Sizes & wall thickness
Two standards — two dimension systems
EN 10255 and ASTM A53 do not share the same outside diameter: 6″ is 165.1 mm to EN 10255 and 168.3 mm to ASTM A53, and 2½″ is 76.1 mm against 73.0 mm. Tell us the standard you buy to and we quote the exact OD and wall thickness for that standard.
EN 10255 — threaded or plain end, DN8 – DN150 (¼″ – 6″)
| Nominal bore | Inch | Outside dia. (mm) | Medium wall (mm) | Heavy wall (mm) | Length |
|---|
| DN8 | ¼″ | 13.5 | 2.35 | 2.90 | 6 m standard
or cut to order |
| DN10 | 3/8″ | 17.2 | 2.35 | 2.90 |
| DN15 | ½″ | 21.3 | 2.65 | 3.25 |
| DN20 | ¾″ | 26.9 | 2.65 | 3.25 |
| DN25 | 1″ | 33.7 | 3.25 | 4.05 |
| DN32 | 1¼″ | 42.4 | 3.25 | 4.05 |
| DN40 | 1½″ | 48.3 | 3.25 | 4.05 |
| DN50 | 2″ | 60.3 | 3.65 | 4.50 |
| DN65 | 2½″ | 76.1 | 3.65 | 4.50 |
| DN80 | 3″ | 88.9 | 4.05 | 4.85 |
| DN100 | 4″ | 114.3 | 4.50 | 5.40 |
| DN125 | 5″ | 139.7 | 4.85 | 5.40 |
| DN150 | 6″ | 165.1 | 4.85 | 5.40 |
EN 10255 covers DN8 – DN150 only. The light series (thinner wall, plain end) is available on request; medium and heavy series are suitable for threading to EN 10226-1 / ISO 7-1. Wall thickness tolerance −10 %.
ASTM A53 / ASME B36.10M — NPS ½″ – 8″
| NPS | DN | Outside dia. (mm) | Schedule 40 / STD (mm) | Schedule 80 / XS (mm) |
|---|
| ½″ | DN15 | 21.3 | 2.77 | 3.73 |
| ¾″ | DN20 | 26.7 | 2.87 | 3.91 |
| 1″ | DN25 | 33.4 | 3.38 | 4.55 |
| 1¼″ | DN32 | 42.2 | 3.56 | 4.85 |
| 1½″ | DN40 | 48.3 | 3.68 | 5.08 |
| 2″ | DN50 | 60.3 | 3.91 | 5.54 |
| 2½″ | DN65 | 73.0 | 5.16 | 7.01 |
| 3″ | DN80 | 88.9 | 5.49 | 7.62 |
| 4″ | DN100 | 114.3 | 6.02 | 8.56 |
| 5″ | DN125 | 141.3 | 6.55 | 9.53 |
| 6″ | DN150 | 168.3 | 7.11 | 10.97 |
| 8″ | DN200 | 219.1 | 8.18 | 12.70 |
Threads to ASME B1.20.1 (NPT) or ISO 7-1. Other schedules (10 / 160 / XXS) and seamless or ERW execution quoted on request.
Zinc coating — what we supply
| Coating | Coating mass | Approx. thickness | Availability |
|---|
| Hot-dip galvanized — standard supply | 350 – 500 g/m² | ≈ 49 – 70 µm | All sizes in the two tables above |
| Hot-dip galvanized — heavier coating | Over 500 g/m² | Over 70 µm | Made to order |
| To ASTM A53 §17 | ≥ 550 g/m² average | ≈ 77 µm | Made to order |
| Pre-galvanized (in-line zinc coated coil) | Per coil certificate | — | Normal supply, for dry indoor service |
Coating mass is stated on the mill certificate for every lot and can be verified with a magnetic gauge at loading. A coating weight outside 350 – 500 g/m², special thread forms, cut lengths, drilled holes and non-standard wall thicknesses are all made to order.
Zinc coating — how the standards read
| Standard | Requirement | Approx. equivalent |
|---|
EN 10240 class A.1
(galvanizing for EN 10255 tube) | Internal surface ≥ 55 µm local minimum (28 µm at the weld bead) | ≈ 393 g/m² internal |
EN 10240 class B.1 / B.2 / B.3
(outer surface) | 55 µm / 40 µm / 25 µm local minimum | ≈ 393 / 286 / 179 g/m² |
ASTM A53 §17
(hot-dip, weight of coating) | Average of two samples ≥ 1.8 oz/ft² (0.55 kg/m²); single sample ≥ 1.6 oz/ft² (0.49 kg/m²); either surface ≥ 1.3 oz/ft² (0.40 kg/m²) | ≈ 77 µm average |
ISO 1461
(when specified) | Wall 3 – 6 mm: 55 µm local / 70 µm mean
Wall over 6 mm: 70 µm local / 85 µm mean | 395 / 505 g/m² mean |
Pre-galvanized
(in-line zinc coated coil) | Coating mass as declared on the coil certificate — normally for dry indoor service | — |
Square and rectangular tube: 20×20 up to 200×200 mm, wall 1.2 – 8 mm, 6 m lengths. Everything is sourced from Tianjin, north China's steel distribution centre — the full range is available, and special sizes, wall thicknesses, coating weights, threads and cut lengths are made to order.
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