Selecting the right flange material is one of the most critical decisions in any pipeline or pressure vessel project. The wrong material can lead to corrosion failure, mechanical breakdown, or non-compliance with design codes - all of which carry significant cost and safety consequences.
CNCJ supplies flanges and pipe fittings in a comprehensive range of flange material grades, from standard stainless steel flanges (304, 316L, 321, 347) and duplex steel flanges (S32205, S32750) to special alloy flanges (Inconel 625, Hastelloy C-276, Monel 400) and carbon steel flanges (A105, A350 LF2, A694). All materials are sourced from certified mills and verified by in-house PMI spectrometer testing before production begins.
Our materials conform to ASTM A182, ASTM A105, ASTM A350, EN 10222, and other major international standards. Each material listed below links to a dedicated data sheet covering chemical composition, mechanical properties, applicable standards, and flange material selection guidance. For project-specific material queries, contact our technical team directly.
For chemical composition details of any specific grade, check our Material Data Sheet by clicking the material name below.
Flange Material Comparison Chart
Group 1: Stainless Steel Flanges
|
Grade |
Key Properties |
Typical Applications |
|
304 |
Good corrosion resistance |
Water treatment, food, general chemical |
|
316L |
Mo-enhanced; superior chloride resistance |
Seawater, pharma, offshore |
|
316Ti |
Ti-stabilized; resists intergranular corrosion |
High-temp chemical, GOST projects |
|
321 |
Ti-stabilized 304; high-temp stable |
Exhaust systems, heat exchangers |
|
347 |
Nb-stabilized; better weldability than 321 |
Refinery, high-temp piping |
|
904L |
High Mo+Cu; excellent acid resistance |
Sulfuric acid, phosphoric acid service |
|
31254 |
Super austenitic; pitting resistant |
Seawater desalination, bleach |
Group 2: Duplex Steel Flanges
|
Grade |
Key Properties |
Typical Applications |
|
S31803 |
2× strength of 316L; good stress corrosion resistance |
Oil & gas, chemical, desalination |
|
S32205 |
Enhanced version of S31803; higher Cr/N |
Offshore platforms, subsea |
|
S32750 |
Super duplex; extreme pitting resistance |
Seawater, aggressive acids, FGD |
|
S32760 |
W+Cu added; enhanced corrosion resistance |
Subsea wellheads, chloride service |
Group 3: Special Alloy Flanges
|
Grade |
Key Properties |
Typical Applications |
|
N04400 |
Cu-Ni alloy; HF acid and seawater resistant |
HF alkylation, marine, desalination |
|
N06600 |
High-temp oxidation & corrosion resistant |
Nuclear, heat treatment equipment |
|
N06625 |
Excellent fatigue & corrosion resistance |
Subsea, aerospace, chemical reactor |
|
N10276 |
Best overall corrosion resistance of any alloy |
Wet chlorine, oxidizing acids, FGD |
|
N08825 |
Ni-Fe-Cr + Mo/Cu; H₂SO₄ and H₃PO₄ resistant |
Acid gas wells, pickling equipment |
|
N08800 |
High-temp strength and carburization resistance |
Petrochemical furnace tubes, steam reforming |
|
N08926 |
Super austenitic; extreme pitting resistance |
Seawater, chloride-rich process |
Flange Material Selection Guide
Selecting the correct flange material depends on medium corrosion, temperature, pressure, standards, and compliance requirements.
Stainless Steel Flanges
Best for general chemical, water, steam, and mild corrosive service.
Typical grades ：
304/304L, 316/316L, 321, 347
Duplex Steel Flanges
Higher strength and excellent resistance to chloride & SCC.
Typical grades ：
2205 (F51), 2507 (F53/F55)
Special Alloy Flanges
Designed for extreme corrosion, high temperature, and sour service.
Typical alloys ：
Inconel 625/718, Hastelloy C276, Monel 400, Titanium
Selection Priority
Medium corrosion → Temperature & Pressure → Standard & Process → Environment load → Cost → Compliance
1. Medium
Medium is always the first factor in material selection.
- Chloride: 316L → 2205 → 2507
- Sour gas (H₂S/CO₂) : NACE materials required
- Strong acid : Nickel alloys (625 / C276)
- Abrasive slurry : Duplex steel recommended
2. Temperature & Pressure
High temperature requires creep & oxidation resistance.
- Low temp <-20℃: 304L / 316L / Nickel alloys
- High temp >400℃: 321 / 347 / Inconel alloys
- High pressure >10MPa: forged flanges required
3. Standards & Process
Material standard must match project requirements.
- ASME: ASTM A182 (SS/Duplex/Alloy forging)
- EN: EN 10222 forged steel
- GB: GB/T 9124 flange system
- Forged vs Casting : critical piping must use forging
4. Environment Load
External corrosion and vibration may require upgraded materials.
- Marine atmosphere : 316L or 2205
- Vibration & fatigue : tougher materials preferred
- Underground : coating + cathodic protection
5. Cost & Maintenance
Life cycle cost is more important than initial cost.
- 304: lowest cost, limited chloride resistance
- 316L: best balance for industrial projects
- 2205: higher cost but longer service life in seawater
- Nickel alloys: expensive but essential for extreme corrosion
6. Compliance
Critical service requires certification and strict inspection.
NACE MR0175 / ISO 15156: sour service compliance
- PMI: positive material identification
- UT / RT: NDT inspection
- EN10204 3.1 / 3.2: material test certificate
Material Comparison Chart
Compare stainless steel, duplex steel, and special alloys based on corrosion, temperature, and cost.
| Material | Typical Grades | Corrosion | Chloride | High Temp | Strength | Cost | Best Application |
|---|---|---|---|---|---|---|---|
| Stainless Steel | 304/316L/321/347 | Good | Medium | Medium | Medium | $$ | General chemical, water, steam |
| Duplex Steel | 2205 / 2507 | Excellent | High | Medium | High | $$$ | Seawater, cooling water, SCC risk |
| Special Alloys | Inconel / Hastelloy / Monel / Titanium | Top | Top | High | High | $$$$ | Extreme corrosion & high temperature |
Quick Selection Table
| Service | Recommended Material | Reason |
|---|---|---|
| Water & steam | 304 / 304L | Best cost performance |
| Chemical pipeline | 316L | Best balance for corrosion & cost |
| Seawater | 2205 / 2507 | High chloride resistance |
| High temperature >400℃ | 321 / 347 / Inconel | High-temp stability |
| Sour service (H₂S) | 316L / 2205 (NACE) | Hardness control required |
| Strong acid | Hastelloy C276 / Inconel 625 | Best chemical resistance |
FAQ
Frequently asked questions from EPC contractors and industrial buyers.
If chloride concentration is high or temperature is elevated, duplex 2205 is recommended due to stronger pitting and SCC resistance.
Special alloys are required for strong acids, high temperature oxidation environments, and extremely corrosive chemical processes.
Forged flanges provide higher density, fewer internal defects, and better sealing stability under pressure.
NACE MR0175 / ISO 15156 is the international standard for material selection in H₂S sour service. It includes hardness limits and material restrictions.
Typical documents include EN10204 3.1 MTC, PMI report, UT/RT NDT reports, dimensional inspection, hardness test, and hydro test if required.