Introduction
Stainless steel flanges are essential components in piping systems, used in industries like oil & gas, chemical processing, water treatment, and power plants. However, selecting the wrong pressure rating can lead to system failures, leaks, or even safety hazards.
This guide explains:
✅ How flange pressure ratings work
✅ Key standards (ANSI, ASME, DIN, EN)
✅ Material impact (304 vs 316L vs duplex stainless steel)
✅ How temperature affects pressure capacity
✅ How to choose the right flange for your application
1. Understanding Flange Pressure Ratings
Flanges are classified by pressure classes, which indicate their maximum allowable working pressure (MAWP) at a given temperature.
Common Pressure Class Standards:
| Standard | Pressure Classes | Typical Applications |
|---|---|---|
| ANSI/ASME B16.5 | 150, 300, 600, 900, 1500, 2500 | Oil & gas, petrochemical |
| ASME B16.47 | 150, 300, 400, 600, 900 | Large-diameter pipelines |
| DIN/EN 1092-1 | PN6, PN10, PN16, PN25, PN40 | European water & chemical systems |
Key Takeaway:
-
Higher class number = higher pressure resistance (e.g., Class 300 handles more pressure than Class 150).
-
Temperature matters! A flange rated for 300 psi at room temperature may only handle 150 psi at 400°F.
2. How Material Affects Pressure Ratings
Not all stainless steel flanges perform the same under pressure.
| Material | Max Pressure Resistance | Best For |
|---|---|---|
| 304 Stainless Steel | Good for medium pressure (Class 150-600) | Water, food processing |
| 316/316L Stainless Steel | Higher corrosion & pressure resistance | Chemical, marine, oil & gas |
| Duplex Stainless Steel (2205) | Excellent for high-pressure, corrosive environments | Offshore, chemical plants |
Pro Tip: If your application involves high temperature + pressure (e.g., steam systems), 316L or duplex is the best choice.
3. Flange Types & Pressure Performance
Different flange designs handle pressure differently:
| Flange Type | Max Pressure Suitability | Common Use Cases |
|---|---|---|
| Weld Neck Flange | Best for high-pressure systems (Class 300+) | Oil refineries, high-pressure steam |
| Slip-On Flange | Medium pressure (Class 150-300) | Water pipelines, low-risk systems |
| Blind Flange | Used to seal high-pressure pipe ends | Testing, maintenance closures |
| Lap Joint Flange | Lower pressure (Class 150) | Systems requiring frequent disassembly |
Rule of Thumb: For critical high-pressure applications, always use weld neck flanges for maximum safety.
4. Temperature’s Impact on Pressure Ratings
A flange’s pressure rating decreases as temperature increases. Always check:
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ASME B16.5 pressure-temperature charts
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Material derating factors (e.g., 316L loses ~20% strength at 500°F vs room temp)
Example:
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A Class 150 flange may handle 285 psi at 100°F but only 150 psi at 500°F.
5. How to Select the Right Flange for Your Project
1️⃣ Determine max pressure & temperature of your system.
2️⃣ Choose the right material (304 for low-corrosion, 316L/duplex for harsh environments).
3️⃣ Select flange type (weld neck for high pressure, slip-on for cost efficiency).
4️⃣ Verify standards compliance (ANSI, ASME, DIN).
Why Choose Us for Stainless Steel Flanges?
Why Trust Us?
✅ 8+ Years in Stainless Steel Flanges – From ANSI to DIN standards, we supply precision-engineered flanges.
✅ Certified Quality – ISO 9001, PED, and NACE compliance for critical applications.
✅ Fast delivery – Fast delivery across Europe, Middle East & Americas.
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