Valves and actuator integrity and blast load calculations

The mounting kit for a valve consists of a coupling, drive keys, dowel pin, and bolting hardware. The design of a mounting kit should be stress-based or based on previous experience and validation testing. The mounting kit is the most important section for providing valve and actuator integrity, so it should be capable of withstanding loads from actuator, wind, snow, seismic, and blast. Parameters such as type of valve and actuator and orientation, frequency of actuator cycling and speed of operation, coupling connections, adapter fabrication, and material of coupling can affect the strength of the coupling. This paper presents an example where improper machining of the drive shaft jeopardizes the integrity between the valve and actuator. Mismatch between machined parts of the stem inside bracket and coupling makes the stem not to be aligned correctly in the vertical position. Additionally, this paper discusses the integrity between a 6″ × 4″ ball valve in 22Cr duplex material and class 300 and the pneumatic actuator on this valve against longitudinal and shear stresses created by blast and internal pressure. Both shear and longitudinal stresses are less than 90% of the bolting yield stress for 22Cr duplex, so the conclusion is that the connections between the 6″ × 4″ Class 300 ball valve and the pneumatic actuator are strong enough against blast loads.