Month: November 2021

Six years ago Oliver Valvetek changed its method of cleanliness inspection of hydraulic actuators and has not looked back.

Flush cleaning of actuators involves passing clean hydraulic fluid through an actuator at a sufficient flow rate to ensure turbulent flow is achieved.  Turbulent flow is when the Reynolds number exceeds 4000, the Reynolds number is calculated using the flow and the physical properties of the hydraulic fluid.

Originally during flushing of gate valve actuators with hydraulic fluid, in-line particle analysers were used to monitor the number and size of particles against a the NAS 1638 standard.  However, the analysers were poor at differentiating air bubbles and could give no indication as to the type of particles.

The NAS standard was superseded by ISO 4406 and SAE AS 4059F all of which clearly list the maximum contamination limits for cumulative particle counts.

For comparison and understanding of particle sizes, the analysis process and acceptable limits of SAE AS 4059F look at particulates in the process which are approximately 1/10^th of the thickness of a human hair or 6um and bigger !!

In 2015, Oliver changed from in-line analysers to the far more sensitive optical analyser method.  The Pamas Fast Patch 2 Go system was chosen and provides the level of detail needed to ensure the cleanliness levels called for by our customers is met.  Since its installation over 6000 patches have been analysed.

The Customer was using a combination of several valves and fittings to achieve the hook-up as per below picture on a Christmas tree. Oliver’s Middle East Sales Team worked hard with the End User, Christmas Tree Manufacturer, Integrator and in house Engineering to provide a value engineered product over a period of several months. Design reviews included Orientation of Valve Handles, ports, Pressure gauges and Clash Analysis of valves, handles and Pressure Gauges in a very confined space and of course weight reductions needed by the client.

This finally ended up in a Bespoke designed Double Block and Bleed with extra Test Port to give a much smaller, safer installation, avoiding extra leak paths, significant reduction in Weight (over 50%) thus reducing cost and eliminating vibrations and frequent replacements.

The complete supply is in 6Mo material, 10,000 psi rated with Handle Locking, Anti tamper vent facility, maintaining the minimum bore of 5mm. Supplied with fully traceable 3.1B materials for all wetted components.

So far we have supplied over 300 of these valves and this will now become the standard Hook Up for the future.