Passivation and Derouging Contractor in Wisconsin

Yes, statewide: tanks, vats, process piping, brine systems and the racks and fixtures that live inside them. Work is done to ASTM A967, with ASTM A380 covering the cleaning and descaling that has to come first. On brine equipment we will also give you an opinion on whether the installed alloy is suited to the duty before quoting the treatment, because passivating an unsuitable grade in saturated chloride sells you a result that will not last.

Because they combine nearly every factor that promotes chloride attack: saturated rather than trace chloride, long-term recirculation and reuse, cooling equipment creating temperature gradients and crevices, racks and fixtures forming metal-to-metal contact points, and protein and fat residue giving chloride places to concentrate beneath. It is the most aggressive duty in a dairy plant by a wide margin.

It will give you the best passive film the alloy can form, which helps, but it will not make an alloy chloride-resistant that is not. If standard austenitic steel is pitting in saturated brine, passivation buys time rather than solving the problem, and the real answer is a more resistant grade for that duty. We would rather tell you that at quotation than be called back in two years.

Because chloride attacks the passive film locally rather than generally, so there is no gradual thinning to observe. The surface looks sound until a pit appears, and the pit then propagates downward beneath the deposit it creates, sheltered from the oxygen that would let the film repair. By the time it is visible, penetration may already be substantial.

Scale gives chloride somewhere to sit against the metal undisturbed, and it blocks the oxygen the passive film needs to heal itself, so attack begins underneath the deposit rather than out in the open where it would be seen. Because milkstone is mineral, a caustic-only program never removes it, which means a plant cleaning that way is quietly manufacturing its own corrosion. Of all the causes on this page it is the one most often self-inflicted and the cheapest to stop.

Yes, if practice has drifted. Chlorine-based sanitizers are a chloride source, manageable at correct dilution with correct contact time and proper rinsing. Used stronger and longer because a plant is trying to force down a microbial problem, they attack the surface that microbial control depends on. Corrosion near dosing points, or following a period of intensified sanitation, usually points here.

Contamination picked up in the fabrication shop, not a defect in the steel. Carbon-steel particles transfer from grinding wheels and wire brushes used on both materials, from tooling, and from a floor where mild steel is also worked. Each embedded particle rusts, and the rust then holds damp and salt in place against the stainless beneath it, so a cosmetic blemish becomes a pit initiation site. Treatment clears the contamination; segregating consumables and tooling by material is what stops the next batch arriving the same way.

Not on a calendar. Treat it as event-driven: after fabrication or a significant modification, after any intervention that could have put carbon steel against stainless, and whenever inspection or an actual corrosion finding says so. If a plant has settled into passivating every so many months and the problem keeps returning, the interval is masking a cause rather than managing one, and in Wisconsin that cause is usually scale or sanitizer practice.

Only marginally, through heating the passivation solution, which is a short one-off load. At 8.54 cents per kilowatt-hour against a national average of 8.13 (EIA, 2024), it is not a meaningful part of the cost. The dominant cost is downtime, which is why sequencing vessel by vessel around production matters far more than the tariff.

Use the form on this page or call 201-450-8280. Tell us what the equipment is and what alloy it is made from, whether we are treating new fabrication or chasing damage that has already started, and whereabouts on the equipment it shows. Photographs are genuinely valuable, because the pattern usually identifies the cause before anyone is on site. If brine equipment is involved, say so first.

Frequently not, and this is the core of the problem. Ordinary austenitic grades pit in saturated brine, particularly at the temperatures and with the deposits involved, so vessels and pipework specified as ordinary dairy equipment fail. Higher alloys, or non-metallic construction for tanks, are the honest answers.

For metallic construction, alloys with substantially higher pitting resistance than standard grades, selected against the actual chloride concentration and temperature. Many plants use non-metallic or lined brine tanks instead, which sidesteps the problem for the vessel while leaving the pipework, pumps and heat exchangers to be specified carefully.

Considerably. Pitting resistance falls as temperature rises, so a brine system running warm, or a heat exchanger surface warmer than the bulk, sits at greater risk than the same chloride concentration cold. The hottest surface in the brine circuit is usually where the first pitting appears.

Under deposits of cheese fines and protein, at crevices around fittings and welds, at the liquid line where wetting and drying alternate, and on the warmest surfaces. Those four locations account for most of what we find, and all four are predictable enough to inspect deliberately.

Indirectly and usefully, because removing cheese fines and protein removes the deposits that drive under-deposit attack. Brine clarification and pasteurisation systems are installed primarily for microbiological and product quality reasons, and the corrosion benefit is a genuine secondary gain.

Drained, cleaned and examined closely with good light and magnification, with particular attention to the liquid line, welds, fittings and any area where deposit collects, and with photographs from fixed positions. Dye penetrant examination is used where pitting or cracking is suspected on a critical vessel.

Chlorine-based sanitisers can, particularly at elevated temperature, in the presence of existing deposit, or where residue is left to dry rather than rinsed after contact time. Dairy plants use them widely and effectively; the damage comes from application practice rather than from the chemistry being inherently unsuitable.

Chlorinated caustic improves protein removal and introduces chloride into a hot alkaline cycle, which over repeated use contributes to the pitting these plants suffer. Where it is used the rinse must be thorough, and it should be a considered choice rather than a default because it cleans better.

They can, at gasket crevices and where deposit accumulates, and the consequence is more serious than on a tank because a perforated plate cross-contaminates between product and service sides. Plate inspection during pack opening should look for corrosion as well as for fouling and gasket condition.

Where attack is shallow, mechanical remediation followed by passivation restores a serviceable surface. Where pitting is deep, has undercut welds, or affects a brine system in an unsuitable alloy, replacement in an appropriate material is the answer, because remediating the wrong material simply resets the clock.

The equipment treated with boundaries, the procedure, chemistry, concentration, temperature and contact time, the coverage verification for sprayed vessels, the rinse endpoint, the verification method and result, and photographs before and after. For brine systems the alloy actually installed should be recorded too.

It can be more aggressive, because whey streams are acidic in some processes and carry higher salt concentrations after concentration, and whey processing frequently runs at elevated temperature. Equipment specified for milk service and later used for whey concentrate is a common source of unexpected corrosion.

Acid whey from strained yoghurt and similar products is genuinely aggressive, combining low pH with dissolved salts, and plants that added such production to existing equipment sometimes find corrosion appearing in vessels that served happily for years on a different product.

They do, through the cleaning chemistry more than the process: membrane systems are cleaned frequently with acids and alkalis at temperature, and the housings, piping and fittings endure that cycle continuously. Material selection for a membrane skid should reflect the cleaning regime rather than the permeate it produces.

By treating it as a chemical process rather than a food process: establish the chloride concentration and temperature, select materials on pitting resistance, design out crevices, provide for filtration to control deposits, and make the tank inspectable. Specifying it as ordinary dairy equipment is how these systems fail.

Deposit control, through filtration and cleaning, because under-deposit attack accounts for a large share of the damage and the deposits are removable. It does not fix an unsuitable alloy, and it slows the mechanism enough to make a planned replacement rather than an emergency one.

Citric for in-place work, which is most of it. Saturated brine is the most aggressive chloride duty in the building and the equipment usually cannot be dismantled, so a circulated citric treatment to ASTM A967 is the practical route. The rinse water chloride content matters as much as the acid, because a brine-water final rinse undoes the treatment.

On an interval the plant's own inspection history sets rather than a calendar rule. Brine systems that show early pitting at welds and fittings need treating more often, and the more durable answer is usually a material upgrade on the worst components. Repeated citric passivation on an under-specified alloy is managing a symptom.