In-situ repairs of pipelines using metal arc welding under oil (MAW-UO) aided by eddy current crack detection

Almostaneer, Hamad; Jones, Zachary S.; Liu, Stephen V.; Olson, D. L.

doi:10.1063/1.4716361

Cited by 2 publications

(4 citation statements)

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“…9 It is not self-sustaining and, therefore, requires a power supply to provide conditions for the generation of the plasma and to maintain the ionisation process. 1 Diatomic gases at low temperatures will behave as 'rigid rotators' as shown in Fig. 1a.…”

Section: Dissociation and Ionisationmentioning

confidence: 99%

“…Not only is welding the preferred process for joining pipeline segments during construction, it is also used for repair. 1 Metal arc welding under oil (MAW-UO) is an in situ repair process that can be used to conduct welding repairs on the inside wall of an in service pipeline, tank or vessel, with no operation interference or safety problems. 2 When fully deployed, the process will use an intelligent pig equipped with MAW-UO equipment.…”

Section: Introductionmentioning

confidence: 99%

“…For this reason, pipelines have gained importance in oil and gas transport. Not only is welding the preferred process for joining pipeline segments during construction, it is also used for repair 1…”

Section: Introductionmentioning

confidence: 99%

“…In arc welding, thermal ionisation due to the collision of agitated particles in the shielding gas predominates 9. It is not self-sustaining and, therefore, requires a power supply to provide conditions for the generation of the plasma and to maintain the ionisation process 1…”

Section: Introductionmentioning

confidence: 99%

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Hydrocarbon–metal reactions during metal arc welding under oil (MAW-UO)

Almostaneer

Cadigan

Liu

et al. 2011

Science and Technology of Welding and Joining

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Metal arc welding under oil is a new, revolutionary process for the repairs of pipelines which should minimise the need of hot tapping repairs and the construction of bypass lines. The process uses an automated metal arc welding set-up with a continuous wire feed. This process was developed for the in situ internal repairs of in service cross-country pipelines, tanks and vessels by using a smart pig with a modified mechanical design that allows for joint preparation and welding. The unique characteristics found in the under oil arc are discussed in detail. The large range of temperatures that exists between the arc at the order of 10 000uC (18 000uF) and the surrounding oil (ambient) allows for complex reactions between the oil hydrocarbon chains and the steel weld metal. These reactions may considerably impact the weld microstructure. Details of the dissociation of hydrocarbon chains and ionisation of the resulting species must be known to better control the process. In addition, vaporisation of the oil will form oil vapour bubble to surround the welding arc. The oil vapour bubble will also be high in decomposed products that can significantly affect the weld metal composition. Gas chromatography-mass spectrometry was used to investigate the behaviour of a welding arc under oil and the carbon pick-up. Analyses were conducted on oil samples with different welding exposure times to validate the arc behaviour mechanistic model and the gas chromatography-mass spectrometry analysis results.

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Section: Dissociation and Ionisationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations