What are corrugated metal gaskets?

Corrugated metal gaskets are a type of mechanical element used for sealing. They are made of thin metal sheets through a special process and are pressed into a circular ring-shaped gasket with regular wavy concave and convex patterns (i.e., "corrugations"). CMG gaskets are considered the standard for corrugated metal gasket technology. CMG gaskets are an ideal choice for Class 150 and Class 300 ASME flanges with minimal bolt load.

1. Main Features and Working Principles
(1) Elasticity and Resilience:
The corrugated structure is like a tiny spring. When the flange bolts are tightened, the corrugations are compressed; and when the equipment vibrates due to temperature and pressure changes during operation or the flanges are slightly separated, the compressed corrugations can rebound to compensate for this change, always maintaining contact between the sealing surfaces and preventing leakage. This is the key to its superiority over flat gaskets.
(2) High sealing pressure ratio: 
Since the contact area of ​​the corrugation is relatively small, the pressure (specific pressure) per unit area is greater under the same bolt preload, making it easier to compress and fill tiny flange surface defects, thereby achieving initial sealing.
 (3) A variety of metal materials are available: 
Different metal materials can be selected according to different media (such as corrosiveness) and working conditions (temperature, pressure). Common ones are: 304/316 stainless steel: the most commonly used, with good corrosion resistance and comprehensive performance. Carbon steel: used for non-corrosive working conditions, such as high-temperature steam. Special alloys: such as Hastelloy, Monel, and Inconel, used in corrosive or high-temperature environments. 
(4) Soft cover layer available: 
In order to achieve better airtightness or seal special media, a layer of soft sealing material can be covered on the upper and lower contact surfaces of the corrugated metal gasket, such as: Graphite: high temperature resistant, chemically inert, and the most widely used. PTFE (polytetrafluoroethylene): excellent chemical corrosion resistance. Mica: Used for extremely high temperatures (such as high-temperature applications in oxidizing atmospheres).
This structure is called a metal-jacketed gasket, which combines the strength and temperature resistance of metal with the excellent sealing properties of a soft cover layer.

2. Main Types
Corrugated metal gaskets are commonly found in two main types:
Basic corrugated metal gasket:
Made solely of corrugated metal strips, without a cover layer. It relies on the metal's inherent elasticity and high sealing pressure ratio to achieve a seal. It is commonly used in applications where temperatures and pressures are high but the media is not highly corrosive.
Corrugated metal gasket with cover layer (metal-jacketed gasket):
A layer of soft sealing material (such as graphite sheet) is applied to the upper and lower surfaces of the basic corrugated metal gasket, and then the edges are wrapped and secured with a mold. This is the most commonly used type in industry.

3. Advantages and Applications
Advantages:
Adaptability: Can accommodate fluctuations in pressure and temperature, and slight flange deformation.
Reliable sealing: Much better sealing performance than flat gaskets.
High-temperature and high-pressure resistance: The metal body can withstand temperatures and pressures far higher than non-metallic gaskets. Corrosion Resistance: Material selection allows for adaptability to various media.
Long Service Life: Excellent resilience makes it less susceptible to stress relaxation and failure.

Typical Applications:
Pipes, valves, pumps, and pressure vessel flanges in the petrochemical industry.
Steam turbines and boiler systems in the power industry.
Pharmaceutical and food industries (316 stainless steel with PTFE overlay is common).
Any medium-, high-pressure, and high-temperature flange connection requiring reliable sealing.