Drop Weight Tear Testing of High Toughness Pipeline Material

2004 ◽  
Author(s):  
Kjell Olav Halsen ◽  
Espen Heier
Keyword(s):  
Fracture Initiation ◽  
Test Method ◽  
Side Impact ◽  
Battelle Memorial Institute ◽  
Line Pipe ◽  
Pipeline Steels ◽  
High Toughness ◽  
Drop Weight ◽  
Drop Weight Tear Test ◽  
Impact Side

Drop Weight Tear Testing is a common test method for determining a material’s ability to arrest a propagating crack. This testing method was developed by Battelle Memorial Institute, and is conducted in accordance with standards as API RP 5L3 ‘Recommended Practice for Conducting Drop Weight Tear testing on Line Pipe’ and EN 10274 ‘Metallic Materials - Drop Weight Tear Test’. One problem that has been encountered when performing Drop Weight Tear Testing of high toughness TMCP materials is that the pre-deformed material in the pressed notch is not sufficiently embrittled to ensure initiation of a brittle fracture. According to prevailing standards a brittle initiation is necessary for a valid test result. The material opposite the notched side (impact side) will deform quite considerably and is due to strain hardening expected to loose toughness prior to the actual fracture initiation takes place. Consequently high toughness material may give poor test results. In that respect, DNV initiated a Joint Industry Project called ‘Drop Weight Tear Testing of High Toughness Pipeline Material’, where the main objective was to obtain a better understanding on how the results from the DWTT should be interpreted for high toughness pipeline steels. During the project an extensive amount of Drop Weight Tear tests (DWTT) were performed on relevant modern pipeline steels. The resulting shear ratios were determined according to conventional fracture surface evaluation methods as well as newly developed methods as presented in the literature. The appearance of energy curves for both regular DWTT specimens and specimens with varying back gouge depths was also considered in the investigation and the consistency between the estimated shear ratios and the corresponding measured absorbed energies were thoroughly evaluated. This paper summarizes the results and recommendations obtained in the performed investigations.

Flow Behaviour and Ductile Fracture Toughness of a High Toughness Steel

2004 ◽  
Author(s):  
S. Xu ◽  
R. Bouchard ◽  
W. R. Tyson
Keyword(s):  
Flow Stress ◽  
Ductile Fracture ◽  
Tensile Tests ◽  
Test Method ◽  
Opening Angle ◽  
Absorbed Energy ◽  
Crack Propagation Resistance ◽  
High Toughness ◽  
Drop Weight ◽  
Drop Weight Tear Test

This paper reports results of tests on flow and ductile fracture of a very high toughness steel with Charpy V-notch absorbed energy (CVN energy) at room temperature of 471 J. The microstructure of the steel is bainite/ferrite and its strength is equivalent to X80 grade. The flow stress was determined using tensile tests at temperatures between 150°C and −147°C and strain rates of 0.00075, 0.02 and 1 s−1, and was fitted to a proposed constitutive equation. Charpy tests were carried out at an initial impact velocity of 5.1 ms−1 using drop-weight machines (maximum capacity of 842 J and 4029 J). The samples were not broken during the test, i.e. they passed through the anvils after significant bending deformation with only limited crack growth. Most of the absorbed energy was due to deformation. There was little effect of excess energy on absorbed energy up to 80% of machine capacity (i.e. the validity limit of ASTM E 23). As an alternative to the CVN energy, the crack tip opening angle (CTOA) measured using the drop-weight tear test (DWTT) has been proposed as a material parameter to characterize crack propagation resistance. Preliminary work on evaluating CTOA using the two-specimen CTOA test method is presented. The initiation energy is eliminated by using statically precracked test specimens. Account is taken of the geometry change of the specimens (e.g. thickening under the hammer) on the rotation factor and of the effect of strain rate on flow stress.

