Question:
The material most suitable for the Evaporator pipeline is
The material most suitable for the Evaporator pipeline is
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Dairy Metallurgy Standards:
Standard Milk Piping & Tanks = AISI 304 (18/8 Cr-Ni).
EVAPORATOR TUBES, Cheese Vats, Salting Equipment = AISI 316 (Contains 2--3% Molybdenum).
Standard Milk Piping & Tanks = AISI 304 (18/8 Cr-Ni).
EVAPORATOR TUBES, Cheese Vats, Salting Equipment = AISI 316 (Contains 2--3% Molybdenum).
Updated On: Sep 15, 2026
- AISI 304
- AISI 316
- AISI 400
- AISI 302
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Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
Sanitary metallurgy and corrosion resistance in dairy evaporators: AISI 316 austenitic stainless steel (16-18% Cr, 10-14% Ni, 2-3% Molybdenum) provides superior resistance against chloride pitting, hot concentrated lactic acid, and aggressive hot CIP nitric acid/caustic soda in milk evaporators compared to AISI 304.
Key Formula or Approach:
\[ \mathbf{AISI \text{ } 316} = 18\% \text{ Cr} + 10 - 12\% \text{ Ni} + \mathbf{2 - 3\% \text{ Molybdenum (Mo)}} \implies \mathbf{High \text{ } Pitting \text{ } Resistance \text{ (PREN)}} \]
Step 2: Detailed Explanation:
In dairy materials engineering and evaporator fabrication:
1. AISI 304 (18/8 Stainless Steel): The standard general-purpose stainless steel used for milk storage tanks, pipes, and pasteurizers.
2. AISI 316 Stainless Steel (B):
- In milk evaporators, concentrated milk ($50\%$ TS), whey, and CIP chemicals operate under continuous boiling temperatures ($45^\circ - 75^\circ ext{C}$) with concentrated chloride minerals and lactic acid.
- AISI 316 contains 2.0% to 3.0% Molybdenum (Mo), which dramatically increases the Pitting Resistance Equivalent Number (PREN) and prevents localized pitting, crevice corrosion, and stress corrosion cracking from hot sanitizing acids.
- Therefore, AISI 316 is the material most suitable for evaporator pipelines and calandria tubes.
Step 3: Final Answer:
Therefore, the material most suitable is AISI 316, corresponding to option (B).
Sanitary metallurgy and corrosion resistance in dairy evaporators: AISI 316 austenitic stainless steel (16-18% Cr, 10-14% Ni, 2-3% Molybdenum) provides superior resistance against chloride pitting, hot concentrated lactic acid, and aggressive hot CIP nitric acid/caustic soda in milk evaporators compared to AISI 304.
Key Formula or Approach:
\[ \mathbf{AISI \text{ } 316} = 18\% \text{ Cr} + 10 - 12\% \text{ Ni} + \mathbf{2 - 3\% \text{ Molybdenum (Mo)}} \implies \mathbf{High \text{ } Pitting \text{ } Resistance \text{ (PREN)}} \]
Step 2: Detailed Explanation:
In dairy materials engineering and evaporator fabrication:
1. AISI 304 (18/8 Stainless Steel): The standard general-purpose stainless steel used for milk storage tanks, pipes, and pasteurizers.
2. AISI 316 Stainless Steel (B):
- In milk evaporators, concentrated milk ($50\%$ TS), whey, and CIP chemicals operate under continuous boiling temperatures ($45^\circ - 75^\circ ext{C}$) with concentrated chloride minerals and lactic acid.
- AISI 316 contains 2.0% to 3.0% Molybdenum (Mo), which dramatically increases the Pitting Resistance Equivalent Number (PREN) and prevents localized pitting, crevice corrosion, and stress corrosion cracking from hot sanitizing acids.
- Therefore, AISI 316 is the material most suitable for evaporator pipelines and calandria tubes.
Step 3: Final Answer:
Therefore, the material most suitable is AISI 316, corresponding to option (B).
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