Material Selection Overview
| Material | UNS Number | Max Temp | Corrosion Resistance | Cost Factor |
|---|
| Carbon Steel (WCB) | J02502 | 425°C | Poor in corrosive | 1.0x |
| 304 SS (CF8) | J92600 | 425°C | Good general | 2.5x |
| 316 SS (CF8M) | J92900 | 425°C | Better (Mo content) | 3.0x |
| Duplex (CD3MN) | J93370 | 315°C | Excellent | 5.0x |
| Hastelloy C276 | N10276 | 675°C | Outstanding | 15x |
| Titanium (Grade 2) | R50400 | 315°C | Seawater, chlorides | 20x |
| Monel 400 | N04400 | 450°C | HF acid, seawater | 12x |
Chemical Compatibility Chart
Acids
| Chemical | 304 SS | 316 SS | Duplex | Hastelloy C276 | Titanium |
|---|
| Sulfuric (dilute) | Fair | Good | Good | Excellent | Fair |
| Sulfuric (concentrated) | Poor | Poor | Fair | Good | Poor |
| Hydrochloric | Poor | Poor | Poor | Excellent | Fair |
| Nitric | Good | Good | Good | Good | Good |
| Phosphoric | Good | Good | Good | Excellent | Good |
| Acetic | Good | Good | Good | Excellent | Good |
| Formic | Fair | Good | Good | Excellent | Good |
Alkalis
| Chemical | 304 SS | 316 SS | Duplex | Hastelloy C276 | Titanium |
|---|
| Sodium Hydroxide (<50%) | Good | Good | Good | Good | Good |
| Sodium Hydroxide (>50%) | Fair | Fair | Good | Good | Fair |
| Potassium Hydroxide | Good | Good | Good | Good | Good |
| Ammonia | Good | Good | Good | Good | Good |
Chlorides
| Chemical | 304 SS | 316 SS | Duplex | Hastelloy C276 | Titanium |
|---|
| NaCl (seawater) | Poor (pitting) | Fair | Good | Excellent | Excellent |
| HCl (dilute) | Poor | Poor | Poor | Excellent | Fair |
| Chlorinated water | Poor | Fair | Good | Excellent | Excellent |
Material Selection by Industry
Oil & Gas
- Standard service: Carbon Steel (WCB/WCC)
- Sour service (H2S): NACE MR0175 compliant (HRC ≤ 22)
- Seawater: Duplex or Super Duplex (CD3MN/CE3MN)
- High temperature: Chrome-moly (WC6/WC9/C5)
Chemical Processing
- Dilute acids: 316 SS (CF8M)
- Strong acids: Hastelloy C276 or Alloy 20
- Chlorinated solvents: Hastelloy or Titanium
- Caustic service: Nickel 200/201
Water Treatment
- Potable water: 304 SS or ductile iron
- Desalination: Super Duplex (CE3MN)
- Wastewater: 316 SS or Duplex
Food & Pharmaceutical
- Sanitary applications: 316L SS (low carbon)
- FDA/EC 1935/2004 compliance: Electropolished surfaces
Material Selection Decision Tree
- Is the media corrosive? → If no, use Carbon Steel
- Is it seawater or chloride-rich? → Duplex or Titanium
- Is it a strong acid (HCl, H2SO4 concentrated)? → Hastelloy C276
- Is it a dilute acid? → 316 SS may be sufficient
- Is high temperature involved (>425°C)? → Chrome-moly or nickel alloys
- Is cost the primary concern? → 304 SS or 316 SS with corrosion allowance
Cost vs. Lifetime Analysis
| Material | Initial Cost | Expected Life (seawater) | 20-Year TCO |
|---|
| Carbon Steel | $1,000 | 1-2 years | $15,000 |
| 316 SS | $3,000 | 5-8 years | $8,000 |
| Duplex | $5,000 | 15-20 years | $5,500 |
| Super Duplex | $8,000 | 25+ years | $8,500 |
| Titanium | $15,000 | 30+ years | $15,500 |
ValveSpecs Pro Resources
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