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Hydrostatic Pressure Testing

Enerquip shell and tube heat exchanger getting hydrostatic pressure tested before shipment.

Pressure testing heat exchangers is a critical process to ensure their safety, reliability, and functionality. Strict adherence to procedures is essential to avoid damage to equipment or harm to personnel. While new heat exchangers are pressure tested before shipment, there may be times you need to re-pressure test older units in the field.

Here, we outline best practices and safety guidelines for conducting pressure tests on heat exchangers.

What is Hydrostatic Pressure Testing?

Hydrostatic testing is a vital process for verifying the safety and integrity of pressure vessels. Adhering to ASME Section VIII Division 1, UG-99 standards ensures compliance with the highest industry benchmarks. This testing method verifies that vessels can withstand operational pressures by safely filling them with water and applying pressure to identify leaks, weaknesses, or potential safety hazards.

General Guidelines for Pressure Testing

Do Not Exceed Operating Pressures: Always test within the specified operating pressures for the unit. Testing above these pressures can lead to equipment damage or catastrophic failure.

Special Considerations for Steam on Shell Side: If testing with steam to check for tube leaks, expect steam to exit until the tube side is fully dried. This process must be closely supervised to prevent burns or injuries. Avoid using steam on fixed tube sheet straight tube units, as the heat can cause excessive thermal expansion, resulting in permanent damage.

Testing One Side at a Time: Empty one side of the heat exchanger and pressurize the other. Monitor for pressure drops, as leaks in testing equipment (connections and valves) can lead to false results.

Required Materials & Equipment

Before starting a hydrostatic test, you’ll need the following materials and equipment:

  • Fittings, Blind Flanges, Plugs, & Valves: Ensure these are rated for the required test pressure.
  • Dial Indicating Pressure Gauges: Choose gauges with a range between 1.5 and 4 times the required test pressure, calibrated per the manufacturer’s quality control manual.
  • Digital Reading Pressure Gauges: Use these for greater accuracy and a broader pressure range.

Step-by-Step Guide to Hydrostatic Testing

Now that you’ve gathered all the necessary supplies, the following steps will guide you through the process of hydrostatic pressure testing.

  1. Complete Final Weld NDT Tests: Before starting, confirm that all weld non-destructive testing (NDT) is complete. This ensures there are no underlying issues that could compromise the test.
  2. Purge Air Pockets: Install vents at all high points of the vessel to eliminate trapped air during filling. Air pockets can distort pressure readings and compromise test results.
  3. Inspect Equipment: Double-check that all hydro equipment, fittings, blind flanges, and plugs are securely tightened before you start applying pressure. A loose connection can lead to test failure or safety hazards.
  4. Apply Test Pressure: Refer to the applicable vessel drawing to determine the correct test pressure. Be cautious not to exceed 10% above the calculated pressure, as this could damage the vessel or invalidate the test.
  5. Monitor Temperature Requirements: Use water with a temperature of at least 60°F. Ensure the vessel and water temperatures are similar before applying pressure. Keep the metal temperature at least 30°F above the vessel’s minimum design metal temperature. Wait until the vessel cools to below 120°F before conducting any inspections.
  6. Install Calibrated Gauges: Attach a calibrated gauge directly to the vessel. Place a second calibrated gauge near the hydro pump for clear visibility during the test.
  7. Test Multi-Chamber Vessels Separately: For vessels with independent pressure chambers, test each chamber individually, ensuring no pressure is applied to adjacent chambers during the process.
  8. Never Leave the Vessel Unattended: Once the vessel is under test pressure, it must be supervised at all times to ensure immediate response to any issues.
  9. Inspect for Leaks: Conduct a visual inspection of all joints and connections while the vessel is at least two-thirds of the test pressure. Look for visible wetness or drips to identify leaks. Any leaks must be resolved before completing the test.
  10. Drain and Dry the Vessel: After a successful test, fully drain and dry the vessel to prevent corrosion or contamination.

Safety First

Hydrostatic testing carries inherent risks, so it’s crucial to follow safety protocols:

  • Test pressure vessels according to their engineering drawings and design specifications.
  • Equip personnel with the proper protective gear.
  • Ensure all team members are trained in hydrostatic testing procedures.

Confidence in Compliance

By following these steps, you can confidently conduct hydrostatic testing on heat exchangers and other pressure vessels. This not only guarantees compliance with safety standards but also ensures your equipment is ready to perform under pressure—literally and figuratively.

Partner with Enerquip for Reliable, High-Performance Heat Exchangers

At Enerquip, we understand the importance of maintaining safe and efficient operations. Our equipment is designed to meet the highest standards, giving you peace of mind in every operation.

If you’re ready to optimize your system or explore new heat exchanger options, contact our knowledgeable team. We’re committed to ensuring your process equipment operates at peak performance.

Contact Us or Request a Quote to learn more!

 

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