In most Illinois and Wisconsin plants, the same two weeks in October carry two opposite jobs. The cooling tower or chiller comes down for the season, and the boiler comes back up. Both jobs usually have a checklist. Neither checklist usually has a line on it for corrosion.
That omission is quiet and expensive. Cortec® published guidance on seasonal layup and startup at the end of September making the same point: corrosion protection belongs on the shutdown and startup checklist, and it is left off more often from lack of information than from lack of budget. Here is what that looks like for a Northern Hemisphere plant, which is to say, for ours.
An idle cooling loop corrodes faster than a running one
For a lot of operations, cooling tower winterization means draining what needs draining, shutting the system down, and walking away until spring. The problem is that the treatment chemistry that protected those metal surfaces all summer stops circulating the moment the pumps stop. The water that remains, and the humid air in the space above it, do not stop working.
What happens next is gradual and easy to miss because nobody is looking at the inside of the loop. Wall thickness comes down a little each off-season. Corrosion products build up and release into the water. The bill arrives later, as higher iron at startup, as clogging, as a leak in a section of pipe that looked fine on the last inspection, and eventually as a replacement that should have been years further out.
The fix is not complicated. A film-forming inhibitor circulated through the system for 12 to 24 hours before layup leaves a protective layer behind on the metal. Cortec® published data indicates that layer protects both above and below the water line, as long as the system stays closed, and it works for wet or dry layup. The part that matters operationally: it does not have to be removed at startup. You are not adding a spring flush to save yourself a fall problem.
Boiler startup is the riskiest hour of the heating season
The boiler side is the mirror image, and it is the one more people get wrong, because the damage happens fast rather than slowly.
When a boiler comes back online, fresh makeup water floods the system. That water is cold and it is loaded with dissolved oxygen. The normal operating water treatment program is not fully established yet. For a window of hours, you have highly oxygenated water sitting against bare metal with nothing scavenging the oxygen. Pitting corrosion in that window is common, and pitting is the kind of damage that does not average out over a large surface. It concentrates, and it is what eventually puts a hole in a tube.
A water-soluble oxygen-scavenging pouch dropped into the boiler before startup dissolves in the makeup water and passivates the metal surfaces through exactly that critical phase. Cortec’s product for this carries NSF G7 certification, which matters if you are in food processing and the treated water or steam has no food contact. For a lot of our customers in the Midwest, that certification is the difference between a product they can use and one they cannot.
What this means if you run both systems
If your plant has a cooling tower and a boiler, the practical takeaway is that you have one window, usually a single week, in which both corrosion steps need to happen. Treat the cooling loop on the way down. Treat the boiler on the way up. Neither step takes a specialist, and neither one adds a removal step in the spring.
Two notes on availability. The specific seasonal water treatment products for cooling loop layup and for boiler startup are quoted on request rather than listed on our site today, so call or use the contact form and we will get sizing and lead time back to you. The dry boiler layup product below is stocked. And if you are south of the equator, or you run a facility that is, the seasonal logic reverses: boiler layup and cooling system commissioning, with a different set of products for each.
Which products apply here
These are the related items we stock and can ship from Illinois:
- Cortec® Boiler Lizard® dry layup corrosion inhibitor — for boilers going into dry layup rather than coming online. Drop the bag in, close the openings, and in most cases restart without removing anything.
- Cortec® VpCI®-609 water-soluble powder, 50 lb — for hydrotest water and wet layup where you are dosing a volume rather than dropping in a pouch.
- Cortec® VpCI®-337 waterborne fogging inhibitor, 5 gallon — for the drained vessel, header box or void that holds no water to treat.
- Cortec® EcoAir® 337 aerosol — the same chemistry in a can, for small enclosed volumes where setting up a fogger is not worth it.
- Cortec® CorroLogic® VpCI tube strips — for protecting the inside of tubes and pipe runs that are coming out of service.
- Cortec® VpCI®-308 powder pouch, 35 ft³ — multimetal protection for enclosed spaces such as control cabinets and spare parts crates that sit through the off-season.
If you are not sure which product matches your metals and your storage conditions, our VpCI product selection guide sorts it by metal type and environment.
While the system is down anyway
An outage is the one time of year the pumps, valves, heat exchanger plates and strainer bodies are out and accessible. If those parts are currently going into a bucket of solvent or getting wire-brushed by hand, it is worth looking at an aqueous parts washer while you have the shutdown window to install one. Cleaning the parts properly on the way out is also what makes the corrosion protection work when they go back in: inhibitors deposit on clean metal, not on scale and old grease.
If you want a second set of eyes on your fall shutdown and spring startup sequence, or sizing on the seasonal products above, get in touch. We work with plants across Illinois and the upper Midwest on exactly this, and the conversation is usually about fifteen minutes.