ASME B18-16.4 pdf download Serrated Hex Flange Locknuts 90,000 psi (Inch Series)
(a) Unless otherwise specified, all dimensions in this Standard shall be as specified in Tables 1 and 2, and sections 6 through 9. All dimensions in this Standard are in inches and apply before plating or coating is specified. When a plating or coating is specified, the finished product dimensions shall be agreed upon between the supplier and purchaser.
(b) Symbols specifying geometric characteristics are in accordance with ASME Y14.5M.
6 SERRATIONS The configuration of the serrations shall be at the discretion of the manufacturer, provided the perform- ance requirements as specified in para. 12.2 are met.
7 TOPS OF NUTS Tops of nuts shall be flat and chamfered. The length of chamfer at hex corners shall be from 5% to 15% of the basic thread size. The surface may be slightly convex or rounded.
8 TRUE POSITION OF HEXAGON TO TAPPED HOLE At maximum material condition (MMC), the axis of the hexagon shall be located attrue position with respect to the axis ofthe thread pitch diameterwithina tolerance zone having a diameter equivalent to 4% of the maximum width across flats.
9 COUNTERSINK Tapped hole shall be countersunk on the bearing face and may be countersunk on the top. The maximum countersink diameter shall be the thread basic (nominal) major diameter plus 0.030 in. for 3 ⁄ 8 in. nominal size nuts and smaller, and 1.08 times the basic major diameter for nuts larger than 3 ⁄ 8 in. No part of the threaded portion shall project beyond the bearing surface.
10 THREADS Threads shall be Unified coarse or fine thread series (UNC or UNF series) Class 2B, in accordance with ASME B1.1. Inspection shall be based on System 21 of ASME B1.3.
11 MATERIAL AND HARDNESS Unless otherwise specified, nuts shall be manufac- turedfromcarbonsteelinaccordance withASTMF2282. The nuts shall have a case hardness of HR 15N 78-90 on the surface of the nut in accordance with ASTM F 2328. For referee purposes, case hardness shall be measured in the serrations.
12 MECHANICAL REQUIREMENTS
12.1 Proof Load Test Nuts shall meet the proof load test using the values in Table 3. The proof load test procedure from ASTM F 606 shall be followed.
12.2 Break Loose Torque Test Nuts shall have a break loose torque value equal to or greater than 100% of the seating torque value. The seating torque value shall be ±10% of the values listed in Table 3.
(a) Procedure. Place a test bolt through a cold-rolled steel strip and spacers as required. Assemble a test nut so that at least three thread pitches of the bolt extend beyond the top of the nut. While preventing the steel strip from rotating, apply the torque value listed in Table 3. Record the seating torque values, break the nut loose from its seated position, and record the highest torque value. That value is the “break loose torque.” A different unused test bolt, test nut, and hole in the test strip must be used for every test. The test bolt shall be prevented from turning during testing. Additional lubricant shall not be added.
(b) Test Bolt. The test bolt shall be plain finished with threads conforming to Class 2A tolerances as specified in ASME B1.1. The bolt shall have an ultimate tensile strength not less than the specified proof load of the nut to be tested. Bolt length shall be such that a minimum length equivalent to six thread pitches as measured from the end of the bolt will protrude through the nut when the nut is seated.
(c) Test Strip. The steel strip must be a minimum of 0.060 in. thick, having a hardness between HRB 60 and HRB 90. The strip must have holes for placing the bolt through that are 0.010 in. to 0.025 in. over the bolt’s nominal thread diameter.
(d) Torque Measuring Device. Test results may be mea- sured by an analog or digital device that is capable of indicating and holding a peak torque value. The analog or electronic measuring system shall have a certified accuracy of ± 2% or less.
13 FINISH Unless otherwise specified, nuts shall be furnished with an electrodeposited zinc-plated finish in accor- dance with ASTM F 1941, Fe/Zn 3A. 14 GRADE AND IDENTIFICATION MARKING Unless otherwise specified by the purchaser, these nuts shall have no grade marking requirements.