What are common problems with angle stop valves?

What are common problems with angle stop valves include leaks, failure to shut off, and difficulty operating, especially with older multi turn compression type valves that have been unused for years. Most common problem is valve leaks at stem packing, where water drips from around handle, due to worn packing material or O ring, can often be fixed by tightening packing nut or replacing packing. Second common problem is valve will not fully shut off water, allowing water to trickle to faucet even when closed, due to worn rubber washer, mineral buildup on seat, or damaged ball seal in quarter turn valve. Third, valve handle is hard to turn, stuck, or spins freely without stopping flow, caused by corrosion, calcium deposits in hard water, or stripped threads, particularly in cheap valves. Fourth, compression nut leaks at inlet where valve connects to pipe, due to damaged ferrule, overtightening, or scratched pipe. Fifth, valve body cracks, especially plastic or thin brass valves. Sixth, valve outlet leaks at supply line connection due to worn ferrule or cross threaded nut. These problems often occur when valve has not been exercised regularly, allowing deposits to harden. Regular operation, turning valve off and on once a year, helps prevent seizing. When angle stop fails, best solution is replacement with quality quarter turn brass ball type angle stop from Dahl or BrassCraft for long term reliability.