Many industrial components undergo stringent pressure testing to determine their structural integrity before use. Conduits such as pipelines and storage vessels undergo various pressure-mediated checks to ensure they meet all relevant industrial safety standards. Depending on manufacturer or operator preferences, pressure testing can be done either hydrostatically or pneumatically.

Contact NiGen today if you’re in the market for pressure testing services from a reputable and experienced company!

Pressure Testing for Pipelines & Pressure Vessels

The purpose of pneumatic and hydrostatic testing is to ensure a pipeline or vessel is free from leaks and can withstand the pressure of normal usage. Before being put into service or returned to service after repairs, many different types of industrial equipment and facilities require this testing. In many situations, government regulations clearly specify what testing is required. In addition, many companies have their own additional internal testing guidelines and policies.

The most commonly used set of specifications for pressure and leak testing is the ASME B31 Pressure Pipeline Code. This code details testing steps and requirements for different types of piping. Hydrostatic testing is performed with a liquid like water, and pneumatic tests use a gas like nitrogen.

When Should You Perform a Pressure Test?

Pressure testing is a vital part of the completion process for industrial equipment and systems. These checks ensure the inspected components function properly under operational conditions without posing an industrial safety hazard to the personnel who operate them.

There are various points in the operational lifespan of industrial systems where pressure testing is mandatory. Newly fabricated pipelines, containment vessels, and fittings must be subjected to a suitable pressure testing method. Further, pressure testing is indicated following equipment maintenance, component replacement, or repair. In both scenarios, the goal remains the same: safety of operation and maximum efficiency.

NiGen Pressure Testing Services

No matter your application or industry, our pressure testing company has the knowledge and expertise required to protect the integrity of your processes. We offer two methods for pressure tests: hydrostatic and pneumatic.

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Pneumatic Testing in Houston, Texas

Pneumatic testing uses a gas (typically air, nitrogen, or other inert, non-toxic gases) to assess the structural integrity of a pipeline or vessel. This type of testing requires pressure monitoring and relief devices for maximum operator safety.

What is Pneumatic Testing?

Pneumatic testing involves inserting a gas into the pipeline or vessel and increasing the pressure above the operational level to identify leaks, faulty joints, or other structural issues. This method is especially useful in situations where introducing moisture would be harmful.

Pneumatic Pipe Testing Procedure

Pneumatic testing is typically conducted at pressures at least 10% higher than the maximum specified by the manufacturer. The system is gradually pressurized and held at the test value while inspected for defects using bubble-forming substances. All valves are shut off except the delivery port during this process.

Pneumatic Test Procedure for Pressure Vessels

Pressure vessels are any containers designed to hold materials at a different pressure than the ambient pressure outside of the vessel. Vessels that are designed to hold or transport liquids or gases under pressure require testing to ensure that they are free from leaks and can operate safely.

Pneumatic testing safety is of key importance so there are several steps required to perform a pneumatic leak test. Pressure vessel testing procedures require that all joints that have not previously been pressure tested be exposed so they can be examined during the test to make sure they are free from leaks. Adjacent equipment, vessels, or pipelines that are not being tested need to be isolated or disconnected before the test.

Pressure Vessel Testing Standards

Pneumatic leak tests need to be performed using a non-flammable gas. Air can be used but it is less desirable since that mixture of gases will include water molecules. This is an undesirable contaminant as moisture can accelerate corrosion. That is why dry nitrogen is the preferred gas to use in pneumatic pressure testing.

Pneumatic Test Procedure for Pipelines

Pipelines are generally tested at 110% of the designed pressure for the pipeline. If desired, a preliminary pneumatic test at a lower pressure can be performed to check for any major leaks before the higher-pressure test. To facilitate pneumatic tests with nitrogen, on-site nitrogen generators can be conveniently located onsite. These generators are suitable for use anywhere–even remote locations.

Like with pressure vessels, all pipeline joints that have not previously been pressure tested must be exposed and checked for leaks during the test. Expansion joints can be temporarily isolated or equipped with temporary restraints prior to testing. The testing pressure must be maintained for at least 10 minutes. During that time, each joint and seam must be checked for leaks.

Pipe Pressure Testing Standards (ASME B31 Codes)

Different requirements may apply, but the most common pneumatic test procedure for piping follows the ASME B31 Pressure Piping Code:

  • ASME B31.1 (Power Piping): Test at 1.2–1.5× design pressure. Begin at 0.5× pressure, inspect for leaks, then increase in 0.1 increments. Hold at target pressure for 10 minutes.
  • ASME B31.3 (Process Piping): Start at 0.5× design pressure or 170 kPa. Gradually increase to 1.1–1.33× design pressure. Hold at design pressure for 10 minutes.
  • ASME B31.5 (Refrigeration Piping): Covers systems handling temperatures as low as -320°F (-196°C).

