An extractor drum is a food-contact surface that gets washed, scrubbed and left wet for weeks at a time. The grade of steel it is made from decides whether it still looks presentable in five seasons or starts showing rust bloom around the welds in the second. On a quotation, two grades of stainless look identical; on a container quotation, they differ by enough to matter.
The two grades that come up in honey equipment are 304 and 201. This article sets out what actually differs between them, why the cheaper one usually fails the food-contact check, how to verify what you were sent, and the questions buyers ask before they specify a grade.
What the numbers mean
Both grades are austenitic stainless steels, which is the family that is generally non-magnetic in the annealed condition and cannot be hardened by heat treatment. The difference is the recipe.
Grade 304 is often called 18-8: around 18 percent chromium and 8 percent nickel. The chromium forms the passive oxide film that resists corrosion, and the nickel stabilises the austenitic structure, which is what gives the steel its formability and toughness.
Grade 201 was developed to cut cost by substituting manganese and nitrogen for part of the nickel, which is the expensive element. It keeps the austenitic structure and gains strength, and it gives up corrosion resistance. The figures below are the ranges in ASTM A240/ASME SA240 for sheet, plate and strip; other standards, including EN and JIS, publish slightly different ranges for nominally the same grade, which is worth knowing before arguing about a half percent.
| Property | AISI 201 | AISI 304 |
|---|---|---|
| Chromium (Cr) | 16.0–18.0% | 17.5–19.5% |
| Nickel (Ni) | 3.5–5.5% | 8.0–10.5% |
| Manganese (Mn) | 5.50–7.50% | 2.00% max |
| Nitrogen (N) | 0.25% max | 0.10% max |
| Carbon (C) | 0.15% max | 0.07% max |
| Tensile strength, min | 95 ksi | 75 ksi |
| Yield strength, min | 45 ksi | 30 ksi |
| Elongation | 40% | 40% |
| Hardness, max | 100 HRB | 92 HRB |
Two things follow from that table. First, 201 is genuinely stronger: its minimum yield strength is half again that of 304, which is a real advantage in formed and drawn components. Second, the corrosion-relevant elements — chromium and nickel — are both lower in 201, while manganese and nitrogen are much higher. High manganese in the presence of chlorides is associated with pitting, and a honey house is a chloride environment more often than it looks.
Why a honey house is harder on steel than it seems
Honey itself is not aggressive to 304. It is mildly acidic, and grade 304 is the standard material for food and beverage processing equipment precisely because it holds up against food acids and frequent washing.
What attacks the steel is everything around it. Cleaning is the main one: chlorine-based sanitisers and caustic washes, used warm, will pit a marginally alloyed steel at the weld lines and under gaskets. Coastal air carries salt. Warm, wet, poorly ventilated rooms keep surfaces damp for hours at a time. And heat tint left on a weld — the straw-coloured oxide that forms during welding — is a corrosion site that has to be removed by pickling or mechanical finishing and then passivated, not just covered with a topcoat.
That is why the grade question mostly shows up at the welds. A drum fabricated from 201 can look perfect on delivery and begin staining along the weld seams after a season of washing, and by then the container is long since paid for. Where stainless is being specified for equipment that will be washed with chlorinated cleaners, the grade needs to be named in the specification rather than implied.
Verifying what arrived
Grade is invisible. Two identical drums can differ by several hundred dollars in material cost with no visual difference, which is why verification is part of the purchase rather than an afterthought.
| Method | What it tells you | Practical limitation |
|---|---|---|
| Mill certificate to EN 10204 3.1 | Heat number, grade and composition, traceable to the melt | Documentation only; needs the heat number to match the material marking |
| Handheld XRF analyser | Elemental composition on the spot, including Ni, Cr and Mn | Requires a calibrated instrument and an operator; cost per inspection |
| Chemical spot tests | Presence or absence of specific elements such as molybdenum or manganese | Qualitative and operator-dependent; a screen, not a measurement |
| Magnet response | Rough indication of austenite stability after cold work | Unreliable on its own; both grades can show some magnetism after forming |
| Laboratory spectrometry | Full composition with a report | Cost and turnaround; used when a claim is in dispute |
In practice the mill certificate is the first ask, XRF is the check where a dispute is anticipated or the order is large, and spectrometry is what an insurer or a court will want. Spot tests and magnets are what is available in the field, and they are useful for catching a blatant substitution but not for settling an argument.
