Proper Material Choices Essential to Application Success
Elastomers are ideal sealing materials in many applications, but not all elastomer types are universally suited for all applications. For instance, applications involving steam — among others in the chemical processing industry (CPI) — require specific solutions due to the steam effect on seals.
These are often associated with but are not limited to, oil and gas applications. Some elastomers can withstand a wide range of temperatures but are degraded by the fluid environment in such applications. Other elastomers can deal with extremely high temperatures but are not suited for environments that involve steam and hot water.
In these potentially volatile environments, it’s essential to have the proper sealing materials in place. The cost of not having the right material or formulation in oil and gas — or any CPI — applications is steep and often results in substantial damage to the company, can threaten worker safety, and affect the environment in a negative fashion.
The Dangers of the Steam Effect on Seals
When exposed to high-temperature steam for prolonged periods — such as during the course of working an application — some elastomers have a tendency to become brittle and fracture. This leads to cracks forming in the seals, which in turn cause leaks. Leaks lead to potentially serious safety concerns and also limit operation efficiency.
Sealing leaks in CPI or similar applications often result in damaged equipment, faulty performance, and dramatically increase the danger to workers and the general environment. The system must go offline for maintenance, leading to extensive downtime and lost revenue. With the heat and pressures involved, leaks will likely damage related infrastructure as well. Potential environmental damage, and the resultant costs, must also be considered.
All of which will likely result in severe financial ramifications due to clean-up operations, and will tarnish the reputation of the company publicly. Obviously, it’s a situation every organization would like to avoid if at all possible.
3 Essential Factors to Consider
To avoid the scenario outlined above, it’s important to weigh three important factors when selecting a seal for any application.
The first factor to consider is the temperature range at which the seal will be operating. Low temperatures will cause the seal to lose some of its flexibility and some of its elastomeric properties. In addition, sufficiently high temperatures will alter the material — and possibly cause it to irreversibly harden and become brittle. Failure at one or both ends of the spectrum is possible, and how a material performs at either end should be considered given the specifics of your application.
The second factor is the pressure range the seal will encounter. High-pressure environments can cause gases to absorb into the sealing material causing physical damage to the seal as a result of rapid gas decompression (RGD). While RGD can be avoided if those absorbed gases are released slowly, the rapid expansion of the material can also cause a rupture. Using specialized elastomer compounds is recommended to mitigate the risk of RGD or explosive decompression.
The third factor for consideration in CPI or thermally harsh applications is the fluid environment (or steam) that will be encountered as this can swell the seal. While countering a change in volume (through swelling) of the seal might be possible, the effects of that volume change will have lasting effects on the seal material itself. Incompatibility (and/or swelling) with operational fluids, or steam, can lead to either softening or embrittlement of the material; both of which can result in failure of the seal.
In CPI applications, it’s critical to consider the temperature, pressure, and chemical environment that the seal will be exposed to, and then choose a material that is specifically designed and manufactured to operate within that particular set of variables. Without these considerations, the probability of failure increases steeply. However, there are several materials and formulations engineered for such purposes.
Marco Rubber & Plastics Provides the Solutions Needed
Extensive testing from the U.S. Department of Energy graded the capabilities and degradation of six different elastomeric polymers in five different simulated geothermal environments at 300 degrees Celsius, which included different fluid and steam components. The results indicated that FFKM (perfluoroelastomer) material provided the best potential coverage for issues facing seals in use in steam-focused environments. In addition, EPDM (ethylene propylene diene monomer) was also judged to be a strong option in guarding against the steam effect on seals.
Marco Rubber can provide specifically formulated materials that accentuate the strengths of these particular elastomers. We’ve developed our own ‘ultimate’ FFKM compound — Markez® Z2001 — that is ideally suited for high-temperature steam applications. With near-universal chemical compatibility, Z2001 is the perfect solution for applications with high-temperature steam and extreme chemicals. The material is capable of a broad range of temperature resistance, maintaining functionality and integrity in temperatures ranging from -15 to 320 C.
As a more cost-effective alternative to other brand materials — such as Kalrez® and Chemraz® — Markez Z2001 delivers top-of-the-line performance against steam effects on seals. When tested for 72 hours against a group of FFKM competitors, Z2001 showed the best compression set under high-temperature steam conditions. When tested for 168 hours against other FFKM options, Z2001 was the only compound to not experience significant volume swell; while others swelled up to or over 20% of their original volume, Z2001 had a volume swell of less than 5%.
Marco Rubber compound E1121, a Y267 (L’Garde cured) EPDM material, also provides excellent protection against steam effects on seals in geothermal applications. This EPM compound has been formulated for excellent resistance to steam and hot water, has good chemical resistance, and has been tested to the NACE TM0297-97 ED standard for excellent explosive decompression resistance. E1121 can withstand use in steam up to 288 C with excursions up to 315 C.
Due to the number of options available, you should always talk to qualified engineers and experts to guide you through the process of determining the best combination of variables to fulfill your specific application needs.
Work with Marco Rubber for CPI Solutions and to Mitigate the Steam Effect on Seals
For more than 40 years, Marco Rubber & Plastics has collaborated with those facing demanding applications to execute engineer-assisted custom sealing solutions. Our experience has given us the expertise to help you find or formulate the ideal solution no matter the environment, including CPI applications and those involving steam.