Key takeaways
- Chemical plant scrap is chosen for the process chemistry, so the equipment history points to the grade: molybdenum-rich Hastelloy for chlorides and reducing acids, 825 and 904L for sulfuric acid, 600 for caustic.
- Clad, lined and overlaid equipment must be declared; the carbon steel backing is often most of the weight.
- Aerospace scrap is released through the quality system and must stay one alloy per bin, with part numbers, specifications and mutilation records.
- Decontamination proves the scrap is clean; traceability proves which alloy it is. Supply both where they apply.
Aerospace and chemical plant nickel alloy scrap can share an element, nickel, and sometimes a grade, such as Inconel 625. It reaches the market in completely different shapes. A chemical plant releases it in tonnes at a shutdown: scrubber liners, tube bundles, reactor shells and pipe racks that have spent years in acid. An aerospace supply chain releases it every week in kilograms: drums of chips from disc machining, sheet trim from combustor fabrication, rejected forgings and retired engine parts.
Each sector also has its own question that must be answered before the scrap has a firm value. For chemical plant scrap the question is what has this been touching, and how was it built? For aerospace scrap it is can you prove exactly which alloy this is? This guide maps grades to the equipment they come from, explains how scrap is released in each sector, and shows how to describe each stream so it is priced as the alloy it really is.
Why Aerospace and Chemical Plant Scrap Are Handled So Differently
They are handled differently because the risk sits in different places. In chemical plant scrap the alloy is usually easy to confirm, but the surface and the construction are not: process deposits, linings, cladding and carbon steel attachments. In aerospace scrap the metal is usually clean, but several high-value grades sit side by side in one building, and a handful of wrong chips can put a melt out of specification.
Chemical Plant Scrap
- Large used sections plate, pipe, tube bundles, vessel shells
- Risk on the surface acid residues, sulfur-bearing deposits, scale
- Risk in the construction clad plate, weld overlay, liners on carbon steel
- Main evidence cleaning record, decontamination declaration, PMI
Aerospace Scrap
- Small high-value streams turnings, forging trims, sheet trim, retired parts
- Risk of mixing several grades and titanium in one shop
- Risk on the part coatings, braze, carbide tool fragments
- Main evidence part numbers, material specification, release records, PMI
That difference decides the paperwork. A chemical plant has to show the scrap is clean and say honestly how it was built. An aerospace shop has to show the scrap is one alloy and keep that proof with it from the machine to the truck.
Which Grades Come from Which Chemical Plant Equipment?
Chemical plants choose an alloy for the chemistry inside the equipment, so the process tells you the likely grade before any reading is taken. Molybdenum-rich nickel alloys go where chlorides and reducing acids attack, chromium-rich grades where conditions are oxidising, and iron-nickel alloys or high-alloy stainless where sulfuric or phosphoric acid is handled.
| Equipment | Service | Grades often found | Form when released |
|---|---|---|---|
| Flue-gas scrubbers, absorber linings, chimney liners | Wet, acidic gas with chlorides | Hastelloy C-276, C-22, Inconel 625 | Liner sheet welded to steel, plate, ducting |
| Hydrochloric acid reactors, pumps and valves | Reducing acids | Hastelloy B-2 | Plate, pipe, pump and valve parts |
| Pharmaceutical and fine-chemical reactors | Mixed media, often oxidising with chlorides | Hastelloy C-22 | Plate, pipe, vessel heads |
| Sulfuric and phosphoric acid evaporators, pickling lines | Sulfuric and phosphoric acid | Incoloy 825, 904L, 20Mo-4 | Tube, pipe, plate |
| Caustic soda evaporators | Hot caustic | Inconel 600 | Tube bundles, plate |
| Nitric acid plant catalyst-grid supports | Hot oxidising gas | Inconel 617, Haynes 230 | Grids, supports, sheet |
| Exchangers in hot chloride and reducing acid | Brine, chlorine, reducing acids | Titanium Grade 7, Grade 2 | Tube, tube sheets |
| General process piping, valves and instruments | Milder corrosion | 316 stainless | Pipe, fittings, tube |
The chart explains a lot of plant scrap pricing. B-2 at about 28% molybdenum and C-276 at about 16% carry far more payable alloy than 825 at about 3%, yet a reactor shell of each can look identical once the insulation is off. Sorting by equipment history gets you most of the way; a reading on every piece finishes the job. The Hastelloy grades are covered in more depth in selling Hastelloy scrap.
