Pentair Valves & Controls has been awarded a contract to supply more than 200 high-pressure, electric-operated gate and check valves for units 3&4 of the Tianwan nuclear power plant in Jiangsu province, China.
The Sempell safety relief and isolation valves are due to be installed in the main steam and emergency core cooling systems in the two new VVER-1000 reactors by 2016. The parts will be manufactured in Germany.
Pentair says its Sempell wedge gate valve has been designed with cobalt-free hard facings, and is engineered to eliminate the potential for thermal binding, which can, in extreme cases, prevent valves from opening.
"Wedge plates with an innovative spring design maintain the wedge assembly in a defined position independent from the installation position during the whole valve stroke," Pentair explains. "By creating a permanent gap controlled by the springs, this design prevents thermal binding between the wedge plates and valve body. Wear of the seat surfaces is therefore reduced and defined pressure on the seat and guiding surfaces is ensured."
Pentair worked closely with plant operator Jiangsu Nuclear Power Company and Russian engineering and procurement contractor Atomstroyexport to demonstrate the valve design.
"We are actively working with EPCs in the Russian and Chinese markets to provide advanced valve design and improvements which help to increase the safety level of future nuclear power plants," said Paul Schaller, sales director - nuclear valves at Pentair Valves & Controls. "By using performance data from our extensive installed base, we can demonstrate how our valve design avoids the damaging effect of thermal binding."
Qualification was undertaken on an original gate valve through tests which mimic the extreme requirements caused by pipe rupture. Test results confirmed the suitability and robust performance of the Sempell valves in applications comparable to the Tianwan plant, says Pentair.
Photo: Pentair Sempell wedge gate valve