Hydrostatic Testing in Houston, Texas

Hydrotesting is another pressure testing option where a liquid (usually water) is injected into a pipe system to check for structural flaws permitting leakage. Hydrostatic testing allows the detection of leaks that only become obvious at elevated operating pressures.

What Is Hydrostatic Pressure Testing?

In hydrostatic pressure testing a liquid is used to check for leaks before putting a pressure vessel or pipeline into service. The liquid is pressurized within the pipeline or vessel to make sure that it can withstand the pressures of normal usage.

Hydrostatic Pressure Test Procedure

In hydrostatic pressure testing, a liquid is used to check for leaks before putting a pressure vessel or pipeline into service. The liquid is pressurized within the pipeline or vessel to make sure that it can withstand the pressures of normal usage.

In order to test, the pipe or pressure vessel must be filled with a liquid. The liquid used is typically water unless water will damage the pipe or vessel. To meet ASME hydrostatic test requirements, before the test begins, the high points of the pipe or vessel must have vents to allow any air to escape as water is added. All air must be cleared before the test can be completed.

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Hydrostatic Pressure Testing for Pipes & Pressure Vessels

For testing, the pressure vessel or pipeline must be filled with a liquid. The liquid is typically water unless it will damage the container. To meet ASME hydrostatic test requirements, before the test begins, the high points of the pipe or vessel must have vents to allow any air to escape as water is added. All air must be cleared before the test can be completed.

ASME B31.1 Hydrostatic Test

Power piping is normally tested under the procedures outlined in ASME Section B31.1. For hydrostatic testing, the ASME hydrostatic test pressure is 1.5 times the design pressure.

ASME B31.3 Hydrostatic Test

Process piping is tested under ASME Section B31.3. The ASME b31.3 hydrotest is performed at 1.5 times the design pressure.

ASME B31.5 Hydrostatic Test

ASME B31.5 hydrostatic testing code covers refrigerant, secondary coolant piping, and heat transfer components. These hydrostatic pressure testing standards apply to piping that can be used for temperatures as low as -320°F (-196°C).

Which Pressure Test Method is Right for You?

While both hydrostatic and pressure testing methods can be used to objectively assess equipment integrity, operators must choose the test best suited to their unique systems. For high-pressure operations that are not moisture sensitive, hydrostatic pressure testing is recommended. For low-pressure applications where moisture might damage sensitive components or alter delicate chemical balances, pneumatic testing is the smarter choice.

Learn more about the difference between hydrostatic and pneumatic testing.

There are fundamental differences between a hydrostatic and a pneumatic test for piping systems, and the most obvious difference is the test fluid utilized. While hydrostatic testing utilizes water as its test medium, pneumatic testing is conducted by channeling air through selected components/equipment.

Other variations in the two testing methods include:

  • The pressure level set for hydrostatic testing is typically at least 30% higher than the maximum operational value. Pneumatic test pressure is usually 10% above the maximum value set by the component manufacturer.
  • Hydrostatic testing is more suited for high-pressure applications, while pneumatic testing is utilized more in low-pressure settings.
  • Lower rates of equipment failure are recorded with hydrostatic testing when compared to pneumatic alternatives.
  • Hydrostatic test media can be recycled or transferred to other sites after use, whereas the air used in pneumatic testing is typically not recyclable.
  • Pneumatic testing requires supervision by experienced personnel, while pneumatic testing can be conducted by semi-skilled staff members.
  • Pressure-relieving devices are mandatory in pneumatic testing but recommended in hydrostatic testing.
  • Hydrostatic testing requires a more extensive post-test clean-up (component drying/moisture elimination) when compared to pneumatic testing.

NiGen Offers Hydrostatic & Pneumatic Pressure Testing Services

At NiGen, we offer cutting-edge hydrostatic and pneumatic pressure testing solutions in Houston, Texas. Our team specializes in applications that leverage our on-site nitrogen generators for the pressure vessel and pipeline industry. We have provided services for thousands of miles of pipeline using the latest nitrogen membrane equipment available. We provide services for purging, pigging, inerting, drying/dehydrating, pneumatic testing, commissioning and decommissioning, chemical cleaning, and leak detection.

To learn more about how we can help meet your unique testing requirements, please contact us today!