Steady-State Crack Propagation in Pressurized Pipelines

1977 ◽  
Vol 99 (1) ◽  
pp. 112-121 ◽  
Author(s):  
C. Popelar ◽  
A. R. Rosenfield ◽  
M. F. Kanninen
Keyword(s):  
Steady State ◽  
Crack Propagation ◽  
Driving Force ◽  
Crack Arrest ◽  
Operating Conditions ◽  
Unstable Crack ◽  
Crack Driving Force ◽  
Plastic Yield ◽  
Pressurized Pipelines ◽  
Full Scale Tests

Previous work at Battelle-Columbus on the development of a theoretical model for unstable crack propagation and crack arrest in a pressurized pipeline is extended in this paper by including the effect of backfill. The approach being developed involves four essential aspects of crack propagation in pipelines. These four components of the problem are: 1 – a shell theory characterization of the dynamic deformation of a pipe with a plastic yield-hinge behind an axially propagating crack, 2 – a fluid-mechanics treatment of the axial variations in the gas pressure acting on the pipe walls, 3 – an energy-based dynamic fracture mechanics formulation for the crack-driving force, and 4 – measured values of the dynamic energy absorption rate for pipeline steels. Comparisons given in the paper show that the steady-state crack speeds predicted by the model are in reasonably good agreement with the crack speeds measured in full-scale tests, both with and without backfill. The analysis further reveals the existence of a maximum steady-state crack-driving force as a function of the basic mechanical properties of the pipe steel and the pipeline goemetry and operating conditions. Quantitative estimates of this quantity provided by the model offer a basis for comparison with the empirical crack-arrest design criteria for pipelines developed by AISI, the American Gas Association, the British Gas Council, and British Steel. These are also shown to be in substantial agreement with the predictions of the model developed in this paper.

Steady-State Crack Propagation in Pressurized Pipelines Without Backfill

1976 ◽  
Vol 98 (1) ◽  
pp. 56-64 ◽  
Author(s):  
M. F. Kanninen ◽  
S. G. Sampath ◽  
C. Popelar
Keyword(s):  
Steady State ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Crack Arrest ◽  
State Dynamic ◽  
Plastic Yield ◽  
Scale Experiment ◽  
Pressurized Pipelines ◽  
Dynamic Energy Release Rate

In a previous paper, a simplified dynamic-shell theory representation was formulated for steady-state motion in a pipeline without backfill. The present work extends this model by (1) incorporating a gas dynamics treatment to determine the axial variation in the pressure exerted by the gas on the pipe walls, and (2) incorporating a plastic yield hinge behind the crack tip. Solutions to the governing dynamic equations are obtained for these conditions and used to calculate the steady-state dynamic energy release rate as a function of crack speed. In the single full-scale experiment in which an independent estimate of the dynamic fracture energy is available for a pipe without backfill, the model predicts a steady-state speed of 780 fps. This can be compared with measured speeds which ranged from 725 to 830 fps in the test. Because the calculated steady-state dynamic energy release rate exhibits a maximum, it is suggested that this approach may offer a basis for crack arrest design of pipelines.

Am I Too Rich?: Determining Limits for Gas Composition to Ensure Crack Arrest in an Existing Pipeline

2016 ◽  
Author(s):  
Robert M. Andrews ◽  
Michael Smith
Keyword(s):  
Driving Force ◽  
Probabilistic Approach ◽  
Crack Arrest ◽  
General Purpose ◽  
The Body ◽  
Third Party ◽  
Gas Composition ◽  
Original Design ◽  
Crack Driving Force ◽  
Wide Range

Fracture control studies for new gas transmission pipelines usually produce a specified minimum Charpy energy, often including “correction factors”, which will ensure that a crack will arrest in the body of the pipe. The basic pipeline parameters such as pressure, pipe grade, diameter and wall thickness will be fixed early in design, and the reservoir and process engineering design will set limits on the extremes of the gas composition. The inverse case, where the gas composition in an existing pipeline is to be changed from the original design basis, is more challenging. Changes in composition can arise from ageing of the reservoir supplying a pipeline, or opportunities for the operator to generate additional revenue from 3rd party access. Sales gas specification limits for general purpose natural gas transmission often have broad limits, which can be met by a wide range of compositions. As a wide range of gas compositions can give the same crack driving force, determining the composition limits is a “many to one” problem without a unique solution. This paper describes the derivation of an envelope of richer gas compositions which gave an acceptable probability of crack arrest in an existing pipeline which had originally been designed for a very lean gas mixture. Hence it was necessary to limit the amount of rich third party gas to ensure that the crack driving force did not increase sufficiently to propagate a long running fracture. Manufacturing test data for the linepipe were used with the EPRG probabilistic approach to derive a characteristic Charpy energy which would achieve a 95% probability of crack arrest in 5 joints or fewer. After “uncorrecting” the high Charpy energy, the value was used with the Battelle Two Curve model to analyse a range of gas compositions and derive an envelope of acceptable compositions. Sensitivity studies were carried out to assess the effects of increasing the temperature and of expanding the limits for nitrogen and carbon dioxide beyond the initial assumptions. It is concluded that for a specific case it will be possible to solve the inverse problem and produce composition limits which will allow increased flexibility of operation whilst maintaining safety.