Analysis of abnormal fracture occurring during drop-weight tear test of high-toughness line-pipe steel

2004 ◽  
Vol 368 (1-2) ◽  
pp. 18-27 ◽  
Author(s):  
Byoungchul Hwang ◽  
Sunghak Lee ◽  
Young Min Kim ◽  
Nack J Kim ◽  
Jang Yong Yoo ◽  
...  
Keyword(s):  
Pipe Steel ◽  
Line Pipe ◽  
High Toughness ◽  
Drop Weight ◽  
Drop Weight Tear Test ◽  
Line Pipe Steel

Use of Batteile Drop-Weight Tear Test for Determining Notch Toughness of Line Pipe Steel

JOM ◽  
1965 ◽  
Vol 17 (9) ◽  
pp. 985-994
Author(s):  
E. H. Brubaker ◽  
J. D. Dennison ◽  
R. J. Eiber ◽  
A. B. Wilder
Keyword(s):  
Pipe Steel ◽  
Notch Toughness ◽  
Line Pipe ◽  
Drop Weight ◽  
Drop Weight Tear Test ◽  
Line Pipe Steel

Fracture Control for the Alliance Pipeline

2000 ◽  
Author(s):  
Bob Eiber ◽  
Lorne Carlson ◽  
Brian Leis
Keyword(s):  
Natural Gas ◽  
New Technology ◽  
Fracture Initiation ◽  
Line Pipe ◽  
Control Plan ◽  
High Toughness ◽  
Pipe Burst ◽  
Fracture Control ◽  
Pipe Fittings ◽  
Fracture Arrest

This paper reviews the fracture control plan for the Alliance Pipeline, which is planned for operation in 2000. This natural-gas pipeline is 2627 km (1858 miles) long, running from British Columbia, Canada to Illinois, USA. Interest in the fracture control for this pipeline results from its design, which is based on transporting a rich natural gas (up to 15% ethane, 3% propane) at a relatively high pressure 12,000 kPa (1740 psi). This break from traditional pressures and lean gases, which frequently are constrained by incremental expansion, is more efficient and more economical than previous natural gas pipelines. Use of higher pressures and rich gas requires adequate fracture control for the line pipe, fittings, and valves. This fracture control has been achieved for the Alliance Pipeline by specifying high-toughness steels, in terms of both fracture-initiation and fracture-propagation resistance for the line pipe, fittings and heavy wall components. While beneficial from an economics viewpoint, the need for higher toughnesses raised concern over the validity of the fracture control plan, which was based on existing and new technology. The concern focused on fracture arrest using high toughness steels. The concern was associated with characterizing fracture arrest resistance using Charpy V-notch impact toughness, the most commonly used method to measure fracture arrest resistance. Developments were undertaken to address problems associated with the use of higher-toughness steel and these were validated with full-scale pipe burst tests to demonstrate the viability of the fracture control plan. The solution involved extending existing methods to address much higher toughness steels, which provided a significantly improved correlation between fracture arrest predictions and experimental results. In the burst tests, data was collected to validate the Alliance design and also to extend the database of fracture arrest data to assist future pipelines. Data such as the pressure between the pipe and soil as the gas escapes from the pipe, the sound levels in the atmosphere, the movement and strains in the pipe ahead of the running fracture were instrumented in the test and the available results are presented.

scholarly journals Design, Development and Confirmation of a High Toughness Gas Line Pipe for Alliance Pipeline at Camrose Pipe Company

2000 ◽  
Author(s):  
Alex J. Afaganis ◽  
James R. Mitchell ◽  
Lorne Carlson ◽  
Alan Gilroy-Scott
Keyword(s):  
Design Development ◽  
Line Pipe ◽  
High Toughness ◽  
Assessment Tests ◽  
Chevron Notch ◽  
Energy Measure ◽  
Drop Weight Tear Test ◽  
Fracture Assessment ◽  
Fracture Arrest ◽  
Pipe Manufacturing

Through 1999, Camrose Pipe Company manufactured ∼152 km (∼45 000 tonnes) of 1067 × 11.4mm pipe for Alliance Pipeline Partnership Ltd. This section of Alliance’s pipeline was manufactured to a design whose pipe fracture toughness requirements was significantly beyond those historically manufactured in Canada and initiated a major leap in plate/pipe manufacturing toughness capability. The development of line pipe toughness in Canada culminating in this order will be profiled. Further, this high toughness design is at the far reaches of the traditional fracture arrest models. Besides the traditional Charpy energy measure, and to confirm Alliance’s confidence in their fracture arrest design, another two sets of fracture assessment tests were used on a trial and production basis: the API chevron notch drop weight tear test (CN DWTT) energy and the energy of a similar test using an Alliance notch modification. The results of these tests will be reviewed and compared.

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