1. Trim Design: Materials
Standard Materials
Body/Bonnet
Carbon Steel casting
ASTM A352-LCC (ANSI)
ASTM A216-WCB (ANSI)
A487-1C (API)
Stainless steel
ASTM A351-CF8M
Duplex
Super duplex
Carbon steel with Inconel cladded overlay
Internal parts
Turning fork; casting
Protecting bush
Front disc and bean carrier
Stainless steel
Duplex
Super duplex
Inconel
VONK CHOKES

2. Trim Design General features VONK CHOKES
Seat never in contact with medium
Seat-tightness to ANSI Class V or VI
Minimises cavitation problems
Exhibits low noise
Excellent control
Guaranteed fixed Cv value
Repairable internals
Vibration resistance
Easy maintenance design
Rotating Disc Principle
VONK CHOKES

3. Erosion The Erosion Triangle VONK CHOKES
Sand
Small Valve opening
Pressure drop
Prevent erosion by eliminating one of below conditions:
Sand production
Pressure drop
Small valve opening
VONK CHOKES

4. Erosion How to prevent bean erosion VONK CHOKES 100% open; ideal
Bigger opening results in smaller impact angles
100% open; ideal
10% open: alert!
40% open
VONK CHOKES

5. Small impingement angle
Erosion
How to prevent bean erosion
Operate in green zone
Small impingement angle
No Erosion!
Operate in Green Zone:
Small impingement angle on the Tungsten Carbide liner
Erosion decreases significant with impingement angle < 45 degrees
At 30 degrees the erosion is almost 0.
Operate in green zone!
Select orifice size based on process conditions!
VONK CHOKES

6. Erosion How to prevent bean erosion VONK CHOKES orifice back disc
Design principle of DV trim: Minimize impingement angle at small valve opening
orifice back disc
DV orifice front disc
At small valve opening:
Parallel flow entrance with the Tungsten Carbide liner
VONK CHOKES

7. Developments: DV trim Flow out Flow in VONK CHOKES
Simulation of flow path and erosion for 21 MM DV
10%Opening
20%Opening
40%Opening
60%Opening
80%Opening
100%Opening
Flow out
Area of interest
DV Trim
Bean
Flow in
Bean inner diameter
VONK CHOKES