The S-3000 is Stark’s Internal Door Closure which is manufactured in diameters ranging from 6” to 84” (DN150 to DN2100) in pressure series 150 to 2500. The closure concept relies on the proven method of an internal locking ring that slides into the inner side of the closure hub. When expanded to the closed position, the locking ring assembly securely latches the door into place. Durable components are used to actuate the locking ring and are designed to withstand the demands of long-term operation. Regardless of orientation, size, or pressure rating the S-3000 maintains its benefits and ease of operation, making it the broadest closure choice for Pipeline and Pressure Vessel applications.