✅ 1. Determine the Flange Size
Flange size is primarily defined by:
Nominal Pipe Size (NPS) or Diameter Nominal (DN): Indicates the pipe/flange diameter.
Bolt Hole Dimensions: Number, diameter, and pitch circle diameter (PCD).
Thickness and Outer Diameter: Must match with the pipe and gasket used.
🔍 Tip: Refer to ASME B16.5 or EN 1092-1 dimension tables to match pipe and flange size correctly.
🔧 2. Select the Appropriate Pressure Rating
Choose a rating that suits the pressure and temperature conditions of your system:
| Standard | Common Pressure Classes |
|---|---|
| ASME B16.5 | Class 150, 300, 600, 900, 1500, 2500 (psi) |
| EN 1092-1 | PN10, PN16, PN25, PN40... (bar) |
| JIS B2220 | 5K, 10K, 16K, 20K (kg/cm²) |
🧪 Higher pressure ratings = thicker flanges, more bolts, better sealing.
🧪 3. Choose the Right Stainless Steel Material
Material choice affects corrosion resistance, temperature tolerance, and mechanical strength.
| Grade | Key Properties | Applications |
|---|---|---|
| 304 / 304L | General corrosion resistance, cost-effective | Water, air, food industry |
| 316 / 316L | Superior pitting resistance (chlorides) | Marine, chemical, pharmaceutical |
| 321 / 347 | High temp stability (with Ti or Nb stabilization) | Exhaust, heat exchangers |
| 904L | Resistant to strong acids (sulfuric, phosphoric) | Acid processing, offshore |
| Duplex / 2205 | High strength + chloride stress resistance | Desalination, oil & gas |
| 254 SMO | Extremely high corrosion & pitting resistance | Seawater, bleach lines |
🔗 4. Select the Flange Type Based on Application
| Flange Type | Best For |
|---|---|
| Weld Neck | High pressure/temperature, critical joints |
| Slip-On | Easy installation, low pressure |
| Blind | Pipe end sealing |
| Socket Weld | Small bore piping, high integrity |
| Threaded | Non-welded low-pressure applications |
| Lap Joint | Systems requiring frequent disassembly |
| Long Weld Neck | Vessel nozzles and high-pressure pipelines |
📏 5. Confirm Standard Compliance
Make sure the flange complies with relevant standards:
ASME B16.5, ASME B16.47
EN 1092-1, DIN 2633
JIS B2220
GOST 12820, AWWA C207, API 6A
📎 Always match pipe, flange, gasket, and bolts under the same standard.
🏁 Summary Checklist:
✅ Know your pipe size and pressure class
✅ Select a material suitable for your fluid and environment
✅ Pick a flange type based on system design
✅ Verify standard compliance for interchangeability
✅ Confirm gasket and bolt compatibility
