eTec’s Water Supply Butterfly Guard Valves

eTec were approached to assist with valve refurbishment work required on an overseas project. Prior to award of contract, eTec visited the site to discuss requirements with the station engineers and check installation interfaces. Three locations along the supply scheme were visited to review the maintenance requirements.

The resulting order was for the supply of new valves and spare parts to all three locations and UK based product training for twenty engineers to undertake installation and refurbishment at the three sites identified.

The valves had to meet AWWA specifications for material, allowable stresses and testing along with project corrosion and cathodic protection stipulations. The requirement was for 1300mm diameter Butterfly Valves acting as Guard Valves isolating supply line pumps working at 24 Bar plus a possible 4 Bar surge. To meet pressure test specifications the Body was subject to a 56 Bar hydrostatic test with a 42 Bar strength test applied to the Disc and a 28 Bar zero leakage seal test was also performed. Open and Closed locking provision and 4:1 Open / Close time variation was provided.

Drop tight sealing was achieved at the 28 Bar working pressure. Whilst the ductile iron castings could be engineered to meet this requirement engineering for the valves Disc and Gland sealing arrangements needed to be considered to achieve the test pressures and contract requirements.

To meet the corrosion specifications the valve was designed with the wetted surfaces of the Body and Disc ebonite coated and used Duplex stainless steel shafts. The ebonite correctly bonded to the Body bore provides a seat profile that can then be accurately machined to match the Disc swing. This eliminates the casting from contact with the corrosive water.

Cathodic protection design included non metallic parts replacing traditional stainless and sacrificial anodes. The valves were designed, cast and manufactured in the UK, with actuation of the valve courtesy of fellow BVAA members Opperman Mastergear and Rotork.

On completion eTec welcomed the customer to witness the valves pressure and performance testing. Following delivery eTec provided specific training for the engineers and managers who were to undertake the site work.

For bespoke valve requirements please see our website.

eTec Engineering Services Ltd
Tel: 01709 544111
Website: www.etec.uk.com

Published: 1st March 2012