Valve gearboxes manufactured by Rotork Gears have been supplied for the operation of giant butterfly valves in a 17 billion Renminbi (RMB) project designed to increase, improve and secure the future supply of fresh water to the city of Shanghai.
The Qingcaosha raw water project will provide a daily supply of over seven million cubic metres (tonnes) of clean water through a network of huge pipelines, the main four with a diameter of 5.5 metres (DN5500). Rotork heavy duty model IW17 worm gearboxes have been ordered to operate butterfly valves manufactured by CVVT (China Valve Technology Ltd) on these pipelines.
With a gear ratio of 14142:1 and an output torque of 850,000 Nm, the gearboxes enable manual valve operation or operation with a portable pneumatic tool.
Rotork IW quarter-turn worm gearboxes are designed for rugged service duties with low or no maintenance. Available for clockwise or anti-clockwise valve operation, they feature a minimum safety factor of twice the maximum output torque. Tightly controlled manufacturing tolerances provide negligible backlash between the worm and quadrant to deliver accurate movement and reduced vibration during travel.
Grease filled for life, the gearboxes are ‘O’ ring sealed with an IP67 or IP68 watertight enclosure for service in all environments at ambient temperatures between -20ºC and +80ºC. Options include high or low temperature service, limit switches, flexible drive extensions, padlock kits and an AWWA specification.
The photograph shows work in progress on one of the giant DN5500 CVVT butterfly valves, with Rotork IW17 gearbox attached, prior to installation on the Qingcaosha project.