Increasing efficiency

A furnace was required for the heat treatment of niomic alloys for the bellows sealed gimbal joints on the RB 211 engine for the Lockheed Tristar. These joints form a flexible ducting through which both high and low pressure air bleeds are taken from the engines for auxiliary uses and they are subjected to temperature changes ranging from sub‐zero to over 500°C. They have to maintain their flexibility, corrosion resistance and mechanical strength throughout. The main heat treatments are Nimonic C263 and FV 520B and also the normalising and air hardening of high alloy steels. Any inaccuracies in heat treatment can seriously affect the essential properties.