Chemical industry specific high-pressure testing to determine their ability to withstand the extreme conditions . This testing involves subjecting the gasket to elevated pressures to ensure it can handle the intended operating pressure without failure or leakage .
• Temperature testing : gaskets may also undergo temperature testing to evaluate their performance across a range of temperatures . Hydrogen systems can experience temperature variations , and gaskets must maintain their sealing properties under these conditions . Thermal cycling and exposure to extreme temperatures are common methods used for temperature testing . It is important to note that gasket testing for hydrogen should be performed in accordance with relevant industry standards and guidelines , such as those provided by organisations like the American Society of Mechanical Engineers ( ASME ) or the International Organization for Standardization ( ISO ). These standards provide specific requirements and procedures for gasket testing in hydrogen systems to ensure safety and reliability .
Flanges
The EN 1591 standard refers to the European standard for the design and calculation of flanges . It provides guidelines and requirements for the design , dimensions , materials , and testing of flanges used in various industries , including oil and gas , chemical , and power generation . The standard covers several types of flanges , such as weld neck , slip-on , blind , and threaded flanges , and ensures their compatibility and safety in
Leakage rate [ mg /( m * s )]
1.00E + 00
1.00E-01
1.00E-02
1.00E-03
1.00E-04
1.00E-05
1.00E-06
1.00E-07 0 10
Figure 1 . Gasket test stand .
Figure 2 . Leakage rate comparison helium and hydrogen for graphite gasket .
different operating conditions . Compliance with the EN 1591 standard helps ensure the integrity and reliability of flanged connections in industrial applications . EN 13555 specifies the gasket parameters required by EN 1591-1 and provides the test procedures for establishing the values of these parameters . Graphite is a versatile material that can be used especially at elevated temperatures . Several standard graphite gaskets made from sheet material were evaluated at a
Gasket stress [ MPa ]
Helium Leakage Rate Hydrogen Leakage Rate
20 30 40 50 60 70 80 90 100 110 120 130 140 150 160
test laboratory , which is an ESA associated member , and one of these gaskets shall be looked at in this article as an example . The test set-up is shown in Figure 1 . Both tests with helium and hydrogen were performed using the same mass spectrometer equipment . Depending on the test gas the mass spectrometer is calibrated with a reference gas sample . The tests were done according to EN 13555 with 2 mm thick graphite gaskets at room temperature . Standard DN40 PN40 gaskets according to EN 1514-1 were used and the test pressure was 4 MPa . The applied gasket stresses ranged from 10 to 160 MPa . The leakage rates for helium and hydrogen including the loading and unloading curves , are shown in Figure 2 . At low stresses up to 30 MPa , hydrogen showed slightly higher leakage rates compared to helium . For higher flange stresses this reversed . All measured leak rates were below the L0.01 limit of the German TA-Luft regulations except for those measured at a very low gasket stress . To truly comprehend the leakage characteristics of graphite gaskets , rigorous testing is essential . Until now most tests with helium and hydrogen have shown leak rates in the same ballpark range . Unlike hydrogen though , helium , is very unreactive . It will not burn or oxidise and doesn ’ t form compounds , all of which make it safe and easy to handle . Because of this , researchers prefer helium as the main test gas due to the reduced safety risks . www . valve-world . net Valve World February 2024
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