There can be occasions when it is required to idle equipment for extended periods of time due to production requirements, economic conditions, or other situations. There are some basic practices that can ensure equipment is mothballed properly so that equipment is protected during storage or idle time. A little investment will protect equipment value for resale or reliable performance for production startup.
The information provided here are general guidelines. Many times there are procedures outlined by OEMs for mothballing equipment that should be reviewed. Practices specific to type of equipment and recommended preservation procedures will vary with asset type, design, and environment, which can involve a number of procedures. The goal is to optimize protecting the value of the asset and ensure trouble free startup after extended periods of shutdown
Proper mothballing of idle equipment should involve adequate preparation. With critical equipment it’s recommended the mothball procedure and return startup procedure are documented. Not documenting what has been done to equipment during the mothballing process can lead to situations being overlooked that can damage equipment. The goal is to restore production effectively without harm caused to the equipment
During extended shutdown periods corrosion buildup and moisture accumulation can occur. Also, depending on the surrounding environment, microwelding or fretting corrosion of contacting surfaces due to vibration from the surrounding environment can happen. Particulate contaminants can accumulate that are abrasive during startup. Wet or cold environments present greater challenges for moisture problems.
For some circulating system proper draining and flushing may be required. Neutralizing and removing process materials, especially if corrosive, should occur. Depending on the type of equipment and storage requirements, circulating systems may be filled with various fluids; OEM recommended lubricant, mineral oil containing a five percent rust-preventive concentrate, commercial inhibiting oils, or coating of component parts with preservative.
Equipment should be inspected periodically during the mothball period. Machinery should be protected from environments with a high amount of airborne particulate. Breathers on certain equipment should be sealed during the mothball period to prevent an accumulation of moisture condensation and airborne particulate. Where applicable, to prevent damage to bearings and other components, periodically cycling or rotating equipment during storage without powering up is advisable. In the case of internal combustion engines drain all fuel from the equipment, since fuel does not store well for long periods.
Systems should be properly prepared for restart. Replace filters and clean strainers. Replacing the lubricant before startup and flushing critical systems will remove accumulated contaminants and deposits that can plug internal passages.
Laboratory analysis will provide useful insurance when preparing for mothballing and extended shutdown. Testing the system fluid can be particularly important when preparing for startup after an extended idle time. Analysis of the lubricant fluid will provide valuable insight for the following to help ensure trouble free startup:
- Adequate flushing procedures have occurred (preparing for mothball and after preparing for startup)
- Proper lubricant is in service for startup production
- Monitor for excessive iron/rust
- Monitor for elevated copper/yellow metal corrosion
- Detect excessive moisture
- Ensure oil is not old and degraded
- Look for other contaminants such as coolant and dust/dirt, particulate, or corrosive materials
Again these are general guidelines. Your OEM representative, maintenance staff, and lubricant supplier are valuable resources for proper mothballing procedures, combined with the information provided through analytical testing of the system lubricant fluid.
David Doyle, CLS, OMA I, OMA II
Key Accounts and Special Projects