parts

Control and safety devices in pressure vessels

November 8, 2025
admin

Pressure vessels are     essential equipment in the oil and gas, petrochemical, energy, pharmaceutical, and food industries. They are used for storing and transporting pressurized liquids, and even minor errors in their design or operation can lead to leaks, explosions, or serious damage.

To ensure the safety and proper operation of these tanks,  control and safety devices are required      . These include pressure gauges and temperature sensors, safety valves, alarm systems, and other control equipment. This article describes the different types of control and safety devices, their applications, advantages, and design features.

The importance of control and safety devices

Control and safety devices play a crucial role in pressure vessels:

  1. Pressure and temperature control:     Prevents situations that could lead to excessive pressure or excessive temperature in the storage tank.

  2. Explosion protection measures:     Safety valves and alarm systems can prevent explosions.

  3. Extending tank lifespan:     By controlling operating conditions, stress and corrosion can be reduced.

  4. Ensuring optimal process performance:     Maintaining liquid levels, pressure and temperature within acceptable limits at all times.

  5. Compliance with standards and safety regulations: International standards such as     ASME Section 8   prescribe the use of these tools.

Types of control and safety devices

1. Pressure gauge

  • Application:     Measures the internal pressure in the tank and displays it to the operator.

  • Types:     analog (Bourdon tube) sensors, digital sensors and pressure sensors.

  • Advantages:

    • Real-time pressure monitoring function

    • Quickly detect unauthorized pressure increases or decreases.

  • Design tips:

    • Determine the appropriate design pressure range for the storage tank.

    • The installation location must be easily accessible and clearly visible.

2. Safety valve

  • Application:     Protection of storage tanks from overpressure by opening the liquid outlet.

  • Man:

    • Spring type:     the most common type, simple mechanical action.

    • Experienced operator:     Suitable for high-voltage and precision applications.

  • Advantages:

    • Prevention of explosions or bursting of tanks

    • It can function automatically, without driver intervention.

  • Design tips:

    • Set the opening pressure according to the design pressure in the tank.

    • The output power is proportional to the size and type of liquid.

3. Thermocouple housing and thermometer

  • Application:     Measuring the temperature of liquids in a tank without direct contact with the liquid.

  • Advantages:

    • Protection of measuring instruments from pressure and corrosion.

    • Ability to replace the thermometer without emptying the water tank.

  • Types:   Thermocouple     temperature measuring devices, resistance thermometers (RTDs) and analog or digital thermometers.

4. Fill level indicator

  • Application:     Indicates the liquid level in the water tank to prevent overflowing or emptying.

  • Man:

    • Rearview mirrors:     simple and clear

    • Buoyancy type:     Works on the basis of buoyancy movement.

    • Ultrasound or radar:     No direct contact with liquids is required.

  • Advantages:

    • Careful monitoring of the  liquid level

    • Reduced risk of flooding and damage to peripheral equipment

5. Pressure/temperature sensors

  • Application:     Transmission of pressure and temperature data to the central control system.

  • Advantages:

    • Remote monitoring function

    • Connection to a PLC or SCADA system for automatic process control.

6. Warning

  • Application:     To warn the operator when changes   in pressure   , temperature, or liquid level exceed the permissible range.

  • Type:     Audio, fiber optic or hybrid

  • Advantages:

7. Additional safety valve and control panel

  • In large storage tanks, an additional pressure relief valve is usually used alongside the main pressure relief valve     .

  • The control panel includes a display, an alarm system, and an   emergency    stop system.

  • This equipment enables     automated and precise process control     .

Important points to consider when selecting and installing control and safety devices

  1. Standards compliance:     The selected devices must comply with the  ASME, API, IEC or EN standards  .

  2. Determine the appropriate range:     Pressure and temperature must be within the operating range of the storage tank.

  3. Installation location:     Pressure gauges and safety valves should be installed in the most sensitive and easily accessible locations.

  4. Corrosion protection and environmental protection:     The use of coatings and linings for thermal equipment is essential to protect the instruments.

  5. Regular checks and calibration:     The device should be checked regularly to ensure its accuracy and proper functioning.

Practical examples

Let’s assume a wastewater treatment plant has a 50 cubic meter tank with a design pressure of 2.5 MPa. The following equipment is installed to ensure the safety and control of the tank:

  • Analog and digital pressure gauges     for real-time pressure monitoring

  • Spring-loaded safety valve     with a pressure adjustment range of 2.5 MPa.

  • Thermometers and resistance measuring devices    are used to measure the temperature of liquids.

  •   A level indicator is used to display the liquid level   .

  • Audio and    video alarm system in     the control room

By installing these devices, operators can continuously monitor pressure, temperature and fluid levels and take immediate action in case of emergency.

Advantages and importance of surveillance and security devices

Tool To use Meaning
manometer Real-time pressure monitoring Avoid excessive stress
Safety valve Explosion-proof Ensuring the safety of storage tanks and the working environment
Thermal cover and thermometer Accurate temperature measurement Avoid damaging the fuel tank and liquid tank.
Level indicator Fluid level control Reduction of the risk of flooding and the danger of a complete evacuation
Pressure and temperature sensors Remote monitoring Automatic process control
early warning system Urgent Notice Accident prevention

In conclusion

Control and safety devices play a crucial role in the operation of high-pressure vessels. The proper use of pressure gauges, safety valves, thermocouples, level indicators, and alarm systems ensures personnel safety, extends the vessel’s service life, and guarantees optimal performance.

For proper construction and function:

  • The team selection must meet international standards.

  • Installation and calibration must be performed regularly.

  • The choice of installation location and tool type should be based on the   operating conditions     of the tank.

Adherence to these principles reduces the risks associated with overpressure, high temperatures or changes in liquid level, and ensures the safe and reliable operation of pressure vessels.