Archives du mot-clef welded tube

Fatigue cracking of high pressure oil tube

Publié le par
Répondre

1-s2-0-s2213290213000321-gr1An article about a Case study of failure analysis published in « Case Studies in Engineering Failure Analysis« , July 2013.

A high pressure oil tube with nominal diameter 50.8 mm and nominal thickness 4 mm has prematurely failed with a longitudinal crack. The failure was detected after 11 months of operation. The tube is part of the hydraulic power unit of an off shore oil and gas platform. The maximum designed internal pressure was 20 MPa and the service temperature was 25 °C with no significant variation. In practice, the internal pressure varies from 16 to 20 MPa under operation, and shutdowns rarely occur.

Read more

Cracking of underground welded steel pipes caused by HAZ sensitization

Publié le par
Répondre

An article on case study, published in « Case Studies in Engineering Failure Analysis« , on january 2013.

Low alloy steel welded pipes buried in the ground were sent for failure analysis investigation. Failure of steel pipes was not caused by tensile ductile overload but resulted from low ductility fracture in the area of the weld, which also contains multiple intergranular secondary cracks. The failure is most probably attributed to intergranular cracking initiating from the outer surface in the weld heat affected zone and propagated through the wall thickness.

Read more ….

Corrosion of Welded Joint in Alloy Steel Pipe

Publié le par
Répondre

2015-11-15_10h33_54An interesting article published on 4 November 2015 in the International Journal of ELECTROCHEMICAL SCIENCE.

In this paper an investigation on corrosion behaviour of welded joints was performed to facilitate determination the causes of preferential degradation by corrosion of the welded metal (WM) and the heat affected zone (HAZ), in a welded pipeline of grade ASTM A355P5, used in a petrochemical plant as transfer line between a thermal cracking heater and a column which are part of an atmospheric distillation and vacuum (DAV) unit. It was found that the corrosion of the weld analyzed in this research has resulted due to its dendritic structure (pearlite, ferrite, complex carbide, bainite and martensite in localized areas), which reveals the lack of post welding heat treatment (PWHT). Read more …..

 

Fatigue cracking of high pressure oil tube

Publié le par
Répondre
  • High pressure pipe failed by fatigue in the fusion line of longitudinal weld.
  • Fatigue was caused by vibration of the line due to clamp missing.
  • Crack initiated and propagated through the high concentration region of weld joint.
  • Change of specified material (UNS S31803) by AISI 304L contributed to the failure.
  • As recommendation, seamless tube of duplex stainless steel must be used.

More informations : Fatigue cracking of high pressure oil tube.