ASME B18.5 pdf download Round Head Bolts (Inch Series) 2.4.3 Straightness. The length of any permissible swell on the body under the head or neck of bolts shall be excluded from checks for shank straightness. A sug- gested gage and a gaging procedure for checking straightness are shown in ASME B18.2.9. 2.5 Threads Uncoated threads shall be Unified coarse (UNC...