Application of WES2808 to Brittle Fracture Assessment for High Strength Gas Pipelines

2007 ◽  
Author(s):  
Takahiro Kubo ◽  
Satoshi Igi ◽  
Tsunehisa Handa ◽  
Nobuhisa Suzuki ◽  
Masao Toyoda ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Large Scale ◽  
Biaxial Loading ◽  
Tensile Deformation ◽  
High Strength ◽  
Assessment Method ◽  
Gas Pipelines ◽  
Charpy Test ◽  
Assessing Method

This paper presents the results of a preliminary study to establish an assessing method for the tensile strain limit against brittle fracture of pressurized gas pipelines subjected to axial tensile deformation. The basis of the assessment method is the Japan Welding Engineering Society standard WES2808–2003. WES2808 provides a procedure for evaluating the fracture limit using the CTOD design curve relating flaw size, applied strain and fracture mechanical parameter (CTOD). The main characteristics of the method are a consideration of the deterioration of the fracture toughness of material resulting from large cyclic and dynamic straining, a correction of CTOD fracture toughness for constraint loss in structural components in large scale yielding, and an estimation of critical CTOD value from Charpy test results. Modifications of the procedure to enable evaluation of the fracture properties of high strength gas pipelines under biaxial loading conditions are studied.

scholarly journals The Effects of Specimen Configuration and Plate Thickness on Large Scale Yielding Brittle Fracture Toughness

1980 ◽  
Vol 1980 (148) ◽  
pp. 177-182
Author(s):  
Kin-ichi Nagai ◽  
Shigetoshi Shimizu ◽  
Shun-ichi Kawano ◽  
Shuhei Kuribayashi
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Large Scale ◽  
Plate Thickness ◽  
Scale Yielding

Shallow Flaws Under Biaxial Loading Conditions—Part I: The Effect of Specimen Size on Fracture Toughness Values Obtained From Large-Scale Cruciform Specimens1

2000 ◽  
Vol 123 (1) ◽  
pp. 10-24 ◽  
Author(s):  
Wallace J. McAfee ◽  
B. Richard Bass ◽  
Paul T. Williams
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Temperature Region ◽  
Large Scale ◽  
Biaxial Loading ◽  
Crack Tip ◽  
Specimen Size ◽  
Biaxial Stress ◽  
Lower Transition ◽  
Crack Tip Constraint

A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed. This technology is for application to the safety assessment of RPVs containing postulated shallow-surface flaws. It has been shown that relaxation of crack-tip constraint causes shallow-flaw fracture toughness of RPV material to have a higher mean value than that for deep flaws in the lower transition temperature region. Cruciform beam specimens developed at Oak Ridge National Laboratory (ORNL) introduce far-field, out-of-plane biaxial stress components in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock (PTS) loading of an RPV. The biaxial stress component has been shown to increase stress triaxiality (constraint) at the crack tip, and thereby reduce the shallow-flaw fracture toughness enhancement. The cruciform specimen permits controlled application of biaxial loading ratios, resulting in controlled variation of crack-tip constraint. An extensive matrix of intermediate-scale cruciform specimens with a uniform depth surface flaw was previously tested and demonstrated a continued decrease in shallow-flaw fracture toughness with increasing biaxial loading. This paper describes the test results for a series of large-scale cruciform specimens with a uniform depth surface flaw. These specimens were all of the same size with the same depth flaw and were tested at the same temperature and biaxial load ratio (1:1). The configuration is the same as the previous set of intermediate-scale tests, but has been scaled upward in size by 150 percent. These tests demonstrated the effect of biaxial loading and specimen size on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. For specimens tested under full biaxial (1:1) loading at test temperatures in the range of 23°F (−5°C) to 34°F (1°C), toughness was reduced by approximately 15 percent for a 150-percent increase in specimen size. This decrease was slightly greater than the predicted reduction for this increase in specimen size. The size corrections for 1/2T C(T) specimens did not predict the experimentally determined mean toughness values for larger size shallow-flaw specimens tested under biaxial (1:1) loading in the lower transition temperature region.

The Effect of Low Sulfur Content on the Weldability of Linepipe Steel

2012 ◽  
Author(s):  
Kimberly K. Cameron ◽  
Alfred M. Pettinger
Keyword(s):  
Fracture Toughness ◽  
Sulfur Content ◽  
Large Scale ◽  
Pipeline Steel ◽  
Active Agent ◽  
High Strength ◽  
Pipeline System ◽  
Line Pipe ◽  
Low Sulfur ◽  
Linepipe Steel

