Trim Design: 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

VONK CHOKES

Internal parts

Turning fork; casting

Protecting bush

Front disc and bean carrier

• Stainless steel

• Duplex

• Super duplex

• Inconel

Standard Materials

Trim Design

• 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

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Rotating Disc Principle

General features

Erosion

VONK CHOKES

The Erosion TriangleSand

Small Valve openingPressure drop

Prevent erosion by eliminating one of below conditions:

- Sand production

- Pressure drop

- Small valve opening

Erosion

VONK CHOKES

How to prevent bean erosion

100% open; ideal 10% open: alert! 40% open

Bigger opening results in smaller impact angles

Erosion

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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!

Erosion

Design principle of DV trim: Minimize impingement angle at small valve opening

VONK CHOKES

How to prevent bean erosion

DV orifice front disc

orifice back disc

At small valve opening: Parallel flow entrance with the Tungsten Carbide liner

Developments: DV trim

VONK CHOKES

7

10%Opening 20%Opening 40%Opening 60%Opening 80%Opening 100%Opening

Flow in

Flow out

Area of interest

DV Trim Bean

Bean

inne

r dia

met

er

Simulation of flow path and erosion for 21 MM DV