How do you check blue matching of valves?

To check the blue matching of valves, first ensure that the valves are properly aligned and seated. Then, apply a blue dye or ink to the seating surfaces and close the valve to create a seal. Once opened, inspect the marks left by the dye; a consistent blue pattern indicates proper matching, while uneven or missing marks suggest misalignment or wear. Finally, repeat the process if necessary to confirm results.