Crack Growth in Microalloyed Pipeline Steels for Sour Gas Transport

2005 ◽  
Vol 14 (2) ◽  
pp. 224-228 ◽  
Author(s):  
S. Serna ◽  
B. Campillo ◽  
J.L. Albarrán
Keyword(s):  
Crack Growth ◽  
Gas Transport ◽  
Pipeline Steels ◽  
Sour Gas

A Single Specimen CTOA Test Method for Evaluating the Crack Tip Opening Angle in Gas Pipeline Steels

2004 ◽  
Author(s):  
Sayyed H. Hashemi ◽  
Ian C. Howard ◽  
John R. Yates ◽  
Robert M. Andrews ◽  
Alan M. Edwards
Keyword(s):  
Steady State ◽  
Crack Growth ◽  
Crack Tip ◽  
Gas Pipeline ◽  
Test Method ◽  
Opening Angle ◽  
Single Specimen ◽  
Data Set ◽  
Test Technique ◽  
Pipeline Steels

Failure information from recent full-scale burst experiments on modern TMCP gas pipeline steels having a yield strength level of 690MPa and higher has shown that the CTOA fracture criterion can be effectively used to predict the arrest/propagation behaviour of the pipe against possible axial ductile fractures. The use of CTOA as an alternative or an addition to the Charpy V-notch and DWTT fracture energy in pipelines is currently under review. A significant difficulty currently limiting the more extensive use of CTOA in pipeline assessment is its practical evaluation either in the real structure or in a laboratory scale test. Different combinations of experimental and finite element analyses have been proposed for the measurement of the CTOA of a material. Although most of these models are able to predict the CTOA effectively, their implementation requires extensive calibration processes using the test load-deflection data. The authors have recently developed a novel test technique for direct measurement of the steady state CTOA using a modified double cantilever beam geometry. The technique uses optical imaging to register the uniform deformation of a fine square grid scored on the sides of the specimen. The slope of the deformed gridlines near the crack tip is measured during crack growth from captured images. Its value is a representative of the material CTOA. This paper presents recent results from the implementation of the technique to determine the steady state CTOA (steady state in this work refers to regions of ductile crack growth where CTOA values are constant and independent of crack length) of API X80 and X100 grade gas pipeline steels. In each case the approach was able to produce large amounts of highly consistent CTOA data from both sides of the test sample even from a single specimen. This extensive data set allowed an evaluation of the variance of the stable CTOA as the crack grew through the microstructure. The test method generated a steady CTOA value of 11.1° for X80 and 8.5° for X100 steels tested, respectively.

Sour gas transport in poly(ether-b-amide) membranes for natural gas separations

2020 ◽  
Vol 595 ◽  
pp. 117497 ◽  
Author(s):  
Daniel J. Harrigan ◽  
John Yang ◽  
Benjamin J. Sundell ◽  
John A. Lawrence ◽  
Jeremy T. O'Brien ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Transport ◽  
Gas Separations ◽  
Sour Gas

The Effect of Microstructure on the Hydrogen-Assisted Fatigue of Pipeline Steels

2013 ◽  
Author(s):  
Andrew J. Slifka ◽  
Elizabeth S. Drexler ◽  
Douglas G. Stalheim ◽  
Robert L. Amaro ◽  
Damian S. Lauria ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
High Pressures ◽  
Load Ratio ◽  
Fatigue Tests ◽  
Hydrogen Gas ◽  
The Other ◽  
Stress Intensity Factor Range ◽  
Pipeline Steels

Tests on the fatigue crack growth rate were conducted on four pipeline steels, two of grade API 5L-X52 and two API 5L-X70. One X52 material was manufactured in the mid-1960s and the other was manufactured in 2011. The two X70 materials had a similar vintage and chemistry, but the microstructure differs. The fatigue tests were performed in 5.5 and 34 MPa pressurized hydrogen gas, at 1 Hz and (load ratio) R = 0.5. At high pressures of hydrogen and high values of the stress intensity factor range (ΔK) there is no difference in the fatigue crack growth rates (da/dN), regardless of strength or microstructure. At low values of ΔK, however, significant differences in the da/dN are observed. The older X52 material has a ferrite-pearlite microstructure; whereas, the modern X52 has a mixture of polygonal and acicular ferrites. The X70 materials are both predominantly polygonal ferrite, but one has small amounts (∼5%) of upper bainite, and the other has small amounts of pearlite (<2%) and acicular ferrite (∼5%). We discuss the fatigue test results with respect to the different microstructures, with particular emphasis on the low ΔK regime.

Effect of hydrogen and low temperature on fatigue crack growth of pipeline steels

2013 ◽  
Vol 103 ◽  
pp. 10-25 ◽  
Author(s):  
P. Fassina ◽  
M.F. Brunella ◽  
L. Lazzari ◽  
G. Re ◽  
L. Vergani ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Low Temperature ◽  
Crack Growth ◽  
Pipeline Steels

A New Method on Low-Cycle Corrosion Fatigue of Pipelines Taking Strain as Parameter

2011 ◽  
Vol 391-392 ◽  
pp. 323-327
Author(s):  
Wen Jun Bi ◽  
Yong Zhu ◽  
Ying Jin
Keyword(s):  
Crack Growth ◽  
Corrosion Fatigue ◽  
Gas Transport ◽  
Experimental Results ◽  
New Method ◽  
Growth Speed ◽  
Nacl Solution ◽  
The West ◽  
Transport Project ◽  
Welded Pipe

As for the more and more severe corrosion fatigue of pipelines in service and the results of the former analyzing means and tests, a new method was brought forward to study the low-cycle corrosion fatigue by using a large pure-bended sample (480 mm×38 mm×12 mm). The experimental samples were obtained from the gas-transmission spiral welded pipe (X65) used in the west-east gas transport project of China. The experiential formula about crack growth speed, , is established via the experimental results under two different environments of air and 3% NaCl solution, and the two constants of a and b were identified.

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