Technical Presentations at the April 2016 Meeting

1.1  ‘Developments in Coating Inspection Methods’, John Fletcher, Elcometer (President of ICorr)

Good coating application practise results in significant improvements in the service life of a protective coating. A number of new and improved inspection methods for protective coating processes have been introduced over the last two years and these apply to many of the stages in the protective coating application process.

Material thickness measurement using ultrasound to assess the thickness of the steel surface when surveying a steel structure prior to applying a protective coating makes maintenance painting a more effective process. Does the steel meet the structural requirements and therefore can be re-painted or does the steel need to be replaced to restore the integrity of the structure? New ultrasonic gauges have been developed for Material Thickness (MTG) and Precision Thickness (PTG) measurement.

Assessing the soluble salt concentration of a blast cleaned steel surface is critical to the protective coating process. The saturated filter paper method allows the soluble salt contamination level to be determined swiftly on the blast cleaned steel. The conductivity meter has been developed to include a matrix of contacts so that trends within the area of the filter paper can be measured.

The prevailing climatic conditions can be determined quickly and accurately using an electronic hygrometer and the conditions can be monitored to ensure that the surface temperature is always at least 3° C above the Dewpoint Temperature.

The collection of dry film thickness data needs to be achieved quickly and accurately and a scanning probe has been developed to allow readings to be collected and stored electronically at a rate which is up to 10 times quicker than the traditional place and read probe.

Control of the adhesion testing method leads to more consistent results and closer observance of the standard test methods. An automated adhesion tester has been developed to apply the pull force at a controlled rate at the push of a single button.

These digital test instruments allow data to be transferred to Digital Data Management Software for further analysis, simple and quick reporting of combined date and archiving.

The new digital testing methods will be described and the common approach to data management will be highlighted.

Key words: Inspection methods, protective coatings, material thickness, soluble salt determination, climatic monitoring, dry film thickness, adhesion, digital data management.

[Elcometer Limited, Edge Lane, Manchester M43 6BU,]

[A pdf of this presentation has kindly been supplied and is available to members from the Secretariat]

1.2 ‘Internal Corrosion Issues within Offshore Wind Monopile Foundations’, Claire Canning, EDF Energy/IDCORE

The impact of internal corrosion on offshore wind turbine foundations is considered to be a key issue in terms of operation and maintenance (O&M) which must be better addressed. The majority of offshore wind farms currently use monopile foundations to support the turbines.

Early design assumptions for monopiles determined that no corrosion protection was required for the internal surfaces since they should be completely sealed and water tight, and therefore corrosion would cease quickly once oxygen was consumed in the confined space. However, it is becoming increasingly apparent that this air/water-tight design is difficult to achieve in practice; with many foundations experiencing significant internal leakages through failing export cable seals, and oxygen ingress during ventilation. The primary concern is that this situation replenishes corrosive species within the monopile and may accelerate corrosion of the internal surfaces.

The implementation of internal cathodic protection has given rise to several additional challenges in many wind farms; namely the production of dangerous levels of hydrogen gas, the requirement for ventilation, acidification of internal seawater, and significant zones of under/overprotection. These issues are discussed in a case study of Teesside Offshore Wind Farm; a 62.1MW installation of 27 2.3 Siemens turbines situated in the North-East of England, which is owned and operated by EDF Energy.

[A pdf of this presentation has kindly been supplied and is available to members from the Secretariat]

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1.3   ‘New Duplex Stainless Steel for Line Pipe Material in Slightly Sour Environment’, Toshio Mochizuki NSSMC

The weldable super martensitic stainless steels and duplex stainless steels have been widely applied especially to the sub-sea flow lines, which transport the hydro-carbon containing the corrosive wet CO2/H2S gas.

It is reported that the heat affected zone (HAZ) of weldable super martensitic can be susceptible to the stress corrosion cracking (SCC) in sweet environment at elevated temperatures. It is widely recognized that post weld heat treatment (PWHT) is beneficial to avoid the SCC in HAZ, however, the PWHT might have the negative impact in the efficiency of laying operations in some cases. Although the duplex stainless steel such as 22Cr (UNS S31803) and 25Cr super duplex (UNS S39274) can be applied in as-welded condition, these higher grade materials would be considered to have a higher impact in capital expenditure (capex).

Recently, the new duplex stainless steel which can be applicable in as-welded condition through its sufficient resistance to SCC in a slightly sour condition at elevated temperature has been developed. In this presentation, the concept of alloy design to maintain the sufficient properties in as-welded condition is explained. The newly developed duplex stainless steel consists of 25Cr-5Ni-1Mo-2.5Cu-0.2N chemical compositions. The corrosion performances of the newly developed duplex stainless steel including the welded joint are also discussed.

[A pdf of this presentation has kindly been supplied and is available to members from the Secretariat]

3.1    ‘200 Year Old Technology Still Delivering Hard to Beat Cost Effective Protection - how the excitement of new technology risks us overlooking the continuing advantages of the old’, Geoff Crowley, Highland Galvanizers & Colour Coaters

Hot dip galvanizing is old technology. While new technology should be welcomed, we should not abandon those that continue to deliver performance and cost effectiveness.

The process has been commercially available for over 150 years, and is relatively inexpensive, but is confined to being a factory process not suitable for site application.

Galvanizing is a system of both barrier and sacrificial protection and involves an alloyed coating of zinc onto all surfaces of steel. Typical thickness of coating is 100 microns.

The process is well documented elsewhere, but there’s less information available about its performance in marine situations. In seawater galvanizing offers typically 4-20 years corrosion protection, the lower is warmer climates. Performance can be quite location dependent. On land galvanizing offers between 30 and 100 years protection (to first rust).

Galvanizing is not well used in the UK, and especially in Scotland. Most European countries use 3-5 times the amount of galvanizing per capita than Scotland despite the higher corrosion opportunity in that country. A UK map of life expectancy of galvanizing is available.

[A pdf of this presentation has kindly been supplied and is available to members from the Secretariat]

3.2   ‘Effective Implementation of Asset Integrity Management Systems with Visualisation Tools’, Jozef Soltis, MACAW Engineering Ltd

The concept of Integrity Management Systems is not new and in general, any of such systems are meant to provide operators with a safe working environment, production yields and profitability. Whilst most of the tools required for corrosion management do already exist, it is their actual implementation and cross-communication (for a number of different reasons) that seems to be a challenge.

For instance, traditionally, topside process plants and related subsea pipelines would maintain separate management schemes for their assets’ daily operations, and fail and/or ignore to recognise a possible interdependence between topside and subsea components. Consequently, such an approach often leads to the overall corrosion management being dysfunctional, with key integrity activities not being rightly implemented, and/or being ineffective and management activities often increasing operational costs from the asset’s integrity point of view. One possibility to overcome such complications is through integration of all integrity management activities within a given production field into a singular place.

A continuously evolving system (i.e. AIVT) has been developed to allow for such a holistic approach, with the aim to facilitate the operator with a dynamic visualisation of assets’ integrity, along with corrosion risks, status of the key integrity management activities, as well as assist with integrity decision-making.

[A pdf of this presentation has kindly been supplied and is available to members from the Secretariat]

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