Oliver Twinsafe, a leading UK manufacturer of specialist pipeline valves, has upgraded its production facilities with the installation of a self-contained Enviraclean blast room with abrasive recovery system and high-performance sound insulation from Sheffield-based Hodge Clemco.

Oliver Twinsafe valves are designed to provide double-block and bleed capabilities in a compact design, typically providing the same capability as standard valves that require twice the space. They are highly regarded for their quality and reliability in extreme conditions and have to meet stringent industry standards, including testing up to 10,000psi.

For many years surface preparation for the final paint finishes was carried out by sub-contractors off site, which required extra handling of the valves, some weighing five tonnes. The new blast room is located beneath a canopy outside the factory beside the main production area, so it is convenient and efficient to use while avoiding any potential problems of noise or dust within the building.

The Enviraclean chamber measures four metres long x three metres wide x 2.5 metres high and has double access doors at one end to allow large components to be accommodated. Modular double-skinned panels with an acoustic lining have been used for the construction, which greatly reduces the noise that can be heard outside the chamber whern blasting is taking place. Doors are interlocked to prevent people entering while blasting is in progress, and the walls are lined with rubber curtains to reduce abrasion.

Air inlet ducts and exhaust air outlets have been designed and positioned to ensure highly effective cross-draught ventilation within the room in order to provide good visibility for operators. Media used for surface preparation is either aluminium oxide or garnet, which is projected by a 2452 SGV blasting machine via a 3/8in. (10mm) ID tungsten-carbide-lined nozzle. The nozzle is designed to maintain maximum blasting velocity, uniform abrasive distribution and high work-rate over a long operating life. The blasting system includes a fail-safe dead-man’s handle, water separator/air filter and convenient dial-type air pressure regulator.

Abrasive is recovered for re-use by means of a pneumatic suction filter unit linked to a sweep-in hopper in the floor of the blast room. A vacuum silo receives all spent media, dust and debris from the floor hopper, separates out re-usable abrasive and places it into a storage hopper from where it automatically re-fills the blast machine. The system is adjustable to allow for different types of abrasive.

Dust collected by a dry filter unit is dislodged automatically when the fan stops and falls directly into a bin for disposal. The bins are fitted with a plastic liner to make dust disposal easier and cleaner. An attenuator completely encloses the fan motor and discharge.