Technical tables
Quick reference tables for industrial piping design and component selection.
DN – Inches – mm conversion
Correspondence between Nominal Diameter (DN), inches and pipe outside diameter per ANSI/ASME.
| DN | Inches | mm (approx) | Pipe OD (mm) |
|---|---|---|---|
| DN15 | 1/2" | 15 | 21.3 |
| DN20 | 3/4" | 20 | 26.7 |
| DN25 | 1" | 25 | 33.4 |
| DN32 | 1 1/4" | 32 | 42.2 |
| DN40 | 1 1/2" | 40 | 48.3 |
| DN50 | 2" | 50 | 60.3 |
| DN65 | 2 1/2" | 65 | 73 |
| DN80 | 3" | 80 | 88.9 |
| DN100 | 4" | 100 | 114.3 |
| DN150 | 6" | 150 | 168.3 |
| DN200 | 8" | 200 | 219.1 |
| DN250 | 10" | 250 | 273 |
| DN300 | 12" | 300 | 323.9 |
PN (DIN/EN) – ANSI Class correspondence
European PN and American Class are NOT directly equivalent. This table provides approximate pressure correspondence.
| PN | Bar at 20°C | ANSI Class ~equivalent |
|---|---|---|
| PN10 | 10 | - |
| PN16 | 16 | Class 150 |
| PN25 | 25 | Class 150-300 |
| PN40 | 40 | Class 300 |
| PN100 | 100 | Class 600 |
| PN160 | 160 | Class 900 |
| PN250 | 250 | Class 1500 |
Important: PN and ANSI flanges have different bolt patterns and are NOT physically interchangeable.
ANSI flange allowable pressure vs temperature
Values in bar for carbon steel flanges ASTM A105. Allowable pressure decreases with temperature.
| Temp (°C) | Class 150 | Class 300 | Class 600 |
|---|---|---|---|
| 38°C | 19.6 | 51.1 | 102.1 |
| 100°C | 17.7 | 46.6 | 93.2 |
| 150°C | 15.8 | 45.1 | 90.2 |
| 200°C | 13.8 | 43.8 | 87.6 |
| 300°C | 10.2 | 37.3 | 74.5 |
| 400°C | 6.5 | 27 | 53.9 |
Saturated steam: pressure and temperature
Properties of dry saturated steam at various pressures. Useful for sizing steam traps and heat exchangers.
| Pressure (bar abs) | Temperature (°C) |
|---|---|
| 1 | 99.6 |
| 2 | 120.2 |
| 4 | 143.6 |
| 6 | 158.8 |
| 10 | 179.9 |
| 14 | 195 |
| 20 | 212.4 |
| 30 | 233.8 |
Gasket compatibility and temperature limits
Quick guide for gasket material selection based on temperature and chemical compatibility.
| Material | Min °C | Max °C | Good for | Avoid |
|---|---|---|---|---|
| NBR (Nitrile) | -30 | 100 | Mineral oils, greases | Ozone, ketones |
| EPDM | -40 | 150 | Steam, hot water, diluted acids | Mineral oils |
| FPM / Viton® | -20 | 200 | Oils, fuels, acids | Ketones, steam 200°C+ |
| PTFE (Teflon®) | -200 | 260 | Almost all chemicals | Molten alkali metals |
| Graphite | -200 | 450 | Steam, acids, bases (reducing) | Strong oxidisers |
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