Clad, Lined and Overlaid Equipment
Much chemical equipment is not solid alloy. Large vessels, columns and scrubbers are often carbon steel with a thin corrosion-resistant layer, because solid nickel alloy at full thickness would be costly. The layer may be roll-bonded or explosion-bonded clad plate, a weld overlay, or thin "wallpaper" sheets seam-welded onto the steel shell.
- Process depositsscale, salts and residues, removed before sale
- Alloy layerC-276, C-22, 625 or 825, often a small share of the weight
- Bond or weldsclad interface, overlay or seam welds
- Carbon steel backingmagnetic, usually most of the weight
- Insulation and sheetingstripped before the piece is weighed
A magnet sticks to the outside of these pieces, and an XRF reading on the process side shows a textbook nickel alloy. Both are true, which is why clad and lined material must be declared. It is sold either as clad, with the layer described, or after the alloy has been separated from the steel. Selling it as solid alloy turns an honest lot into a dispute.
How Chemical Plant Scrap Is Released
Chemical plant scrap is released through the plant's shutdown or decommissioning procedure, and the steps that make equipment safe to cut are the same steps that make the scrap saleable. A typical sequence runs like this.
- 1Isolate and drainequipment emptied and cut off from the process
- 2Flush and neutraliseprocess fluids washed out, acid or caustic neutralised
- 3Clear for hot workgas-free check and permit before cutting
- 4Dismantle and separategaskets, insulation, refractory and carbon steel removed
- 5Identify and tagPMI on each piece, tagged by grade and source equipment
- 6Declare and documentdecontamination declaration, weight list, photographs
Two of these steps matter to the buyer beyond site safety. Cleaning matters for melt quality as well as handling: process deposits can carry sulfur and other elements a nickel melt does not want, as explained in tramp elements in remelting. And tagging by source equipment ties each piece back to the plant's own records.
Those records are the chemical plant's version of traceability. Equipment datasheets, fabrication data books and the original mill certificates often still sit in the maintenance or inspection office. Ask for them before the equipment is cut, while the tag numbers still match the drawings.
What Does Aerospace Nickel Alloy Scrap Actually Contain?
Aerospace scrap contains wrought heat-resisting alloys from machining and fabrication, cast superalloys from turbine blades and vanes, titanium from structures and compressors, and some stainless steel from exhaust systems. The grade is fixed by the part, and the part's material specification, usually an AMS number, names the alloy. See AMS aerospace material specifications.
| Source | Typical parts | Grades | Scrap form |
|---|---|---|---|
| Machining of forgings and bar | Discs, shafts, rings, casings, fasteners | Inconel 718 | Turnings, forging trims, bar ends |
| Hot-section fabrication | Combustion liners, transition ducts, casings | Hastelloy X, Haynes 282, Nimonic C-263, Haynes 230 | Sheet trim, rings, retired parts |
| Exhaust and nacelle | Exhaust ducting, thrust-reverser parts, bellows | Inconel 625, 321 and 347 stainless | Sheet, tube, formed parts |
| Turbine blades and vanes | Cast blades, vanes, nozzles | René 80, René N5, MAR-M 247, Inconel 713C | Service and foundry revert |
| Seals, springs and bolting | Honeycomb seals, hot bolts, springs | Haynes 214, Nimonic 80A, Inconel 718 | Small parts, wire |
| Structures, fan and compressor | Frames, brackets, fan and compressor parts | Titanium Grade 5 | Turnings, solids |
Nominal values from the grade pages; specification limits vary by product form.
