High-Performance Mechanical Seals for Oil & Gas Operations

There are many different types of mechanical seals, and understanding those differences can help with choosing the right seal for a given application.

By assembly, cartridge seals arrive as pre-assembled units containing the seal faces, secondary seals, gland, sleeve, and hardware. They reduce installation error and simplify maintenance. Component seals are installed as individual parts, which allows them to fit tighter spaces and offers more material flexibility, but they require a higher level of installation precision. Split seals divide across the shaft axis so the seal can be replaced without disassembling the equipment, a significant advantage wherever downtime is costly.

By arrangement, single seals use one pair of seal faces and work well where leakage risk and fluid hazard are moderate. Double seals use two sets of faces with a barrier or buffer fluid between them, and are specified when the process fluid is hazardous, abrasive, or requires zero atmospheric leakage.

By design, pusher seals use springs that compress axially as the faces wear, with a dynamic O-ring that moves along the shaft. Non-pusher seals (bellows seals) replace the dynamic O-ring with a metal or elastomeric bellows, making them better suited to high-temperature service and fluids that coke or crystallize.

Specialty seals cover applications with extreme temperatures, high pressures, corrosive environments, or dry-running conditions. In oil and gas compressor service, this includes gas liftoff seals, where a thin film of pressurized gas separates the faces during operation.

There are three main things that can cause a mechanical seal to leak, and identifying the right one is the starting point for any effective repair. The most common cause is face failure. The two seal faces, one stationary and one rotating, rely on a thin fluid film for lubrication. When that film breaks down due to heat, contamination, misalignment, or dry running, the faces make contact, wear unevenly, and lose their ability to seal. Secondary seal failure is the next source. O-rings, gaskets, and flexible graphite elements can degrade due to chemical attack, temperature excursion, or physical damage during installation. When a secondary seal fails, the leak path bypasses the faces entirely. In dual-seal arrangements, barrier pressure imbalance is the third cause. If the differential pressure between the barrier fluid and the process fluid climbs too high, the faces can be forced open, which leads to excessive barrier fluid consumption and potential process contamination.

Most mechanical seals can be repaired, and Flexaseal repairs seals from all major manufacturers, not only its own products.

Every seal that comes into Flexaseal’s repair facilities goes through a detailed five-step process: 

• Careful disassembly
• Examination of components for wear and damage
• Failure analysis communicated to the customer
• Repair estimate options including like-new restoration or exchange to a Flexaseal seal
• Final reassembly

Flexaseal has dedicated engineering staff for reverse engineering competitor seals and vertically integrated machining and lapping capabilities across all repair locations.

Repair programs typically cost 30%–50% less than purchasing a new OEM seal. If a seal cannot be repaired, Flexaseal will quote a new replacement or offer an exchange program.

Contact us, and we will evaluate your seal for repair options.

The lowest cost mechanical seal in any oil and gas application is the one that lasts the longest.

Purchase price is only one part of seal cost. A seal that fails in six months and requires unplanned downtime, a maintenance crew, and a rush replacement order costs far more than a seal that runs for three years without intervention. Flexaseal helps customers evaluate total cost of ownership, not unit price alone, when specifying seals for demanding applications.