These symptoms typically indicate a mismatch in fluid conditions, valve selection, or system configuration. If left unaddressed over prolonged operation, they can accelerate valve wear and pose safety risks.

 

Based on field experience, this article outlines the common causes of valve vibration and noise and provides practical guidance for troubleshooting.

 

1. Basic Manifestations of Valve Vibration and Noise

 

Valve vibration usually appears as noticeable oscillations of the valve body, stem, or connected piping.

Noise may present as humming, whistling, or banging sounds.

 

These phenomena often occur simultaneously and are primarily related to the following factors:

● Abnormal flow velocity or pressure differential

● Unstable internal forces within the valve

● Mismatch between actual operating conditions and valve design

 

2. Common Causes Analysis

 

1. Excessive Flow Velocity or Pressure Differential

When the fluid passes through the throttling section of a valve at high speed, strong turbulence and pressure fluctuations are likely to occur, causing periodic impact on internal components.

This issue is particularly pronounced when using standard globe valves or ball valves under regulating conditions.

 

Typical manifestations include:

● Noise increases as the valve opening decreases

● Vibration intensifies under high-pressure-drop conditions

 

2. Improper Valve Selection

Incorrect valve selection is a common root cause of vibration, such as:

● Using on/off valves for prolonged throttling

● Oversized valve operating at small openings for extended periods

● Insufficient pressure rating or structural rigidity of the valve

These conditions can cause unstable movement of the valve plug or ball, resulting in vibration and noise.

 

3. Loose or Worn Internal Components

After long-term operation, the following issues are commonly observed:

● Wear of valve plugs or discs

● Increased clearance between the stem and guiding parts

● Loosened fasteners

 

Non-design clearances amplify fluid impact, leading to persistent noise.

If vibration is accompanied by metallic knocking sounds, the condition of internal components should be checked as a priority.

 

4. Cavitation or Flashing

In liquid service, cavitation or flashing occurs when local pressure drops below the saturation vapor pressure.

Bubble collapse in high-pressure regions impacts internal components, often accompanied by noise and vibration.

 

Typical signs include:

● Sand- or gravel-like scraping sounds

● Rapid wear of internal components

● Significant pressure fluctuations

 

5. Insufficient Piping Support or System Resonance

Some vibrations are not directly caused by the valve.

When upstream or downstream piping lacks adequate support, or when the piping structure resonates near the fluid pulsation frequency, system resonance may occur, amplifying existing vibrations.

 

3. On-Site Troubleshooting Approach

 

It is recommended to follow the sequence below when troubleshooting:

● Verify whether the pressure, flow rate, and fluid are within the design limits

● Check if the valve type is suitable for the current operating conditions

● Inspect the installation orientation and piping support

● If necessary, disassemble and inspect internal valve components

 

Troubleshooting from the outside inwards generally improves efficiency.

 

4. Measures to Reduce Vibration and Noise Risks

 

● Control flow velocity and pressure differential appropriately during the design phase

● Use dedicated control valves or low-noise designs under regulating conditions

● Avoid prolonged operation at small valve openings

● Consider anti-cavitation designs for high-risk conditions

● Ensure sufficient rigidity of the piping system

Most issues are not caused by valve quality, but by system mismatch.

 

5. Common Questions (Q&A)

 

Q1: The valve is noisy but still operational. Should it be replaced immediately?

Not necessarily. If there is no leakage, short-term operation is acceptable, but the cause should be investigated promptly to prevent accelerated wear of internal components.

 

Q2: Will replacing the valve with a higher-rated one always solve vibration issues?

Not necessarily. If the operating conditions themselves are inappropriate, even a more expensive valve may experience the same problems.

 

Q3: Why do ball valves tend to make noise at small openings?

Ball valves are primarily designed for on/off service. Throttling at small openings can result in locally high flow velocity, causing turbulence and noise.

 

Q4: Does cavitation always produce noticeable noise?

Not necessarily. Early-stage cavitation may not generate obvious noise, but damage to internal components can already begin.