Comparison of fracture tougness of curved and flat CT specimens for the gas pipeline integrity management

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378297%3A_____%2F14%3A00437767" target="_blank" >RIV/68378297:_____/14:00437767 - isvavai.cz</a>

Výsledek na webu

—

DOI - Digital Object Identifier

—

Jazyk výsledku

angličtina

Název v původním jazyce

Comparison of fracture tougness of curved and flat CT specimens for the gas pipeline integrity management

Popis výsledku v původním jazyce

When examining the integrity of thin-walled pressure pipelines, we face the problem of ensuring the flatness of the semi-products used for manufacture of fracture specimens. The only available way is the straightening of pipeline bands. Due to plastic strains the semiproduct is exposed to during the straightening process, this operation brings internal stresses not only into the semi-product subjected to straightening but also to finished specimens. This is why some fracture mechanical researchers contest the validity of fracture toughness values obtained on specimens made from straightened semi-products although it has been verified by experiments on several pipeline bodies that the prediction of fracture conditions of cracked pipelines, based on fracture toughness values determined on straightened specimens, is relatively exact and reliable. This paper deals with the problem of the effect of straightening of pipeline bands taken from a gas linepipe on the fracture toughness of finished fracture-mechanics specimens. Some aspects of this issue have already been discussed at the gas industry colloquium [1]. As it is known (e.g. [2], [3]), the fracture toughness may be described by J integral values Jin, J0.2 or Jm where Jin is the so called initiation value of the J integral for the stable subcritical crack growth, J0.2 is the value of the J integral corresponding to the actual crack growth a = 0.2 mm at a stable monotonic loading and Jm is the value of the J integral that corresponds to the achievement of the maximum force on the „force – force point displacement“ curve. When verifying the straightening effect on the fracture toughness properties, the objective was (i) to construct the so called R curves [4] both for specimens made from straightened pipeline bands and for curved specimens with natural pipe curvature loaded by a tangential force and (ii) to compare the magnitudes of the fracture parameters for both types of CT specimens.

Název v anglickém jazyce

Comparison of fracture tougness of curved and flat CT specimens for the gas pipeline integrity management

Popis výsledku anglicky

When examining the integrity of thin-walled pressure pipelines, we face the problem of ensuring the flatness of the semi-products used for manufacture of fracture specimens. The only available way is the straightening of pipeline bands. Due to plastic strains the semiproduct is exposed to during the straightening process, this operation brings internal stresses not only into the semi-product subjected to straightening but also to finished specimens. This is why some fracture mechanical researchers contest the validity of fracture toughness values obtained on specimens made from straightened semi-products although it has been verified by experiments on several pipeline bodies that the prediction of fracture conditions of cracked pipelines, based on fracture toughness values determined on straightened specimens, is relatively exact and reliable. This paper deals with the problem of the effect of straightening of pipeline bands taken from a gas linepipe on the fracture toughness of finished fracture-mechanics specimens. Some aspects of this issue have already been discussed at the gas industry colloquium [1]. As it is known (e.g. [2], [3]), the fracture toughness may be described by J integral values Jin, J0.2 or Jm where Jin is the so called initiation value of the J integral for the stable subcritical crack growth, J0.2 is the value of the J integral corresponding to the actual crack growth a = 0.2 mm at a stable monotonic loading and Jm is the value of the J integral that corresponds to the achievement of the maximum force on the „force – force point displacement“ curve. When verifying the straightening effect on the fracture toughness properties, the objective was (i) to construct the so called R curves [4] both for specimens made from straightened pipeline bands and for curved specimens with natural pipe curvature loaded by a tangential force and (ii) to compare the magnitudes of the fracture parameters for both types of CT specimens.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

20306 - Audio engineering, reliability analysis

Projekt

<a href="/cs/project/GAP105%2F10%2F2052" target="_blank" >GAP105/10/2052: Poškozující napětí pod mezí únavy určená změnami magnetické permeability</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2014

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

IGRC International Gas Union Research Conference Copenhagen

ISBN

—

ISSN

0736-5721

e-ISSN

—

Počet stran výsledku

10

Strana od-do

"WP3"-"44"

Název nakladatele

International Gas Union

Místo vydání

Kodaň

Místo konání akce

Kodaň

Datum konání akce

17. 9. 2014

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

—