MSS SP-91:2009

The handwheels or handles provided with manually actuated valves are designed so that reasonable effort exerted by the operator(s) is sufficient to actuate. However, operability of manually controlled valves is dependent on many factors, such as fluid pressure and temperature, location of valve in relation to operators, desired speed of operation, physical capabilities of operators, ambient conditions, and frequency of operation. The purchaser, based upon anticipated on site conditions, should therefore evaluate suitability of valves with manual actuators. This document was prepared to assist users in establishing actual requirements relative to valve operation. Most valves can be provided with actuators suitable for specific service conditions, regardless of severity, when conditions are defined.
The purpose of this Standard Practice is to provide valve users with information for use in evaluating the manual operation of valves.
It must be understood that this information is general in nature and must be supplemented by specific operational data for the valve and service conditions to be experienced. The maximum and minimum torque ratings of specific valve and actuator types are not covered by this Standard Practice, but must be considered when applying manual input devices to any specific valve. Data from the valve and actuator manufacturers should be consulted regarding valve and actuator types and ratings.
Scope:
This Standard Practice provides guidelines for the operation of manually actuated valves as affected by the valve operator’s input.
The handwheels or handles provided with manually actuated valves are designed so that reasonable effort exerted by the operator(s) is sufficient to actuate. However, operability of manually controlled valves is dependent on many factors, such as fluid pressure and temperature, location of valve in relation to operators, desired speed of operation, physical capabilities of operators, ambient conditions, and frequency of operation. The purchaser, based upon anticipated on site conditions, should therefore evaluate suitability of valves with manual actuators. This document was prepared to assist users in establishing actual requirements relative to valve operation. Most valves can be provided with actuators suitable for specific service conditions, regardless of severity, when conditions are defined.
The purpose of this Standard Practice is to provide valve users with information for use in evaluating the manual operation of valves.
It must be understood that this information is general in nature and must be supplemented by specific operational data for the valve and service conditions to be experienced. The maximum and minimum torque ratings of specific valve and actuator types are not covered by this Standard Practice, but must be considered when applying manual input devices to any specific valve. Data from the valve and actuator manufacturers should be consulted regarding valve and actuator types and ratings.
Scope:
This Standard Practice provides guidelines for the operation of manually actuated valves as affected by the valve operator’s input.