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Plate Work by the Numbers

Laying out, rolling and fitting steel plate: shells, cones, hoppers, openings, rings, marking out and the plate list

Lay out and fit steel plate with numbers: mean diameters, rolled shells, springback, cones and hoppers in thick plate, openings, rings, nesting, roundness and mass.

10 chapters · About 100 minutes · Free to read · Intermediate plate layout and fabrication

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KEVOS® LibraryMANUFACTURINGREGIONTIMEPRODUCTPlate Work bythe NumbersKEVOS® ORIGINAL BOOK10 CHAPTERS

About this book

Plate is sheet that has become thick enough to matter. In thin sheet, a pattern developed on the inside or the outside is out by a fraction of a millimetre, and nobody notices. In 6 mm plate rolled into a 2.4 m shell, the same choice is worth 19 mm of girth, the plate springs back to three times the radius it was rolled to, a hole cut round on the flat is too narrow once rolled, and a cone’s mean line is not where a sheet worker would put it. Plate work is pattern development with the thickness left in.

This book works through those numbers in the order a plated structure is made: why thickness changes the pattern, rolled shells and their seams, rolling and springback, conical shells, flat-sided hoppers, openings, rings and flanges, marking out and nesting, fit-up and roundness, and finally the plate list, mass and lifting. Each chapter calculates with one running case, includes a plausible mistake and how it was found, and ends with an exercise and its worked answer.

It is for platers, boilermakers and their apprentices, fabrication drafters, and engineers who specify plate structures or check a fabricator’s drawings and plate lists. It assumes school algebra and trigonometry and some familiarity with pattern development; the Library’s Sheet Metal Parts by the Numbers covers the folded-part side of the subject, and Sheet Metal Patterns by the Numbers develops the same patterns for thin sheet.

The running case

Every chapter follows one fictional job. This is an illustration. A stockfeed business has ordered a storage bin from a plate fabrication shop. The bin is a vertical cylinder of 2,400 mm inside diameter and 4,800 mm high, made from two 2,400 mm courses of 6 mm mild steel plate, standing on a conical hopper of 8 mm plate whose walls slope at 60° to the horizontal and which discharges through a Ø400 outlet. A 75 × 75 × 6 angle ring stiffens the top of the shell, a flat 5 mm plate forms the roof, a Ø500 manway is set into the lower course, and a separate square loading hopper, 1,200 mm square at the top and 300 mm square at the bottom, feeds the roof inlet. The shop buys plate in 2,400 × 6,000 mm sheets and rolls on a three-roll machine.

The business, the shop, the dimensions, the yield strengths, the prices and the mistakes are invented. None describes KEVOS® work or a real business.

How to use the book

Chapter 1 sets out the conventions, especially which line of the thickness each pattern is developed on. Chapters 2 to 4 cover the main curved plates, and Chapters 5 to 7 the parts that attach to them. Chapters 8 to 10 cover the shop work that turns patterns into a finished structure. Values are given to 0.1 mm so that the arithmetic can be followed; plate is usually marked to the nearest millimetre and fitted within the tolerances the drawing sets.

Source limits and professional responsibility

The geometry in this book is exact, and every calculation was checked by running it. The springback estimate in Chapter 3 is a published model for an idealised material, which describes the trend well and the exact value only approximately; plate is rolled to a template, not to a calculation.

Bins, hoppers and silos carry bulk loads that can be large, uneven and dynamic, and their failure can kill. Their structural design is governed by AS 3774 for loads, AS 4100 for steel structures and AS/NZS 1554.1 for welding, among others, and must be done and approved by a competent engineer. Pressure vessels are outside this book and are governed by AS 1210. Lifting, rolling and handling heavy plate are high-risk work under Australian work health and safety law. This book teaches layout and fabrication geometry. It is not a design for any structure, and its numbers must not be used for one.

Who this book is for

Platers, boilermakers, fabrication drafters and engineers who lay out, roll, cut and fit steel plate for shells, cones, hoppers and bins, or check a fabricator's plate list and drawings.

What you will learn

  • Explain where thickness enters a plate pattern and develop shells and cones on the right line.
  • Estimate springback in rolled plate, set up templates, and judge roundness, peaking and fit-up with numbers.
  • Develop hoppers, openings and rings in thick plate, including corner angles and holes marked before rolling.
  • Mark out, nest and list plate so that seams fall where they should and offcuts are used.
  • Calculate mass, centre of gravity and plate yield for a fabricated vessel and its lifting plan.

