Modular Actuator Assembly for Partial Stroke Testing

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Solution Overview

Problem

Existing partial stroke testing systems for emergency shut-off valves in the oil, gas, and power industries face issues with spurious valve travel and false failures, requiring extensive operator training and causing process disruptions, especially when valves stick due to infrequent use and material buildup.

Innovation Solution

A modular valve actuator assembly that eliminates spurious valve travel and false failures by using a dual yoke and tandem piston design with adjustable stops and sensors, allowing full actuator torque output and immediate emergency operation, while enabling precise control of valve position during partial stroke testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical hard stop devices are used for partial stroke testing, then hard travel stops are provided to prevent spurious over travel and full actuator torque output is available to operate valves experiencing stiction, but extensive operator training and procedures are required for engagement and disengagement operations

Engineering Contradiction:

Improveprevention of spurious over travelVSAvoidoperator training and procedures

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The actuator automatically engages and disengages the hard stop device based on detected valve position, eliminating the need for manual operator intervention. The system self-regulates the testing process by monitoring valve stroke and automatically controlling the hard stop engagement timing

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical engagement systems with an automated control system using sensors and electronic control logic to manage hard stop device activation, reducing reliance on operator skill and manual procedures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Force

If mechanical hard stop devices are used for partial stroke testing, then full actuator torque output is available to operate valves experiencing stiction, but the devices typically cannot be immediately disengaged should an ESD occur during partial stroke testing

Engineering Contradiction:

Improveactuator torque outputVSAvoidemergency response capability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The system continuously monitors valve position and ESD status through sensors, providing real-time feedback to the control logic. When an ESD condition is detected, the system immediately responds by disengaging the hard stop device and actuating the valve to the emergency position, ensuring safety takes precedence over testing

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The hard stop device transitions from a static mechanical constraint to a dynamic, controllable element that can be rapidly engaged and disengaged based on real-time system conditions, allowing full torque availability during normal operation while enabling immediate emergency response when needed

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If air pressure is carefully released to allow spring inside actuator to move valve to desired partial stroke position, then valve motion is achieved without disrupting controlled process, but only a small percentage of air pressure can be released resulting in very small percentage of actuator rated torque or force

Engineering Contradiction:

Improveprocess disruptionVSAvoidactuator torque output

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The system applies partial air pressure release specifically for positioning during normal PST operations, but reserves the capability to apply full actuator force when needed for valves experiencing stiction or during emergency conditions, effectively combining both approaches

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution ensures reliable partial stroke testing without disrupting the process, eliminates false failures, and maintains full emergency operation capability, allowing for an unlimited number of worry-free testing cycles while ensuring valve functionality during emergencies.

Implementation Method 1

A tandem piston assembly (70) is connected to an end of the force module casing (20) distal the yoke housing (12). The tandem piston assembly (70) includes a piston (76) and piston rod (78) which extend into a chamber (22) formed by the force module casing (20)

Methodology Applied

Scientific EffectPneumatic pressure: Pressure Gradient

Implementation Method 2

A compression spring assembly (30) is disposed in the chamber (22) in surrounding relationship to the piston rod (28). The compression spring assembly (30) biases the piston (24) in a direction away from the yoke housing (12)

Methodology Applied

Scientific EffectElastic potential energy: Spring

Data Source

PatentUS10132337B2Actuator assembly for conducting partial stroke testing

Publication Date: 2018.11.20 QTRCO INC

AI summary

A modular actuator assembly which can be used for partial stroke testing of a valve, the assembly having a force module and a tandem piston module. The force module has a primary piston and piston rod interconnected to a shaft which is movably mounted therein. The tandem piston module is connected to the force module and has a tandem piston and piston rod. An indicator plate is connected to the piston rod and is selectively positionable on the tandem piston rod. The tandem piston rod extends into the force module and acts as a pneumatically engaged hard stop for preventing spurious travel of the primary piston and hence spurious valve travel.