* Astm, Sae And ISO Grade Markings And Mechanical Properties For Steel Fasteners Continuous Thread Studs FASTENER IDENTIFICATION MARKING (01): In addition to the indicated grade marking, all grades, except A563 grades O, A and B, must be marked for manufacturer identification. (02): The markings shown for all grades of A194 nuts are for cold formed and hot forged nuts. When nuts are machined from bar stock the nut must be additionally marked with the letter 'B'. (03): Nuts are not required to be marked unless specified by the purchaser. When marked, the identification marking shall be the grade letter O, A or B. (04): Properties shown are those of nonplated or noncoated coarse thread hex nuts. (05): Properties shown are those of coarse thread heavy hex nuts. (06): Properties shown are those of coarse thread heavy hex nuts. (07): Properties shown are those of coarse 8-pitch thread heavy hex nuts. (08): Hardnesses are Brinell Hardness Numbers. (09): The nut manufacturer, at his option, may add other markings to indicate the use of atmospheric corrosion resistant steel. (10):Specifications --ASTM A563 -- Carbon and Alloy Steel Nuts.ASTM A194/A194M -- Carbon and Alloy Steel Nuts for Bolts for High Pressure and High Temperature Service.