Inside this book

Chapters

  1. 01When thickness changes the patternWhere plate thickness enters a pattern: rolled girths, corners, intersections, cones and holes. The running case's 2,400 mm bin, the conventions used, and a shell laid out on its inside girth.
  2. 02Rolled shells: courses, plates and seamsTurn a shell's inside diameter into plate lengths: mean girth, root gaps, weld shrinkage, two ways to split each course, seam stagger between courses, and a seam laid out through the manway.
  3. 03Rolling plate: flat ends, springback and templatesWhy 6 mm plate rolled to a 1,203 mm radius springs back to 3,867 mm, how flat ends make a peaked seam, how to read a sweep template, and a course rolled to its final radius by calculation.
  4. 04Conical shells in plateDevelop the bin's 8 mm hopper cone on its true mean line, split it into segments that fit the plate, nest three on one sheet, and find a cone made on its inside line 29 mm short.
  5. 05Flat-sided hoppers and corner anglesDevelop a square plate hopper: true side shapes, valleys flatter than the sides, the dihedral angle for folding or mitring, thickness at the corners, and a 60° hopper with 50.8° valleys.
  6. 06Openings and nozzles in a rolled shellCut the Ø500 manway into the shell: which surfaces touch, cut depths, the hole marked on flat plate in arcs, set-in and set-on nozzles, and a round hole that rolled 5 mm narrow.
  7. 07Rings, stiffeners and flangesRoll a 75 × 75 × 6 angle into a ring on its centroid, not its back: length, toe and heel strains, toe-out against toe-in, splices, bolt circles on the outlet flange, and a ring cut 132 mm short.
  8. 08Marking out and nesting plateMark plate from a datum and prove it square by diagonals, allow for kerf, nest the whole bin on 6, 8 and 5 mm sheets, and find a roof 12 mm too wide and a plate squared from a mill edge.
  9. 09Fit-up, roundness and peakingMeasure a rolled course against its tolerances: diameters, out-of-roundness, girth by tape on the right surface, peaking, misalignment, and a course trimmed 19 mm by mistake.
  10. 10The plate list, mass and liftingBring the bin together on one plate list: net and gross mass, plate cost with GST, centre of gravity from its parts, sling loads for planning, and a lift plan that assumed the load was shared evenly.

Apply This in Practice

Use these KEVOS® tools to try the method from this reading with your own numbers.

References and source notes

The manuscript and worked examples are original KEVOS® writing. References inform particular concepts; their authors do not endorse this book. Web references were consulted on 26 October 2026.

  • Evan A. Atkins, Sir Isaac Pitman & Sons, London. Practical Sheet and Plate Metal Work (second edition) (1912). Supplied source, read as a subject map of traditional plater's work, including its treatment of the neutral line in bent plate. No text, figures, examples or exercises are reproduced, and all numbers, cases and methods of checking in this book are its own.
  • F. J. Gardiner, Transactions of the ASME, vol. 79. The springback of metals (1957). Source of the elastic-plastic springback relationship for pure bending used in Chapter 3 to estimate how far plate must be overbent in the rolls.
  • Standards Australia. AS 3774 Loads on bulk solids containers (edition as called up). Named by number and scope as the Australian standard for loads on bins and silos. The running case is an illustration of layout and fabrication, not a bin design, and no values are quoted from the standard.
  • Standards Australia. AS 4100 Steel structures (edition as called up). Named by number and scope as the Australian standard for steel structural design. No values are quoted from it.
  • Standards Australia and Standards New Zealand. AS/NZS 1554.1 Structural steel welding, Part 1: Welding of steel structures (edition as called up). Named by number and scope as the standard that governs welding of the kind of structure in the running case. No values are quoted from it.
  • Standards Australia. AS 1210 Pressure vessels (edition as called up). Named by number and scope to make clear that pressure vessels are outside this book. Their design, fabrication tolerances and inspection are governed by it and by Australian work health and safety requirements.
  • Standards Australia and Standards New Zealand. AS/NZS 3678 Structural steel: Hot-rolled plates, floorplates and slabs (edition as called up). Named by number and scope as the product standard for the kind of plate used in the running case. The yield strengths and plate sizes in this book are illustrations, not values from the standard.

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