Plate layout development

It means drawing on flat plate the outline that becomes the part once rolled or bent. The calculator does this for cone frustums, eccentric cones, square-to-round transitions, mitered elbows and branch saddles, and gives a dimensioned drawing and an ordinate table to mark on the plate.

When rolling, the outer face stretches and the inner face shrinks; only mid-thickness keeps its length. In the default example (40 in outside diameter, 1/4 in plate), the neutral-line girth is about 124.8 in; laying out by the outside diameter would give 125.7 in, about 0.85 in too long, and the part would not close.

With 40 in and 24 in ends, 20 in high and 1/4 in plate, the sector has an outer radius of about 53.5 in, an inner radius of about 31.9 in and an angle of 133.7°. Strike both arcs from the same center and open the angle; the whole part needs a plate of about 98.4 × 40.9 in and uses 53% of it, which is why large cones are often made in 2 or more segments.

From the assembly drawing or the equipment: diameters at both ends, height between them and plate thickness. State whether dimensions are outside, inside or mean. For pipe, use the outside diameter from the pipe table (for example, 12.75 in for NPS 12).

Twelve divisions are enough for small parts; above about 40 in diameter, use 24 or 32 so points are less than about 6 in apart. The calculator works with 8 internal subdivisions per division, so girth and area are already accurate; divisions only set how many points you mark.

No. It gives the part at the neutral line, with no root gap, bevel or extra stock. Add what the welding procedure requires and make a trial piece in thin sheet or cardboard when the shape is new.

For pressure vessel, boiler and pressure piping parts, geometry is only the start: wall thickness, branch reinforcement and miter bends need design per the governing code (ASME Section VIII, B31.3) by a qualified engineer.