Bellow Seal Design Features

  • Design Standards

API 602 for forged gate valves
BS EN ISO15761 for forged globe valves
API 600 for Cast Gate Valves
BS1873 for Cast Globe Valves
ASME B 16.34 for Cast Globe and Gate Valve
  • Bellow Inspection and Test : MSS SP -117

  • Cycle Life upto and including class 800 Forged Valves : as per MSS-SP 117

Min. 5,000 Cycles for Globe Valves
Min. 2,000 Cycles for Gate Valves
For class above 800, Minimum 2000 cycles for Globe Valve,
Minimum 2000 cycles for Gate Valve
  • Cycle Life for Forged Valves & all classes Cast Valves : as per MSS SP-117

Size(inch) upto and including class 800 above class 800
Gate Valve Globe Valve Gate Valve Globe Valve
<2 2,000 5,000 2,000 2,000
2-1/2 ~ 4 2,000 5,000 1,000 2,000
>4 1,000 2,000 1,000 1,000
  • Cycle Life Test is performed with the valve under the pressurised conditions.

  • Non-Rotating stem prevents torsion of bellows.

  • Two Secondary Stem Seals :

Stem backseat and stem packing ensure perfect sealing
when a bellow is damaged.
  • Long Life Seating Surface :

Hard faced with Stellite grade 6 for both seat and wedge/disc to
prevent seizing and galling.
  • End Flanged Dimension : ASME B16.5

  • Butt Weld End Dimension : ASME B16.25

Face to Face & End to End : ASME B16.10
  • Helium Leak Test is performed for each bellow assembly using a Helium detector with        sensitivity of 10-9 Std cc/sec.

  • Bellow Material : SS321, SS316Ti, Inconel 625, Hastelloy C276, etc.

  • Multi-Ply Bellows : Minimum 2 ply bellows

  • Soft Seat Insert on Globe Disc :

soft seat also available for Gas or Vacuum Service.