Minimum bend radius is the smallest permitted radius for a curve in an identified pipe or tube under stated bending conditions. It limits how tightly that product may turn. The value belongs to the material, dimensions and approved method, rather than supplying permission to bend any pipe that looks flexible.
Minimum bend radius is the smallest permitted radius for a curve in an identified pipe or tube under stated bending conditions. It limits how tightly that product may turn. The value belongs to the material, dimensions and approved method, rather than supplying permission to bend any pipe that looks flexible.
Radius and angle describe different geometry
A bend's angle describes how far its direction changes. Its radius describes how tight the curved path is. Two bends can change direction by the same angle while requiring very different amounts of space.
Check the manufacturer's drawing for the measurement reference and units. Do not substitute the distance between walls, an elbow's overall length or the inside edge of a bend for a dimension defined differently in that drawing. A street elbow describes a fitting's connection ends, not a tube-bending limit.
The Copper Development Association's handbook separates copper tube size, type and temper in its bending table. Its footnote says the listed minimum radii apply to mechanical bending equipment only. A table number without that footnote would lose an essential condition.
Read the product and method together
Charlotte Pipe publishes bending and deflection conditions for identified FlowGuard Gold CPVC CTS products, including specific coiled-pipe sizes. That is different from approving heat bending, arbitrary deflection or every CPVC product.
Its manual warns against installing fittings under stress and requires the pipe arrangement to keep stress from deflection from reaching the fitting. A route that stays within one radius limit can still have an unsuitable connection or restraint arrangement.
Swagelok's hand-bender manual likewise identifies tool and tube dimensions and explains that springback depends on material, wall thickness and bend geometry. A tool's available bend radius does not establish suitability for an unidentified tube.
What to ask about a proposed route
Ask which pipe or tube product, size, wall designation and temper are specified, which bending method is permitted and where its limit appears in the current instructions. Keep the applicable drawing with the proposed route.
For a thermal-movement arrangement, an expansion loop has a separate design purpose. Meeting a bending limit does not complete its support, movement or service requirements.
Do not force a kinked line back into shape or apply improvised heat to make an unidentified pipe fit. Have the installer evaluate the affected material and connection. Our copper tube types guide helps identify another part of the specification before a repair method is chosen.