The Fracture Arrest Behaviour of 914 mm Diameter X100 Grade Steel Pipelines

Abstract

The drive to reduce the installed cost of high-capacity long-distance pipelines has focused attention on increasing the strength of the pipe material, in order to reduce the tonnage of material purchased, transportation and welding costs. In parallel with developments in plate rolling and pipe fabrication, the properties and performance of prototype pipe materials and construction welds have already been extensively evaluated. While these studies have provided considerable confidence in the performance of X100 pipe, a major remaining issue in the introduction of such steels has been an understanding of the resistance to propagating fractures. The scarcity of relevant fracture propagation data and concerns about the measurement and specification of toughness in high strength steel pipes have led to doubts that the existing methods for control of ductile fracture can be extrapolated to X100 strength levels. In order to provide experimental data on which to base fracture control approaches, a Joint Industry Project has been undertaken using conditions representative of potential applications. Results are presented from two full-scale fracture propagation tests on 914mm pre-production grade X100 pipes pressurised using natural gas. The full-scale results are compared with small-scale test specimen data and also with results from other full-scale tests on high strength steel pipes. This provides a valuable insight into the fracture response of these materials. Information has also been obtained concerning the predictive capability of current gas decompression models. These results provide a contribution to the development of fracture control plans in pipelines using X100 steel linepipe.

Analysis of crater formation in buried NG pipelines: A survey based on past accidents and evaluation of domino effect

“…This information is known only in 50% of the cases. Most of the ruptures ranged from 1 to 30 m (82.2%, 37 cases), followed much less frequently by lengths between 30 and 60 (11.1%, 5 cases), which agree with the indicated by Andrews et al (2004). Only 2.2% of these records (one case) had a rupture greater than 100 m long.…”

“…This phenomenon takes place in a three-stage process (initiation of crack, propagation of it and, finally, the total rupture of the line), which is defined by the characteristics of the pipeline (e.g., construction material, age) and the operating pressure. Andrews et al (2004) point out that the combination of the operating pressure and crack opening angle can result in cracks propagating for 20 m and longer, at a speed of 200-300 m/s. The opening angle of the crack was not analysed in this study.…”

Prediction of crack propagation and arrest in X100 natural gas transmission pipelines with the strain rate dependent damage model (SRDD). Part 1: A novel specimen for the measurement of high strain rate fracture properties and validation of the SRDD model parameters

“…A combination of high internal gas pressure and inertia of the opening crack flanks can result in cracks propagating for 20m and longer (see Fig. 1) at speeds of 200-300 m/s [1,2]. Full scale burst test is the best way of assessing the crack propagation resistance of a natural gas pipeline.…”

“…Full scale burst test is the best way of assessing the crack propagation resistance of a natural gas pipeline. However, burst tests are very expensive and time consuming [3,1,4,2], and cannot therefore be used routinely. To complement detailed but infrequent burst test assessment, the industry now routinely uses FEA structural integrity assessment.…”

Investigation of the Effects of Pipe Wall Roughness and Pipe Diameter on the Decompression Wave Speed in Natural Gas Pipelines

“…A number of full-scale burst tests were conducted to investigate pipeline gas decompression since the 1970s [2][3][4][5][6][7][8]. However, full scale burst tests are prohibitively costly, except for major projects.…”