As a critical device in industrial measurement, the accuracy of a stainless steel pressure gauge's pointer returning to zero directly impacts the reliability of process parameters and the safety of equipment operation. However, in practical use, the phenomenon of the pointer failing to return to zero frequently occurs, potentially caused by multiple factors including production, transportation, installation, operation, and environmental conditions. This article will conduct an in-depth analysis of the causes behind the failure of stainless steel pressure gauges to return to zero from multiple dimensions and propose corresponding solutions.

I. Manufacturing Defects

1. Assembly Process Oversights

The assembly of stainless steel pressure gauges involves multiple precision components, such as upper and lower movement housings, dials, movements, and connectors. If screws are not fully tightened, they may loosen during logistics transport or on-site vibrations. This can cause rod displacement, dial misalignment, or movement shifting, ultimately leading to pointer failure to return to zero.

For instance, a pressure gauge used by a chemical plant exhibited pointer deviation after transportation. Disassembly revealed loosened screws connecting the movement to the case.

2. Calibration Process Errors

During calibration, if the pointer-securing rivets are not fully tightened, transportation jolts may cause pointer loosening. Additionally, improper initial torque setting of the hairspring affects zero-return accuracy.

Experiments indicate that a 10% reduction in hairspring torque increases pointer return error by 0.5% FS.

3. Welding Quality Defects

Porosity or incomplete fusion at the weld joint between the bourdon tube and copper seat can develop fatigue cracks under pressure cycling, leading to medium leakage and disruption of the zero-return force balance.

II. Environmental Impacts

1. Excessive Mechanical Vibration

When on-site vibration frequency approaches the pressure gauge's natural frequency, resonance occurs, amplifying vibration amplitude.

For instance, a pressure gauge at a wind farm exhibited pointer sticking during turbine operation due to resonance. Spectral analysis revealed the primary vibration frequency closely matched the gauge's natural frequency.

2. Medium Properties Impact

Corrosive media (e.g., chloride ions, hydrogen sulfide) can damage the passivation film on the bourdon tube surface, triggering pitting corrosion. Medium crystallization may clog the bourdon tube or transmission mechanism.

At a soda ash plant, a pressure gauge pointer jammed during winter due to medium crystallization, but function was restored after thermal cleaning.

3. Extreme Temperature Variations

Stainless steel pressure gauges typically operate within -40°C to 70°C. Deviations from this range require accounting for temperature-induced errors.

For instance, at -20°C, changes in the bourdon tube's elastic modulus may cause pointer deflection.

III. Improper Operation and Maintenance

1. Overrange Use

When pressure exceeds 150% of the scale range, the bourdon tube may sustain permanent deformation.

A pressure testing machine used a 10MPa-range pressure gauge under 20MPa pressure, causing a 30% increase in the free-end displacement of the bourdon tube and preventing the pointer from returning to zero.

2. Lack of Maintenance

After prolonged use, reduced hairspring elastic modulus, gear wear, or transmission mechanism jamming can all affect zero-return accuracy.

After five years of operation at a power plant, a pressure gauge exhibited a 40% decay in hairspring torque, resulting in pointer return error reaching 1.5% FS.

3. Improper Installation

Non-vertical mounting or loose fixation of pressure gauges in vibrating environments can cause movement of the movement.

For example, a marine pressure gauge without vibration damping devices exhibited excessive pointer oscillation during navigation.

IV. Solutions and Technical Improvements

1. Production Quality Control

• Laser welding technology reduces welding defect rates.

• Online torque monitoring ensures screw tightening torque meets standards.

2. Operating Environment Optimization

• Employ oil-filled pressure gauges in high-vibration settings, where silicone oil damping absorbs over 60% of vibration energy.

• Use pre-filters for corrosive media to extend bourdon tube lifespan.

3. Operational Standardization

• Establish a range redundancy system requiring actual working pressure not to exceed 2/3 of the gauge range.

• Implement regular calibration schedules, typically every 6 months for general industrial applications.

4. Technical Upgrade Directions

• Develop constant-modulus alloy bourdon tubes with elastic modulus variation <0.5% within the -40°C to 150°C temperature range.

• Create smart pressure gauges integrating pressure sensors and microprocessors for real-time pointer position monitoring and automatic alarms.