About the Project
Corrosion fatigue of carbon/low alloy steel pipelines and risers in corrosive (high CO₂ and/or H₂S, wet) service takes time to develop, during which period, corrosion products (scale) will likely form on the surface. These corrosion products will affect the interaction of the environment with the surface, and are likely to affect the initiation of corrosion fatigue cracks. This is further complicated by the presence of chemical corrosion inhibitors added to help control the corrosion of the carbon/ low alloy steel. Corrosion fatigue endurance tests are commonly carried out over a spread of stress ranges which allow a plot of stress range: life (an S-N plot) to be produced.
Owing to time constraints, most of the data points on these curves are generated at a relatively high stress range, and therefore may be completed before any significant surface scaling has had time to take place. It is important to understand the effect of corrosion products on the initiation and development of corrosion fatigue cracks in typical oil & gas environments, so that test data can be applied with confidence. In addition, if it is shown that the effect is significant, it would be advantageous to have a technique available for accelerated development of the relevant corrosion scale/s, which could be applied to at least some specimens prior to application of cyclic loading.
The end goal of this project is to understand the significance of surface scaling on corrosion fatigue crack initiation and development, and to indicate how testing protocols may be developed to best simulate oil & gas environments.
A thorough literature survey shall be undertaken on the effects of prior corrosion on corrosion fatigue performance, and also the effects of environmental variables (solution composition, gas partial pressure, temperature, corrosion inhibition) on the nature of the scales produced. Reported techniques for accelerating scaling (through, for example, electrochemical polarisation) will be researched.
An initial experimental phase of work will consist of exploring the effects of pre-corrosion on fatigue endurance using two stress ranges. Both sweet (CO₂ only) and sour (containing H₂S) environments will be used, with some variation in solution composition designed to produce different types of corrosion product. An evaluation of the role of corrosion inhibition shall also be undertaken. Depending on the results of these tests, techniques for accelerating the development of corrosion products will be explored for possible application as a pre-conditioning technique for corrosion-fatigue testing.
A number of fully-funded PhD scholarships are available for suitable candidates with a strong interest in fundamental and applied research in the area of structural integrity. Scholarships cover an amount to £16,000 per annum for 3 years, Home/EU tuition fees and support for research. Overseas applicants are welcomed, with total funding capped at £20k/year. Please be aware that tuition fees for International students are between £16k - £20k per year.
Candidates should have a relevant degree at 2.1 minimum or an equivalent overseas degree in mechanical, Electrical/Electronics or Civil/Structural Engineering, Material Science, Metallurgy or Physics. Candidates with suitable work experience and strong capacity in numerical modelling and experimental skills are particularly welcome to apply. Overseas applicants should also submit IELTS results (minimum 6.5) if applicable.
About NSIRC
NSIRC will be a state-of-the-art postgraduate engineering facility established and managed by structural integrity specialist TWI, working closely with lead academic partner Brunel University, the universities of Cambridge, Manchester, Loughborough, Birmingham, Leicester and a number of leading industrial partners. NSIRC aims to deliver cutting edge research and highly qualified personnel to its key industrial partners.
For more information about The National Structural Integrity Research Centre, visit www.nsirc.co.uk
Please direct general enquiries to: [Email Address Removed]
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