Full-scale ductile fracture propagation test on gas pipelines under offshore service conditions
The increasing use of offshore gas pipelines has raised the problem of determining the ductile fracture behaviour of pipelines under these conditions. Research was conducted to establish reliable standards for materials that ensure safe operation of offshore gas pipelines. Three full-scale burst tests, two offshore in varying conditions and one onshore, were performed. In both offshore tests the results confirm the restraining effect of the surrounding water masses on the propagation of ductile fracture in submarine pipelines. Charpy-V energy values of the order of 60 J/cm2 appear sufficient for arresting ductile fracture in 36" diameter pipelines and even lower levels would suffice for smaller diameter pipes. Certain conclusions can be drawn regarding the fluid dynamics associated with fractures: - The backfill represented by the surrounding water masses does not influence the way the gas carried in the pipeline undergoes decompression, which occurs in the same way as in underground pipelines - rupture of the tube generates a spherical pressure wave which travels through the surrounding medium at the local speed of sound. The peak pressure developed at a given point is inversely proportional to the distance from the rupture.
Bibliographic Reference: EUR 11671 IT (1988)
Record Number: 198910055 / Last updated on: 1994-12-01
Original language: it
Available languages: it