Modified Two-Curve Model for Predicting Fracture Arrest Toughness and Arrest Distance of Full-Size Burst Tests

2016 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Test Data ◽  
Pipeline Steel ◽  
Large Diameter ◽  
High Strength ◽  
Full Scale ◽  
Burst Test ◽  
Pipe Segment ◽  
Single Pipe ◽  
Fracture Arrest ◽  
Arrest Toughness

Running fracture control is a very important technology for gas transmission pipelines with large diameter and high pressure. The Battelle two-curve (BTC) model developed in the early 1970s has been widely used in pipeline industry to determine arrest toughness in terms of the Charpy energy. Because of its semi-empirical nature and calibration with test data only for grades up to X65, the BTC does not work for higher grades. Simple corrections were thus proposed to extend the BTC model to higher grades, but limited to those grades considered. Moreover, the BTC model only predicts the minimum arrest toughness, but not arrest distance. To fill the technical gaps, this paper proposes a modified two-curve (MTC) model and a fracture arrest distance model in reference to the Charpy energy. The MTC model coupling with an arrest distance algorithm can predict fracture arrest toughness and arrest distance in one simulation of numerical integration for a single pipe or a set of multiple pipes with given toughness. Two sets of full-scale burst test data for X70 and X80 are used to validate the proposed model, and the results show good agreements between the predictions and full-scale test data of arrest toughness and arrest distance as well. The MTC model is then applied to optimize a design of pipe segment arrangements for a mockup full-scale burst test on a high-strength pipeline steel. The MTC simulation results confirm the experimental observation that different pipe arrangements determine different arrest toughness and arrest distance for the same grade pipes.

Applicability of Existing Models for Predicting Ductile Fracture Arrest in High Pressure Pipelines

2006 ◽  
Author(s):  
John Wolodko ◽  
Mark Stephens
Keyword(s):  
High Pressure ◽  
Ductile Fracture ◽  
High Pressures ◽  
Fracture Propagation ◽  
High Strength Steels ◽  
High Strength ◽  
Full Scale ◽  
Stage Of Development ◽  
Fracture Arrest ◽  
Arrest Toughness

The ductile fracture arrest capability of gas pipelines is seen as one of the most important factors in the future acceptance of new high strength pipeline steels for high pressure applications. It has been acknowledged for some time that the current methods for characterizing and predicting the arrest toughness for ductile fracture propagation in high strength steels are un-conservative. This observation is based on the inability of existing models to predict the required arrest toughness in full-scale ductile fracture propagation tests. While considerable effort is currently being applied to develop more accurate methods for predicting ductile facture arrest, the resulting models are still in a preliminary stage of development and are not immediately amenable for use by the general engineering community. As an interim solution, a number of authors have advocated the empirical adjustment or reformulation of the existing models for use with the newer, high strength pipe grades. While this approach does not address the fundamental issues surrounding the fracture arrest problem, it does provide methods that can be used in the near term for analysis and preliminary design. The desire to use these existing methods, however, is tempered by the uncertainty associated with their applicability in situations involving high pressures and/or high toughness materials. In an attempt to address some of these concerns, a statistical analysis was conducted to assess the accuracy of a number of available fracture arrest models by comparing predictions to actual values determined from full-scale fracture propagation experiments. From the results, correction factors were developed for determining the required toughness levels in high pressure applications that account for the uncertainty in the theoretical prediction methods.

Cost Effective Fabrication of Large Diameter High Strength Titanium Catenary Riser

2002 ◽  
Author(s):  
Agnes Marie Horn ◽  
Mons Hauge ◽  
Per-Arne Ro̸stadsand ◽  
Bjarne Bjo̸rnbakk ◽  
Peer Dahlberg ◽  
...  
Keyword(s):  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Large Diameter ◽  
High Strength ◽  
Cost Effective ◽  
Full Scale ◽  
Scale Production ◽  
Wear Properties ◽  
Field Development ◽  
Main Challenge

