NDTnet 1998 Aug, Vol.3 No.8

Full-Text - Abstract

Hydrogen in steel is known to have a devastating effect on strength and integrity, and may result in internal fissuring, loss of ductility and cracking.

Hydrogen may be introduced into the steel at ambient temperatures as a result of electrochemical reactions, such as acid pickling, plating and corrosion. In oxygen free, wet H₂S environments, as frequently encountered in the oil and gas industry, the corrosion process involves discharging of hydrogen ions at the corroding surface, and part of the liberated hydrogen atoms are absorbed into the steel substrate as interstitial atoms. The hydrogen concentration gradient leads to a measurable H-flux through the steel.

Hydrogen induced damage in the form of laminar cracking, stepwise cracking and stress oriented cracking are, therefore, briefly discussed. Hydrogen permeation data are presented and compared with hydrogen concentration profiles and hydrogen induced cracking behaviour. A concept for monitoring the hydrogen permeation flux/concentration on refinery vessels in service in order to evaluate the need for ultrasonic testing will be described. The general principle in the concept is illustrated in the Figure below.

Fig.: The risk of hydrogen induced damage as function of H-flux.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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