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

Author(s):  
Robert M. Andrews ◽  
Neil A. Millwood ◽  
A. David Batte ◽  
Barbara J. Lowesmith

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.

Author(s):  
Andrea Fonzo ◽  
Andrea Meleddu ◽  
Giuseppe Demofonti ◽  
Michele Tavassi ◽  
Brian Rothwell

The determination of the toughness values required for arresting ductile fracture propagation has been historically based on the use of models whose resulting predictions can be very unreliable when applied to new high strength linepipe materials (≥X100) and/or different operating conditions. In addition, for the modern high strength steels a methodology for determining the material fracture resistance for arresting running shear fracture starting from laboratory data is still lacking. The work here presented (developed within a PRCI sponsored project) deals with the use of CSM’s proprietary PICPRO® Finite Element code to develop methodologies for ductile fracture propagation control in high grade steel pipes. The relationships providing the maximum crack driving force which can be experienced in a pipe operated at known conditions have been determined, for different types of gas. On the other side, an empirical relationship has been found to correlate the critical Crack Tip Opening Angle (CTOA) determined by laboratory testing, to the critical CTOA on pipe (which represents the material fracture propagation resistance) with the aid of devoted simulations of past full-scale burst tests. By comparing Driving Force and Resistance Force, ductile fracture control for high strength steel pipelines can be achieved.


Author(s):  
Carlo Maria Spinelli ◽  
Furio Marchersani

International gas market development is towards very long transportation distances (3000–6000 km); the only suitable onshore technology to conjugate economics, large amount of gas conveyed and possibility to exploit remote gas fields appears to be the Very High Pressure (P > 14 MPa), Very High Strength Steel (Steel grade X100 API 5L [1] equivalent) option. Eni Group is going to sponsor a 3 years long project, called TAP (Trasporto gas Alta Pressione) [High Pressure gas Transportation] aimed to demonstrate: • economic evaluation; • technology reliability; • real possibility to build Very High Pressure Pipeline. The project itself is framed into five logical areas: • Evaluation of the applicability of alternative technological solution in extreme enterprise; • Technological innovation, mainly within Eni Group; • FEED (Front End Engineering Development) for strategic route gas pipeline and comparison with LNG option; • Demonstrative construction of a High Strength Steel (X80) pipeline section on Snam Rete Gas Network in Italy; • Demonstrative construction of a Very High Strength Steel (X100 API equivalent) provisioning pilot section pipeline. To achieve this object Eni has involved: • Eni Gas & Power Division as Business Developer; • Snamprogetti as Technology Developer; • Aquater, Enidata, Enitecnologie, Saipem, Snam Rete Gas as specific item expertises; • CSM and Universita` di Bergamo as high qualified partners for lab and full scale testing; • Pipe steel makers and coating producers as fundamental partners to develop new solutions. TAP, within Eni Group, is the final step of a long development research and innovation activity started 8 years ago with two explorative “Long distance pipeline High Grade Steel” projects on Very High Strength Steel performances (strength, toughness, weldability) carried out mainly with the support of Snam, Snamprogetti and Saipem. TAP final goal is to collect, transfer, develop all the possible technological solutions to be ready for building “The pipeline network for Very High Pressure Transportation”.


Author(s):  
Karl Christoph Meiwes ◽  
Susanne Höhler ◽  
Marion Erdelen-Peppler ◽  
Holger Brauer

During reel-laying repeated plastic strains are introduced into a pipeline which may affect strength properties and deformation capacity of the line pipe material. Conventionally the effect on the material is simulated by small-scale reeling simulation tests. For these, coupons are extracted from pipes that are loaded in tension and compression and thermally aged, if required. Afterwards, specimens for mechanical testing are machined from these coupons and tested according to the corresponding standards. Today customers often demand additional full-scale reeling simulation tests to assure that the structural pipe behavior meets the strain demands as well. Realistic deformations have to be introduced into a full-size pipe, followed by aging, sampling and mechanical testing comparable to small-scale reeling. In this report the fitness for use of a four-point-bending test rig for full-scale reeling simulation tests is demonstrated. Two high-frequency-induction (HFI) welded pipes of grade X65M (OD = 323.9 mm, WT = 15.9 mm) from Salzgitter Mannesmann Line Pipe GmbH (MLP) are bent with alternate loading. To investigate the influences of thermal aging from polymer-coating process one test pipe had been heat treated beforehand, in the same manner as if being PE-coated. After the tests mechanical test samples were machined out of the plastically strained pipes. A comparison of results from mechanical testing of material exposed to small- and full-scale reeling simulation is given. The results allow an evaluation of the pipe behavior as regards reeling ability and plastic deformation capacity.


