254 SMO Scrap: Composition, Uses, Look-Alikes and How It Is Traded

What Is 254 SMO Scrap?

254 SMO scrap is recovered UNS S31254 (W.Nr. 1.4547), a super-austenitic stainless steel, from pipe, plate, fittings, flanges and exchanger parts that have been cut off, rejected or taken out of service. The trade calls the same grade “SMO 254”, “6Mo”, “Alloy 254” and, for forgings, “F44” after ASTM A182 F44.

“Super-austenitic” means a fully austenitic stainless steel, like 316L in structure, but with much higher chromium, nickel, molybdenum and nitrogen. The “6Mo” label refers to the molybdenum level, about 6%, which is the reason the grade exists: molybdenum and nitrogen give resistance to pitting and crevice corrosion in chloride water, where 316L fails.

Why Is 254 SMO Used, and What Is It Used for?

254 SMO is used where seawater or chloride-bearing process liquids would pit or crack 316L, but a nickel alloy would be more than the job needs. It closes the gap between ordinary stainless steel and alloys such as Inconel 625.

• Seawater cooling and firewater systems on offshore platforms, terminals and coastal plants.
• Desalination plants, including high-pressure reverse-osmosis piping and intake systems.
• Pulp-bleach equipment, where chlorine dioxide bleach stages are hard on ordinary stainless.
• Flue-gas cleaning and scrubber components.
• Offshore process piping, valves and heat exchangers in chloride service.

The chart explains the grade’s position. 254 SMO carries more molybdenum than duplex 2205, the super duplex grades, Incoloy 825 and 20Mo-4, but less than Inconel 625. On pitting resistance it is close to super duplex 2507; the difference is that 254 SMO is fully austenitic and non-magnetic, while super duplex is half ferrite and strongly magnetic.

Where Does 254 SMO Scrap Come from?

254 SMO scrap comes from seawater, desalination and pulp-bleach plant, with smaller volumes from fabrication shops. Each source has its own typical form and its own contaminants.

Seawater and Offshore Systems

Firewater rings, seawater cooling pipe, strainers and valve bodies from platform and terminal upgrades. Expect flanges in other materials, marine growth and paint. See oil and gas scrap and marine scrap.

Desalination Plants

High-pressure piping, manifolds and fittings from reverse-osmosis trains, often found alongside super duplex and titanium from the same plant. The desalination plant scrap page covers the mix of grades a desalination rebuild produces.

Pulp Mills

Bleach-plant washers, drums, piping and tank sections. These may carry deposits from the bleach chemicals and usually need cleaning before sale.

Fabrication and Machining

Plate and pipe offcuts, flange forgings to F44 and some turnings. Fabrication offcuts are often the cleanest 254 SMO scrap available, because they are new metal with the stencils still on.

254 SMO vs 904L: How Do You Tell Them Apart?

Read molybdenum and nickel: 254 SMO has about 6% molybdenum and 18% nickel, while 904L (UNS N08904) has about 4–5% molybdenum, 23–28% nickel and 1–2% copper. Both are non-magnetic, both are used in acid and chloride service and both look the same, so in a yard they are mixed often.

The comparison runs against intuition: 904L carries more nickel but less molybdenum. 904L is not part of Mipra Steel’s range, but it matters here as a look-alike. A few lengths of 904L in a 254 SMO lot pull the molybdenum average down and add copper, and a buyer who finds them will re-read the whole lot.

Other 6Mo grades, such as UNS N08367 and N08926, read close to 254 SMO on molybdenum but carry noticeably more nickel, about a quarter of the alloy. If your readings show 6% molybdenum with 24–26% nickel, describe the material by what it reads rather than calling it 254 SMO. Nitrogen does not show on a handheld XRF at all; if a buyer needs it confirmed, that takes spark OES with nitrogen capability or a laboratory test, as explained in choosing XRF, OES or laboratory analysis.

How Does 254 SMO Differ from Duplex and Super Duplex Scrap?

254 SMO is austenitic and non-magnetic, with about 18% nickel; duplex and super duplex grades are half ferrite, clearly magnetic, with only 5.5–7% nickel. That makes a magnet genuinely useful here, as a first sort rather than an identification.