Over time, the demand for high-strength linepipe has increased significantly. One of the challenges for developing higher strength linepipe has been maintaining an appropriate level of fracture toughness, yield to tensile strength ratio, and weldability. Fortunately, significant progress has been made in the production of high strength line pipe steel. A major improvement in steel making has been the utilization of secondary steel treatments to refine the steel and accurately control alloy additions to achieve a higher level of steel cleanliness. In particular, these refining treatments have enabled the achievement of extremely low sulfur levels. For most purposes, restricting sulfur content is desirable to help prevent a reduction in mechanical properties such as fracture toughness of the steel. Fortunately, steelmaking and desulfurization technologies have advanced to the point where pipeline steel with sulfur contents less than the requirements by API 5L are available on a large scale. Extremely low sulfur contents, however, can lead to other problems when welding steels. These weldability problems are related to the fact that sulfur is a known surface active agent for steels. Low sulfur concentrations lead to a reversal of the Marangoni convection in the weld pool, which is responsible for the large differences in weld penetration on otherwise identical steels. Additionally, when welding heats of unmatched sulfur concentrations, the arc will tend to deviate towards the low sulfur heat and axially shift the root of the weld if one of the heats was below a critical value for the sulfur content and the other was above this value. Although this phenomenon has been primarily observed in stainless steels, the increasing ability to produce linepipe steel with extremely low sulfur contents has led to the possibility that this phenomenon could also occur in low carbon pipeline steels. One pipeline system utilizing cellulosic consumables for shielded metal arc welding (SMAW) of X70 steel with sulfur contents an order of magnitude below that permitted by API 5L and with widely varying sulfur contents shows evidence of this effect. The profiles of the welds in this system exhibited a tendency for lack of penetration, asymmetric weld roots, and concave welds. One approach to ameliorate this would be the specification of a lower permissible amount of sulfur.

scholarly journals The Effects of Plate Thickness on Large Scale Yielding Brittle Fracture Toughness

1979 ◽  
Vol 1979 (146) ◽  
pp. 497-505
Author(s):  
Kin-ichi Nagai ◽  
Shigetoshi Shimizu ◽  
Mitsumasa Iwata ◽  
Shun-ichi Kawano ◽  
Ken-ichi Kozono
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Large Scale ◽  
Plate Thickness ◽  
Scale Yielding

The Effects of Constraint and Compressive or Tensile Residual Stresses on Brittle Fracture

2009 ◽  
Author(s):  
Simon Kamel ◽  
Robert C. Wimpory ◽  
Michael Hofmann
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Brittle Fracture ◽  
Driving Force ◽  
High Strength ◽  
Element Analysis ◽  
Crack Driving Force ◽  
Temperature Fracture ◽  
Crack Tip Constraint ◽  
Two Parameter

Residual stress is a key feature in components containing defects which can affect the crack driving force and alter the crack tip constraint to give a modified fracture toughness. In this paper experimental and numerical investigations are performed on ‘C’ shape fracture mechanics specimens, extracted from a high strength low alloy tubing steel, to examine the effects of constraint and tensile or compressive residual stress on brittle fracture. The residual stress is introduced into the specimens by a tensile or compressive mechanical pre-load to produce, respectively, a compressive or tensile residual stress in the region where the crack is introduced. Neutron diffraction measurements are performed on the pre-loaded specimens prior to introduction of a crack, and compared with predictions of the residual stress from finite-element analysis, using tensile properties derived at room temperature. Fracture toughness tests are carried out on the as-received (non-preloaded) and pre-loaded specimens and the effect of residual stress on crack driving force and constraint is evaluated using the two-parameter J-Q approach.

Toughness Requirement of Chinese Pressure Vessel Steel 07MnNiMoDR Based on Fracture Mechanics Assessment Method

2018 ◽  
Author(s):  
Lele Gui ◽  
Tong Xu ◽  
Yonghui Sun ◽  
Xuexin Shang
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Fracture Mechanics ◽  
High Strength ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Master Curve Method ◽  
Tension Tests

07MnNiMoDR is a widely used quenched and tempered high strength steel in fabrication of low-temperature pressure vessels in China. It can be used at/above −50°C according to the current design specification of GB 150. Some data show that this provision severely underestimates the performance of this material at low temperature, while others indicate that it overestimates the cryogenic performance of this material. In the paper, a series of tests including uniaxial tension tests, impact test and fracture toughness tests were carried out at low temperature to investigate the properties of 07MnNiMoDR with different thickness specimens. Fracture mechanics assessment procedures in API 579-1/ASME FFS-1 (Fitness-For-Service) is adopted to evaluate the low temperature design curve of 07MnNiMoDR, and the fracture toughness is obtained by master curve method (MC method) in the transition region. The results show that 07MnNiMoDR can be classified between exemption curve B and D in current edition of ASME Section VIII, Division 2.

