scholarly journals J and CTOD Estimation Equations for Shallow Cracks in Single Edge Notch Bend Specimens

1993 ◽  
Vol 21 (4) ◽  
pp. 228 ◽  
Author(s):  
DR Petersen ◽  
MT Kirk ◽  
RH Dodds
Keyword(s):  
Single Edge ◽  
Single Edge Notch ◽  
Estimation Equations ◽  
Edge Notch ◽  
Single Edge Notch Bend

Warm Pre-Stressing and Leaks in Pipelines

2014 ◽  
Author(s):  
Andrew Cosham ◽  
Phil Hopkins ◽  
David G. Jones ◽  
Julian Barnett
Keyword(s):  
Beneficial Effect ◽  
Pipe Steel ◽  
Theoretical Models ◽  
Manganese Steel ◽  
Single Edge ◽  
Line Pipe ◽  
Single Edge Notch ◽  
Edge Notch ◽  
Line Pipe Steel ◽  
Single Edge Notch Bend

Line pipe steel is a carbon manganese steel. The toughness of line pipe steel undergoes a transition from high toughness (on the upper shelf) to low toughness (on the lower shelf) as the temperature decreases. A fluid will cool significantly as it expands through a leak in a pipeline. This has led to the suggestion that localised cooling of the material surrounding the leak might be sufficient to cool the material down to below the ductile to brittle transition temperature and cause a brittle fracture. Warm pre-stressing occurs when a load is applied to a structure containing a defect and then the temperature of the structure is reduced. Warm pre-stressing causes the defect in the structure to fail at a higher load at the lower temperature than if it had not experienced this prior loading at the previously higher temperature. A programme of single edge notch bend tests has been conducted on behalf of National Grid Carbon to demonstrate the beneficial effect of warm pre-stressing in a line pipe steel. The material tested was a sample of 914.4 mm outside diameter, 19.1 mm wall thickness, Grade API 5L X60 line pipe. Single edge notch bend specimens were subject to the ‘load-cool-fail’ cycle and the ‘load-unload-cool-fail’ cycle. The effect of different levels of stable ductile crack growth during the pre-load was also investigated. Warm pre-stressing is shown to have a beneficial effect. The load at failure in the specimens that had been subject to warm pre-stressing was higher than those that had not been subject to warm pre-stressing, and, in most cases, it was higher than the pre-load. The fracture toughness (in terms of the stress intensity factor) of the specimens that had been subject to warm pre-stressing was 1.4 to 1.7 times higher than that of those that had not been subject to warm pre-stressing. The results of the tests were conservatively predicted using the theoretical models. Also, the results are consistent with previous tests on structural steels. Therefore, localised cooling of the material around a leak in a pipeline is not predicted to result in a failure.

Fracture Toughness Estimation for Pipeline Girth Welds

2002 ◽  
Author(s):  
Henryk G. Pisarski ◽  
Colin M. Wignall
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Specimen Geometry ◽  
Single Edge ◽  
Single Edge Notch ◽  
Edge Notch ◽  
Loading Modes ◽  
Girth Welds ◽  
The Relationship ◽  
Single Edge Notch Bend

The relationship between fracture toughness estimated using standard single edge notch bend (SENB), single edge notch tension (SENT) test specimens and fracture toughness associated with a circumferential flaw in a pipe girth weld is explored in terms of constraint using the Q parameter. It is shown that in the elastic-plastic regime, use of standard deeply notched SENB specimens provides a conservative assessment of fracture toughness, for both weld metal and HAZ, because of the high constraint associated with this specimen geometry. Use of specimen geometries and loading modes associated with lower constraint (e.g. SENT and shallowed notched SENB specimens), allow for improved estimates of fracture toughness to be made that are appropriate for the assessment of circumferential flaws in pipe girth welds. Recommendations are given on the specimen designs and notch orientations to be employed when evaluating weld metal and HAZ fracture toughness.

Rotation Corrections in Three-Point Single Edge Notch Bend Specimens

1989 ◽  
Vol 17 (6) ◽  
pp. 381 ◽  
Author(s):  
A Wolfenden ◽  
JE Perez Ipiña ◽  
EL Santarelli
Keyword(s):  
Single Edge ◽  
Single Edge Notch ◽  
Edge Notch ◽  
Single Edge Notch Bend

The use of an eccentric compressive load to aid in precracking single edge notch bend specimens

1993 ◽  
Vol 12 (16) ◽  
pp. 1258-1260 ◽  
Author(s):  
D. A. Dillard ◽  
P. R. McDaniels ◽  
J. A. Hinkley
Keyword(s):  
Compressive Load ◽  
Single Edge ◽  
Single Edge Notch ◽  
Edge Notch ◽  
Single Edge Notch Bend

The use of the C∗ parameter in predicting creep crack propagation rates

1977 ◽  
Vol 12 (3) ◽  
pp. 167-179 ◽  
Author(s):  
M P Harper ◽  
E G Ellison
Keyword(s):  
Crack Propagation ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Single Edge ◽  
Single Edge Notch ◽  
Creep Crack ◽  
Edge Notch ◽  
Single Edge Notch Bend ◽  
Good Agreement

The applicability of the C∗ parameter for the prediction of creep crack propagation rates is considered. A new method for estimating C∗ is presented, the results from which show good agreement with those from an existing technique. Experimental results from creep crack growth tests, conducted on a 1 Cr Mo V steel using both compact tension and single edge notch bend specimens, indicate that good correlation with C∗ is obtained once the effects of stress redistribution become negligible. Finally, comparisons are drawn between C∗ and other possible correlating parameters, and the limitations of each approach are discussed.

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