A large diameter high strength titanium free-hanging catenary riser was evaluated by the Demo 2000 Ti-Rise project, from initiative of the Kristin Field development license. In order to reduce the uncertainties related to the schedule, cost, and special technical issues identified in the work related to a similar riser for future installation on the A˚sgard B semi-submersible platform, a fabrication qualification of a full scale riser in titanium was run. Several full-scale production girth welds were made in an in-situ fabrication environment. The welding was performed on extruded titanium grade 23 (ASTM) pipes with an ID of 25.5″) and wall thickness of 30 mm. The main challenge was to develop a highly productive TIG orbital welding procedure, which produced welds with as low pore content as possible. It is well known that sub-surface pores often are initiation sits for fatigue cracks in high strength titanium welds. This paper describes how a greatly improved productivity was obtained in combination with a high weld quality. NDT procedures were developed whit the main on the reliability to detect and locate possible sub-surface weld defects, volumetric defects such as pores and tungsten particles and planar defects such as lack of fusion. The results from the actual Non Destructive Testing (NDT), the mechanical testing, and the fatigue testing of the subjected welds are presented. The response of the catenary is optimised by varied distribution of weight coating along the riser’s length. A satisfactory weight coating with sufficient strength, bond strength, and wear properties was developed and qualified. The riser is planned to be fabricated from extruded titanium pipes, welded together onshore to one continuous piece. The field coating is added and the riser is loaded into the sea and towed offshore and installed.

CVN and DWTT Energy Methods for Determining Fracture Arrest Toughness of High Strength Pipeline Steels

2012 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Nonlinear Models ◽  
High Strength ◽  
Correction Method ◽  
Gas Pipeline ◽  
Pipeline Steels ◽  
Curve Model ◽  
Drop Weight Tear Test ◽  
Viable Approach ◽  
Fracture Arrest ◽  
Arrest Toughness

Battelle two curve model (BTCM) was developed in the 1970s and successfully used for determining arrest toughness for ductile gas transmission pipelines in terms of Charpy vee-notched (CVN) impact energy. Practice has shown that the BTCM is accurate only for pipeline grades up to X65, but not for high strength pipeline grades X70 and above. Different methods to improve the BTCM were proposed over the years. This paper reviews the BTCM and its modified methods in terms of CVN energy or drop weight tear test (DWTT) energy for determining arrest toughness of ductile gas pipeline steels, particularly for high strength pipeline steels X80 and beyond. This includes the often-used Leis correction method, the CSM factor method, Wilkowski DWTT method and others. The CVN and DWTT energy-based methods are evaluated and discussed through the critical analysis and comparison with full-scale experimental data. The objective is to identify reasonable methods to be used for determining the minimum fracture toughness required to arrest a ductile running crack in a modern high strength, high pressure gas pipeline. The results show that available nonlinear models to correlate the standard DWTT and CVN energies are questionable, and the Leis correction method is a viable approach for determining arrest toughness for high strength pipeline steels, but further study is needed for ultra-high pipeline grades. Suggestions for further improving the BTCM are discussed.

Crystallographic Texture as a Factor Enabling Ductile Fracture Arrest in High Strength Pipeline Steel

2011 ◽  
Vol 702-703 ◽  
pp. 770-773 ◽  
Author(s):  
Igor Pyshmintsev ◽  
Alexey Gervasyev ◽  
Roumen H. Petrov ◽  
Victor Carretero Olalla ◽  
Leo Kestens
Keyword(s):  
Pipeline Steel ◽  
High Strength ◽  
Rolling Plane ◽  
Steel Plates ◽  
Clear Correlation ◽  
Ductile Crack ◽  
Surface Separation ◽  
X80 Steel ◽  
Oriented Parallel ◽  
Fracture Arrest

Low ductile crack arrestability in a full-scale burst test of 1420 mm-diameter X80 steel line pipes was accompanied by a high intensity of fracture surface separation. The texture of the steel plates was studied using different techniques in order to evaluate the influence of {001} planes oriented parallel to the rolling plane on the separation intensity during fracture. Though no clear correlation between the content of {001} planes parallel to the rolling plane and intensity of separation was found, the local distribution of the {001}<110> texture component among the microstructure components was different in different steels providing long areas suitable for cleavage fracture parallel to the rolling plane in steel with low arrestability.

Simulation of Dynamic Crack Propagation and Arrest Using Various Types of Crack Arrestor

2016 ◽  
Author(s):  
Mohammed Uddin ◽  
Gery Wilkowski
Keyword(s):  
Crack Propagation ◽  
Large Diameter ◽  
Small Diameter ◽  
Full Scale ◽  
Fe Model ◽  
Ductile Crack ◽  
Burst Test ◽  
Ductile Crack Growth ◽  
Diameter Pipe ◽  
Linepipe Steels

