Swing Check valves allow water to pass from one direction. Swing check valves are commonly used at the inlet of fill pipe manifolds and stop water rushing out when the camlock is disconnected. The swing disc allows water to pass freely.
Foot valves are installed at the inlet end of a suction hose. They allow water to flow into the hose but not out. Keeping the hose full of water makes priming pump much faster.
Need a socket in a pipe but don't want to weld in a socket? Mechinal Tee is just what you need. Just use a hole saw and drill a hole, Slip the Tee into the hole and fasten the backing clamp and done, No welding, No rust, No paint.