Recommended Specimen Dimensions and Boundary Conditions for Measurement of Hydrogen Permeation in Thick Carbon Steel Plates

• Published in: Corrosion (Houston, Tex.) Vol. 71; no. 5; pp. 585 - 597
• Main Authors: Traidia, A, El-Sherik, A M, Attar, H
• Format: Journal Article
• Language: English
• Published: Houston NACE International 01.05.2015
• Subjects: Boundary conditions; Carbon steel; Carbon steels; Corrosion; Diffusion; Diffusion barriers; Diffusion effects; Diffusion plating; Dimensional measurements; Dimensions; Finite element method; Heat treatment; Heat treatments; Hydrogen; Hydrogen charging; Hydrogen permeation; Laboratories; Lateral diffusion; Mathematical analysis; Mathematical models; Penetration; Pipelines; Steel plates; Thick plates; USA, Texas, Houston
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1327

The present work discusses the influence of specimen dimensions and boundary conditions on the deviation towards 2D diffusion during hydrogen permeation measurements on thick carbon steel plates. It was mathematically found and experimentally confirmed that hydrogen losses through lateral diffusion could significantly affect the validity of laboratory measurements on thick plates, since the common 1D simplification of diffusion equations is no longer valid. Based on a finite element analysis, two options are proposed to minimize the effects of side diffusion on permeation measurements. The first option, which encompasses ISO 17081 criteria, recommends optimum radii for hydrogen charging and extraction surfaces and is valid for a wide range of specimen thicknesses. The second option relies on modification of boundary conditions and consists of applying a hydrogen-diffusion barrier on the specimen side edges. This second option was experimentally tested and validated by means of an oxide layer deposited using a heat treatment. The present paper will describe in detail the mathematical modeling and experimental approaches and the basis for our recommendation.