My client requires gate valve with trim 5 (STL 21). Their specs mentions wedge, stem & trim as HARDFACED(STELLITED 21). My supplier is offering wedge in STL 21 but he is offering stem in F6a. Could any one inform if F6a is better than STL 21.
F6a can be used as stem material, but should carry Stellite 21 overlay. These aren't imcompatible. As for "My supplier is offering wedge in STL 21", this means that the wedge is stellited. The wedge itself isn't made of Stellite 21.