Consequences of the German TA Luft for Bolted Flange Connections and Valves in Industrial Plants

Abstract

The high grade performance of gaskets for bolted flange connections in terms of TA Luft and VDI guideline 2440 assumes the fulfilment of the following requirements: Long-term suitability of the gasket particularly with regard to the exposure to the operating temperature and the medium; this requires the investigation of the long-term behaviour, e.g. according to DIN 28090-2 and DIN 28090-3 The design of flange connections (strength and tightness proof) on the basis of realistic gasket characteristics determined experimentally, e. g. according to DIN 28090-1 or prEN 13555 Compliance with the specific leakage rate of 10-4 mbar 1 / (s·m) in a type test at 1 bar test pressure. Similar requirements are effective for packings of stuffing boxes, in which the type test is carried out under more intensive boundary conditions compared to the flange connections: real operating pressure and stem strokes. In the frame of a research project sponsored by the German chemical industry a choice of gaskets were tested which cover all gasket types in the European gasket standard EN 1514 part 1 to 7. The gasket types were classified in view of their high grade performance potential. Similar investigations and analyses were carried out for standard packings for stuffing boxes. These results and their consequences are presented. In addition to the explicitly mentioned requirements in VDI 2440 further requirements should be seen as important in view of the assurance of high grade performance: Quality control during gasket production This can be ensured by manufacturers quality management and by compliance with requirements of corresponding quality standards, e.g. DIN 28091 (an European quality standard (prEN 14772) for gaskets is in preparation) Controlled assembly, which is necessary to realise the design assembly bolt load with limited scattering High grade performance proof of gaskets, more correctly of gasketed bolted flange connections has to be regarded as a complex matter in opposition to common interpretations and involves more than just the compliance with a certain leakage rate criterion of a special type test.