Neles™ soft seated trunnion ball valve, series 6D

Improving the customer process reliability, safety and efficiency


Neles™ series 6D is an API 6D certified (cert. no. 6D-2173) full bore trunnion supported piggable modular ball valve. The valve incorporates industry proven technology for body, ball, stem, stuffing box and seat designs. Packed with features, these valves can deliver long lasting performance in isolation service. Application based trim selection ensures the valve can serve for various conditions.

Compliance to industry standards & customer specifications

Rugged construction


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  • 3 mm added wall thickness as standard for longevity and enhanced corrosion protection
  • Robust cast/forged body and bolting complying with ASME Section VIII div. 1 of pressure vessel code and ASME B16.34 for maximum structural integrity
  • Dowel pins and keys provided to avoid bolts being subjected to combined torsional/bending loads in body, stem housing, trunnion, and stuffing box
  • Fully machined valve internal surfaces for reduced flow induced frictional losses (fully piggable valve)
  • Cavity vent port, bottom drain port, and sealant injection ports in body as standard feature
  • Dual body seal with primary O-ring and secondary graphite gasket for excellent performance when subjected to thermal shocks (in-service temperature & pressure excursions, event of fire, etc.)
  • One-piece solid mirror finished ball with internal relief hole to avoid cavity over pressurization in valve open condition
  • Spring loaded Single Piston Effect (SPE) seat with Double Block and Bleed (DBB) design that absorbs pressure and thermal shocks, wear, and provides a long service life
  • DBB seats allows venting of the body cavity in closed position
  • Self-relieving Primary Soft Secondary Metal seat (PSSM) design with double barrier O-ring and graphite seal to prevent solids entrapment/accumulation and also provides excellent Fire-TiteTM  performance
  • Nickel alloy (Inconel X-750) helical springs behind seat ensures uniform & consistent seat leak tightness even in low pressure
  • Corrosion resistant rugged trunnion secured with pins & low friction bearings ensure precise guiding of ball during valve operation
  • Emergency seat and stem sealant injection
  • Anti-static arrangement between ball-stem and stem-body (electrical resistance <10 Ω measured using 12V DC source)
  • Single piece, internal entry stem, blow-out proof, and precision guided with polymer & graphite thrust washer (for Fire-TiteTM performance) & internal bushings which handle side loading
  • Engineered mounting hardware with high strength coupler & guide bearing for near perfect torque transmission for various types of actuations (including optional compliance to API 6DX)

Reduced emissions

  • Off-center body joint provides

    • Uninterrupted circular O-ring and graphite gasket
    • No bending forces from pipeline to gland packing for lowest emissions

  • Triple barrier stem seal assures long operating life, low emission levels, and online gland packing replacement
    • Internal pressure energized sandwich stem thrust washer (Fluoropolymer + Graphite)
    • O-rings
    • Graphite packing

Standard 6D construction includes,

  • Double block and bleed seat (DBB)
  • Body bottom drain & cavity vent port on all valves (NPT threads)
  • Emergency stem sealant injection provision
  • Emergency seat sealant injection provision 
  • Body attachments - austenitic stainless steel 316

Typical application includes:

  • Hydrocarbons
  • Oil & gas (upstream and midstream)
  • Pipelines
  • Refinery and petrochemical plants
  • Renewable energy
  • Emergency valves ESD/ ESV/ HIPPS
  • Other general process industries

Technical specifications

Flanged, trunnion mounted, full bore ball valve
Size range
DN 50 – 600 / NPS 2 – 24 
Pressure ratings
ASME 150, 300, 600 
Soft seat with metal back-up
Seat tightness
ISO 5208 Rate-A, No visible external leakage & seat leakage
Face to face API 6D, ASME B16.10
Temperature range
-29 °C...+200 °C / -20 °F...+392 °F
Fire safe
API 607 & ISO 10497
Safety level
SIL 3 capable
Fugitive emissions
ISO 15848
CE-PED, ATEX (optional), NACE MR-0175