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Quick Note

Another SRB Resistant SS Anchor

The sulphate cliffs of Cabo da Roca demolish stainless steel. This fixed hanger is an exception. Many thanks to Luis Fernandes Silva for the sample. To date, the main thrust of this blog has been to attribute the extreme corrosivity of sulphate crags to the action of sulphate reducing bacteria (SRB). It has been observed […]

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Multi-Part Report

Corrosion at Cabo da Roca -6

Origin of Sulphur The sixth part of a multi-part series Introduction: It has been my observation that, almost without exception, highly corrosive sea cliffs are associated with very high levels of sulphate, either coating the rock surface, or oozing from the groundwater. Further to this fact is the observation that, in almost all cases, an […]

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Short Report

Now This Is Different

An example of an SS anchor chain exhibiting marked resistance to SRB attack Many thanks to Luis Fernandes Silva for the sample. On previous occasions I have reported on the sulphate-rich sea cliffs of Cabo da Roca. They are notorious for the aggressive corrosion of low grade austenitic stainless steels such as 304 (A2). Sulphate […]

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Multi-Part Report

Corrosion at Cabo da Roca -5

Hydrogen Embrittlement THE FIFTH PART OF A MULTI-PART SERIES In conducting this work I have been greatly assisted by Luis Fernandes Silva and Rui Rosado who have provided multiple samples and photos for analysis. Luis has spent a great deal of time measuring spot-sulphate levels, and the pH profiles of the bolts that he has […]

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Quick Note

Go-slow at Crag Chemistry

Since the last post, events have overtaken your host that mean the already slow rate of posting is going to be even slower. Some three months ago I demonstrated my long held thesis that old climbers simply don’t see height as a hazard, and I took a long fall off an easy un-roped section I […]

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Multi-Part Report

Corrosion at Cabo da Roca – 4

We Find SRB Deep Inside the Bolt The fourth part of a multi-part series In conducting this work I have been greatly assisted by Luis Fernandes Silva and Rui Rosado who have provided multiple samples and photos for analysis. Luis has spent a great deal of time measuring spot-sulphate levels, and the pH profiles of […]

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Multi-Part Report

Corrosion at Cabo da Roca – 3

We Observe Brittle Fracture The third part of a multi-part series In conducting this work I have been greatly assisted by Luis Fernandes Silva and Rui Rosado who have provided multiple samples and photos for analysis. Luis has spent a great deal of time measuring spot-sulphate levels, and the pH profiles of bolts he has […]

Categories
Short Report

Not all 304 SS is the same

This is so, even for a matching nut and bolt Thanks to Luis Fernandes Silva for providing the sample. It is not possible to talk sensibly of corrosion resistance without reference to the specific environment that is to be resisted.Whilst it is true we might not see performance differences between commercial samples of 304 SS […]

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Quick Note

Nice Bar Stock – pay much for it?

A tale of poor materials quality control. I needed a couple of samples of 304 for the development work I was doing, so I cut them from the threaded end of the bolt illustrated below. It’s nothing special, just a random sample from my large collection of old, glue-in, machine bolts extracted from crags around […]

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Short Report

SSC vs SCC

Thanks to Luis Fernandes Silva for providing the sample. Which is it, sulphide stress cracking (SSC) or chloride-induced stress corrosion cracking (SCC)? I raised this question in one of my earlier posts where I described the aggressive corrosion of stainless steel at Cabo da Roca. In that particular post I highlighted the main differences between […]