gopalsankar
Mechanical
- Nov 26, 2001
- 11
We had frequent failure of Visbreaker feed line control valve stem(Breaking into two pieces).Stem metallurgy is SS321.Feed sulphur percentage is about 4-4.5% Wt and temperature is around 425-450 deg.C. After repeated failure the designer has changed the metallurgy to Nitronic grade and even after changing the metallurgy the failure is continuing.We expect some amount of vibration in the line during run and valve details are as below:-
Valve size : 6"-300#(body 9Cr material)
Seat ring material : SS321 Stellited
Valve plug : -- do--
Steam material : -- do--
Stem size : 3/4"
Port size : 5"
Port : Single port
Inlet pressure : 7.6 kg/sq.cm
pressure drop : 5.7 kg/sq.cm
Shut-off press : 12.0 kg/sq.cm
Liquid flow rate : 81 m3/hr
Inlet velocity : 5.61 m/s
Outlet velocity : 11.6 m/s
Upstream area : 79 sq.inch
Downstream are : 79 sq.in
Sonic velocity : 233 m/s
Balance : Unbalanced
Medium handled : Soaker effluent(hydrocarbon liquid plus vapor)
VALVE TYPE ANGLE/GLOBE DOWNWARD FLOW.
Mounting : Vertical
Type of failure: Britlle fracture.
Any member had similar failure?Any other suitable material to withstand the minimum amount of chattering ?
Valve size : 6"-300#(body 9Cr material)
Seat ring material : SS321 Stellited
Valve plug : -- do--
Steam material : -- do--
Stem size : 3/4"
Port size : 5"
Port : Single port
Inlet pressure : 7.6 kg/sq.cm
pressure drop : 5.7 kg/sq.cm
Shut-off press : 12.0 kg/sq.cm
Liquid flow rate : 81 m3/hr
Inlet velocity : 5.61 m/s
Outlet velocity : 11.6 m/s
Upstream area : 79 sq.inch
Downstream are : 79 sq.in
Sonic velocity : 233 m/s
Balance : Unbalanced
Medium handled : Soaker effluent(hydrocarbon liquid plus vapor)
VALVE TYPE ANGLE/GLOBE DOWNWARD FLOW.
Mounting : Vertical
Type of failure: Britlle fracture.
Any member had similar failure?Any other suitable material to withstand the minimum amount of chattering ?