Stainless Steel 304 vs 316: Scrap Identification & Why It Matters

Stainless steel looks uniform — it all looks like stainless. But 304 and 316 are priced very differently in the scrap market, and mixing them loses money. This guide covers how to tell them apart as a non-metallurgist.

The Composition Difference

• 304: 18% chromium, 8% nickel. The most common “food-grade” stainless. Used in kitchens, appliances, countertops, and general-purpose equipment.
• 316: 16% chromium, 10% nickel, plus ~2% molybdenum. “Marine grade” stainless — resists salt, chloride, and aggressive chemicals.

The molybdenum in 316 is what makes it more valuable. Moly is expensive, so 316 costs more new — and scraps higher.

Test 1: Context Clues

Before any test, look at where the stainless came from:

• Kitchens, food service, hospitals, architectural: usually 304
• Marine, pharmaceutical, chemical plants, offshore: usually 316
• Pool pumps, chloride-exposed equipment, high-temp boilers: 316 or 316L

Test 2: The Magnet Test

Both 304 and 316 are “austenitic” stainless — supposed to be non-magnetic. In practice, cold-worked 304 can show weak magnetism after stamping or bending. Cold-worked 316 resists magnetization better.

Result:

• No magnetic pull at all: most likely 316
• Weak pull on cold-worked edges: probably 304
• Strong magnetic pull: not 304 or 316 — could be ferritic (430) or martensitic stainless, or plain steel

Test 3: Molybdenum Spot Test

The definitive test is a moly spot test kit — a reagent that turns yellow on 316 (indicating moly presence) and stays clear on 304. Kits cost ~S$30-60 and work in seconds. Worth buying if you regularly handle stainless scrap.

Pricing Impact

• 316 (solid): from $2.60/kg
• 304 (solid): from $1.80/kg

That’s a 44% premium for 316. On a 100 kg load, sorting correctly is worth $80. On a 1-tonne load, $800.

What About 309 and 310?

High-nickel heat-resistant grades used in furnaces, kilns, and high-temp industrial equipment. They scrap even higher — from $3.00/kg. If you’re clearing a boiler room or heat-processing facility, any heavy stainless may be 309 or 310, worth isolating.

When in Doubt, Let Us Grade

Molten Steel’s yard has XRF spectrometers for positive material identification. Bring in your stainless, and we’ll grade it definitively — you get the right rate for each piece, not a blanket low rate for the whole load.

Is 304 or 316 Food Grade?

Both 304 and 316 are considered food-grade stainless steel and are widely used in commercial kitchens, food processing, and beverage production in Singapore.

• 304 stainless steel is the default food-grade choice — used in stock pots, worktops, sinks, saucepans, cutlery, and general food service equipment. Its 18/8 chromium-nickel composition resists common food acids and cleaning agents.
• 316 stainless steel is the upgraded food-grade for harsh environments — saltwater proximity (marine kitchens, seafood processors), high-chloride foods (salted/preserved products), brewing, dairy, and pharmaceutical food applications.

From a scrap perspective, food-grade stainless equipment — kitchen sinks, commercial cookware, brewery vessels — is a regular source. The grade matters for your payout: if a brewery or food plant is being decommissioned, checking whether the tanks are 304 or 316 before selling can mean the difference between a $1.80/kg and a $2.60/kg rate. That's ~44% more on potentially tonnes of metal.

Look for grade stamps like 304, 316, SUS304, or SUS316 stamped into tank bodies, or 18/8 (= 304) and 18/10 (often 316) in cookware. When in doubt, bring the item in and we'll XRF-test it for exact grading.