Der er noget på Britisk her:
3.1. The minimum material specification for all tubing will be nominal 38mm / 1½" bore steel "blue band" tubing to BS 1387. (This will actually be nearer 42mm / 15/8") This has a minimum wall thickness of 3.2mm / 1/8" and a minimum outside diameter of 48.3mm / 17/8". See table below for practical imperial and metric stock sizes. Tensile strength will be between 320 - 416 N/mm2. Yield strength will be at least 195N/mm2. Tubing which exceeds this specification is recommended where the outside diameter at least matches the above type and a minimum nominal wall thickness of 2.5mm where the quality and origin can be traced.”
Se meget mere her:
http://www.alrc.co.uk/new%20regulations/rbq03.htm..............altså hvis du vil gøre helt rigtigt og til dit eget bedste.
Mvh
Kenneth Poulsen- der lige nappede Kjøllers link. ;)