ASME B18.2.6-2019 pdf free download.Fasteners for Use in Structural Applications
2 HEAVY HEX STRUCTURAL BOLTS: ASTM F3125/F3125M
2.1 Heavy Hex Structural Bolt Dimensions Bolts shall conform to the dimensions given in Table 2.1-1. Formulas for heavy hex structural bolts are given in Nonmandatory Appendix A of ASME B18.2.1.
2.1.1 Top ofHead. Top of head shall be full form and chamfered or rounded with the diameter of chamfer circle, or start of rounding being equal to the maximum width across flats within a tolerance of -15% of the maximum across flats dimension. The shape of the top of the head may be flat, concave, or convex at the manufacturer’ s option. If the shape is concave or convex, head height as described in para. 2.1.4 shall remain within specified limits at lowest or highest points, respectively.
2.1.2 Width Across Flats. The width across flats of heads shall be the distance measured perpendicular to the axis of the overall product between the two opposite sides of the head.
2.1.3 Head Taper. The maximum width across flats shall not be exceeded. No transverse section through the head between 25% and 75% of actual head height, as measured from the bearing surface, shall be less than the minimum width across flats.
2.1.4 Head Height. The head height shall be that overall distance measured parallel to the axis of the product from the top of the head to the bearing surface and shall include the thickness of the washer face. Raised grade and manufacturer’s identification are excluded from head height.
2.1.5 True Position of Head. The head shall be located at true position with respect to the body within a tolerance zone having a diameter equivalent to 6% of the maximum width across flats at maximum material condition (MMC]. For measurement purposes, hold the body a distance under the head equal to one diameter.
2.1.6 BearingSurface. Bearing surface shall be flat and washer faced. However, a die seam across the bearing face shall be permissible. Diameter of washer face shall be equal to the maximum width across flats within a tolerance of – 10%. Thickness of the washer face shall be not less than 0.015 in. nor greater than 0.025 in. for bolt sizes 3%4 in. and smaller, and not less than 0.015 in. nor greater than 0.035 in. for sizes larger than 4 in. The plane of the bearing surface shall be perpendicular to the axis of the body within the full indicator movement (FIM] limits specified for total runout. Measurement of FIM shall extend as close to the periphery of the bearing surface as possible while the bolt is being held in a collet or other gripping device at a distance of one bolt diameter from the underside of the head. The angularity measurement shall be taken at a location to avoid interference from a die seam.
2.1.7 Bolt Length. The bolt length shall be the distance measured parall to the axis of the product from the bearing surface of the head to the extreme end of the bolt including point. Bolts are normally furnished in 4-in. length increments.
2.1.9 Threads. Threads shall be cut or rolled in accordance with ASME B1.1 Unified Coarse, Class 2A. Structural bolts shall not be undersized to accommodate heavy coatings. Threads that have been coated shall meet the requirements specified in ASTM F3125/F3125M.
2.1.9.1 Thread Acceptability. Unless otherwise specified by the purchaser, gaging for screw thread dimensional acceptability shall be in accordance with Gaging System 21, as specified in ASME B1.3.
2.1.9.2 Thread Length. The length of thread on bolts shall be controlled by the grip gaging length, La max, and the body length, Lg min. Grip gaging length, LG, is the distance measured parallel to the axis of bolt from the underhead bearing surface to the face of a noncounterbored or noncountersunk standard GO thread ring gage, assembled by hand as far as the thread will permit. It shall be used as the criterion for inspection. The maximum grip gaging length, as calculated and rounded to two decimal places for any bolt not threaded full length, shall be equal to the nominal bolt length minus the thread length [Lc max. = L nom. – L). For bolts that are threaded full length, LG max. defines the unthreaded length under the head and shall not exceed the length of 2.5 times the thread pitch for sizes up to and including 1 in. diameter, and 3.5 times the thread pitch for sizes larger than 1 in. diameter. LG max. represents the minimum design grip length of the bolt and may be used for. determining thread availability when selecting bolt lengths even though usable threads may extend beyond this point (see Table 2.1.9.2-1). .ASME B18.2.6 pdf download.ASME B18.2.6-2019 pdf free download
