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 and 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 newly assembled systems and component maintenance scenarios, the purpose of testing remains the same: safety of operation and maximal 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 pipe testing is conducted using air as the test media to ascertain the structural integrity of a pipeline or other industrial containment or transport vessels. Pneumatic testing can be done using air, nitrogen, or other inert, non-toxic gases. Pneumatic testing requires the incorporation of pressure monitoring and release devices to allow for maximum operator safety.

What Is Pneumatic Testing?

Pneumatic testing is the process of using a gas to determine if a vessel can safely withstand the pressures required under normal usage. To do this, a gas is inserted and the pressure is increased above the normal pressure the vessel is designed to withstand once put in service. The pneumatic testing will help to identify any leaks, faulty joints, or other operational issues.

Pneumatic Pipe Testing Procedure

As earlier mentioned, pneumatic pipeline/vessel testing is conducted at a pressure that exceeds the maximum value specified by the manufacturer by at least 10%. The test procedure involves shutting off all equipment valves except the delivery port for the test medium.

The test gas is used to gradually build the pressure within the pipeline until the required test value is met. This pressure is maintained while the system is analyzed for defects. Breaches can then be identified using a bubble-forming substance applied to the exterior of the component being tested.

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

Different requirements may apply but the most common pneumatic test procedure for piping is the ASME B31 Pressure Piping Code. Within that, ASME B31.1 is generally applied to power piping and ASME B31.3 is used for process piping. Refrigeration piping testing procedures are based on ASME B31.5.

Under ASME Section B31.1 pneumatic power piping testing is performed at a minimum of 1.2 times the design pressure, but less than 1.5 times. To reach that pressure, the test starts by increasing the pipeline’s pressure to .5 of design pressure. Then a preliminary inspection is performed to check for leaks. If no leaks are found, pressure is increased in the pipe in increments of .1 of design pressure until the target test pressure is reached. At that point, the pressure will be maintained for at least 10 minutes. The pressure is then reduced to design pressure or 700 kPa, whichever is lower. That pressure is maintained while the pipe is again checked for leaks.

Process piping pneumatic testing is done under ASME B31.3. The pipe is brought up to .5 of the design pressure or 170 kPa, whichever is less. At that point, all joints and seals are checked for leaks. Pressure is gradually increased holding at each increment long enough to equalize the piping strains. The pipe is eventually brought up to between 1.1 and 1.33 times the design pressure. Pressure is then reduced until it is to equal the design pressure. The pressure is held at that level for a minimum of 10 minutes during which the pipe will be checked for leaks.

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.

ASME hydrostatic test pressure B31 Hydrostatic Pressure Testing

Hydrostatic Pressure Testing for Pipes and 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 and 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!