In linepipe steels, there has been a growing interest in using damage mechanics that provides physical models of the fracture process which are embedded into a two- or three-dimensional finite element (FE) model. Among the various damage models, the cohesive zone model (CZM) has recently been used to simulate the ductile crack growth behavior in linepipe steels because of its computational efficiency and it requires only two parameters which can be determined in experiments. While CZM is not yet to be used as predictive tool, but it has a great application in crack arrestor design as well as in providing insight to ductile crack propagation. In this paper, the authors have demonstrated some practical applications of CZM in linepipe steels. The CZM was used to simulate the ductile crack propagation in full-scale pipes which was able to capture the global deformation as well as the experimental crack speed. The model was then used to determine the effect of anchor blocks at the end of the pipe in a large diameter full-scale burst test. Later, the model was used to simulate two small diameter pipe tests with steel crack arrestors to mimic two arrestor cases with one showing crack propagation and the other showing crack arrest. The CZM model was also applied to demonstrate the circumferential ring-off behavior of a small diameter pipe test with rigid crack arrestor. The arrestor model was then extended to simulate a large diameter full scale Mojave burst test with “soft crack arrestor (SCA)”. A single element FE model was developed to verify the SCA material which was later extended with stain-based failure criteria. Finally, ductile crack growth in full-scale pipe with SCA was demonstrated to show that the FE CZM model can be used to optimize the design of SCA.

Analysis of Full-Scale Burst Test Data by Examining Effects of Insulation and Using Fully-Instrumented Standard Pressed-Notch and Modified Backslot DWTT Specimens

2018 ◽  
Author(s):  
M. Uddin ◽  
G. Wilkowski ◽  
C. Guan
Keyword(s):  
Ductile Fracture ◽  
Fracture Behavior ◽  
Large Diameter ◽  
Test Site ◽  
Radial Clearance ◽  
High Water Content ◽  
Burst Test ◽  
Pipe Burst ◽  
Service Conditions ◽  
Arrest Toughness

An intensive effort was undertaken to understand the fracture behavior in a recent TCPL pipe burst test. The 48-inch diameter X80 pipe was buried in soil at the Spadeadam Test Site, but since it was desired to have the gas and pipe cooled to the minimum service conditions of −5°C, a 50-mm thick polyurethane foam (PUF) insulation was sprayed on the entire pipe test section. This was a reasonable precaution since freezing of a high water content soil around a large-diameter pipe burst test can require significant cooling capacity or a much longer duration to get to the burst test conditions. In this burst test, the crack propagated much farther than anticipated by traditional predictive approaches such as using Charpy energy to predict the minimum ductile fracture arrest toughness, assuming that soil backfill conditions existed. To explore this burst test behavior, two aspects were examined. The first was an assessment of the properties of the PUF insulation relative to the soil properties, and the second was the toughness evaluated by instrumented DWTT testing. The 50-mm thickness of the PUF insulation corresponded to about 8.3% of the pipe radius. In past loose-fitting steel sleeve crack arrestor burst tests, if the radial clearance was greater than 5.5% of the pipe, then a ductile fracture propagated under the arrestor regardless of its length with no change in speed. Hence if the PUF could be easily compressed, then the pipe in this burst test would behave as if it was in a non-backfilled condition. Non-backfilled pipe requires much higher toughness to arrest a ductile fracture. So perhaps the pipe in this burst test condition acted somewhere between non-backfilled and backfilled conditions — an aspect that might need a much more comprehensive computational model to better assess. Additionally to assess how material toughness played a role in this burst test, detailed instrumented toughness testing was conducted on material taken from several of the pipe lengths in the burst test. The evaluations of the Charpy energy to the DWTT energy suggested that one of the pipe materials may have behaved more like an X100 steel than an X80 steel. Correction factors on the predicted arrest toughness are well known to be needed for the Battelle Two Curve method (BTCM) when applied to X80 and X100 pipes. However, even with these corrections on the Charpy energy, arrest was predicted with soil backfill in several cases where in the actual test, the crack propagated through the pipes. Hence toughness corrections by themselves did not explain the test results. Additional calculations were then done assuming a non-backfilled condition (as suggested from the PUF property evaluation) along with the appropriate grade effect correction from the DWTT testing, and propagation was properly predicted in each case consistently with the burst test. So the fracture behavior in this burst test was somewhere between those of backfilled and non-backfilled pipe. As a result of this investigation it appears that the PUF insulation played an important role in crack arrest behavior, and because of its presence may have required much higher toughness than was actually needed for the actual service conditions of pipe buried in actual soil backfill.

