Technical Presentations at the July 2014 Meeting

1.1   CP Strategies for FPSOs’, Alex Delwiche, Deepwater EU Ltd

This presentation discussed how many FPSOs utilise existing ICCP systems that are used for ship board systems. Some of the pitfalls of these systems is that the life of these systems are short, as many ships are frequently dry docked, which is not possible for FPSOs on station; the ICCP systems for the hull work compete against sacrificial anodes that would be mounted on the turrets causing downtime of the ICCP systems and shortened life of the turret anodes. There are losses to risers and anchor chains that often aren't considered in any CP design process that then cause issues in the field. In addition the cathodic protection design lives are typically 10 years but in actuality the life of the FPSOs on station is often extended well beyond this time.


1.2   ‘Assessing the Corrosion Rates of World War I and II Royal Navy Shipwrecks', Matt Skelhorn & Jamie Johnson, Salvage & Marine Operations, MoD

Salvage and Marine Operations (S&MO) are responsible for managing the safety and environmental concerns associated with the ammunition and oil remaining on approximately 4000 post-1870 Ministry of Defence (MOD) owned wrecks.

As the wrecks decay over time there is an increasing potential for the oil and ammunition to escape from them. S&MO are therefore seeking to develop a greater understanding of the rates at which the wrecks are corroding in order to identify those that are at greatest risk of collapse. This presentation examines the work carried out to date on a cross section of wrecks lying in Scapa Flow as well as examining possible future strategies.

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

 

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4.1  ‘The Resistance of Stainless Steels to MIC’, Roger Francis, RF Materials

Microbially influenced corrosion, or MIC, has been causing failures of stainless steels for many years. The mechanisms that cause this and the factors that exacerbate it were discussed. It was concluded that all 300 series austenitic alloys can suffer MIC and this can occur at chloride concentrations below the normal limit that applies in sterile solutions. Higher alloys, such as 904L and 2205 duplex have worked in some lower chloride waters, but have suffered rapid failure in some higher chloride waters. Hence, the resistance of these alloys to MIC must be regarded as marginal. Alloys with a PREN>40, such as Zeron 100 superduplex and AL6XN super austenitic, have performed well even in aggressive environments, and there are no known failures due to MIC of these alloys. Some successful applications of superduplex and super austenitic alloys were described.

[This review was written for Rolled Alloys and a copy can be obtained from the author at rfrancis@rfmaterials.com]
 

4.2    ‘Advances in the Inspection and Assessment of Corrosion in Engineering Structures’, Shaun Smalley & Alex McLay, TUV Rheinland Sonovation Ltd

The presentation was on the advances in NDT regarding the use of advanced digital technologies. Explanations were given on modern ultrasonic techniques for Corrosion Under Insulation, High temperature on line inspections, fast screening corrosion mapping, Oil well conductor inspection and the latest software reporting aids. 

 

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