Why PTFE-Based Gaskets Provide the Best Seal for Low-Stress Flanges
Limited bolt load, limited load capacity for flanges, and having flanges at risk of cracking are just a few things to keep in mind when selecting low-stress gaskets. An ideal gasket for low load flanges will not only require minimal clamping load to have a tight, quality seal initially, but will maintain that tight seal to reduce leakage and lower the amount of upkeep needed over time.
There are many factors to take into consideration when deciding on which type of gasket would best suit your needs. When choosing a low-stress gasket, you want one that has been tested and is qualified at low loads to ensure the tightest seal possible and will maintain that seal even when clamping load is reduced, which will result in a more quality product and a considerable cost savings.
What Makes a Gasket Seal?
A certain amount of pressure and stress are needed to achieve a proper gasket seal. Standard industry gaskets can have y-values of 1,000-10,000 psi which can be problematic for low-stress flanges. If the y-value can be as low as 500 psi for a low-stress gasket, that makes the flanges less susceptible to cracking than when using traditional gaskets.
Pressure cycle and thermal cycle both play a critical role in how to choose the right gasket for sealing at limited loads. When the connection is made to initially seal a gasket, maintaining the adequate clamping load will help in reaching the desired tight seal. Over time, however, the gasket will conform to the compression load and the bolted joint assembly connection will start to loosen as a result. Keeping that tight seal even when you lose initial load over time is a key indicator of a superior gasket.
Typical Material
Because PTFE-based material is chemically resistant and chemically compatible, it is ideal for use in facilities dealing with dangerous, unpleasant chemicals such as in chemical processing plants or even in some refineries. In addition, PTFE-based material conforms to typical flange irregularities, and some are available with FDA and NSF61 approval.
Typical gasket options when working with a low load flange include Expanded PTFE (ePTFE), Modified PTFE, and Corrugated Modified PTFE. These gaskets are usually tested against each other as testing methods are validated for low-stress gaskets currently on the market.
Matrix CPG
The Matrix CPG gasket is an ideal choice when high gasket stress is not possible or poses danger to the flanges such as glass lined, plastic, cast-iron, and fiberglass reinforced plastic (FRP) flanges. This unique, patented corrugated profile using biaxially oriented filled PTFE gasket was created to reduce the minimum gasket seating stress required to seat a gasket, and offers a tighter seal compared to other gaskets when applying the same clamping load.
CPG’s special corrugation profile contains concentric rings where each ring gives its own seal, as well as peaks which allow for a higher stress concentration, offering a better seal that outperforms our competitors. Providing a tighter seal significantly reduces the likelihood of leakage by 80-90%. In terms of monetary savings, if leakage of a current gasket costs $1M per year, our CPG gasket could lower that to under $50K per year.
To better meet customer needs, Lamons now offers our CPG gasket up to 24” NPS in pressure class 150# and 300#. Our corrugated PTFE gasket is made in the USA and is FDA Compliant and NSF61 Certified. It is available in Ring and Full-face gasket types and a variety of filled PTFE-based materials that offer superior chemical resistance, making it the ideal gasket option for your low gasket stress needs.
