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S-3000 Internal Door Closure

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.

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  • Broad Size Range and Pressure Series
  • O-Ring design with a large cross-section on horizontal and vertical closures, for positive seal, protection from light wear and corrosion, and cost-efficiency
  • Lip seal design on horizontal and vertical closures
  • Improved operation with load binder assist on horizontal sizes 24” (DN600) and larger
  • Fail-safe Design


  • Certified to ASME B31.3/B31.4/B31.8/CSA Z662 Cat. II /ASME SEC VIII DIV. 1
  • Pressure Alert Valve per UG-35.2 of ASME BPVC VIII DIV. 1
  • Nace MR0175 compliant material
  • -50° to + 400°F (-45° to 204°C)
  • Viton O-Ring supplied with closure


  • Flanged Closure – welded connection or one-piece
  • ASME BPVC VIII DIV. 1 with U-Stamp for the door only or whole closure (hub, door, locking ring)
  • Stainless Steel, duplex, super-duplex
  • Inconel or Stainless Steel weld overlay
  • External hinge trim for Offshore uses
  • Special materials and O-Rings
  • Horizontal, Vertical, or Inclined orientation
  • Hydraulic lift on vertical closures
  • Stainless Steel and Inconel weld overlay on sealing surfaces
  • Custom Wall Thickness, vents, and other modifications
  • Special Materials and O-Rings
  • Horizontal, Vertical, or Inclined hinging