National Physical Laboratory

Corrosion Audit

Corrosion control – use it, or lose it!

No one expects a well-designed and manufactured product to fail to function as soon as it is taken out of the box. Equally it is unrealistic to expect the same product to last forever! A realistic expectation is that it will give useful service for a period of time that offsets the cost of replacement and when it fails this will be in a benign manner that does not affect safety or the environment. When this 'lifetime' issue is primarily a result of mechanical performance most design and maintenance engineers, and product manufacturers, are well armed with tools, procedures and qualified personnel. It is also very likely that products are redesigned often to optimise their performance, minimise cost and take advantage of developments in technology and understanding. Unfortunately, this situation is not true for all the factors that affect the lifetime; corrosion and its control is rarely given enough resources or regular attention yet it is a common cause of failure. When was the last time that your organisation reviewed its capability in this area and the effect that a problem would have on your customers and your business?

Most corrosion problems are a result of a localised problem and not the general 'rusting'that we see as a result of uniform corrosion that is usually quite a slow and manageable process. Localised corrosion can occur much more rapidly than expected with disastrous consequences although the mechanisms are understood and prevention measures already known. An unfortunately high profile example is the Flixborough Disaster of 1974 when Stress Corrosion Cracking contributed to the failure of a chemical reactor initiating a series of events that resulted in 28 fatalities and 36 serious injuries with fires burning for over 10 days [1,2]. This case dramatically illustrates the impact that corrosion can have on safety, the environment and the viability of a business in terms of costs. It also shows how easily a situation can run out of control and although it may appear that this is not a relevant example in your organisation how much do you know about Stress Corrosion Cracking how it could affect your products and impact on your organisation?

Corrosion control is not limited to the prevention of disasters but can bring a positive package of benefits to those organisations that are willing to adopt best practices and regularly review their products and processes. A good example of this is a proposed protection system for water tanks reviewed for a customer by the National Corrosion Service. Corrosion control of the steel was provided in this case by coatings and cathodic protection. The report made 14 recommendations to improve the operation of the system, extend the period between maintenance, and prevent premature failure due to localised corrosion. The changes were simple to implement some as simple as re-specifying coating thickness, primer type or re-routing cables. Others concerned an improved electronic control measures to cope with the variability of the environment. How well do you understand the environment that your products operate in? The important aspect of this example is that the lifetime of the water tanks was specified, a system of protection was proposed and it was critically examined and reviewed. Do you specify the lifetime of your products and design them accordingly? Would you put together a package of protection measures based on the main areas of concern? Would you then have these reviewed by an expert? This is part of best practice. The National Corrosion Service has produced a checklist to corrosion control to support this process. It outlines the most common factors that need to be considered to enable the first stage appraisal to be made. This document is free to UK organisations and can be ordered by contacting us.

It is possible to overdo corrosion control leading to expenses that give no benefit. A recent example of this is advice given to a construction company refurbishing a building that saved a total of £250,000, avoiding road closures, and reducing disturbance to neighbouring buildings. A well specified system of corrosion control will give enduring benefits to your organisation and customers and as such is a useful marketing tool. Would you give repeat business to a company whose products let you down because of a corrosion problem?

Corrosion control, although a technical activity, is a management responsibility as the consequences of a problem can impact a business in many ways. Supply and sub-contracting chains introduce communication problems that become accentuated when a problem occurs. The immediate reaction is too often: "Who can we blame for this?". A corrosion expert is then appointed to make a judgement on the "technical" cause of the failure - too late to reduce the impact on all parties. The UK has considerable expertise in Universities, Consultancies, Trade Associations, Research Organisations and commercial companies that could be better used to prevent problems. The experts involved network often. How close is your organisation to this network?

Networking begins at home, with your customers and suppliers. Sharing of resources, information, knowledge and expertise can improve the specification of the corrosion performance of the products you supply or are supplied with. The process of drafting the specification jointly will lead to a better understanding of the products actual capability, highlight areas of concern and act as a starting point for product improvement and innovation.

The message of this article is simple; corrosion control has a positive effect on business and should be audited regularly. Improved communication in the supply chain and the use of experts to prevent corrosion would significantly reduce the impact on all parties. Loss of control can have severe consequences.

Last Updated: 22 Nov 2017
Created: 26 Oct 2010


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