scholarly journals The Full Scale Burst Test of Large Diameter, High Pressure Gas Pipelines

1983 ◽  
Vol 23 (5) ◽  
pp. 453-459
Author(s):  
Tatsuichi OBINATA ◽  
Fusao KOSHIGA ◽  
Noboru MATSUO ◽  
Kunio NISHIOKA ◽  
Kazuo IKEDA
Keyword(s):  
High Pressure ◽  
Large Diameter ◽  
Full Scale ◽  
Gas Pipelines ◽  
Burst Test

Recent Progress and Application of Bainite Steels for High Strength Linepipe up to X120

2010 ◽  
Vol 638-642 ◽  
pp. 3032-3037
Author(s):  
Hitoshi Asahi ◽  
Yasuhiro Shinohara ◽  
Takuya Hara
Keyword(s):  
Dual Phase Steel ◽  
Pipeline Steel ◽  
Large Diameter ◽  
High Strength ◽  
Production Costs ◽  
Dual Phase ◽  
Low Carbon ◽  
Construction Costs ◽  
Production Parameters ◽  
Steel Weight

For the constant transmission of gas through a pipeline, steel weight decreases linearly with an increase in the strength of the linepipe irrespective of pipe size and internal pressure. Thus, high-strength large-diameter linepipe up to X120 has been developed and is now being applied to reduce pipe costs, transportation costs and construction costs. To meet the excellent weldability and low production costs required for the linepipe application of bainite produced through using Thermo-Mechanical Control Processing (TMCP) from low carbon chemistry is essential. Dual phase steel made by means of the introduction of ferrite in the bainite matrix mitigates the inferior properties of bainite. Herein, the production parameters affecting the microstructure and the properties are overviewed.

Analysis of Data From a Full-Scale Burst Test on 1219 mm OD Grade 550 Pipe: Implications for the Prediction of Fracture Velocity

2016 ◽  
Author(s):  
Brian Rothwell ◽  
Cindy Guan ◽  
Satoshi Igi
Keyword(s):  
Traditional Approach ◽  
Large Diameter ◽  
Crack Tip ◽  
Management Program ◽  
Full Scale ◽  
Correction Factors ◽  
Long Distance ◽  
Line Pipe ◽  
Fracture Arrest ◽  
Fracture Velocity

In recent years, considerable doubt has arisen over the prediction of the level of toughness required to arrest a propagating fracture in higher-strength line pipe. It has been clear for many years that the most widely used traditional approach, the Two-Curve Method (TCM) developed at Battelle in the early 1970s, could not be applied directly when the required toughness, expressed as full-size Charpy energy, exceeded about 80–90 J. Initially, this issue was addressed by the adoption of empirical correction factors, but more recently, there have been indications that this approach is no longer effective for modern, high-strength materials. Additional information, which in general can only be derived from well-characterized burst tests, is essential to furthering understanding of the fracture arrest problem under conditions that are typical of modern, long-distance, large-diameter pipeline design. In the context of the Coastal GasLink (CGL) project, TransCanada has carried out a program of full-scale burst testing at the Spadeadam test site of DNV GL. The tests were supported by LNG Canada and the TransCanada Technology Management Program. These tests are described in another paper at this conference [1]. Though most of the testing was directed towards the assessment of different crack arrestor designs, one half of one test contained a run of four pipes of progressively increasing Charpy energy, up to a very high level (over 450 J). The fracture was observed to run through all four pipes, before being arrested by a crack arrestor fitted to a fifth pipe having lower toughness. Nearly all approaches to determining requirements for fracture arrest depend, directly or indirectly, on relationships between fracture velocity (for given levels of fracture resistance) and the driving force, generally considered to be directly related to the pressure in the plane of the crack tip. By comparing measured fracture velocity with the crack tip pressure determined either directly at pressure transducer locations or by comparison with propagation velocities within the expansion wave, conclusions can be drawn regarding the accuracy of existing relationships. Most previous work regarding correction factors has been based simply on discrepancies between predicted and observed propagation and arrest behaviour. Direct comparisons of observed and predicted fracture speed potentially provide much more data and focus more clearly on where model deficiencies may lie. The current analysis focuses on comparisons with the predictions of the traditional TCM and those of a transient model developed by JFE. While data from the present work are clearly limited, this approach appears to present a way of recalibrating fracture velocity formulations that may extend the range over which traditional, Charpy-based approaches can be applied. For the future, the incorporation of additional results from other recent, well-characterized burst tests would be extremely valuable in this respect.

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