Pipe Strap Drawing Package

Pick a pipe size, type the bar, bolts and gaps on the drawing if you need others, and get a three-sheet shop drawing set, with the press brake set-up, as PDF and DXF, for a one-piece bent pipe strap with its cut file, drawn from a 3D model of the strap.

Dimensions

The generator opens full screen: you pick the pipe size, fit, bolts and liner in the bar and type the other sizes on the drawing. It needs JavaScript; if you are reading this, it is off or still loading.

Pipe NPS 1/2 to 8; fit grip or guide; bolts 5/16 to 3/4; liner none, 1/16, 1/8 or 3/16
Bar thickness (0.063 to 0.5 in)
Bar width (0.75 to 4 in)
Hole to foot end (0.25 to 2 in)
Gap under the feet (0 to 0.25 in)
Clearance round the pipe (0 to 0.25 in)
Steel thickness (0.125 to 2 in)
Title block: company, project, drawing number, designed / drawn / checked, date

Results

General arrangement: section through the strap, top and side views, isometric, detail of the foot and bolts, parts list, holes to drill in the steel
Item 1 strap: formed views with hidden lines, flat pattern, bend table, cut length
Press brake set-up: the flat with the bends numbered in order, angle and direction, punch and die, step table (bend-to angle for springback, gauge, ram travel)

The ZIP also holds the set as PDF and DXF, the cut DXF, a manifest, the checking script and a README.

Preview

Click a blue number on the drawing to change it; the results that change light up.

Assumptions and limits

read before you cut

Read these before you cut anything. They describe exactly what this tool does and does not account for.

A one-piece strap of flat bar bent over the pipe: an arch bent in hits on a press brake round the pipe, two straight legs and two feet bolted down through the supporting steel with hex bolts, narrow flat washers and hex nuts. Steel pipe NPS 1/2 to 8 at its standard outside diameter. The bar and bolts for each pipe size follow makers’ heavy pipe straps (Anvil Fig 262, B-Line B2400 and others); you can change any of them.
Grip: the arch is formed to the pipe (or to the liner) and the feet stand 0.063 above the steel until the nuts are tightened, so tightening clamps the pipe. Guide: 0.063 clear all round with the feet on the steel, so the pipe can slide.
Each hole sits clear of the foot bend for the washer and out of the V-die while the foot is bent, and the foot runs on past it by at least the end distance of AISC 360-16 Table J3.4 (1.5 × the bolt below 1/2 in). Normal-fit clearance holes.
The arch is bent in hits with a standard 88° punch in a V-die: its flat faces touch the pipe, each corner takes the punch’s radius, and the hits are kept at least half the V-die apart (the largest gap to the pipe is printed). The bar thickness picks the tools: the punch radius (also the foot bends’ inside radius) and a V-die of 8 × the thickness for mild steel up to 1/2 (6 × below 2.5 mm), so a thicker bar gets a wider die. The holes are placed out of the die while the feet are bent, at least 0.7 × the V-die and 3 × the thickness plus the radius from the bend line, so they do not pull out of round. Sizes that cannot be made are refused in words: a bar too thick for the pipe (the arch would be coarser than 1/8 off the pipe or have under 3 hits), a bar narrower than twice its thickness, holes smaller than the bar is thick, or no bending order that clears the punch and die; the other checks are in the questions below. The flat uses K by inside radius over thickness (0.40, 0.44 or 0.50); make a test bend and adjust the cut length before cutting a batch.
Geometry and fabrication only: the strap, bolts and steel are not sized for any load. It is not a rated pipe hanger, and nothing on it is checked against MSS SP-58.
Inches only. No DWG file: the drawing-set DXF opens in AutoCAD and other CAD programs and can be saved as DWG there.

Output is a planning and fabrication aid. You are responsible for verifying dimensions, tolerances and material behaviour before production — full disclaimer.

Worked example

The sample: NPS 2 pipe (OD 2.375), grip, flat bar 3/16 × 1-1/4, two 3/8-16 bolts through 3/8 steel. The arch is five hits of 36° with a R 0.125 punch in a 1.500 V-die, 0.816 apart, the largest gap to the pipe 0.055. The strap is 6.375 long and 2.500 high with Ø13/32 holes at 5.250 centres, their edges 1.079 from the foot bend lines (at least 0.7 × the 1.500 die = 1.050); its flat is 9.709 long with the bend lines at 1.845 (foot), 3.222 to 6.487 (the hits) and 7.864 (foot); it weighs 0.64 lb. Press brake: the feet first, then the hits from the outside in, bent to 87.9° and 142.4° for the springback, every step clear of the punch and die by at least 0.036. Its cut file passes all 22 checks of the script (output).