Put these five side by side and the trap is obvious. Inconel 718 and Hastelloy X both carry about 18.5% iron; Haynes 282 and Nimonic C-263 differ most visibly in cobalt, about 10% against 20%, with 282 also higher in molybdenum. As chips in a drum they are indistinguishable. Only separate bins from the first cut keep them apart, which is why turnings are valued below solids unless a shop can show that discipline.
How Aerospace Scrap Is Released
Aerospace scrap is released through the quality system, not a shutdown. Production scrap such as chips and trims leaves the shop as a by-product of making parts. Rejected parts are held under nonconformance control, then scrapped. Retired engine parts are removed at overhaul, recorded, and normally mutilated before release so they can never return to service. Mutilation does not change their melt value.
- Melt ingot and bar made to an AMS specification
- Form and machine forging, casting and machining, chips and trims binned by alloy
- Service parts fly under part-number and serial records
- Overhaul and retire parts removed, recorded and mutilated
- Sort and return revert and chips sorted by alloy and sent back to the melt
Every turn of that loop depends on the scrap keeping its identity. The melter works to tight limits on alloying and trace elements, and can only charge scrap whose chemistry it trusts. Cast blade alloys add another layer: coated blades, rhenium-bearing single-crystal alloys and foundry revert are all kept apart. Those details are in how superalloy revert returns to the melt and selling turbine blade scrap.
Keep titanium away from nickel alloys at every stage. A few titanium chips in a nickel lot, or nickel chips in titanium, can spoil either melt, and titanium turnings bring their own fire risk.
Decontamination Versus Traceability: What Each Stream Has to Prove
Decontamination proves the scrap is clean and safe to handle and melt; traceability proves which alloy it is. Chemical plant scrap leans on the first and aerospace scrap on the second, but a good lot from either sector carries some of both.
| Chemical plant | Aerospace production | Aerospace overhaul | |
|---|---|---|---|
| Decontamination declaration | ● | ○ | ◐ |
| Clad, lining or coating declared | ● | ◐ | ● |
| Part, heat or tag numbers | ◐ | ● | ● |
| Mutilation or scrapping record | ○ | ◐ | ● |
| PMI reading on solid pieces | ● | ● | ● |
| Titanium kept separate | ◐ | ● | ● |
● yes ◐ partly ○ no
A decontamination declaration is a signed statement that the material has been drained and cleaned and is free of hazardous process residues. Many buyers, shippers and destination countries ask for it, and it travels with the papers listed in documents for exporting alloy scrap. It says nothing about the alloy.
Traceability works the other way. A part number, heat number or AMS specification tells a buyer the intended alloy, and a PMI record confirms each piece matches. Neither says anything about what is on the surface. Treat them as two separate sets of evidence and supply both where they apply.
Scrap from nuclear plants, such as Inconel 690 and 600 steam generator tubing, is a third case: it is traded only after radiological clearance, on top of everything above.
How to Describe Each Stream So a Buyer Can Price It
Describe each stream by grade and UNS number, form, source, condition and evidence, in that order. A buyer reading "Hastelloy scrap, 3 tonnes" has to assume the worst case. A buyer reading a full line can make a firm offer on the description, subject to confirmation on arrival.
| Stream | Vague description | Description a buyer can price |
|---|---|---|
| Scrubber relining | Hastelloy plate | Hastelloy C-276 (N10276) liner sheet, ex-absorber, steel backing removed, deposits cleaned, PMI per piece, decontamination declaration |
| Acid plant retubing | Alloy tubes | Incoloy 825 (N08825) tube bundle, ex-sulfuric acid cooler, tube sheet and baffles removed, drained and flushed |
| Clad column | Inconel 625 scrap | Carbon steel shell with Inconel 625 (N06625) clad layer, sold as clad, layer thickness from drawing |
| Disc machining | Inconel turnings | Inconel 718 (N07718) turnings, single alloy, crushed, centrifuged, no carbide inserts, composite analysis available |
| Combustor fabrication | Nickel sheet scrap | Hastelloy X (N06002) sheet trim to AMS 5536, clean, bagged by alloy |
| Engine overhaul | Turbine blades | René 80 turbine blades, service, coated, mutilated, engine model and count listed |
| Compressor machining | Titanium chips | Titanium Grade 5 (R56400) turnings, dry, no nickel alloy chips, stored away from ignition sources |
The scrap preparation guide covers cutting and packing by form. Checking look-alike pairs such as Hastelloy C-22 and C-276 before you write the description avoids the commonest naming errors.
