Performing regular waterside inspections of your critical system equipment is an important part of a successful preventative maintenance program. As we enter the holiday season, many systems may be temporarily shut down, providing a perfect opportunity for waterside inspections.
Visual inspections provide an indication of the overall health of your system and validate the results of your water treatment program. It is crucial to catalog inspection reports to allow you to determine if the current condition indicates equipment status is unchanged, improving or degrading.
Make sure to inform your water treatment representative in advance of the inspection date and time. This will allow your representative to view the results first hand and provide feedback based on current observations compared to previous inspection results. This will often help avoid costly remedial action as they can assure your insurance inspector that there is a program or plan in place to remedy any issues.
This guide will outline what tools are needed and what you should be looking for to get the most useful information out of your waterside inspections.
How to Perform a Complete Inspection
For a thorough inspection, it is recommended that the waterside be viewed and photographed from all available inspection points above and below the water line.
Steam Boiler: Deaerator or feedwater tank, pumps, piping, economizers, steam drum, mud drum, columns, and tubes or coils.
Chiller: End bells, condenser and chilled water tubes, pumps, and piping.
Recommended tools include:
- A boroscopic camera with recording capability
- Large and small flat head screwdrivers
- Sample bags
- Note book or tablet
- Tyvek suit and all suitable PPE
What to Look For
Scale and Deposits
Scale and deposits may appear on any waterside surface but will primarily be located at the heat exchange surfaces with the highest skin temperatures. The most common deposits you will find in a water system are calcium scale and iron scale.
- Calcium scales will generally appear as a rough coating with a white to grey color, small amounts of iron can tint this to a dark brown.
- Iron scale will typically appear as a rough coating on water surfaces with a brown or reddish brown color.
Water treatment products may soften such scales and even cause them to flake off of waterside surfaces. It is important to check for evidence of scale deposits being removed or flaking off where debris is likely to collect in the system. This might include within the mud drum or at the base of a boiler pressure vessel, or in the end bells or sump/basin in a cooling system. It is important to track the changes in deposit thickness and area covered across subsequent inspections, as this can help determine if the deposits are being removed, or if new deposits are forming.
A good trick is to scrape a gouge mark into the scale at an easily accessible location, then check that mark at the next inspection to see if the gouge is still visible.
Pitting will appear as small, localized encrusted areas of corrosion, forming crevices and uneven metal surfaces. Oxygen pitting can appear on any boiler surfaces below the water line, but will likely be the most prevalent at or near the water line in watertube and firetube boilers, or inside coils on coiltube boilers. It is very important to properly document and track the amount of oxygen pitting on the boiler surfaces year over year, as damage caused by pitting is irreversible and can lead to equipment failure.
Sludge may appear on any waterside surface, but will typically be found in the mud drum or at the base of a boiler, or in the tube bundle and on the end bells of a chiller. Sludge will appear as a thick muddy substance, typically brown in color. Any sludge can be removed or rinsed off while the boiler or chiller are open for inspection.
General corrosion can appear on any of the waterside surfaces below the water line or above the water line where condensation occurs. It will appear as rust formation on metal surfaces, orange to brown in color where surfaces would otherwise be grey to black, as well as in chiller tube bundles. In contrast to sludge formation, general corrosion will appear relatively even across all water contact surfaces, and will not be able to be rinsed away.
Biofouling will appear as a slime or other growth, in a variety of colors and appearances, and can have a light to foul biological odor. Take note to remove some of the biofilm and inspect beneath the film, as this may show evidence of microbiologically induced corrosion, or MIC, that cannot be seen when the biofilm is still on the chiller surfaces. Any biofilm or fouling can be removed physically by brushing or pressure washing or chemically with dispersant and oxidants.
You will get the most out of the time and money invested in your inspections if you incorporate the following:
- Make sure your water treatment representative is present
- Be prepared with the correct tools and knowledge of where to inspect
- Understand what you are looking for
- Keep thorough and complete inspection reports from each inspection performed to track changes in results
Waterside inspections are an important part of any successful preventative maintenance program because they provide the best opportunity to determine the overall health of your system, and to validate the results of your water treatment program.