SAIMC: Vaal branch

SAIMC

IBG - SA Instrumentation & Control Buyers' Guide

June 2014 SAIMC

Keith Mitchell from Heaton Valves was the presenter for the April Technology Evening. His presentation started with a video clip showing the progress made by people in the field of space travel and technology and how rapidly technology itself evolved over the last couple of years. Also shown was the Challenger disaster that was caused by an insignificant component, an O-ring on a booster engine. Similarly in the instrumentation field we find that neglecting the simple, ‘basic stuff’ causes problems. One of these is control valve applications; sometimes we do not take sufficient time to select the correct type of valve for a specific application.

Keith Mitchell.

Valve technology has advanced significantly over the last twenty years. In terms of type, material, construction, temperature and pressure ratings there are thousands of possible options. Keith showed some examples and photos of spectacular emergency shutoff valves; specifically the triple eccentric valve was shown as an excellent solution for many applications. Some benefits mentioned were its simple design and tight seating capability. It can provide a truly zero leakage solution and valves are fire safe because of the construction. Triple-eccentric valves can be manufactured for very large sizes, up to 1500 mm for temperature ratings in excess of 400°C. It can be applied in similar applications to ball valves, but it normally is smaller and lighter in weight therefore requiring less mechanical support. Special materials can also be applied for body material like aluminium-bronze in sub-sea applications and hard coated wetted parts can be obtained with the use of tungsten carbide or chromium carbide coatings. Bolted seat designs are now also available on body and disk seats for improved maintainability and an example was shown where a ‘nose-guard’ was provided to protect the disk in a severe erosion application. In addition to this, fast closing speeds are possible.

This sounds like an advertisement for triple-eccentric valves but in fact this valve was merely the golden thread throughout the presentation that was filled with examples, learning, photos and pictures of innovation and progress over the years. Keith is a person with a passion for control valves who has travelled extensively and gained plenty of experience, including very tough applications. The branch thanks Keith for sharing this knowledge and experience with us.

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SAIMC: Vaal branch

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