Hot Spot ISO DIS 5115 Part-turn Valve Actuation

What is it?

A DIS document has been issued for comment and ballot by ISO TC 153 WG 16 following review of the comments from the CD ballot item last year, several of which were made by BVAA members. The document provides basic requirements for valve torque in order to size a valve actuator for increased safety and reliability.

It applies to part-turn actuated valve assemblies comprising valve (e.g. ball valve, butterfly valve, and plug valve), actuator and, when required, an intermediate support supplied as a package. It defines the design considerations necessary for automating valves and the responsibilities to ensure suitable actuator sizing, selection and assembly on the valve. It is applicable to pneumatic, hydraulic, electro-hydraulic, and electric actuators as well as electric actuators coupled to a gearbox, as defined in ISO 5211. Lever or manual gearbox operated valves are excluded.

Why is it Important?

The purpose of this new standard is to enforce good work practices to ensure the reliable operation of automated quarter turn on-off valves over their service life. Owners and operators of industrial plants have long complained about the failure of automated quarter turn valves to open or close on demand, resulting in safety hazards and chemical spills to the environment.

The fundamental of the proposed standard is to agree safety factors to be applied to the manufacturers’ normal, as-new, breakout and operating torques. These safety factors are intended to ensure that the valve can be operated successfully in all fluid types and all operating frequencies throughout the service life.

The proposed torque safety factors vary from 0.8 to 2.72 depending on the nature of the fluid and the time between operations of the valve, with multiple factors being applied in some circumstances. These safety factors will be applied to select the actuator torque and they may result in valve shaft sizes having to be increased accordingly.

Consequently, it is important that manufacturers and automation specialists participate in developing the standard to ensure that the torque values used are practical and representative of current good sizing practices.

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Hot Spots are intended to alert members and provide a brief overview of new standards, activities or procedures that are being introduced in the industry. If there is key information missing from this Hot Spot that would be helpful, please let the secretariat know so that we can improve our service for the future.

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