ASME B18.2.1 pdf free download

ASME B18.2.1-2012 pdf free download.Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, HexFlange, Lobed Head, and Lag Screws (Inch Series).
2 GENERAL DATA FOR BOTH BOLTS AND SCREWS
2.1 Heads
2.1.1 Top of Head. Top of head shall be full form and chamfered, with the diameter of chamfer circle equal to the maximum width across flats, on square or hex head products and the “B” dimension shown in Table 9 for lobed head screws with a tolerance of —15%.
2.1.2 Width Across Flats. The width across flats of head shall be the overall distance measured perpendicular to the axis of product between two opposite sides of the head in accordance with the notes in respective dimensional tables.
2.1.3 Head Height. The head height shall be the overall distance measured parallel to the axis of product from the top of the head to the bearing surface and shall include the thickness of the washer face where provided.
2.1.4 True Position of Head. The true position of the head shall be no greater than 6% of the maximum width across flats or lobes. For referee purposes, the evaluation shall be made by holding the body in a collet or chuck one bolt diameter from under the head and rotating the part. With the indicator in line with the axis of the bolt or screw, find and record the lowest point on each flat or the highest point on each lobe. The true position is one-half of the largest absolute difference between the high and low values for any opposing set of flats or lobes.
2.2 Bolt or Screw Length
The bolt or screw length shall be the distance measured parallel to the axis of product from the hearing surface of the head to the extreme end of the bolt or screw, induding the point if the product is pointed.
2.3 Body Diameter
The body diameter minimum! maximum limits are defined in each ol the respective applicable tables. Unless otherwise specified by the purchaser, the body style supplied shall be full-size body,
NOTES:
(I) Only bolts and lag screws are permitted to have die %eams on their body that exceed the body diameter. Die seams on the body and all other styles of screws that exceed the body diameter are not permitted.
(2) For recommended clearance ol hole sues for bolts and screws, reler to ASME H1&2J.
2.4 Points
Unless otherwise specified, bolts need not be pointed. Products designated as screws, with the exception of lag screws, are required to have a chamfered point. The chamfer angle may vary depending on the manufacttiring process. When specified, the chamfer angle should be considered a reference dimension only. The presence of a point is to reduce the possibility of damage to the leading threads and to promote ease of assembly with a tapped hole or nut. Point features not defined in a given product standard are at the discretion of the manufacturer.
2.5 Threads
2.5.1 Thread Standard. Threads on all products in this Standard except lag screws shall meet the requirements of ASME BLL Lg screw thread dimensions are specified in Table 16.
2.5.2 Thread Class. Unless otherwise specified, size limits for standard external thread Class 2A apply prior to coating. The external thread allowance may be used to accommodate the coating thickness on plated or coated parts, provided that the maximum coating thickness is no more than one-fourth of the allowance. Thus, the thread after plating or coating is subject to acceptance using a basic size Class 3A GO thread gage and a Class 2A NOT GO size thread gage.
2.5.3 Thread Series, Thread series on all bolts and screws may be coarse (UNC), fine (UNF), or 8 thread series (8 UN), except askew head bolts, which shall be unified coarse (UNC) only, and lag screws, which are specified in Table 16.
2.5.4 Incomplete Thread Diameter. The major diameter of incomplete thread shall not exceed the actual major diameter of the full form thread.
2.5.5 Thread Acceptability. Unless otherwise sped- lied by the purchaser, dimensional acceptability of screw threads shall be determined using thread gaging System 21 in ASME B1.3.
2.6 Straightness
Shanks of bolts and screws shall be straight within the following limits at maximum material condition (MMC). For bolts or screws with nominal lengths up to and including 12 in., the maximum camber shall be 0.006 in/in. (0.006L) of bolt or screw length. For bolts and screws with nominal lengths over 12 in. up to and including 24 in., the maximum camber shall be 0.008 in., in. (0.(XYSL) of bolt or screw length. For inspection, the camber allowance shall be added to the maximum body diameter or maximum major diameter of the thread, whichever is greater. A typical gage and gaging procedure for checking bolt and screw straightness are given in ASME B18.2.9.ASME B18.2.1 pdf download.