrum analysis to determine element loss.