This is the applications library from Nandini Steel, an ISO 9001:2015 certified stainless, nickel-alloy and pressure-vessel steel supplier in Mumbai since 2003. Matched to the industry and the service condition that governs the grade choice.
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.
Oil and gas, petrochemical and sour service
Oil and gas and petrochemical plants put more corrosion mechanisms in play at once than almost any other industry: sour gas, chlorides, high temperature and pressure, often together. Our oil and gas applications and petrochemical applications pages cover separators, piping, heat exchangers and pressure vessels across this duty, and our pressure vessels and boilers applications page covers the vessel-code side of the same plants. For sour wellheads and separators, Incoloy 825 plate is the standard recommendation, since its combined resistance to reducing and oxidizing acids and its NACE MR0175 and ISO 15156 qualification cover the mixed-acid, sour-gas environment that defeats 316L. For carbon steel vessels in sour duty, specify the NACE-HIC tested variant of A516 Grade 70 rather than plain Grade 70, to guarantee resistance to hydrogen-induced cracking. Piping and valve trim on the same units frequently step up to Hastelloy or Alloy 20 where the process stream carries both chlorides and reducing acid at once.
Chemical, fertilizer and acid service
Chemical processing and fertilizer and acid-regeneration plants are built around sustained acid exposure, and the grade that handles general process chemicals is rarely the one that survives concentrated sulfuric acid. Our chemical processing applications and fertilizer and acid service applications pages map the common duties, and in almost every sulfuric-acid or high-chloride acid-plant case the recommendation is 904L plate, a copper-bearing super-austenitic grade that resists sulfuric acid at concentrations and temperatures where standard 316L pits and cracks. Where the acid environment is mixed reducing and oxidizing rather than purely sulfuric, Incoloy 825 is the better fit, and the chemistry behind that choice is covered in more depth in our sulfuric acid resistance guidance.
Pharmaceutical, food and beverage (hygienic grades)
Hygienic processing is less about raw corrosion resistance and more about a cleanable, weldable surface that holds up to repeated CIP and SIP cycles without pitting at the weld seam. The pharmaceutical applications, food and beverage applications and food and dairy applications pages cover tanks, piping and process vessels for this sector, and the standard recommendation is 316L sheet and plate for welded hygienic equipment, since the low carbon content avoids sensitization in the weld heat-affected zone. Where CIP chemistry is unusually aggressive or chloride-bearing cleaning agents are used at higher concentration, some pharmaceutical plants step up to 904L for the same reason acid plants do.
Marine, pollution control and architecture
Marine, pollution control and architectural work share one problem: sustained or cyclic chloride exposure from seawater, flue gas or coastal air, over a service life measured in decades rather than process-run cycles. Our marine applications, pollution control applications and architectural applications pages cover this duty, and the working recommendation is 316 or 316L plate and sheet for marine structures, piping and pollution-control equipment such as flue-gas desulfurization internals, where the molybdenum content resists pitting that plain 304 cannot. For architectural cladding, railing and general fabrication away from direct chloride exposure, 304 remains the economical standard, and our general fabrication applications page covers that broader structural and decorative use case. Where flue-gas duty runs hot and highly acidic rather than just chloride-laden, some pollution-control equipment steps up to 904L for the same acid-resistance reasons used in chemical processing.
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