Ask for the certificate with the quotation rather than with the goods. A supplier who can produce a certificate for a specific heat at quoting stage is a supplier whose material records are in order; a supplier who offers “304” without documentation is describing an intention.
Where each grade is acceptable
Grade 201 is not a counterfeit. It is a legitimate specification with defined uses, and the mistake is putting it in the wrong environment rather than using it at all.
It is reasonable for dry, indoor, low-wear applications: trim, housings, frames for non-contact components, decorative panels, structural sections that are not exposed to washdowns or salt. In equipment terms that means parts that do not touch honey and do not get scrubbed.
It is the wrong choice for anything that is wetted, washed, or exposed to the weather. Extractor drums, honey gates, settling tanks, strainers, pump heads and filling hoppers all fall into the category where corrosion resistance is the whole point of specifying stainless rather than mild steel. The cost saving on the material is small compared with the cost of a drum that has to be replaced, a lot of honey that has to be re-filtered, or a customer complaint about rust staining on a product sold as food-grade.
The specification wording that avoids the argument is simple: name the grade for every wetted part, require a mill certificate for the material, and state the finish required on welds. Where a supplier proposes a substitute, ask for the composition in writing and compare it against the table above before agreeing.
Checking the specification on an extractor order
The grade question is easy to close on an order because it can be written in three lines, and the three lines are the ones inspectors can actually verify.
Name the grade for each wetted part. “304 stainless” over a whole machine leaves the gate, spindle and basket frame open to substitution. Drum, lid, basket, gate and any fitting in the honey path should each be named, and where a component is genuinely different material it should be declared rather than discovered.
State the thickness with a tolerance. Wall thickness drives both the price and the drum’s resistance to distortion under load, and it is one of the few things a buyer can measure on arrival with a pair of calipers. A nominal figure without a tolerance is not a specification.
Require the certificate with the order, not after it. A mill certificate to EN 10204 3.1 carries the heat number and the composition, and it costs the supplier nothing to attach it. Where the heat number on the certificate does not match the material marking, the certificate is describing a different batch.
On the product side, the specification is usually visible in the listing. A 2 to 24 frame extractor in 304 stainless names the grade in the title because it is the selling point, and a 3 frame electric unit with variable speed is specified as food-grade for the same reason. The same question applies to the rest of the honey path: storage tanks hold honey for weeks at a time, which makes material quality more rather than less important. The full selection is in the extractor category.
Where the rules sit
Food-contact obligations are set at the destination, not at the factory. In the EU, materials and articles intended for food contact are covered by Regulation (EC) No 1935/2004, with good manufacturing practice laid down in Regulation (EC) No 2023/2006; the Commission’s food contact materials pages set out how the framework applies. In the United States, indirect food additives — including the polymers used in gates, gaskets, sight glasses and guards — fall under 21 CFR Part 174 and the parts that follow it. Industry material guidance for stainless grades is published by the world stainless association.
Questions buyers ask before specifying a grade
Is 201 stainless actually food-safe? It is used in contact with food in plenty of products, but it is not the grade named in the guidance most importing markets work to for food-contact metals, and it is not what a buyer means when they ask for food-grade stainless. For equipment that is washed regularly, 304 is the specification to write.
Can you tell 201 from 304 by looking? No. Grade 201 can be very slightly darker, and it is rather more likely to show magnetism after cold working, but neither is reliable. Verification needs a mill certificate or an analyser.
Why is the price difference so large? Nickel is the expensive alloying element, and 201 contains roughly half as much. Most of the gap in a quotation is material cost rather than fabrication.
Does 304 rust? It can. Chlorinated cleaners left on the surface, salt-laden air, and weld heat tint that was never removed will all produce staining on 304. The difference is that 304 tolerates much more of this before it fails, and it recovers with proper cleaning and passivation.
Should I ask for 316 instead? 316 adds molybdenum for chloride resistance and is standard in dairy and chemical processing. For honey in normal conditions it is usually more specification than the application needs; for coastal or high-salt operations it is worth pricing.
What should be in the specification? Grade for each wetted part, material thickness with tolerance, surface finish, weld finish and passivation, and the certificate required at shipment. If a term cannot be measured, it cannot be inspected.