Towards a Numerical Design Tool for Composite Crack Arrestors on High Pressure Gas Pipelines

2010 ◽  
Author(s):  
F. Van den Abeele ◽  
L. Amlung ◽  
M. Di Biagio ◽  
S. Zimmermann
Keyword(s):  
High Pressure ◽  
Large Scale ◽  
Steel Wire ◽  
Large Diameter ◽  
High Strength ◽  
Tensile Tests ◽  
Design Tool ◽  
Pipe Material ◽  
Gas Pipelines ◽  
Numerical Design

One of the major challenges in the design of ultra high grade (X100) high pressure gas pipelines is the identification of a reliable crack propagation strategy. Ductile fracture propagation is an event that involves the whole pipeline and all its components, including valves, fittings, flanges and bends. Recent research results have shown that the newly developed high strength large diameter gas pipelines, when operated at severe conditions (rich gas, low temperatures, high pressure), may not be able to arrest a running ductile crack through pipe material properties. Hence, the use of crack arrestors is required in the design of safe and reliable pipeline systems. A conventional crack arrestor can be a high toughness pipe insert, or a local joint with higher wall thickness. Steel wire wrappings, cast iron clamps or steel sleeves are commonly used non-integral solutions. Recently, composite crack arrestors have enjoyed increasing interest from the industry as a straightforward solution to stop running ductile cracks. A composite crack arrestor is made of (glass) fibres, dipped in a resin bath and wound onto the pipe wall in a variety of orientations. In this paper, the numerical design of composite crack arrestors will be presented. First, the properties of unidirectional glass fibre reinforced epoxy are measured and the micromechanic modelling of composite materials is addressed. Then, the in-use behaviour of pipe joints with composite crack arrestors is covered. Large-scale tensile tests and four point bending tests are performed and compared with finite element simulations. Subsequently, failure measures are introduced to predict the onset of composite material failure. At the end, the ability of composite crack arrestors to arrest a running fracture in a high pressure gas pipeline is assessed.

Applicability of the Master Curve Method to Ultra High Strength Steels

2015 ◽  
Author(s):  
Kim Wallin ◽  
Sakari Pallaspuro ◽  
Päivi Karjalainen-Roikonen ◽  
Pasi Suikkanen
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Size Effect ◽  
Temperature Dependence ◽  
Master Curve ◽  
High Strength Steels ◽  
High Strength ◽  
Master Curve Method ◽  
Curve Method ◽  
Ultra High Strength Steels

Although Ultra High Strength Steels (UHSS) with nominal strengths up to 1500 MPa have been available on the market for many years, the use of these steels in the civil engineering industry is still rather uncommon. One critical point limiting the use of UHSS steels lies in their rather poorly documented fracture properties in relation to more conventional steels covered by the codes. The major concept governing the assessment of steels is the Master Curve (MC) methodology. It provides a description for the fracture toughness scatter, size effect and temperature dependence in the ductile to brittle transition region. It enables a complete characterization of brittle fracture toughness of a material based on only a few small size specimens. The method combines a theoretical description of the scatter, a statistical size effect and an empirically found temperature dependence of fracture toughness. The fracture toughness in the brittle fracture regime is thus described with only one parameter, the transition temperature T0. At this temperature the mean fracture toughness for a 25.4 mm thick specimen is 100 MPa√m. The Master Curve method as defined in ASTM E1921-13a is applicable to ferritic structural steels with yield strength between 275 MPa and 825 MPa. Very few studies have been made with respect to the applicability of the Master Curve to Ultra High Strength Steels with yield strengths in the excess of 900 MPa. This is the topic of this work. Focusing on novel directly quenched high performance steels, the applicability of the Master Curve methodology with special emphasis on the temperature dependence will be investigated. Possible improvements to the Master Curve will be proposed for further consideration.

Precipitation in Al-Li-Zr alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 186-187
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Fracture Toughness ◽  
Precipitation Hardening ◽  
Weight Ratio ◽  
High Strength ◽  
Transmission Electron ◽  
Water Quench ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
Lithium Alloys ◽  
Zr Alloys

Aluminum-lithium alloys have a low density and high strength to weight ratio. They are being developed for the aerospace industry.The high strength of Al-Li can be attributed to precipitation hardening. Unfortunately when aged, Al-Li aquires a low ductility and fracture toughness. The precipitate in Al-Li is part of a sequence SSSS → Al3Li → AlLi A description of the phases may be found in reference 1 . This paper is primarily concerned with the Al3Li phase. The addition of Zr to Al-Li is being explored to find the optimum in properties. Zirconium improves fracture toughness and inhibits recrystallization. This study is a comparision between two Al-Li-Zr alloys differing in Zr concentration.Al-2.99Li-0.17Zr(alloy A) and Al-2.99Li-0.67Zr (alloy B) were solutionized for one hour at 500oc followed by a water quench. The specimens were then aged at 150°C for 16 or 40 hours. The foils were punched into 3mm discs. The specimens were electropolished with a 1/3 nitric acid 2/3 methanol solution. The transmission electron microscopy was conducted on the JEM 200CX microscope.

Sign in / Sign up

Export Citation Format

Share Document