Environmental Gasket Company Ltd. 309 Hanzhongmen Ave. Nanjing, PR China. 13EGC-MPA /Hh/Mor/Scr Fishbone Gasket

Transcription

1 P.O. Box Stuttgart Germany Test Report Draft Client: Environmental Gasket Company Ltd. 309 Hanzhongmen Ave. Nanjing, PR China Order-No. (Client): Order-No. (MPA): Test Item: 13EGC-MPA /Hh/Mor/Scr Fishbone Gasket Specification Applied: TA Luft VDI Guidelines 2440 and 2200 Date of Receipt of Test Item Date of Test: October 07. to Date of Report: October Page 1 of 5 text pages Enclosures : 2 Supplements: - Total Number of Pages: 7 Number of Reports: 2 x Environmental Gasket Company Ltd. The test results relate only to the items tested. Publication of this report in full or partly is only allowed with written authorization by MPA. In compliance with DIN EN ISO/IEC accredited Testing Laboratory recognized by DAkkS Deutsche Akkreditierungsstelle GmbH. Accreditation valid for testing methods listed in the certificates (Reg. No. D-PL ).

2 Page 2 of 5 text pages Index 1 Summary Purpose of Investigation Tests and Analyses Performed Test procedure Testing flange couple, assembly of the connection and Tempering Test of the sealing behaviour (leakage test) Determination of the remaining load Results of Investigation Interpretation Summary The tightening behaviour of the gasket was investigated after a 48-hours ageing at high temperature and at test pressure p = 1 bar absolute and 40 bar overpressure (test medium: Helium). The test procedure and boundary conditions comply on VDI guideline 2440 (issue November 2000) respectively VDI guideline 2200 (issue June 2007) for the proof of high grade performance in terms of TA-Luft (issue July 2002). That means in detail: Flanges DN 40 PN 40 DIN EN were used with sealing faces according to DIN , which showed a surface finish of R a 6.3 m. The bolts were tightened with a force, which leads to a surface pressure of 30 MPa (standard gaskets DN40/PN40 of sheet material). After assembly the flange connection was tempered in an oven for 48 h at 300 C. After cooling down to room temperature the absolute leakage rate was measured with a Helium mass spectrometer. For the determination of the specific leakage rate, the average circumference of the actual compressed sealing area was used. The tests proved that the gasket accomplish the requirement of the VDI guide line Materialprüfungsanstalt Universität Stuttgart BW-Bank Stuttgart / LBBW Pfaffenwaldring 32 Phone: +49 (0) Account No BLZ Stuttgart (Vaihingen) Telefax: +49 (0) IBAN: DE USt.-ID-Nr. DE Internet: BIC/SWIFT-Code: SOLADESTXXX

3 Page 3 of 5 text pages 2 Purpose of Investigation The purpose of the investigation was the determination of the sealing behaviour of a gasket supplied by the client after tempering in a flange connection at elevated temperature concerning VDI guide line 2440 (issue November 2000) and 2200 (issue June 2007) resp. TA-Luft (issue July 2002). 3 Tests and Analyses Performed The object of this investigation was referred by the client as Fishbone Gasket of Environmental Gasket Company Ltd.. The dimensions of this gasket are (compressed area): External diameter: 88.0 mm Internal diameter: 43.1 mm Thickness: 4.57 mm The medial effective circumference was m. 3.1 Test procedure Testing flange couple, assembly of the connection and Tempering The sample was investigated in a testing flange couple with the following description: Z DN PN 40 DIN chg La The pipe connections of the flanges were closed by welding according to DIN The sealing faces had a turned surface. The surface finish was 6.3 m (R a ). Four calibrated measuring bolts M16 with washers and inner measuring rod were used. The bolt force was measured by dial gauges and so an even bolt load could be achieved. The total bolt load was tuned to an effective sealing stress 30 MPa for standard gaskets DN40/PN40 of sheet material. The bolts thread and the face side of the nuts were lubricated before assembly. The loading was applied in four steps and re-tightened within 15 minutes, so that all dial gauges were showing the same loading at last. The sbolts were tightened across. After assembly the flange packet was bedded in an oven 48 h at 300 C Test of the sealing behaviour (leakage test) The leakage investigations were carried out after cooling at ambient temperature. The bolts were not re-tightened after ageing. The test pressure was 1 bar absolute at first, test medium was Helium. After leakage measuring at 1 bar absolute the internal pressure was increased to 40 bar and then another leakage measurement was carried out.

4 Page 4 of 5 text pages The test flange couple was placed in a recipient and connected to a Helium mass spectrometer via metallic vacuum tubes. The build-up of the high vacuum occurs by an internal rotary vane pump of the leak detector with an additional turbo molecular pump, which is used for the improvement of the exhaustion rate of the helium level behaviour. The leakage rate was measured by using a 180 -mass spectrometer. The sealing volume is connected with the helium resource and a pressure sensor over a pipe. Figure 1 illustrates the breadboard construction schematically. By the leakage measurement with a mass spectrometer the measured leakage rate is proportional to the Helium concentration. Therefore the volume within the gasket was evacuated several times and filled with Helium at 1 bar pressure (absolute) to minimise the rate of the ambient air in the test gas. The developing of the leakage rate, which was calendared by the mass spectrometer is illustrated logarithmically, Figure 2 and Determination of the remaining load After the leakage measurement the remaining load was determined by mounting the dial gauges on the measuring bolts again and reset them before disassembly. The indication of the dial gauges was annualised into gasket stress after disassembly. 4 Results of Investigation All measuring results are centralised in Table 1. They only apply for the conditions during the test period and do not permit a statement upon other conditions. For the qualification of a sealing connection according to TA-Luft the following conditions have to be warranted: - completion of the leakage criterion according to VDI-guide line 2440 / the used material has to keep its conditions over the whole application period. Furthermore the proof of fastness and leak tightness according to EN 1591 or an other effective procedure has to be effected. 1 bar absolute 40 bar (overpressure) leakage rate absolute [mbar l/s] leakage rate specific [mbar l/(s m)] assembly stress [MPa] 27.2 remaining stress [MPa] 24.6 relaxation [%] 9.6 Table 1: Results of the leakage and remaining pressure analysis

5 Page 5 of 5 text pages Splits of graphite were left on the sealing surface during the disassembly. 5 Interpretation 1 The gasket meets the requirements according to TA-Luft and VDI guideline 2440 (issue November 2000) of mbarl/(sm) at 1 bar absolute and mbarl/(sm) at 40 bar overpressure according to VDI-guide line 2200 (issue 2007). According to VDI guideline 2200 the leakage value after 24 has to be reported, when the signal is below mbarl/(sm), even if the signal is still changing. At both internal pressure steps the leakage rate was well below mbarl/(sm). The tested gasket was very tight. At 40 bar internal pressure the absolute leakage rate was less than 1 ml (millilitre) per year! Prepared by Approved and released by Signed Dipl.-Ing. S. Moritz deputy head of Sealing Technology signed Dipl.-Ing. R. Hahn Head of Sealing Technology 1 Concepts and interpretations are not subject of the accreditation

6 Materialprüfungsanstalt Universität Stuttgart Enclosure 1 Figure 1: Breadboard construction with flange connection (schematically)

7 Materialprüfungsanstalt Universität Stuttgart Enclosure 2 Figure 2: Fishbone Gasket of Environmental Gasket Company Ltd.: logarithmical illustration of the specific leakage rate during the test period at 1 bar internal pressure (absolute) Figure 3: Fishbone Gasket of Environmental Gasket Company Ltd.: logarithmical illustration of the specific leakage rate during the test period at 40 bar internal pressure (absolute)