Duplex 2205, super duplex 2507 and S32760 come from the same offshore and desalination plants as 254 SMO and often arrive on the same truck. Because their nickel content is a third of 254 SMO’s or less, mixing them in costs the 254 SMO seller directly. The magnet test article explains what the magnet can and cannot tell you, and selling duplex and super duplex scrap covers the duplex grades themselves.

What Is 20Mo-4, and How Does It Relate to 254 SMO?

20Mo-4 (UNS N08024) is a related corrosion alloy that is easy to file next to 254 SMO, but it is chemically a different animal: about 37.5% nickel, 24% chromium, 4% molybdenum and 1% copper, with nickel slightly above iron. With more nickel than iron, it trades as a nickel alloy, not as stainless steel.

20Mo-4 is a higher-molybdenum development of Alloy 20, built for sulfuric and phosphoric acid and chloride pitting. Its scrap comes from acid plant piping, vessels and exchangers, and from fabrication offcuts of ASTM B463 plate, B464 welded pipe and B473 bar. On a reading it separates from 254 SMO at once: twice the nickel, less molybdenum and more copper. It also needs to be kept apart from its relatives Alloy 20 (N08020), with about 2.5% molybdenum and 3.5% copper, and 20Mo-6 (N08026), with about 6% molybdenum. The 20Mo-4 scrap page has its specification chart.

What Decides the Price of 254 SMO Scrap?

254 SMO scrap is valued above ordinary stainless steel scrap because of its nickel and molybdenum, but only when the grade is confirmed and the lot is clean. Without proof it is likely to be treated as general austenitic stainless, and the molybdenum goes unpaid.

The usual factors then apply: the nickel and molybdenum markets, grade certainty, whether the lot is a single grade, form, cleanliness, quantity, location and payment terms. Painted and fouled seawater pipe, mixed flanges and bleach deposits are the common deductions. How these factors combine into an offer is explained in nickel alloy scrap price per kg: what decides the rate. This page gives no figure, because a rate printed today would be wrong for most lots tomorrow.

Which Markings and Standards Identify 254 SMO?

Look for “S31254”, “1.4547” or “F44” in a stencil next to an ASTM A specification and a heat number; together with a matching mill certificate, that is the strongest grade evidence a 254 SMO lot can carry. Plate and sheet are made to ASTM A240, pipe to A312, welded exchanger tube to A249, forgings and flanges to A182 grade F44 and bar to A479. Pressure equipment is often dual-marked with the matching ASME SA number.

These marks matter more on 254 SMO than on most grades, because the elements that make it special are the ones field instruments struggle with. A handheld XRF reads molybdenum and nickel well, but nitrogen not at all. A stencil and certificate fill that gap. The specifications are explained in ASTM A specifications for duplex and 6Mo stainless, and how to check a certificate against the metal is set out in reading an EN 10204 3.1 mill certificate.

Which Mistakes Cost 254 SMO Sellers Money?

Most losses on 6Mo super-austenitic scrap come from treating it as ordinary stainless, and they are avoidable.

1. Binning it with 316L. The two look identical and neither responds to a magnet. Read anything that came out of seawater, desalination or bleach service before it goes into a stainless bin.
2. Calling every 6% molybdenum reading 254 SMO. If nickel reads near a quarter of the alloy, it is another 6Mo grade, and should be described by its readings.
3. Leaving super duplex in the lot. Fittings, valves and spools in 2507 or S32760 sit in the same systems. A magnet catches them in seconds.
4. Selling fouled pipe as found. Marine growth, paint and bleach deposits add weight that is not metal and raise questions about residues. Clean it, or say clearly that it is uncleaned.

How Is 254 SMO Scrap Classified and Traded?

254 SMO is an iron-base stainless steel, so its scrap is normally classified as stainless steel waste and scrap under HS 7204.21, while 20Mo-4, with more nickel than iron, normally falls under HS 7503.00 as nickel scrap. At the time of writing that is the usual treatment, but confirm the full national tariff line with your customs broker before shipping. The rest of the paperwork is listed in export documents for alloy scrap.

Mipra Steel buys and supplies 254 SMO and 20Mo-4 scrap by grade from Khetwadi, Mumbai, with offices in Dubai and South Korea, and handles import and export enquiries. To describe a lot, give the grade and UNS number, form, approximate weight, location, photographs, readings showing nickel, chromium and molybdenum, and the plant or service it came from. The duplex and 254 SMO scrap section lists related grades. Send the details and we’ll review your enquiry.

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