Avoiding corrosion in electrical systems


Prevention of corrosion 

Figure 2: This example shows improper material selection for lighting components in a food manufacturing plant. Courtesy: Robroy IndustriesEducation is the first step to preventing corrosion. Once engineers are aware of the prevalence of corrosion in their business, they can take steps to select the best anti-corrosion products and apply them in the most effective ways. Engineers must define the mechanisms of corrosion in the environment and then do their homework to select the correct material for the application. 

To begin, the material of choice must be given equal consideration as the design itself. Choosing the wrong material can result in frustrating or even dangerous situations. Defining the corrosive agents and determining the concentration can be a complex process. Usually several corrosive elements are present and interactions are not always well documented. Water is the most common corrosive element and usually presents itself in one form or another, such as humidity. Adjacent processing operations or other intermittent activities such as industrial cleaning and the general plant environment may expose the product to a variety of corrosive agents and temperatures. Each environment is unique and all possible corrosive agents should be identified for the intended application. 

Aluminum, for example, should not be used in high-mineral acid environments. Stainless steels also should be avoided when there halogens such as fluorine, chlorine, bromine, and iodine are present. Should the decision be made to use one material over another without in-depth investigation, the user may be looking at a very short life span for his or her most vital electrical systems. Next, the engineer must take into account some of the compliance issues and standards for the project. 

Understand policies, regulations, standards, and management practices to increase corrosion savings through sound corrosion management. Below are some of the most relevant polices, regulations, and standards for the electrical industry. 

UL: The UL mark is one of the most recognized symbols of safety in the world. UL is an architect of U.S. and Canadian safety systems. UL tests more than 19,000 types of products, and 21 billion UL marks appear in the marketplace each year. 

ASTM International: ASTM International is one of the largest voluntary standards development organizations in the world—a trusted source for technical standards for materials, products, systems, and services. 

National Electrical Manufacturers Association (NEMA): It is NEMA’s belief that standards play a vital part in the design, production, and distribution of products destined for both national and international commerce. 

National Electrical Contractors Association (NECA): The NECA Codes and Standards Committee are involved with development, administration, and enforcement of installation codes, safety standards, product standards, and other related industry regulations. This includes, but is not limited to, the National Electrical Code (NEC), National Electrical Installation Standards (NEIS), National Electrical Safety Code (NESC), various NFPA standards, UL safety standards, and OSHA regulations.

Independent testing 

Many products meet some or all of these standards; however, this does not guarantee that the product will perform as promised. There is a new need for independent product performance verification as distinguished from verification of product safety compliance. 

So how do you differentiate between similar certified products? 

Start by using empirical data to compare product longevity and accurately assess factors related to the risk of product failure from companies like Intertek. Intertek is the world's largest independent testing, inspection, and certification organization, that provides independent testing results. In many cases, ASTM test methods are just that—test methods. Regulated standards like Intertek’s ETL Verified put context around these test methods that establish test criteria and determine a grade of pass or fail based on the results.

When a manufacturer enters a product into a verification program, it must provide an initial qualification sample to Intertek. The sample is then independently tested to the specifications of the appropriate standard. If the sample is found to meet the requirements, an Intertek field representative will visit the manufacturer's location to independently select a final qualification sample for further independent testing. Once the second sample is found to meet performance requirements, the product may be marked by the manufacturer as

“ETL Verified.” The manufacturing facility is then subjected to quarterly audits to ensure ongoing compliance.

Consulting and specifying engineers must understand corrosion and how to improve specification of products to avoid the high cost, and sometimes disastrous effects, of product failure caused by corrosion. As evident from this article, there is a pressing need to look for, appreciate, and accept specification-related third-party verification standards that reach beyond traditional or historic ways of qualifying products intended to help fight the high cost of corrosion damage. Solid empirical product data—that is, documentation of product performance that is independently validated by recognized, objective, third-party sources—should be considered and used to control the cost of corrosion in order to produce long-term cost savings on projects.

Stephanie Ellis is director of Corrosion College. She holds a basic certification from the National Association of Corrosion Engineers and is a member of the International Association of Electrical Inspectors. Corrosion College is a hands-on course that explains the process of corrosion through intensive instruction by professionals in the field of corrosion protection.

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Than , United States, 02/19/14 05:50 PM:

Corrosion is a pervasive problem that costs 3% or more of GDP for most developed nations.
Corrosion is a global problem that has plagued buildings, monuments, equipment, and infrastructure for centuries. Every day scientists, researchers, chemists, engineers, and other professionals create revolutionary solutions to combat corrosion and protect vital assets from the damaging effects of corrosion-related deterioration and failure. In working with folks in the military packaging industry, I know the importance of being pre-emptive when it comes to corrosion prevention or else you could wind up spending a lot more than you’d like.
Than Nguyen
Anonymous , 03/14/14 12:06 PM:

My company recently experienced an unusual corrosion problem in one of our gas compressor stations. While potholing, a process of locating underground piping with high pressure water and a vacuum truck, a crew found a high pressure gas line with severe corrosive pitting on it. Several more similar problems were uncovered, including the ground grid. We found a few spots where the ground wire was completely gone and others that had severe corrosion at the wire connections. They aren't quite sure what caused this. Some think a short in one of the station pad mount transformers could have caused it, but I have my doubts. The transformer is a few hundred feet from the corrosion problem, and I believe any voltage going to ground was dispersed on the local ground grid around the transformer. Anyways, we will be replacing the entire ground grid pretty soon. Just wanted to share our story.
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