Why Hydroelectric Power Plants Should Use Orkot®

Hydroelectric Power Plants Face Unique Challenges

Hydroelectric power was and is a game-changer for any region. But like everything else, time takes its toll.

Aging Facilities Need Modernization and Upkeep

Multiple advanced economies today depend on hydropower facilities that date from the 1960s through the 1980s. On a global scale, almost 40 percent of the world's hydropower production facilities are at least 40 years old, with an average age worldwide of 32.

Nearly 70 percent of North America's hydroelectric plants are 40 years old or older. In Europe and Eurasia, especially in Russia, the percentage of hydropower plants aged 40 years or more is slightly smaller at 60 percent.

Hydroelectric power plants that are 45 to 60 years old need significant refurbishment and modernization to improve performance and meet the demands of the modern world. These improvements and upgrades are especially vital in countries that depend on these aging facilities to provide the bulk of their renewable electricity — improvements could potentially maintain the facility's output or increase it by five to ten percent.

Water Applications Require Special Environmental Care

Hydropower is a renewable, clean, low-cost energy source. The World Commission on Dams estimates that 45,000 large dams on the world's rivers generate 19 percent of the world's total electricity reserves. Production of energy by using flowing water requires the construction of dams that form reservoirs that transform enormous areas of land and alter the flow patterns of rivers.

For these reasons, using special care in the relocation of local inhabitants is necessary. Similarly, alterations in river flow and permanent flooding of large sections of land impart changes to the habitat of aquatic species. Diverting water for electricity generation can cause substantial flow reduction and unnatural fluctuations in water levels downstream. These changes in river flow and sedimentation impact the habitat of local aquatic species, requiring measures to accommodate the environmental conditions fishes and fowl need to complete their life cycles.

What Is Orkot®?

Orkot® is the brand name for products made from Trelleborg Sealing Solutions' composite materials and has been used by offshore oil and gas, industrial, and shipbuilding applications for over 60 years. Over the past 20 years or more, Trelleborg Sealing Solutions has supplied the hydro industry and hydropower plants with its genuine Orkot® Hydro bearings.

Trelleborg is a leading global manufacturer of self-lubricating hydro bearings. Trelleborg manufactures Orkot® Hydro Bearings from their proprietary Orkot® TLMM and Orkot® TXMM materials by incorporating solid lubricants with woven fabric reinforcement within a thermosetting resin matrix.

Orkot® Shaping

Orkot® is available in various forms, from tubes to sheets to custom shapes. Tube format is standard at 24 inches long and is available in a range of wall thicknesses. If sheet format is the preferred shape, they are standard at 24 inches by 48 inches with larger sizes available upon request. Sheets of Orkot® are producible up to six inches thick or bonded to make custom designs. Specific finished parts, raw tubes, or raw sheets are available upon request.

Orkot® Machining

Conventional machine shop techniques work well with Orkot® materials. For example, methods normally used for aluminum, brass, or lignum vitae will apply for Orkot® materials. If using cutting speeds of 5.5 meters per second, it is preferable to use tungsten carbide turning tools. When machining Orkot® materials, no cutting coolant is required.

Properties of Orkot® in Hydropower Applications

The basic properties of Orkot® make this an ideal material for hydropower plants. Orkot® is comprised of a range of thermoset composite substances that incorporate innovative polymer technologies. These include technical fabrics engorged with thermosetting resins, solid lubricants that are evenly dispersed throughout the materials, and additives that ensure the production of an optimum solution. There are slight differences between the two grades of Orkot®, TLMM and TXMM, that together satisfy a variety of engineering applications. The cumulative effect gives Orkot® materials many advantages over other, more traditional metallic and polymeric bearings.

Some of the specific advantages of Orkot® properties in hydropower applications include:

• Low coefficient of friction: Low friction results in decreased wear rates and applies to both wet and dry environments.
• Dimensionally stable: Orkot® offers virtually zero swell in water (0.1% swell rate).
• High load capabilities: Orkot® materials generally fit in the same design envelope as more traditional bronze bearings, but Orkot® bearings have high ultimate compressive and yield strength. This makes it ideal where high load capabilities are necessary.
• Outstanding edge loading capabilities: Orkot® materials' mechanical properties allow their bearings to operate effectively under severe edge loading conditions without misalignment.
• Self-lubricating: Orkot® eliminates pollution concerns associated with petroleum-based lubricants and greases, offering a much more environmentally-friendly alternative.
• Asbestos free production: The manufacturing process for Orkot® doesn't use asbestos, which makes for a non-toxic product. 
• High-temperature tolerance: Orkot® materials are usable in environments up to 200 degrees Celsius.
• Easy to install: Orkot® can be press-fit, bonded, mechanically fastened, or freeze fitted (without risk of shattering) depending on the circumstances.
• Easy to machine: Methods used for brass, aluminum, or lignum vitae will typically apply to Orkot® materials.

