Preventive Maintenance and Inspections Can Defeat Corrosion

Jan 14, 2010

Stuart Smith

Stuart Smith


From Avionics to HVAC systems corrosion feeds on assets if it is allowed to gain a foothold. Without proper preventive maintenance and inspections, damage from corrosion will cause metal components to fail. The type of equipment and severity of the corrosion will determine the extent of repair or replacement of assets. To understand the importance of preventive maintenance and inspections we first look at the causes and types of corrosion and then how an Enterprise Asset Management (EAM) system minimizes maintenance expense.

Causes of Corrosion

Corrosion is the result of a chemical reaction on metals causing the metal to oxidize. Most people are familiar with water (wet) corrosion, however, there are multiple factors that influence corrosion. Some of these factors are:

  • Type of metal – composition, grain boundary, surface condition, microstructure
  • Environmental – where is the metal located on the asset, is it subject to temperature variations, conductivity, heat transfer rates, humidity, wet and dry cycles
  • Stress – how the asset is being used, what comes in contact with the metal (other objects, chemicals), engineering stress load.
  • Physical – reactivity to chemicals, surface coating, frequency of contact with other surfaces, chemicals or residue(dirt/dust/fuels)

Types of Corrosion

The most common forms of corrosion include:

  • General or uniform corrosion – the least damaging of corrosion forms and occurs over a wide area.
  • Pitting – can be the result of an impurity or penetration of the metal surface.
  • Galvanic – the interaction of two or more dissimilar metals, very common HVAC issue when brass and steel or copper and steel meet.
  • Microbiologically Influenced Corrosion (MIC) – the most severe and threatening form of corrosion caused by microbiological agents.
  • Corrosion due to wear and tear – a gradual deterioration of the metals surface. found at joints, elbows or other abrasions.

Critical Nature Of Preventive Maintenance and Inspections

Left unattended corrosion will cause part and/or system failure on machines. Some corrosion (MIC and Pitted) once started can be very expensive to repair if at all possible and will definitely shorten the lifecycle of an asset. The most viable solution is to perform inspections for signs of corrosion and to regularly schedule preventive maintenance tasks such as washing, coating, changing covers, lubrication and the use of preservatives.

“Compared to the cost of naval aircraft, the cost of corrosion prevention is small. Preventive maintenance is a powerful tool that can control even the most difficult corrosion problem…The Naval Aviation Maintenance Program (NAMP), OPNAVINST 4790.2, requires SE shops to establish a maintenance schedule for each item of equipment. The SE Custody and Maintenance History Record, OPNAV 4790/51, is used to schedule and record all corrosion maintenance actions.”

Source: Excerpts From NAVAIR 01-IA-507

Scheduling inspections and preventive maintenance are two of the core functions of an Enterprise Asset Management (EAM) system. Other functions include asset management and work order management. When integrated with handheld mobile technology, an EAM is the logical choice to reduce capital repair and replacement expense.

Stuart Smith

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