High-Pressure Flange Selection: ASME Class 900-2500 Guide
High-Pressure Flange Selection: Class 900-2500
Published: April 10, 2026 | Category: Technical Guide
What Is High-Pressure?
- Low: Class 150, 300 (up to 720 PSI)
- Medium: Class 400, 600 (up to 2,000 PSI)
- High: Class 900, 1500, 2500 (2,000-9,000+ PSI)
Best Flange Types
Weld Neck (Preferred)
Tapered hub provides excellent stress distribution. Best for fatigue resistance, cyclic loading, thermal shock.
Ring Type Joint (RTJ)
Metal-to-metal sealing. Types: R (standard), RX (pressure-energized), BX (API 6B). Up to 10,000+ PSI.
Pressure-Temperature Ratings
| Class | 100°F | 400°F | 800°F |
|---|---|---|---|
| 900# | 2,160 PSI | 1,980 PSI | 1,530 PSI |
| 1500# | 3,600 PSI | 3,300 PSI | 2,550 PSI |
| 2500# | 6,000 PSI | 5,500 PSI | 4,250 PSI |
Materials
- A105: -20°F to 800°F (general service)
- A350 LF2: -50°F to 650°F (low temp)
- F304/L, F316/L: -425°F to 1000°F (corrosive)
- F11, F22, F91: Up to 1200°F (high temp)
Gaskets
- RTJ: Soft iron, steel, SS, Inconel (up to 10,000+ PSI)
- Spiral Wound: SS/Graphite (up to 2,500 PSI)
- Camprofile: SS core with facing (up to 2,500 PSI)
Bolts
- A193 B7: Standard (up to 800°F)
- A193 B8/B8M: Stainless (corrosive)
- A193 B16: High temp (up to 1000°F)
- A320 L7: Low temp (down to -150°F)
Common Mistakes
- Using slip-on for Class 900+
- Wrong gasket type
- Inadequate bolt torque
- Ignoring temperature effects
Songhai Capabilities
- Classes: 900# to 2500# (4500# on request)
- Types: WN, RTJ, Orifice, Special
- Materials: A105, LF2, F304/L, F316/L, F11, F22, F91
- Certifications: ASME, PED, API, NACE
High-pressure project? Contact Songhai for technical support.
WhatsApp: +86-18658777855
Email: 1007788887@qq.com
