Sanco Valves Pvt. Ltd. Offers Solid / Flex Design Gate Valve. Sanco Valves Pvt. Ltd. Supplies industrial valves. Solid / Flex Design Gate Valve has the circular ring joint bonnet seal which has proven to be the best bolted high pressure bonnet joint available. The ring joint of Solid / Flex Design Gate Valve is self-aligning. The gasket may be reused unless it is physically damaged. Valves in these classes are also available with spiral wound gasket bonnet joints when specified. The class of this gate valve is 600 / 900.