Mistakes That Cost Value in Both Sectors
- Leaving the steel on. Carbon steel backing, flanges, tube sheets and supports add weight that no buyer pays alloy value for.
- One bin for C-276 and C-22. They often share a plant and look identical. Mixed, they sell as neither.
- Calling 825 "Inconel". Incoloy 825 is about 30% iron. Getting the name right tells a buyer the rest of your list can be trusted.
- Titanium chips in the nickel drum, or carbide inserts in either.
- Gaskets, packing and insulation left in place. PTFE, graphite and mineral wool are not metal, and some bring elements a melter does not want.
- Coated and uncoated blades in one box. Coatings change the chemistry the melter receives.
For sector background see chemical plant nickel alloy scrap and aerospace nickel alloy and superalloy scrap. Mipra Steel buys and supplies nickel alloy and stainless steel scrap described by grade. If you have a stream from either sector to sell, or a requirement to buy, send the grade, form, weight, location and whatever evidence you hold, and we'll review your enquiry.
Submit a requirement with the grade, form, quantity and delivery location.
Source a GradeFAQ
Is aerospace scrap worth more than chemical plant scrap?
Not as a rule. Value follows the grade, the form and how certain the chemistry is, not the sector. Hastelloy B-2 plate from an acid plant carries about 28% molybdenum, while aerospace stainless exhaust trim carries far less alloy. Aerospace turnings are often high-alloy but are discounted for oil and mixing risk. A clean, single-grade, well-documented lot from either sector is valued better than a mixed lot of the same alloys.
Can clad or weld-overlaid equipment be sold as nickel alloy scrap?
Yes, but it must be declared as clad or overlaid, not sold as solid alloy. The carbon steel backing is usually most of the weight, so a buyer values the piece on the alloy layer it actually contains, or on separated alloy after the layer has been removed. Give the alloy, the backing material and the layer thickness from the drawing where you have it, and expect the buyer to read both surfaces.
Who should sign a decontamination declaration for plant scrap?
It should come from the party that controlled the cleaning, normally the plant operator or the contractor who drained, flushed and dismantled the equipment under the plant permit. It states what the equipment handled, how it was cleaned and that the material is free of hazardous residues. A scrap trader passing the material on should hold the original and not write a fresh declaration for work it did not supervise.
Do retired aircraft engine parts need paperwork to be sold as scrap?
Usually, yes. Buyers expect a record showing the parts were removed from service and mutilated or otherwise made unusable, plus part numbers or a parts list where they are legible. That paperwork does two jobs: it shows the parts cannot re-enter service, and it helps identify the alloy. For blades and vanes, note the engine model and whether parts are coated or repaired.
Why must titanium be kept away from nickel alloy scrap?
Titanium and nickel alloys go to different melts, and each melter sets limits on the other metal. A few titanium chips in a nickel lot, or nickel chips in titanium turnings, can push a heat out of specification and force the whole lot to be downgraded. Titanium turnings also carry a fire risk. Separate bins at the machine are far cheaper than sorting mixed chips later.
What happens to Inconel 718 turnings from aerospace machining?
Clean, single-alloy 718 turnings are crushed, de-oiled and dried, then remelted, often back into nickel alloy production. The buyer will look for one grade only, no carbide inserts, low oil and moisture, and a composite analysis. Shops that bin 718 separately at each machine produce some of the more reliable turnings streams. See Inconel 718 turnings for preparation details.
Can plant scrap be sold before every piece has been identified?
It can be offered, but the offer will be provisional. Describe the equipment it came from, the likely grades from the plant records, the weights and photographs, and say clearly that readings are still to come. A buyer can then price on the expected grade subject to confirmation. Pieces that cannot be confirmed are best kept apart and sold separately rather than mixed into a graded lot.
