This is the compare library from Nandini Steel, an ISO 9001:2015 certified stainless, nickel-alloy and pressure-vessel steel supplier in Mumbai since 2003. Direct head-to-head grade comparisons with PREN, composition, cost and the service limit at which you step up.
Written and reviewed by our engineering team. Browse the topics below, or send a spec and we will point you to the right grade and standard.
304 family comparisons: 304 vs 304L vs 316
Most grade decisions start inside the 304 and 316 family, and the right answer depends on chlorides, welding and temperature rather than habit. Our 304 vs 316 comparison sets out the core trade-off: 316 carries 2 to 3 percent molybdenum that 304 does not, which is the single alloying difference that lets 316 resist pitting in coastal, chemical and marine-adjacent service where plain 304 corrodes early. For welded fabrication, the 304 vs 304L comparison covers why the low-carbon L variant resists sensitization in the 425 to 815 degree Celsius heat-affected zone without a post-weld anneal. The same logic carries into 304L vs 316L and 316 vs 316L, where the choice is carbon content and weld condition rather than corrosion grade. Across all four pages we flag the most common buyer error: defaulting to 304 for anything chloride-adjacent, and paying for 316 in dry indoor service where 304 would have served.
316L vs 904L vs duplex 2205: when to upgrade
Once a project moves past standard chlorides into concentrated acid, high-chloride brine or elevated temperature, 316L is no longer the safe default. The 904L vs 316L comparison walks through the chemistry behind the upgrade: 904L is a copper-bearing super-austenitic grade with roughly 4.5 percent molybdenum and a PREN near 34, against 316L's PREN near 24, which is why 904L resists sulfuric acid and chloride stress-corrosion cracking that defeats 316L. The harder decision is 904L against duplex, covered in 904L vs duplex 2205: duplex offers a comparable PREN near 35 with higher strength and lower nickel cost, but 904L's fully austenitic structure is easier to weld and fabricate on thick sections. Buyers frequently misjudge this step, either staying on 316L where acid concentration or chloride level demands the upgrade, or specifying 904L where duplex or a 6-Mo grade is the better fit.
Nickel alloy comparisons: Incoloy 825 vs Inconel 625
At the nickel-alloy end of the catalogue, Incoloy 825 vs Inconel 625 is the comparison most sour-service and chemical-processing buyers need. Incoloy 825 (UNS N08825) is a nickel-iron-chromium alloy valued for its combined resistance to reducing and oxidizing acids and its NACE MR0175 and ISO 15156 qualification for sour gas, while Inconel 625 carries more molybdenum and niobium for higher-temperature and higher-pressure duty. A frequent documentation error is calling the grade "Inconel 825" on a purchase order. It is Incoloy, not Inconel, and getting the designation right on the PO and mill test certificate avoids receiving-inspection disputes later.
How we compare grades
Every comparison page on this site is built on the same four data points, so you can check any grade decision yourself: PREN (pitting resistance equivalent number, which ranks pitting and crevice resistance from chromium, molybdenum and nitrogen content), chemical composition (the chromium, nickel, molybdenum and copper ranges that drive each grade's behavior), relative cost index (nickel and molybdenum content, not grade name, is what moves price, since both track the LME alloy surcharge), and service limit (the chloride concentration, temperature or acid duty at which the grade stops being adequate). We never publish price numbers against these cost positions because the alloy surcharge moves with the metals market between quotes. Send your service conditions through an RFQ and we confirm the grade and a firm delivered price the same day.
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