Special Working Conditions 1

Solution for Flash Evaporation Conditions

Solution for Flash Evaporation Conditions

  • Energy Conservation Law

The Formation of Flash Evaporation Conditions

Saturated vapor pressure Pv is closely related to temperature

  • P > Pv liquid phase
  • P < Pv gas phase

The occurrence of flash evaporation is determined by the process and is inevitable!

Flash Mechanical Abrasion

Mechanical

  • Contains droplets
  • Angle of impact

Corrosion/Abrasion

  • Formation of metal oxides

Typical Appearance of Flash Damage

Factors affecting the degree of valve damage under flash evaporation conditions

  • The size of the pressure drop before and after the valve
  • Flash severity (% of bubbles)
  • Traffic size
  • Valve size
  • The corrosiveness of the medium
  • Valve material selection
  • Valve structure

Reduce Damage to Valves Caused By Flash Evaporation Conditions - Plan 1

  • Adopt Venturi angle valve
  • The outlet is enlarged and the valve outlet flow rate is reduced
  • The valve is lined with carbide to reduce damage caused by flash evaporation

Reduce Damage to Valves Caused by Flash Evaporation Conditions - Plan 2

  • The valve adopts flow-close type, and the internal parts adopt C-I internal parts;
  • Accurately calculate the valve outlet flow rate and reasonably select the valve diameter. The valve size cannot be judged only by the valve opening. The valve size must ensure the safety of the valve outlet flow rate;
  • Allow air bubbles to be consumed inside the valve trim as much as possible;

Reduce Damage to Valves Caused by Flash Evaporation Conditions - Plan 3

  • Increase the hardness of the valve material to delay the damage caused by flash evaporation!

Severe Working Conditions 2

Solution for Cavitation Conditions

The Formation of Cavitation Conditions

Saturated vapor pressure Pv is closely related to temperature

  • P > Pv liquid phase
  • P < Pv gas phase

Valve recovery coefficient FL

Markco determined through experiments:

  • Hi FL = low recovery
  • 4 Ball Valve FL= 0.82
  • Low FL = high recovery
  • 4 Butterfly Valve FL = 0.69


High recovery (low recovery coefficient)

Valves are more prone to cavitation

The Formation of Cavitation Conditions

  • Pvc is lower than Pv
  • form bubbles
  • P2 is higher than Pv bubble collapse
  • (1) Impact
  • (2)Gradual rupture
  • (3) High-speed jet is formed during rupture

Typical Appearance of Cavitation Damage 1

Typical Appearance of Cavitation Damage 2

How to Avoid the Occurrence of Cavitation Conditions

Choose a valve structure with high recovery coefficient FL

Through strict calculation, increase the reasonable number of step-down stages

Reasonable selection of valve materials

Markco's unique multi-stage hole design

Multi-Stage Voltage Reduction

Unique Hole Design

Unique Anti-Cavitation Internal Parts Design - Option 1

C-III Single-Stage Cavitation Hole

  • Anti-cavitation effect
  • The larger jet fluid is decomposed into many small jets, thereby decomposing the concentrated single total energy into many small energy units.
  • Control the pressure drop flowing through the valve to not be lower than the vaporization pressure of the fluid medium so that bubbles cannot be generated to avoid cavitation.
  • Part of the energy is attenuated when the fluid flows through the cavitation hole, and the noise caused by cavitation is reduced.

Unique Anti-Cavitation Internal Parts Design - Option 2

C-III Two-Stage Cavitation Hole

C-III Three-Stage Cavitation Hole

Unique Anti-Cavitation Internal Parts Design - Option 3

  • For use with pressure drops of 3,000 - 4,000 psi (211 to 281 kg/cm²)
  • Pressure drop distribution - first and second stage 37%, third stage 16%, fourth stage 10%
  • Smallest hole = .05 (1.27 mm)

C-III Four-Stage Cavitation Hole

Unique Anti-Cavitation Internal Parts Design - Option 3

  • Used to eliminate cavitation
  • Can withstand 6000psid pressure drop (420 kg/cm²)
  • Protective seat design
  • Straight or angle valve for sizes 2-6
  • Minimum aperture = .071(1.8mm)
  • Pressure drop distribution: 38.5% 1st, 37.5% 2nd,
  • 15% 3rd, 9% 4th

C-IV Cavitation Plug

Severe Working Conditions 3

High Pressure Drop of Liquid + Tiny Flow Rate

Hazards caused by liquid high pressure drop and small flow rate

Disadvantages:

