What is valve packing and why is it important?

Valve packing is the sealing system around the valve stem that prevents process fluid leakage to atmosphere. Components: packing rings (PTFE, graphite, or other materials), packing follower, packing spring, and packing gland. Packing must seal against stem movement while allowing smooth operation. Important for: environmental compliance (fugitive emissions), safety (hazardous fluids), and preventing air ingress (vacuum service). Modern low-emission packing designs meet EPA regulations. Packing friction affects valve performance - proper adjustment balances sealing and operability.