Author(s):  
Miki Funahashi ◽  
Walter T. Young

The results of a study on the use of cathodic protection on prestressed and post-tensioned concrete bridge members are summarized. Previous laboratory tests to evaluate hydrogen embrittlement of high strength steel embedded in concrete have proven that cathodic protection will generate hydrogen on high-strength steel in concrete if the potential is more negative than the thermodynamic hydrogen evolution potential. The hydrogen generated will enter the steel and cause a loss in ductility that will adversely affect the steel's performance if a notch is present. Full-scale beams were constructed to further study those phenomena. Four pretensioned beams were constructed. In addition, two post-tensioned slabs were constructed to evaluate cathodic protection of anchorages and tendons encased in metal or plastic conduits. Cathodic protection currents were supplied by IR drop-free potential controlled rectifiers. Good potential control at control points was achieved by using externally mounted silver-silver chloride reference electrodes and a conductive gel bridge. However, inconsistent potential control occurred at locations other than at the control points. Later in the study, constant current power supplies were used on two of the beams. Hydrogen entering the steel as the result of corrosion appears to have masked the presence of hydrogen that might have been produced by cathodic protection. The analysis also revealed that there was corrosion of some pretensioned wires at crossings with interior steel reinforcing bars due to interference (stray current) caused by cathodic protection application. Analysis of the post-tensioned slabs indicated little effect of cathodic protection on tendons inside plastic or metal ducts from the application of cathodic protection. Beneficial effects were noted on anchor points where mortar was in contact with the metal.


2012 ◽  
Vol 446-449 ◽  
pp. 981-988
Author(s):  
Zhen Bao Li ◽  
Wen Jing Wang ◽  
Wei Jing Zhang ◽  
Yun Da Shao ◽  
Bing Zhang ◽  
...  

Axial compression experiments of four full-scale reinforced concrete columns of two groups were carried out. One group of three columns used high-strength steel with the yield strength of 1000MPa as reinforcement hoops, and the second group used the ordinary-strength steel with yield strength of 400MPa. The axial compressive performances between these two groups were assessed. Compared to the specimen using the ordinary-strength steel, the axial compressive bearing capacity of using the high strength steel dose not increase significantly, while the deformation ability increases greatly. The results also indicate that the stress redistributions of the hoops and the concrete sections are obvious, and long-lasting when specimens achieve the ultimate bearing capacity after the yield of the rebar and local damage of concrete materials, at this time the strain of the specimens developes a lot, especially stress - strain curves of speciments with high-strength hoop all show a wide and flat top.


2013 ◽  
Vol 78 (687) ◽  
pp. 1007-1016 ◽  
Author(s):  
Masayoshi NAKAI ◽  
Kazuaki TSUDA ◽  
Shinji MASE ◽  
Hiroyuki NARIHARA ◽  
Takashi OKAYASU ◽  
...  

Author(s):  
D. Michael Johnson ◽  
Peter S. Cumber ◽  
Norval Horner ◽  
Lorne Carlson ◽  
Robert Eiber

A full scale fracture propagation test facility has been developed to validate the design, in terms of the ability of the material to avert a propagating fracture, of a major new pipeline to transport gas 1800 miles from British Columbia in Canada to Chicago in the USA. The pipeline, being built by Alliance Pipeline Ltd, will transport rich natural gas, i.e. gas with a higher than normal proportion of heavier hydrocarbons, at a maximum operating pressure of 12,000 kPa. This gas mixture and pressure combination imposes a more severe requirement on the pipe steel toughness than the traditional operating conditions of North American pipelines. As these conditions were outside the validated range of models, two full-scale experiments were conducted to prove the design. This paper will provide details of the construction of the 367m long experimental facility at the BG Technology Spadeadam test site along with the key data obtained from the experiments. Evaluation of this data showed that the test program had validated Alliance’s fracture control design. The decompression data obtained in the experiments will be compared against predictions from a new decompression model developed by BG Technology. The use of the experimental facility and the model to support future developments in the pipeline industry, particularly in relation to the use of high strength steels, will also be discussed.


Author(s):  
Mamdouh M. Salama

A key imperative to the transportation of natural gas for long distance is the continued technological advances to reduce the development and life cycle cost of high pressure gas pipeline while maintaining the required high level of safety, reliability and environmental stewardship. Therefore, advances in high strength steels such as X100 and X120 have been pursued by several companies. This paper presents an alternative solution namely FAST-Pipe™ (Fiber Augmented Steel Technology - Pipe). The FAST-Pipe™ Concept involves wrapping a conventional strength steel pipe (X70) whose thickness is selected to satisfy axial and bending load requirement with dry fiberglass to achieve the pressure load requirement. The FAST-Pipe™ offers several technical and economical advantages over High strength steel concepts. The paper presents the results of the proof of concept validation program that included cost analysis and performance testing. The paper also summarizes the results of the rigorous qualification program that was implemented subsequent to the successful results of the proof of concept phase.


Author(s):  
Satoru Takano ◽  
Masao Ono ◽  
Sotaro Masanobu

For a fundamental understanding of pipe wear under hydraulic transportation of deep-sea mining, a small scale test is conducted because there are many restrictions in conducting a full scale test. The small scale test apparatus are set up using the pipes of about 80mm in diameter and the rocks of which maximum particle diameters are about 20mm are used. In the test, the pipe materials and the pipe inclination are changed to evaluate the differential of the amount of pipe material loss. Furthermore, the amount of the pipe material loss in full scale is estimated based on the small scale test results.


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