Pneumatic Test
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The pneumatic strength test uses air, or an inert gas medium such as nitrogen, to pressurize the system to 110% of its designed pressure limit. A holding period is then applied for a fixed amount of time and the results monitored to determine the safety and integrity of the system.
In circumstances when hydrostatic testing is not possible, for instance, the weight of hydro test water is too high for the pipe support system (e.g. gas service piping) and when the introduction of water to the piping may be detrimental to the process (e.g. catalyst or reactor contamination, cryogenic service system), then the components or system can be tested with nitrogen. Since the test medium is gaseous, it has the ability to compress and contain a large amount of stored energy (typically 200 times greater than a hydrostatic test at the same free volume and pressure condition). Extreme caution is required when using this technique. However, the specialized team at Intero Integrity Services will ensure design specifications are reviewed and a detailed risk analysis completed before testing with a compressible medium.
Pressure tests are a non-destructive way to guarantee the integrity of equipment such as pressure vessels, pipelines, plumbing lines, gas cylinders, boilers and fuel tanks. It is required by the piping codes to confirm that a piping system is able to bear its rated pressure and it has no leaks. Pressure testing, also called hydrostatic testing, is carried out after the cooling or heating installation of any pipeline and before it is put into use.
By performing a pressure test we find a reliable method for testing all types of pipework, including the ones in district cooling or district heating systems. This type of analysis, besides guaranteeing the right functioning, will also allow us to detect if there are leaks in a specific pipe so that reparations can be made.
The most widely used code for pressure and leak test is the ASME B31 Pressure Piping Code. Among its several sections, the requirements and procedures listed in the codes below are followed by Araner:
Isolation of equipment and piping not subjected to pressure test: Equipment that is not to be subjected to the pressure test shall be either disconnected from the system or isolated by a blank or similar means.
The hydrostatic test pressure at any point in the piping system shall not be less than 1.5 times the design pressure, but shall not exceed the maximum allowable test pressure of any non-isolated component, nor shall it exceed the limits of calculated stresses due to occasional loads.
The test pressure shall be not less than 1.5 times the design pressure. When the design temperature is greater than the test temperature, the minimum pressure shall be calculated by eq. P T = 1,5P S T/S , where =allowable stress at test temperature, S=allowable stress at component design temperature, P=design gage pressure. The test pressure may be reduced to the maximum pressure that will not exceed the lower of the yield strength or 1.5 times the component ratings at test temperature. The pressure shall be continuously maintained for a minimum time of 10 minutes and may then be reduced to the design pressure and held for such time as may be necessary to conduct the examinations for leakage. Examinations for leakage shall be made of all joints and connections.
The pneumatic test pressure shall not be less than 1.2 nor more than 1.5 times the design pressure of the piping system. It shall not exceed the maximum allowable test pressure of any non-isolated component. The pressure in the system shall gradually be increased to not more than 1/2 of the test pressure, after which the pressure shall be increased in steps of approximately 1/10 of the test pressure until the required test pressure is reached. The pressure shall be continuously maintained for a minimum time of 10 min. It shall then be reduced to the lower of design pressure or 100 psig [700 kPa (gage)] and held for such time as may be necessary to conduct the examination for leakage. Examination for leakage by soap bubble or equivalent method shall be made of all joints and connections.
The test pressure shall not be less than 1.1 times the design pressure and shall not exceed the lower of 1.33 times the design pressure or the pressure that would produce a nominal pressure stress or longitudinal stress in excess of 90 % of the yield stress of any component at the test temperature. The pressure shall be increased until a gage pressure, which is the lower of 0.5 times the test pressure or 170 kPa (25 psi), at which time a preliminary check shall be made. Thereafter, the pressure shall be gradually increased in steps until the pressure is reached, holding the pressure at each step until the piping strains are equalized. The pressure shall then be reduced to the design pressure before examining for leakage. During the test, a pressure relief device shall be provided, having a set pressure not higher than the test pressure plus the lower of 345 kPa (50 psi) or 10% of the test pressure.
The test pressure shall be at least 1.1 and shall not exceed 1.3 times the design pressure of any component in the system. The pressure in the system shall be gradually increased to 0.5 times the test pressure, after which the pressure shall be increased in steps of approximately 1/10 of the test pressure until the required test pressure is reached. The test pressure shall be maintained for at least 10 minutes. It may then be reduced to the design pressure and conduct the examination for leakage. During the test, a pressure relief device shall be provided, having a set pressure above the test pressure, but low enough to prevent permanent deformation of any of the system components.
Pressure tests carried out according to the asme procedure allow us to guarantee the correct performance of the system and to detect that there are no leaks and that the installation is robust.
That is why it is important to consider specialised district energy contractors such as Araner. It is essential to work with top-notch, quality-oriented professionals to ensure the safety of the plant.
We are experts in designing, manufacturing and installing tailor-made industrial cooling solutions with a positive economic impact. We have worked worldwide in the development of Turbine Inlet Air Cooling, District Cooling and Thermal Energy Storage. Get in touch with our experts if you are interested in any of our solutions or if you need technical advice. We will be glad to help!
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.
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.
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.
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.
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.
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