Fracture Statistics Models and Crack Propagation in Random Media

1994 ◽  
Vol 47 (1S) ◽  
pp. S141-S150 ◽  
Author(s):  
D. Jeulin
Keyword(s):  
Crack Propagation ◽  
Fracture Energy ◽  
Random Media ◽  
Probabilistic Models ◽  
Heterogeneous Media ◽  
Crack Nucleation ◽  
Crack Arrest ◽  
Two Dimensions ◽  
Unstable Crack ◽  
Probability Of Fracture

Crack propagation in heterogeneous media is of primary interest for engineering purposes, in order to predict the overall toughness and the probability of fracture from data on the microstructure. Probabilistic models for mode I crack propagation in two dimensions are presented. They are developed for brittle elastic materials with a random distribution of fracture energy. These models enable us to calculate in a closed form the probability of fracture involving crack nucleation and propagation that differ from the usual fracture statistics models based on the weakest link model. The use of the Griffith’s crack arrest criterion is applied to random function models for the distribution of the fracture energy and for various loading conditions resulting in stable or unstable crack propagation. From the models are deduced some statistical size effects.

scholarly journals Crystallographic crack propagation rate in single-crystal nickelbase superalloys

2018 ◽  
Vol 165 ◽  
pp. 13012
Author(s):  
Christian Busse ◽  
Frans Palmert ◽  
Paul Wawrzynek ◽  
Björn Sjödin ◽  
David Gustafsson ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Crack Growth ◽  
Driving Force ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Mode I ◽  
Force Parameter ◽  
Intensity Factors ◽  
Crack Driving Force

Single-crystal nickel-base superalloys are often used in the hot sections of gas turbines due to their good mechanical properties at high temperatures such as enhanced creep resistance. However, the anisotropic material properties of these materials bring many difficulties in terms of modelling and crack growth prediction. Cracks tend to switch cracking mode from Mode I cracking to crystallographic cracking. Crystallographic crack growth is often associated with a decrease in crack propagation life compared to Mode I cracking and this must be taken into account for reliable component lifing. In this paper a method to evaluate the crystallographic crack propagation rate related to a crystallographic crack driving force parameter is presented. The crystallographic crack growth rate is determined by an evaluation of heat tints on the fracture surface of a specimen subjected to fatigue loading. The complicated crack geometry including two crystallographic crack fronts is modelled in a three dimensional finite element context. The crack driving force parameter is determined by calculating anisotropic stress intensity factors along the two crystallographic crack fronts by finite-element simulations and post-processing the data in a fracture mechanics tool that resolves the stress intensity factors on the crystallographic slip planes in the slip directions. The evaluated crack propagation rate shows a good correlation for both considered crystallographic cracks fronts.

scholarly journals Investigation on brittle crack propagation and arrest behaviour under high crack driving force in steel

2018 ◽  
Vol 13 ◽  
pp. 116-122
Author(s):  
Fuminori Yanagimoto ◽  
Kazuki Shibanuma ◽  
Teppei Okawa ◽  
Katsuyuki Suzuki ◽  
Shuji Aihara
Keyword(s):  
Crack Propagation ◽  
Driving Force ◽  
Brittle Crack ◽  
Crack Driving Force ◽  
High Crack ◽  
Crack Propagation And Arrest

Experimental Measurement of CTOA During Ductile Crack Propagation in Pipeline Burst Tests

2018 ◽  
Author(s):  
Kazuki Shibanuma ◽  
Hikaru Yamaguchi ◽  
Takahiro Hosoe ◽  
Katsuyuki Suzuki ◽  
Shuji Aihara
Keyword(s):  
Steady State ◽  
Crack Propagation ◽  
Crack Velocity ◽  
High Speed ◽  
Crack Arrest ◽  
Opening Angle ◽  
Small Scale ◽  
Outer Diameter ◽  
Burst Test ◽  
Pipe Burst

Dynamic measurement of drop-weight tear test (DWTT) and pipe burst test for 356 mm outer diameter and 9.5 mm wall thickness steel pipe were conducted using high-speed camera. Crack velocity in the DWTT were 10 m/s during the steady state. Crack Tip Opening Angle (CTOA) values measured in the DWTT showed the constant value of about 20.1° during steady state propagation. On the other hand, crack velocity in the burst test showed monotonically decreasing during crack propagation from 200 m/s but it was found that CTOA value kept constant value of about 13.2° until crack arrest irrespective of the crack velocity. These results showed the validation of the CTOA criterion for the high-pressure gas pipelines. The results also showed that CTOA in a burst test is generally different from that in a test using small-scale specimen. Future developments of the experimental procedure using a small-scale specimen to provide CTOA value corresponding with that in a burst test would be effective.

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