Orkot® Hydropower Plant Parts

Need replacement parts for your hydro turbine, hydropower plant, or another specific hydro bearing replacement? Here are some common parts that Orkot® materials replace:

• Wicket gate and guide vane bearings
• Wicket gate linkage and thrust bearings
• Horizontal and vertical main guide bearings
• Control gate bearings
• Eccentric pin bearings
• Servo motor bearings
• Fish pump steady bearings
• Kaplan runner blade bearings and thrust washers
• Butterfly valve shaft bearings
• Operating rings, vertical and horizontal wear pads
• Trash rake bearings and wear pads
• Bulkhead wear pads
• Spillway gate trunnion bearings and thrust washers

Refurbished Kaplan Turbines with Orkot® Bearings

The Carillon Power Station is a "run-of-river" power plant that's equipped with fourteen generating units with a total capacity of 753MW, making it the most powerful hydroelectric power station on the Ottawa River. When all fourteen turbine generator units were slated for refurbishing, a project that would span sixteen years, they decided to partner with CRC Distribution to supply Orkot® greaseless bearing materials.

Creating a Grease-Free Environment at Dinorwig Power Station

The six-unit, 1,728-MW Dinorwig Pumped-Storage Power Station in North Wales operated with the capability of making 40 mode changes per day across a 12-month period without any scheduled maintenance. Commissioned in 1982, Dinorwig met that obligation, except for some of the grease-lubricated bronze turbine bearings, which required replacement as often as every two years. As electricity demand rapidly increased, this replacement schedule became costly. After three years of exhaustive testing, Orkot® TXMM bearings were selected to replace the original grease-lubricated bronze bearings. By 1999, the station was converted to grease-free turbines. The absence of grease has improved the working environment around each generating unit, eliminated the leak of grease into the lake water, and saved on the cost of grease and equipment for dispensing it. Several methods for replacing the bronze bearings and greasing them were tried, each unsuccessful over time. In 2000, the decision was made to replace the bearings with Orkot® non-metallic, self-lubricating bearings.

Spillway Gate Friction Analysis

Pre-1980 dam gates were commonly designed with trunnion bearings. After five radial gate breakages occurred in Norway and abroad, increased friction and seizure of bearings on dam gates became a critical concern. To inspect and perform maintenance on gate trunnion bearings, dewatering of the dam and dismantling of the bearing are often necessary. This requires lowering the water level in the reservoir, which is time-consuming and costly. Exhaustive testing was done using varying types of greased bearings, with none performing at a superior level. In 2000, the decision was made to replace the bearings completely with Orkot® non-metallic, self-lubricating bearings. Subsequent testing showed the friction coefficients remained within the manufacturer's stated values.

Rehabilitation of Trunnion Assemblies

A spillway gate at Folsom Dam near Sacramento, California, failed in 1995, bringing the hydropower industry's attention to the potential for excessive coefficients of friction in trunnion assemblies. Upon investigation, it was discovered that the gate's trunnion assemblies suffered stress corrosion that cracked the bronze alloy washers. The decision was made to replace the bronze-alloy-based washers and bearings with a corrosion-resistant composite material. Orkot TXMM® is a polyester fabric reinforced thermoset that incorporates a Teflon® bearing surface with solid lubricants to produce a self-lubricating low friction bearing. This was the material chosen for the replacement project. Upon completion, the dam's operators expect a reduction in trunnion friction, optimum operation of the spillway gates, and enhanced reliability of the system.

Orkot® Hydroelectric Parts Provider

CRC Distribution has everything you need to build, maintain, refurbish, and repair your hydroelectric power project. CRC Distribution is fast and reliable in supplying cut-to-specification metals, hydraulic seals, and cylinder components. We offer an extensive selection of pre-honed tubing and chrome-plated piston rods along with custom seals that can be machined to order, up to 1400mm.

A hydroelectric power plant is a vital piece of an area's infrastructure. If it goes down, thousands of people can have their daily lives disrupted. To minimize the chances of downtime, make certain your hydropower plant is up to the task. Make certain you're running Orkot® materials.