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PRCI Report 182
- The Use of Flattened Specimens to Measure Charpy V-Notch Impact Properties of Thin-Wall Pipe
- Report / Survey by Pipeline Research Council International, 01/01/1989
- Publisher: PRCI
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L51605e
CORRENG Consulting Service Inc.
Need: Interest in the use of high-strength thin-wall pipe in gas transmission service is increasing. This interest has resulted in the demand for a better method for evaluating the toughness of thin-wall pipe, pipe from which it is not possible to extract either a full-size or a 2/3-size non-flattened Charpy V-notch (CVN) impact specimen.
Result: The objective of the investigation described in this report was to determine whether the use of flattened specimens provides a reliable way to measure the CVN impact properties of thin-wall pipe. Sixteen thin-wall pipes from which non-flattened 2/3-size specimens could not be obtained were evaluated to determine CVN impact properties using flattened full-wall-thickness specimen, flattened 2/3-size specimens, and non-flattened 1/2-, 1/3-, or 1/4-size (sub size) specimens. Properties were also evaluated with pressed-notch drop-weight- tear test (DWTT) specimens to provide a base for comparison; these specimens are full wall thickness. Nominal pipe wall thickness ranged from 0.312 to 0.156 inch.
Benefit: The results of the present study provide considerable support for the use of flattened full-wall-thickness (or flattened 2/3-size) CVN specimens rather than non-flattened sub size CVN specimens when evaluating the toughness of thin-wall pipe. Flattened full-wall-thickness specimens provide a better estimate of ductile-to-brittle transition behavior than do non-flattened sub size specimens based on comparison with the results of drop-weight-tear tests while USE values when adjusted to anticipated full-size values are comparable. Strain introduced during flattening has relatively little effect on impact properties in contrast to the well-documented effect of reducing the specimen thickness.
CORRENG Consulting Service Inc.
Need: Interest in the use of high-strength thin-wall pipe in gas transmission service is increasing. This interest has resulted in the demand for a better method for evaluating the toughness of thin-wall pipe, pipe from which it is not possible to extract either a full-size or a 2/3-size non-flattened Charpy V-notch (CVN) impact specimen.
Result: The objective of the investigation described in this report was to determine whether the use of flattened specimens provides a reliable way to measure the CVN impact properties of thin-wall pipe. Sixteen thin-wall pipes from which non-flattened 2/3-size specimens could not be obtained were evaluated to determine CVN impact properties using flattened full-wall-thickness specimen, flattened 2/3-size specimens, and non-flattened 1/2-, 1/3-, or 1/4-size (sub size) specimens. Properties were also evaluated with pressed-notch drop-weight- tear test (DWTT) specimens to provide a base for comparison; these specimens are full wall thickness. Nominal pipe wall thickness ranged from 0.312 to 0.156 inch.
Benefit: The results of the present study provide considerable support for the use of flattened full-wall-thickness (or flattened 2/3-size) CVN specimens rather than non-flattened sub size CVN specimens when evaluating the toughness of thin-wall pipe. Flattened full-wall-thickness specimens provide a better estimate of ductile-to-brittle transition behavior than do non-flattened sub size specimens based on comparison with the results of drop-weight-tear tests while USE values when adjusted to anticipated full-size values are comparable. Strain introduced during flattening has relatively little effect on impact properties in contrast to the well-documented effect of reducing the specimen thickness.
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