<P> The terms angle iron, channel iron, and sheet iron have been in common use since before wrought iron was replaced by steel for commercial purposes . They have lived on after the era of commercial wrought iron and are still sometimes heard today, informally, in reference to steel angle stock, channel stock, and sheet, despite that they are misnomers (compare "tin foil" still sometimes used informally for aluminum foil). In formal writing for metalworking contexts, accurate terms like angle stock, channel stock, and sheet are used . </P> <P> Most steels used throughout Europe are specified to comply with the European standard EN 10025 . However, many national standards also remain in force . </P> <P> Typical grades are described as' S275J2' or' S355K2W' . In these examples,' S' denotes structural rather than engineering steel; 275 or 355 denotes the yield strength in newtons per square millimetre or the equivalent megapascals; J2 or K2 denotes the materials toughness by reference to Charpy impact test values; and the' W' denotes weathering steel . Further letters can be used to designate fine grain steel (' N' or' NL'); quenched and tempered steel (' Q' or' QL'); and thermomechanically rolled steel ('M' or' ML'). </P> <P> 1 . S275JOH Specification S275JOH is steel grade in EN 10219 specification, EN 10210 standard . And the most widely used specification is EN10219 standard, which is Cold formed welded structural hollow sections of non-alloy and fine grain steels . EN10219 - 1 specifies the technical delivery conditions for cold formed welded structural hollow sections of circular, square or rectangular forms and applies to structural hollow sections formed cold without subsequent heat treatment . Requirements for S275JOH pipe tolerances, dimensions and sectional s275 pipe properties are contained in EN 10219 - 2 . 2 . S275JOH Steel Pipes manufacture Process The steel manufacturing process shall be at the discretion of the steel producer . S275JOH carbon steel pipes can be made in ERW, SAW or seamless process . All S275JOH steel material and S275JOH pipes should conform to EN10219 standards . </P>

Mild structural steel is designated by the astme number is