: Classes range from A (Fine), B (Medium), C (Coarse), to D (Very Coarse).
The standard applies to:
EN ISO 13920-1:2014, also known as "Hot finished structural hollow sections - Part 1: General requirements", is a European Standard that defines the requirements for hot-finished structural hollow sections (HSS) made of steel. I'll break down the article into sections to make it easier to understand. en iso 13920-bf
The designation refers to a specific set of general tolerances for welded constructions, combining two distinct classes of accuracy defined by the ISO 13920 standard . Breakdown of the Code : Classes range from A (Fine), B (Medium),
(ISO 13920 has no BF). It most likely means: "Weld edge preparation type BF according to ISO 9692-1, with general tolerances according to EN ISO 13920." : Classes range from A (Fine)