Germany-based AMTEC GmbH (Advanced Measurement Messtechnischer Service GmbH) performed the TA-Luft Helium test for the DeltaV-Seal in accordance with VDI 2440 guidelines.
Goal of the Test:
The goal of the investigation was the determination of the following gasket characteristic:
- Approval of a high-grade sealing system according to VDI 2440 (dated November 2000: Emission control – Mineral oil refineries).
Test conditions: Test Specimen
The geometry of the tested specimen was DN40/PN40 for test according to
VDI 2440. This test was performed in 2016. The calculated contact area is adjusted to A, as shown below. This calculation method is recommended by AMTEC in 2020 and is equal to all other tests performed by AMTEC in 2020 or later. The design of the metal gasket is shown below.
Test specimen of DeltaV-Seal™ DN40PN40 material 316L
Calculation of total gasket contact area
The geometry of the gasket contact face, which is considered for the calculation of the gasket stress, is defined to A=357.46mm2
The gasket initial gasket thickness was 3.8 mm.
The gasket tests were carried out on the following test rig:
VDI 2440. DN40/PN40 – pair of flanges. Ident-No. 010245.
Testing Equipment VDI 2440
Test Procedure: VDI 2440
The gasket was tested according to the requirements of VDI 2440 in a standard-sized pair of flanges (DN40/PN40). For the measurement of the applied load 4 psc, calibrated stud bolts with an internal rod are used. The gasket was compressed in three steps with initial gasket stress of 343.23 MPa corresponding to the geometry of a standardized flat gasket (DN40/PN40). The load is measured by the bolt elongation.
After assembly of the specimen in the pair of flanges, the equipment is heated up in an electrical oven with a heating rate of 2 K/min. The gasket is exposed at temperature 400℃ for 48 hours before the heating is switched off and the flanges cool down to ambient temperature. After cooling-down of the flange,
first, the remaining gasket stress is determined.
Afterward, the equipment is connected to the Helium test unit.
After pressurization with 3 bar internal pressure for 3 times, the test pressure is adjusted to 1 bar.
For 24 hours the leak rate is measured continuously with a helium leak detector.
The acceptance criteria is a leak rate lower than the limit of 1.0*10-4 mbar·l/(s·m) defined in VDI 2440.
Initial gasket stress: 343.23 MPa
Exposure temperature: 400℃
Time of temperature exposure: 48:00 hh:mm
Remaining gasket stress: 269.85 MPa
Internal pressure p: 1.0 bar
Test temperature: 23℃
Measuring time: 24:00 hh:mm
Result: VDI 2440
The result of the test according to VDI 2440 is shown below.
One specimen was examined. The temperature exposure was set for the material DeltaV-Seal, 316L to 400 °C, the test pressure level was 1 bar absolute.
The test was performed with a temperature exposure of 48 hours and a leakage measurement for 24 hours at ambient temperature after cooling-down of the flange. The leak rate was measured with the Helium leak detector. The recorded leak rate was 1.0*10-8 mbar·l/(s·m) which is lower than the limit of 1.0*10-4 mbar·l/(s·m) defined in VDI 2440.
Leak rate acc. VDI 2440 permissible
elapsed time [hrs]
Therefore the gasket is in compliance with the tightness criteria of VDI 2440. If the design of the sealing system can be expected to permit normal function in the long term in the given operating conditions and the characteristic sealing value as per
DIN 28090-1 or EN 13555, respectively, are observed when choosing and dimensioning the flange connection, the examined gasket material can be regarded as a high-grade sealing system for the purposes of TA-Luft.