DBB/DBI Valves – Posiwell


PosiWell® patented Full Bore “dual expanding discs” Gate Valves are DBB – Double Block & Bleed and DIB-1 – Double Insolation & Bleed Valves; designed by engineers with in-depth understanding from over 3 decades of servicing & repairing of traditional Valves as DBB valves and modifying std. valves to DBB type.

With corrosion and chemical additives being one of the main caused of failure within traditional DBB valves design, PosiWell® internal trim is manufactured from Stainless Steel, RPTFE soft seats as standard with alternative materials available.

PosiWell® patented Spring-loaded disc design ensure low friction operation during opening and closing thus increase the life span of the valves and ensures lower torque for automation – Smaller actuators than traditional DBB valves.

Full Bore design allows for maximum flow rate over traditional reduced bore DBB valves and the in-line Pigeable feature.

User friendly in design, allows ease of in situ seat replacement and repair. PosiWell® DBB Valves are designed with lifting gear that eliminates the need for costly Crane hire especially on Tank side and Jetties.

Design Features
  • Design : API 6D, Dual Expanding Discs – DBB-DIB Gate Valves
  • Size Range : 2” to 36” ANSI Class 150 – Class 300 (40” is design stage) : ANSI 600 on request.
  • Pressure & Temperature : ASME B16.34
  • Face to Face : ANSI B16.10 RF Smoot Finish, 125-250AARH
  • Flanged Connection : ASME B16.5, MSS-SP-44-B16.47
  • Testing : API 6D, API598, PosiWell® Standards
  • Certification : API 6FA – 3rd ed. 1999 (Firesafe) : EN ISO 15848-1 (Fugitive Emission)
  • Standard Operating : Handwheel Operated for 2” to 10” (Gearbox Optional) : Gearbox for 12” and above as Standard : Automation “all types” available to specification
  • Bottom Drain : SS 316 Ball Valve, NPT Threaded (Flanged end optional)
  • Bonnet Vent : SS 316 Ball Valve with SS 316 Tubing – as Standard
  • Thermal Relief : SS 316 Thermal Relief Valve – Cavity pressure relief with SS 316 Tubing – 25 PSI differential pressure to relief.
  • Stem & Discs : SS 304 – as Standard (other Material on request)
  • Soft Seat : RPTFE (15% Glass Reinforced) – PTFE optional
  • Stem Seals : Graphite – Live Load Packing Seals
  • Bonnet Gasket : Graphite
  • Anti-corrosion : Phosphate “Bath” Treatment
  • Painting : 2 Part Epoxy Coating (to customer specification)

Bonnet Vent, Thermal Relief and Bottom Bleed

Bonnet Vent Valve for verifying leakage. Thermal Relief Valve Set @ 25 PSI – with Isolation Valve that can be installed on either of the Valve’s End Flanges. Large bottom bleed valve for cavity draining

Product Range


Rising Stem Valves

Valve in fully open position with Discs
fully retracted in bonnet ensures


Valve in closed position, discs retracted
and located on disc shoulder. Discs-Seat
clearances depending on Valve sizes are
1.5 to 2.5mm


Valve in fully closed position with discs
expanded sealing on Metal to Metal and
Soft Seat achieving ZERO leakage per API
6D – DBB/DIB-1


Non-Rising Stem Valves


Operating principle are the same as the Standard Rising Stem Valves except stem travels internally in the yoke (Fig 1).



PosiWell® non-rising stem valves maintain all functionalities and ZERO leakage performance.

Fig 2 shows valve on close position with discs still retracted.

Fig 3 shows discs expanded and compressing the seat.