In order to verify the possible application of high pressure, long distance natural gas transportation, in 1995 E.N.I. sponsored a research program. This activity has been developed by a joint co-operation among SNAM, Centro Sviluppo Materiali (CSM) and ILVA to assess the fracture behaviour of large diameter (up to 1442 mm), heavy wall thickness (up to 30 mm), high steel grade (API 5L X70 and X80) pipes for operating pressure over 15 MPa. Aim of this research was to check the current material criteria, for the avoidance of brittle fracture initiation and long shear ductile fracture propagation for pipes under investigation. The fitness of the DWT Test, to define the ductile to brittle transition temperature, has been validated by comparing laboratory and full scale West Jefferson tests. The validity of the current approach to ductile fracture propagation control, based on the agreement between the Battelle equation predictions and the existing full scale tests data base, has been investigated by means of two full scale propagation tests on X70 and X80 steel pipes, operated at hoop stresses of 408 MPa and 440 MPa respectively. The experimental activities have shown the possibility to extend fracture transition forecasting criteria up to high walled - high stressed steel pipe. While fracture propagation criteria need to be corrected for taking in account the effect of the high stressed material. Such values are rather high when compared to current requirements, but are within the capabilities of the best pipe producers on the market.
High pressure long distance transmission gas lines: structural integrity of high strenght steel grade pipeline
Hochdruck-Gasfernleitungen: Strukturintegrität von Stahlpipelines aus hochfesten Stahlsorten
2000
12 Seiten, 10 Bilder, 2 Tabellen, 7 Quellen
Conference paper
English
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