Monel 400 Applications Guide - Seawater, HF Acid, Alkali & Cost Comparison
Date: 2026年8月16日 Categories: News Views: 196
By Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier | ISO 9001:2015 | Est. 2012
Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp (Lisa): +86 13611656360
Quick Answer: Where Is Monel 400 Used and Why?
Monel 400 (UNS N04400) is a 67% nickel-30% copper alloy that is the reference material for seawater service, hydrofluoric acid (HF), and hot caustic soda — environments where it outperforms stainless steels by 10-100x. It is supplied in bars, tubes, plates, wire, and forgings per ASTM B164/B127/B165. Shanghai Hangbo Alloy Group supplies Monel 400 in all forms with EN 10204 3.1 certification. This guide covers the three signature applications, cost data, and selection rules.
Application 1: Seawater & Marine
Why Monel 400 wins: Nearly immune to chloride stress-corrosion cracking and pitting in ambient seawater. Corrosion rate < 0.025 mm/year in flowing seawater.
| Application | Component | Alternative |
|---|---|---|
| Seawater piping | Shipboard saltwater lines | 316L (pits in months) |
| Heat exchangers | Marine condenser tubes | Titanium (cost) |
| Valve trim | Seawater valves, stems | 316L (seizure) |
| Shafts | Propeller shafts | Bronze (strength) |
Application 2: Hydrofluoric Acid (HF)
The unique Monel capability: Monel 400 is the ONLY economical alloy resistant to both dry and aerated HF acid. It forms a protective NiF₂/CuF₂ film.
| HF Concentration | Temperature | Rate |
|---|---|---|
| Anhydrous HF | 25-100C | < 0.05 mm/yr |
| 40% HF | 25C | < 0.1 mm/yr |
| 40% HF | Boiling | 0.5-1.0 mm/yr |
Note: Do NOT use Monel 400 with aerated HF above 40C — oxygen increases attack. Specify Monel K-500 or HF-grade for hot aerated service.
Application 3: Caustic Soda (NaOH)
Monel 400 resists caustic soda at all concentrations up to the boiling point, making it standard for evaporator tubes and caustic piping.
| NaOH % | Temperature | Rate |
|---|---|---|
| 25-50% | 80-130C | < 0.05 mm/yr |
| 50-73% | Boiling | < 0.1 mm/yr |
Caution: Above 370C, Monel 400 becomes brittle in caustic service — consider Nickel 200/201 above this temperature.
Monel 400 vs K-500 (Selection Table)
| Property | Monel 400 | Monel K-500 |
|---|---|---|
| Yield (annealed) | 210 MPa | 790 MPa (aged) |
| Tensile | 550 MPa | 1100 MPa (aged) |
| Corrosion | Same base | Same base |
| Formability | Excellent | Fair |
| Price | Baseline | +40-60% |
| Use | Piping, exchangers | Shafts, fasteners, tools |
Price Guide (2026, EXW)
| Form | Price |
|---|---|
| Round Bar Ø25-100 mm | \$24-38/kg |
| Seamless Tube OD 25 mm | \$35-55/kg |
| Plate 6-25 mm | \$28-42/kg |
| Wire | \$30-45/kg |
Quality & Supply
- ASTM B164 (bar), B127 (plate), B165 (tube) certified.
- EN 10204 3.1 MTC per heat.
- PMI + hydrostatic testing standard.
- SGS/TUV/BV available.
- 40+ countries via FOB/CIF/DAP.
Contact & Complete Product Range
Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier
Email: sales@hangboalloy.com | WhatsApp (Lisa): +86 13611656360 | www.nickel-alloy.com
All Grades
Ni: NI200-N6 | Monel: 400-502, K-500, R-405 | Inconel: 600-740H, X-750, 725 | Incoloy: 800-27-7MO | Hastelloy: C-276-HYBRID-BC1, N | Super Austenitic: 904L-AL-6XN | Chromium-Rich: Alloy 33 | High-Strength Stainless: Nitronic 50/60, PH13-8Mo | Chlorination: Alloy 45 | Nimonic: 75-263 | Haynes: 25-HR-160 | RA: 330/333 | Precision: 1J22-4J45 | High-Strength: 18Ni250-AerMet100 | Heating: Cr20Ni80/60 | Specialty: Alloy 20-602CA
Product Forms: Bars(6-500mm) | Tubes(OD 6-610mm) | Plates(0.1-100mm) | Forgings | Welded Pipes | Fittings | Wire(0.05-10mm) | Strip(0.02-4.0mm)
SGS/BV/TUV. www.nickel-alloy.com
