MOV Long Life Extra

There is no such thing as a universal grease. Greases can vary in many ways including the base oil viscosity, base oil type, thickener and additives as well as the target cost. Because of this the characteristics and performance can range widely. There are many that can do okay in a variety of uses but there can still be significant cost benefits to have specialty greases suitable for specific applications. This includes essential components. Safety related MOV (motor operated valves) are one such application. The grease must satisfy the requirements of the actuator supplier as well as having the required radiation, temperature and steam/water resistance to continue to be able to perform their design function after a serious event. For example, after a reactor heat transport pipe break. In addition, for both the actuator and the stems the grease must maintain a consistent coefficient of friction to ensure that the bounds are not exceeded and do not impact on the torque switch settings nor cause excessive wear.

For some actuators, the historical grease worked okay, but reportedly had issues with rapid hardening in service. Alternatives were being actively sought by the industry and by EPRI (Electric Power Research Institute). The goals were to find a better grease and one that could be used in all three applications. This is in the actuator gearbox, in the limit switch gearbox and on the threaded valve stems. Fortunately, in 2001 when it was announced that the prior grease was to be discontinued, evaluations had already identified a suitable product. Testing in 2002 confirmed that it was better and, in that year, MOV Long Life became the factory fill for Limitorque SMB actuators. Later work showed it to be suitable for the limit switch gearbox and on the stems. It is also being used by other actuator suppliers.