Weight per metre and Barlow pressure formulas with unit discipline, worked examples (NPS 6 Sch 40, X52 line pipe), nominal versus minimum wall, a free embedded calculator, and sanity-check tables for the most common sizes.
The container loading arithmetic for steel pipe: payload versus floor-space limits, worked capacity tables for common sizes, the European road-weight trap, and lashing practice.
How square and rectangular hollow sections are made, EN 10210 versus EN 10219, ASTM A500 versus A1085, the tolerances to inspect, galvanising rules, and what really moves HSS price.
P = 2St/D explained with yield, code-allowable and mill-test worked examples, thin-wall limits, and how to reverse it for ordering wall thickness.
What random, single-random, double-random and exact lengths mean in practice, why they price differently, and how to write length into a PO.
Verified wall and OD tolerance tables across the four standard families, nominal-wall vs minimum-wall logic, and how to write tolerances into a PO.
The Standard Formula The weight of a carbon steel pipe per metre is calculated from its OD and wall thickness: W (kg/m) = (OD − WT) × WT × 0.02466, with OD and WT in millimetres. The constant comes from the steel density of 7,850 kg/m³: a hollow cylinder’s cross-sectional area times density. For lb/ft,
Two Nominal Systems, One Pipe NPS (Nominal Pipe Size, inches) is used in ASME-based markets; DN (Diamètre Nominal, mm) is the metric ISO/EN designation. Both are nominal — neither equals the actual OD exactly, except from NPS 14 upward, where NPS happens to equal the OD in inches. NPS (in) DN (mm) Actual OD (mm)
Introduction to Pipe Schedules Pipe schedule numbers indicate wall thickness, directly relating to pressure rating and mechanical strength. Schedule 40 and Schedule 80 are the most common schedules, with significant differences in dimensions and applications. Wall Thickness Comparison by Pipe Size NPS (in) OD (mm) Schedule 40 Schedule 80 Thickness Diff. 1/2″ 21.3 2.77 mm