  • Small CV value, thin valve core
  • The high pressure drop of liquid produces cavitation (cavitation, flash evaporation, cavitation + flash evaporation)
  • The valve core is easy to break under high pressure drop
  • Internal parts are seriously damaged by cavitation
  • Valve life is short

Small Flow Rate + High Pressure Drop Resistance Internal Design - Option 1

  • For use with 1 and 2 valves
  • Minimum Cv = .04

Small Flow Rate + High Pressure Drop Resistance Internal Design - Option 2

  • Multi-stage pressure drop design
  • Level 7 can withstand 5500 PSI (387Kg/cm2)
  • Minimum controllable Cv = 0.01
  • For straight-way valves and angle valves

C-III/M Plug

C-VII Plug

Severe Working Conditions 4

Dirty Liquid + High Pressure Difference

Dirty Liquid + High Pressure Differential Internal Parts Design

Plan 1

  • Trim to overcome dirty liquid + high pressure differential working conditions D-I Trim is a multi-stage patented structure.
  • Control valve trim with anti-cavitation function.
  • Used in fluid applications that contain many particles. In this case, the flow channels of traditional anti-cavitation trims will be clogged or eroded.
  • D-I Trim is commonly used in high-pressure drop applications in the chemical, refining, oil and gas production, and energy industries.
  • The maximum pressure drop can reach 2600psid (183Kg/cm2).
  • Control cavitation - Level 3, 4 or 6 available, effectively eliminating cavitation and related damage and noise.
  • Good adaptability - can be used for straight-way valves and angle valves.
  • Longer service life of internal parts - this patented internal part uses a combined axial and radial flow channel to make the flow channel larger and wider.
  • ·Convenient maintenance--the internal parts can be removed online, and the parts can be inspected without removing the valve from the pipeline. D-I Trim can allow particles with a diameter of 1/4~3/8 to pass through without causing clogging.
  • Trim Materials - Typical trim materials include 17-4PH SST cage, 416 or 440CSST valve core, or 316/ENC cage with 316/Alloy 6 valve core. Other materials can also be selected according to working conditions.
  • Sealing--D-I Trim adopts a valve seat protection design to separate the sealing function of the valve from the throttling area of the internal parts.

D-I Plug

Dirty Liquid + High Pressure Differential Internal Parts Design

Plan 2

  • Trim to overcome dirty liquid + high pressure differential working conditions D-III Trim is a multi-stage patented structure;
  • Control valve trim with anti-cavitation function;
  • Used in fluid applications that contain many particles. In this case, the flow channels of traditional anti-cavitation trims will be clogged or eroded;
  • D-III Trim is commonly used in high-pressure drop applications in the chemical, refining, oil and gas production, and energy industries;
  • The maximum pressure drop can reach 4000psid (281Kg/cm2).
  • Control cavitation - Level 2, 3, 4 or 6 available, effectively eliminating cavitation and associated damage and noise;
  • Good adaptability - can be used for straight-way valves and angle valves;
  • Longer service life of internal parts - this patented internal part uses a combined axial and radial flow channel to make the flow channel larger and wider;
  • ·Convenient maintenance--the internal parts can be removed online, and the parts can be inspected without removing the valve from the pipeline. D-III Trim can allow particles with a diameter of 1/4~3/8 to pass through without causing clogging.
  • Trim Materials - Typical trim materials include 17-4PH SST cage, 416 or 440CSST valve core, or 316/ENC cage with 316/Alloy 6 valve core. Other materials can also be selected according to working conditions.
  • Sealing--D-III Trim adopts a valve seat protection design to separate the sealing function of the valve from the throttling area of the internal parts.

D-III Plug

Severe Working Conditions 5

High Noise

Noise Type

Typical noise-emissions of gas, steam and liquids



  • Mechanical Noise
  • Hydrodynamic Noise
  • Gas Dynamic Noise

dBA Level

Noise Example dBA


Empty Room 40

Office Room 65

Busy Street 85

Spray Injector 125

Why consider noise?

  • People
  • Equipment

Noise Source Processing Methods

  • Use porous methods to reduce the energy converted into sound energy and change the noise frequency.

How is the noise generated by the valve distributed?

  • Noise reduction through valves is the key to solving noise.

Noise Reduction Internal Parts Design - Plan 1

W-I Cage

Noise Reduction Internal Parts Design - Plan 2

W-III Cage

Noise Reduction Internal Parts Design - Plan 3

W-III/D Cage

Aperture and Noise Reduction Level

Noise Reduction Internal Parts Design - Plan 4

Add noise reduction plates and pipe silencers to the valve outlet

Noise Reduction Internal Parts Design - Plan 5

Markco M-Trim

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