Bearings are a vital component in the wastewater industry. Breakthroughs in bearing technologies help wastewater companies extend the life and operational efficiency of critical applications—even when those applications are operating in harsh conditions, with corrosive fluids and under heavy loads. The main problem facing wastewater applications is not the operating fluid itself. It is the ongoing threat of seal failure that causes bearing contamination, ultimately leading to destructive and costly system failure. Many wastewater applications such as transfer pumps, electric submersible pumps (ESPs), stationary pumps, vertical turbine pumps, dredging pumps and injection pumps can operate in demanding and abrasive environments. Unfortunately, a typical sealed bearing must be kept clean and lubricated for the pump to function properly. Even the smallest break in the bearing seal can quickly flood the bearing with abrasive and corrosive working fluids, bringing pumping operations to a halt. Recently, a coastal wastewater treatment facility in Washington demonstrated the effects of running in a corrosive saltwater environment. The biggest difficulty that the facility faced was the intrusion of saltwater into its sewage-outflow pipes."If higher water levels are able to push salty water into the county's wastewater-treatment system, corrosion will worsen. This has already been seen to a certain extent with equipment that should be lasting 50 years breaking down after 20" (Seattle Weekly, "King Tide Shows What Climate Change Has In Store," January 2015). Corrosion is a killer when it comes to application integrity. Bearings and seals have a direct impact on wastewater equipment and system performance. They simply cannot fail. Because these applications generally run in corrosive conditions, wastewater engineers design bearings and seals that are protected from operating fluids. However, these bearings generally require a watchful eye and ongoing maintenance. When a seal fails, operational fluid leaks into the bearing housing quickly, decreasing equipment life, increasing surface friction and energy consumption, and affecting equipment operation.
These components do not have to be sealed from harsh operating media.
05/19/2015
Table 1. Physical and mechanical property comparison of bearing materials. Sources: Bertagnolli, U.S. Synthetic; Roberts et al., De Beers; Cooley, U.S. Synthetic; Jiang Qian, U.S. Synthetic; Glowka, SNL; Sexton, U.S. Synthetic; Lin, UC Berkeley, MatWeb.com, Cerco
Figure 1. Comparative data in thermal conductivity and friction co-efficiency (Courtesy of U.S. Synthetic)
Figure 2. Comparative data in fracture toughness and material hardness. (Courtesy of U.S. Synthetic)
High thermal conductivity reduces the likelihood of causing localized welding of the surfaces during starting and stopping, which in turn leads to scoring and galling of the bearing surface. In sliding bearings, low coefficients of friction are desired to decrease heat generation and reduce power losses. A bearing material exhibiting a large fracture toughness will decrease the likelihood of race damage during extreme operation conditions. Because of its extreme hardness, high thermal conductivity, fracture toughness and strength, diamond is very resistant to wear and damage from abrasive particles in lubricants or process fluids.
Breakthroughs in diamond bearing technology extend the life and operational efficiency of critical wastewater applications. Diamond technology can operate in harsh conditions, corrosive fluids and under heavy loads. Abrasive-laden, water environments that are challenging to traditional sealed bearings are generally ideal conditions for diamond bearing technology.