Case
Case
Based on 20+ engineering case studies, this guide highlights 7 critical differences in structural design, pressure capacity, installation, and maintenance to help you select the optimal solution.
Design Features: No flanged body; fixed via long bolts through pipeline flanges.
Advantages: Lightweight (30%-50% lighter than flanged type), compact (40% shorter installation length).
Limitations: Relies on pipeline flange precision; sealing surfaces vulnerable to uneven bolt preload.
Design Features: Valve body incorporates standardized flanges (ANSI/DIN/JIS) for direct bolt connection.
Advantages: Independent pressure-bearing structure; higher sealing reliability (ideal for frequent operation).
Limitations: Bulky; higher cost (20%-35% more expensive than wafer type).
| Parameter | Wafer Type | Flanged Type |
| Pressure Rating | ≤PN16 (standard) | PN10-PN40 (preferred for high pressure) |
| Temperature Range | -20°C~150°C (rubber seal) | -50°C~300°C (metal + graphite seal) |
| Installation | Requires precise alignment; prone to leaks | Simple flange alignment; high sealing tolerance |
| Maintenance Cost | Requires disassembling pipeline bolts | Easy valve-only disassembly |
| Vibration Resistance | Long bolts prone to loosening | Self-locking flange structure enhances stability |
| Cost Efficiency | Lower initial cost; higher hidden maintenance | Higher upfront cost; lower lifecycle cost |
| Applications | Low-pressure, ambient fluids (water/air) | High-temperature/pressure/corrosive media (chemicals/oil & gas) |
Pressure > PN16 or Temperature > 150°C? → Choose Flanged Type
Media contains particles/corrosives? → Choose Flanged Type (metal seal)
Limited budget & infrequent maintenance? → Choose Wafer Type
Root Cause: Pipeline flange flatness deviation (>0.2mm) or uneven bolt preload.
Solutions:
Check flange parallelism with a laser level pre-installation.
Use diagonal progressive tightening (torque values per API 598).
Case Study: DN300 flanged valve failed due to chloride corrosion in 6 months.
Solution:
Upgrade valve material to duplex stainless steel (2205).
Apply tungsten carbide coating on sealing surfaces (3x lifespan).
| Valve Type | Leakage Rate (ppm) | Sealing Status After 500 Cycles |
| Wafer Type | 120-180 | Rubber seal shows significant wear |
| Flanged Type | ≤30 | Metal seal exhibits minor abrasion |
Conclusion: Flanged valves demonstrate superior sealing durability in
high-pressure/high-frequency conditions.
Low-Cost Wafer Valve Trap: Some manufacturers omit valve body guide grooves, causing plate jamming.
→ Verify axial positioning ribs on the valve body during inspection.
Flange Standard Confusion: ANSI vs. JIS flange bolt holes differ by 5mm.
→ Require suppliers to provide flange drawings for verification.
Fake Material Certificates: 201 stainless steel misrepresented as 304.
→ Use portable spectrometers to test Cr/Ni content on-site.
Wafer Type: PN10-PN16 (e.g., HVAC systems, low-pressure air).
Flanged Type: PN16-PN40 (e.g., refinery pipelines, steam systems).
| Temperature | Wafer Type | Flanged Type |
| -50°C~80°C | EPDM rubber seal (low cost) | EPDM/FKM rubber seal |
| 80°C~200°C | Not recommended (rubber degrades) | Graphite-filled metal seal |
| 200°C~450°C | Prohibited | Special alloy + bellows seal |
| Media Type | Wafer Valve Risks | Flanged Valve Solutions |
| Solid Particles | Seal edge wear | Add wear-resistant rings (HRC58+) |
| Corrosives | Bolt corrosion → loss of clamp force | Hastelloy C276 valve body |
| High-Viscosity | Excessive torque on actuator | Install guided oblique plate design |
Test Data: In media with 5% quartz sand, flanged valves with wear-resistant rings lasted 7x longer than wafer types (5,000 vs. 700 cycles).
“For systems exceeding PN16 or experiencing water hammer, flanged valves are mandatory. Wafer valves’ long-bolt design risks creep relaxation under high pressure.”
