[Craig1313]

Does the flow arrow or the cap point up and do the gaskets need to be removed prior to soldering

 

[joecaption]

The arrow should point in the direction the waters going to be flowing.
Got a picture if the valve your going to use?

 

[AllanJ]

Ideally all plastic, rubber, or other non-metal parts should be removed before soldering although often this is not possible. A faucet or hose bibb or in line valve that is soldered (sweated) on should be in the open position.

The advent of lead free solder has increased the chance of damage to valves and other fittings during soldering. Electronic solder, which has a lower melting point, is safer for the valves and fittings although that joint would have a tendency to come apart at the moment another nearby joint was soldered using regular plumbing solder.