Flange Class Lookup | PN Rating ↔ ASME Class | DN Converter | Free Online Tool

Published by Nikolai Shelkovenko on

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Flange Class Lookup & PN↔ASME Converter

Convert between European PN ratings and ASME pressure classes. View bolt count, bolt size, gasket type, and face type for any DN size.

EN 1092-1 ASME B16.5 PN6 – PN400 Class 150 – 2500

Results

Equivalent Rating
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Approx. Max Pressure (20°C)
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Bolt Count / Size
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Face Type
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Recommended Gasket
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PN to ASME Class Cross-Reference

The following table shows approximate equivalence. Note: PN and ASME ratings are based on different standards and material groups, so equivalence is approximate.

PN RatingASME ClassApprox. Pressure (bar at 20°C)
PN 6—6 bar
PN 10—10 bar
PN 16Class 15016 / 19.6 bar
PN 25Class 150–30025 bar
PN 40Class 30040 / 51.1 bar
PN 63Class 60063 bar
PN 100Class 600100 / 102.1 bar
PN 160Class 900153.0 bar
PN 250Class 1500255.1 bar
PN 400Class 2500425.1 bar

Face Types

  • RF (Raised Face) — Most common for Class 150–600 / PN 16–100. Small raised ring provides gasket seating.
  • FF (Flat Face) — Used for PN 6–16 with cast iron flanges or where full-face gaskets are required.
  • RTJ (Ring-Type Joint) — Used for Class 600+ / PN 100+ in high-pressure and critical services. Metal ring gasket seated in machined grooves.

Gasket Selection Guide

  • Non-asbestos compressed fiber — General purpose, PN 10–40, temperatures to 250°C
  • Spiral wound (SS/graphite) — Most common for RF flanges, PN 16–250, temperatures to 600°C
  • Metal ring gasket (RTJ) — High-pressure services, PN 100+, Class 600+
  • PTFE envelope — Chemical services, corrosive fluids, low to moderate pressure

⚠️ Note: PN and ASME class equivalences are approximate. PN ratings are based on EN material groups while ASME classes depend on specific material grades. Always verify with the applicable standard (EN 1092-1 or ASME B16.5) for your specific application.

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