The joint ring K 43593 is an essential sealing component designed for the screw plug K 43591 within the automatic starting-air stop valve assembly of the Adriadiesel/Jugoturbina/Zgoda/Sulzer ZV40/48 engine. Its primary function is to provide an effective sealing interface between the screw plug and its corresponding seating surface, helping prevent unwanted compressed-air leakage and maintain the pressure integrity of the associated valve components. Working together with the screw plug K 43591 and retaining ring K 43592, the joint ring supports a secure and pressure-tight closure, contributing to consistent pneumatic control and reliable starting-system performance. The sealing effectiveness of the K 43593 joint ring depends on accurate dimensions, suitable material properties, correct seating geometry, surface condition, and appropriate compression during assembly. During operation, the joint ring may be exposed to repeated compressed-air pressure cycles, vibration, temperature variations, and prolonged periods of standby readiness, requiring resistance to deformation, deterioration, and loss of sealing capability. During maintenance or overhaul, the joint ring should be inspected for flattening, cracking, corrosion, surface damage, and signs of wear, while the corresponding sealing surfaces of screw plug K 43591 and its mating component should also be examined for irregularities, contamination, or damage. Replacement and installation should comply with the manufacturer's specifications to ensure dependable sealing performance. By maintaining an effective seal around screw plug K 43591, the joint ring K 43593 contributes to reduced compressed-air losses, reliable operation of the automatic starting-air stop valve, stable starting-air control, and long-term operational readiness of the ZV40/48 engine.