Most of what gets written about boiler layup assumes a big boiler. Thousands of gallons, a maintenance crew, a planned outage with a work order behind it. That is not the boiler that rusts in most Midwest plants. The one that rusts is the small package boiler in the corner that carries a seasonal load, gets shut down sometime in spring, and sits until somebody fires it again. Nobody writes a procedure for it because it is small, and small is the reason it gets skipped.
Cortec® published a demo video on October 19 that addresses exactly that boiler. It runs about a minute and a half, and it shows the whole dry layup procedure for a small system using VpCI® Gecko™, an air-powered spray can that fogs Vapor phase Corrosion Inhibitors into the boiler instead of putting a solid product inside it.
Why the small boiler is the one that gets skipped
Idle boiler internals corrode for two reasons that have nothing to do with boiler size: oxygen and residual moisture. A boiler that has been drained is not a dry boiler. There is film left on the tubes, there is humid air moving in and out as the building heats and cools, and there is a long stretch of months where nothing is happening to stop the reaction. Pitting that starts during layup does not announce itself. It shows up later as a tube failure during a heating season, which is a far more expensive conversation than the layup would have been.
The traditional answer on a small system has been desiccant: throw bags in, close it up, pull them out in the fall. The problem with that is the pull-out step. Desiccant has a finite capacity, so on a long layup in a humid plant it can be saturated and doing nothing by midsummer. And it has to physically come back out before startup. Cortec’s point in this release is the one every maintenance manager has seen play out at least once — desiccant left inside a boiler at startup is a real problem, and the longer the layup, the better the odds somebody forgets where it went.
Vapor phase inhibitors work differently. They move as a vapor through the enclosed space and adsorb onto the metal as a molecular layer, including on surfaces that nothing was ever sprayed directly onto. Nothing is consumed the way a desiccant is consumed, and nothing has to be retrieved. Cortec’s published position on this product is that the boiler can simply be filled as normal at startup, with no removal or flushing typically required.
What the procedure actually looks like
The reason this video is worth the ninety seconds is that the procedure is short enough to be believable, and the one judgment call in it is shown rather than described.
- Dose by volume. One can covers 100 gallons (380 L) of boiler volume. That is the whole sizing calculation on a small package boiler.
- Treat each space separately. Water side, fire side and condensate tank are three separate enclosed volumes. A small boiler that is laid up on the water side only, with a wet condensate receiver left open to the room, has been half protected.
- Fog until it comes out somewhere else. This is the judgment call. You spray into one opening and watch for fog emerging from a different opening. That is the visual confirmation that the vapor has actually travelled the length of the space rather than puddling at the nozzle. It is a better check than a stopwatch.
- Use the extension kit on tight openings. Cortec recommends an aerosol fogging extension for steady misting into very small access points, which is most of the openings on a small boiler.
- Close it. The last step is the one that does the work. The inhibitor only protects a closed space. Access points left open let the vapor leave, and an open boiler with VpCI in it is an open boiler.
One thing worth flagging for anyone whose maintenance window is in the fall: this is a layup procedure, not a startup procedure. If you are bringing a boiler back online right now rather than putting one away, the relevant work is on the cooling and condensate side, which we covered separately in our post on winterizing the cooling tower while the boiler comes back on.
Which products do what, by boiler size
The Gecko sits at the small end of a family, and picking the wrong size of the same idea is the most common mistake we see. The table below is the short version.
| System | Form | Where it fits |
|---|---|---|
| VpCI® Gecko™ | Air-powered spray can, fogged | Small boilers, roughly 100 gallons per can; fire side and condensate tanks |
| Cortec® Boiler Lizard® | Water-soluble PVA bag | Mid-size boilers; laid flat inside, dissolves on refill |
| Cortec® VpCI®-337 | Waterborne fogging fluid | Larger vessels, piping runs and void spaces fogged with equipment |
| Cortec® VpCI®-609 | Water-soluble powder | Hydrotest water and layup dosing by weight |
- Cortec® Boiler Lizard® dry layup corrosion inhibitor — the mid-size counterpart, and the one most of our customers start with
- Cortec® EcoAir® 337 interior fogging inhibitor, 13 oz — aerosol fogging for void spaces and enclosures
- Cortec® VpCI®-337 waterborne fogging inhibitor, 5 gallon — bulk fogging for larger volumes
- Cortec® VpCI®-609 water-soluble powder, 5 lb — hydrotest and wet layup dosing
- Cortec® Desicorr® VpCI® pouch, 1/6 unit — where you want desiccant and vapor inhibitor together, in a package rather than a boiler
- VpCI product selection guide — by metal and environment, if the system in question is not a boiler
We do not currently have a VpCI® Gecko™ listing on the site. It is quoted on request, and if you are laying up small boilers this season it is worth asking about now rather than in January.
The part nobody puts in the layup procedure
Everything above protects a closed system from the inside. The outside of that system, and everything around it, is usually what the plant actually looks at when it walks through in the spring — and an outage is the only window in the year when the pumps, heat exchangers and process parts around the boiler can come out and get cleaned without stopping production. If those parts are going back in dirty, or going on a shelf dirty, oil and shop soil underneath a protective film is the single most common reason the film does not work. Our Build-All and Magido aqueous parts washers exist for that window, and the fall outage is when most of our customers buy one.
For the dosing arithmetic behind fogging a larger volume, see our post on replacing nitrogen blanketing with VpCI fogging. For the bagged procedure on a mid-size boiler, see how to apply Boiler Lizard.
Talk to us before the boiler goes cold
Layup products are cheap relative to a tube bundle, and the decision is almost always made too late in the season. If you have a small boiler, a condensate receiver or a fire side that has been going into the off season unprotected, tell us the volumes and we will size it. Get in touch with Solvent Recycling Systems and we will work through it with you.
