Putkikoko

Putkikoko is a Finnish term that translates to pipe size. It denotes the size designation used for pipes and tubing in plumbing, heating, and mechanical systems. The concept centers on dimensions such as the nominal diameter (DN), the outer diameter (OD), and the wall thickness. The selected putkoko ensures compatibility with fittings, valves, and flanges and influences flow capacity and pressure rating.

In practice, putkikoko is specified in different ways depending on the material and standard. Nominal diameter roughly indicates the internal bore, while the outer diameter matters for fitting interfaces. For many plastics, additional descriptors such as SDR or PN are used; for metal pipes, wall thickness and material grade determine strength and allowable pressure. In European and Finnish practice, sizes are usually given in metric millimeters and referenced by DN.

Common pipe materials include steel, stainless steel, copper, PVC, and polyethylene. The pipe size therefore affects installation choices, accessory compatibility, and performance characteristics.

Manufacturers and standard bodies publish catalogs listing putkoko options for each product family. Designers and installers verify that the pipe size matches the intended fittings and service conditions.

See also: Nominal diameter, Piping, EN standards, Plumbing.