1 Main valve cone 8 Piston disc D Steam inlet 2 Relief cone 9 Spring cap E Trip oil 3 Steam strainer 10 Piston F Start-up oil 4 Guide bush 11 Compression spring H Test oil 5 Valve bonnet 12 Test piston K Leakage steam 6 Labyrinth bush 13 Pressure-gauge connection T1 Drain oil 7 Valve spindle 14 Hand valve T2 Leakage oil