How do maintenance concerns vary by seal material? Which materials are the most common?
Fluid handling seals often must be resistant to a wide variety of media. Material selection may vary depending on the application conditions. Materials such as fluoroelastomers are often used. Polytetrafluoroethylene seals are also quite common because they can be used across a wide range of temperature conditions and media.
What are some of the largest maintenance issues operators experience and how can they be corrected or prevented?
Contamination can be a major issue. Besides containing the process fluid, it is vital that the seals do not allow external contamination into the system. Contamination can drastically decrease the life of the sealing system and compromise the process fluid.
Seals need to be properly selected. Hardware surface finishes need to be maintained. Scratches in the hardware can cause leakage and premature failure.
Which applications are the hardest on seals?
Applications with abrasive media can be very detrimental to seal life. High-pressure applications can reduce the life expectancy of the seal. It is important that the failure modes be reviewed for each application.
Which types of seals are best for applications with low risk and which are best for high-risk, such as those that may be environmentally sensitive?
Low-risk applications may use standard rubber materials. These are often commodities. But for high-risk applications, it is recommended that seal engineers be involved to review application conditions and media.
What are some indicators that it is time to replace a seal?
Seal failures are not always evident by leakage. A loss in efficiency and an increase of friction may also be signs of a failing seal. If the equipment is monitored, these changes can be identified and maintenance scheduled before catastrophic failure.
How does seal maintenance (or lack of) affect other equipment in the pump system?
A failed seal can affect more than just the sealing system. A failing seal on a high-pressure pump can lead to damage of the pump. The damage to the pump may affect downstream equipment by not providing the media at the appropriate conditions.
Tim Rushton has worked for SKF as a product manager of oil and gas seals for eight years. Before SKF, he worked for ATK as a design engineer and at Macrotech Polyseal as a design engineer. He has a degree in materials science and engineering from the University of Utah and an MBA from Western Governors University.