Method

The strap is a solid model built in your browser: its bent profile with the true inside radii of the arch and the foot bends, extruded to the bar width and drilled; the pipe, bolts, washers and nuts are modelled from their standard sizes. The views are hidden-line projections of those solids, section A-A is a cut through them, and the flat comes from the same profile and is checked against the strap’s volume.

Each sheet is one list of lines, arcs, text and tables; the screen, the PDF and the DXF are written from it. How it was built and checked: the case study. For other bent parts, the bend flat pattern calculator; for pipe intersections, the pipe cut template builder.

How this tool is verified

The cut file is checked by a separate Python script using ezdxf, an independent DXF library: the flat length and every bend line, the hits included, worked out again from the inputs with the textbook bend allowance, every corner in order, both holes and their size, nothing else on the cut layer, the bend layers, the metal round the holes and the weight. The script is in every ZIP; a test shows it fails on a moved bend line, a stray cut line, an extra hole, a wrong hole size or a wrong cut length.
The 3D model in the browser was compared with an independent CadQuery (OpenCascade) model at five inputs from NPS 1/2 to 8, with and without a liner: strap and liner volumes within 0.05 % and every derived size equal. At every pipe size the flat times the bar section equals the solid’s volume within 0.01 %.
The press brake numbers come from an elastic-plastic beam model of the bar on the die shoulders; a CalculiX finite-element model of the same bends gave the same springback within 0.02° in five bends from 1/8 to 1/4 bar and a ram travel 4 to 12 % shorter, so the sheet gives the travel as an estimate to set by a test bend. The bending order is checked step by step against the punch, ram, die and bed.
All 13 pipe sizes, in grip and guide, with and without a liner, were drawn in English and French with no text over a line; the tests redraw them on every change. The sample set on this page is the generator’s own output; a test fails if it differs by one byte.

The method, the reports and the responsibility boundary are on the Verification page.

Questions

What is in the download?

One ZIP: the three-sheet drawing set as a PDF and as a DXF (the same sheets), the strap’s cut DXF (1:1 in inches, bend lines on their own layers), a manifest with the inputs, flat, holes, bends and weight, a Python script that checks the cut file, and a README.

What do the three sheets show?

Sheet 1: the strap on the pipe cut through its middle, the top and side views, an isometric, a detail of the foot with the gap and the bolt stack, the parts list and the holes to drill in your steel. Sheet 2: the strap alone as formed, with hidden lines, its flat pattern with the bend lines measured from the left end, the bend table and the cut length. Sheet 3: the press brake set-up — the flat with every bend line numbered in the order to bend it, how far and which way, the punch and die, and a step table with the angle to bend to for the springback, the back gauge and the ram travel.

Grip or guide?

Grip when the strap must hold the pipe: the feet are left high so the bolts pull the strap onto the pipe. Guide when the pipe must move, for example as it warms up: the strap clears the pipe all round. Both gaps can be changed on the drawing.

Are my sizes sent anywhere?

No. The model, the drawing and the ZIP are made in your browser. The site counts that a drawing was made or downloaded; never the sizes or the title block. The sizes are sent only if you send a “Found a mistake?” report and tick the box to attach them.

Why does it refuse some sizes?

A bar too thick for a small pipe leaves the legs no straight part, or needs a die so wide that the arch would be too coarse. A bar narrower than twice its thickness, holes smaller than the bar is thick, a washer wider than the bar, too little metal beside the holes, a hole closer to the end than the end distance above, or a strap no bending order can make without hitting the punch or die are refused too, with the reason.

Missing an option?

A different datum, an offset, a shop allowance, another shape altogether — say what this tool does not cover yet. Requests decide what gets built next, and a report of a wrong result is dealt with before anything new.

Request an option

Rather have the whole job done — drawings, cut files, the shop documentation, mistakes caught before cutting? Quoted per job: how we help shops.