In our previous article, we discussed how to insufficient tightening of flanges can cause problems in piping systems. In this second part, we will explore another common issue: bad flanges and how to select the right gasket materials for different damage, pressure and temperature conditions to maintain system functionality and cost-effectiveness.
Index
Importance of flanges in sealing systems
Flanges are essential components in sealing systems, as they ensure the connection between different sections of piping and equipment. Over time, these flanges can suffer damage due to various factors such as corrosion, mechanical wear, pressure and temperature changes. When flanges are in poor condition, the performance of the sealing system is compromised, which can lead to leaks, loss of pressure and, in extreme cases, catastrophic system failure.
What to do with bad flanges?
When flanges are found to be in poor condition, the options available are to replace or repair them, depending on the cost and size of the flange. However, in cases where damage is minor, it is possible to continue to use slightly damaged flanges if suitable gasket materials are selected. These materials must be able to accommodate deformation or surface damage due to high deformation capacity and elasticity.
Selection of gasket materials for damaged flanges
Restructured PTFE gaskets
Restructured PTFE (polytetrafluoroethylene), such as Garlock's Gylon family of products, is ideal for flanges with minor damage. These gaskets offer excellent deformability and elasticity, allowing them to conform to flange surface irregularities. In addition, restructured PTFE is resistant to a wide range of chemicals, making it suitable for a variety of industrial applications.
Expanded PTFE
For flanges with more significant damage, but with less demanding pressure and temperature requirements, expanded PTFE gaskets can be an effective solution. This material is extremely adaptable and can seal efficiently even on damaged surfaces. However, its use is limited to moderate pressure and temperature conditions.
Flange problems in pipelines due to temperature changes
Temperature fluctuations can cause major joint problems due to repeated expansion and contraction of materials. These thermal variations can lead to joint failure if the proper materials are not selected.
PTFE restructured for moderate temperatures
For applications where temperatures do not exceed 250 °C, restructured PTFE remains an excellent choice due to its superior elastic capacity compared to most other gasketing materials. Its flexibility allows the gaskets to maintain an effective seal despite expansion and contraction caused by temperature changes.
High-temperature graphite-based materials
When temperatures exceed 250º C, it is advisable to use graphite-based materials, whose deformation is more plastic than elastic. It is in these cases where we can play with the elasticity of the screws (or add elastic elements to them). This characteristic allows it to maintain an effective seal at high temperatures. Graphite gaskets are especially useful in applications where temperature fluctuations are frequent and significant.
Flanges on pipelines with extreme temperatures
For extreme temperature and pressure situations, Revoseal metal gaskets with confined graphite represent an advanced solution. These gaskets combine the elasticity of metal with the sealing properties of graphite. Not to be confused with spiro-metallic or kammprofile gaskets, confined graphite metal gaskets are designed to take advantage of both the elasticity of metal and the sealing ability of graphite. This combination allows the gaskets to handle extreme thermal changes and pressures while maintaining superior sealing integrity.
We have already seen the importance of selecting the appropriate gasket materials for flanges on bad pipelines, considering both the level of damage to the flanges and the operating conditions, such as pressure and temperature.
From Epidor Seals and Rubber Technology we offer a wide range of high quality gasket materials, including restructured PTFE and graphite based materials, so if you need more information about how to select the right gasket materials for your specific applications, Please do not hesitate to contact our technical team.