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PVC pipe sizes are nominal labels, not measured diameters. A 2 inch Schedule 40 pipe measures 60.3 mm across the outside, and metric uPVC pipe is sold by its true outside diameter, such as 110 mm. This chart sets both systems side by side, with wall thickness for Schedule 40, Schedule 80 and the Class 4 and Class 5 pressure grades.
Pipe on a Saudi site can come from either of two size systems. Mixing them is a common sizing mistake.
Sold by nominal pipe size, such as 2 inch or 4 inch. The label is a name: a 2 inch pipe has a 60.3 mm outside diameter. Schedule 40 and Schedule 80 share that outside diameter, so a heavier schedule means a thicker wall and a smaller bore.
Sold by outside diameter in millimetres, such as 63, 110 or 160 mm. The pressure class sets the wall. A 110 mm Class 5 pipe has the same outside diameter as a Class 4 one, with a thicker wall.
Bore is roughly the outside diameter minus twice the wall. For 110 mm pipe with a 4.2 mm wall that is about 101.6 mm. With a 6.6 mm wall it is about 96.8 mm.
Nominal size, outside diameter and minimum wall thickness for the inch system, from ½ inch to 8 inch.
| Nominal size | OD (in) | OD (mm) | Sch 40 wall (in) | Sch 40 wall (mm) | Sch 80 wall (in) | Sch 80 wall (mm) |
|---|---|---|---|---|---|---|
| ½″ | 0.840 | 21.3 | 0.109 | 2.77 | 0.147 | 3.73 |
| ¾″ | 1.050 | 26.7 | 0.113 | 2.87 | 0.154 | 3.91 |
| 1″ | 1.315 | 33.4 | 0.133 | 3.38 | 0.179 | 4.55 |
| 1¼″ | 1.660 | 42.2 | 0.140 | 3.56 | 0.191 | 4.85 |
| 1½″ | 1.900 | 48.3 | 0.145 | 3.68 | 0.200 | 5.08 |
| 2″ | 2.375 | 60.3 | 0.154 | 3.91 | 0.218 | 5.54 |
| 2½″ | 2.875 | 73.0 | 0.203 | 5.16 | 0.276 | 7.01 |
| 3″ | 3.500 | 88.9 | 0.216 | 5.49 | 0.300 | 7.62 |
| 4″ | 4.500 | 114.3 | 0.237 | 6.02 | 0.337 | 8.56 |
| 6″ | 6.625 | 168.3 | 0.280 | 7.11 | 0.432 | 10.97 |
| 8″ | 8.625 | 219.1 | 0.322 | 8.18 | 0.500 | 12.70 |
Walls are minimums from the ASTM D 1785 dimension tables as published by Engineering ToolBox. Millimetre values are converted at 25.4 mm per inch. For when to choose each schedule, read Schedule 40 vs Schedule 80 PVC pipe.
4B Factory lists pressure pipe from 50 to 315 mm in Class 4 (PN 10) and Class 5 (PN 16). Bore is the outside diameter minus twice the minimum wall.
| Outside diameter | Class 4 (PN 10) wall | Class 4 bore | Class 5 (PN 16) wall | Class 5 bore |
|---|---|---|---|---|
| 75 mm | 2.9 mm | 69.2 mm | 4.5 mm | 66.0 mm |
| 90 mm | 3.5 mm | 83.0 mm | 5.4 mm | 79.2 mm |
| 110 mm | 4.2 mm | 101.6 mm | 6.6 mm | 96.8 mm |
| 160 mm | 6.2 mm | 147.6 mm | 9.5 mm | 141.0 mm |
| 200 mm | 7.7 mm | 184.6 mm | 11.9 mm | 176.2 mm |
| 250 mm | 9.6 mm | 230.8 mm | 14.8 mm | 220.4 mm |
| 315 mm | 12.1 mm | 290.8 mm | 18.7 mm | 277.6 mm |
Walls follow the ISO 161-1 and EN 1452 dimension tables. The 50 mm and 63 mm sizes sit in the same range, but their wall thickness differs between standard editions, so confirm it on the data sheet. Class 4 against Class 5 is explained in PVC pipe pressure classes and sizes.
The nearest metric size to each inch size is within a few millimetres, and that is exactly why the two get confused.
| Inch size | Inch pipe OD | Nearest metric size | Difference |
|---|---|---|---|
| ½″ | 21.3 mm | 20 mm | 1.3 mm |
| ¾″ | 26.7 mm | 25 mm | 1.7 mm |
| 1″ | 33.4 mm | 32 mm | 1.4 mm |
| 1¼″ | 42.2 mm | 40 mm | 2.2 mm |
| 1½″ | 48.3 mm | 50 mm | 1.7 mm |
| 2″ | 60.3 mm | 63 mm | 2.7 mm |
| 2½″ | 73.0 mm | 75 mm | 2.0 mm |
| 3″ | 88.9 mm | 90 mm | 1.1 mm |
| 4″ | 114.3 mm | 110 mm | 4.3 mm |
| 6″ | 168.3 mm | 160 mm | 8.3 mm |
| 8″ | 219.1 mm | 225 mm | 5.9 mm |
Socket dimensions follow the outside diameter, so a metric fitting will not seat properly on an inch pipe, or the reverse. Join across systems only with a transition fitting or flange made for the pair, and check the PVC pipe fittings guide before you order.
Listed from 110 to 710 mm to SAS 1395 / 1396 for gravity drainage. See uPVC sewer pipes.
Listed from 20 to 63 mm to SAS 254 / 255 and NEMA TC 2. Larger duct has its own pages: D54, D56 and D54 vs D56.
Fabricated to order from 20 to 315 mm. See customised fittings for long bends, repair couplings and special shapes.
Give the size system (inch or metric), nominal size, class or schedule, and quantity. That is everything needed to quote.
Duct and conduit for cable protection, 20 to 63 mm, plus D54 and D56.
More Information →PN is the nominal pressure rating in bar for water at 20 °C. PN 10 means 10 bar, which is the rating of 4B Factory’s Class 4 pipe, and PN 16 means 16 bar, the rating of Class 5. The allowable pressure falls as the water gets warmer.
Yes. ASTM D 1785 and the ISO tables set a minimum wall, and real pipe runs slightly thicker within the tolerance. A bore worked out from these figures is therefore a little generous, so confirm the final dimensions on the data sheet.
Start from the flow you need and the velocity your design allows, which gives a minimum bore. Then choose an outside diameter and a class that leave at least that bore after the wall is taken off. Send the flow, length and pressure with your enquiry and the class can be matched to them.
Send your sizes, class or schedule and quantity to info@4bfactory.com, or use the contact page.
