SAE AS 7251C:2014 pdf free

SAE AS 7251C:2014 pdf free.Nuts, Self-Locking, Steel, Corrosion and Heat Resistant High Strength, AII Metal 1200 °F Use, UNJ Thread Form
The bearing surface shall be square (flat to concave) with the thread pitch cylinder axis within the limits specified on the part drawing. Bearing surface shall not be convex. Bearing surface squareness shall be tested using a table squareness gage and feeler gage. The squareness requirement shall apply to the complete bearing surface of the nut except that, for nonfloating plate nuts having a bearing surface exceeding 1 .5 times the thread major diameter, the squareness requirement shall, unless otherwise specified on the part drawing, apply only to the portion of the bearing surface of the nut contained within a diameter equal to 1.5 times the thread major diameter. The nuts to be inspected shall permit at least three complete turns of engagement on the thread arbor of the squareness gage; plating or coating may be stripped, if necessary, to meet this requirement. Multipiece floating plate nuts shall have the nut element removed from the retainer for checking thread squareness.
This test is applicable to wrenching nuts with hexagon or double hexagon wrenching feature. For this test only, all nuts shall be cleaned to remove all traces of any supplemental lubricant (such as wax, cetyl alcohol, etc.). At least three nuts shall be tested at room temperature for wrench torque by assembling a nut on an alloy steel bolt having sufficient strength.The nut shall be tightened against a bushing with a hole diameter as in 3.9.1 and having hardness not lower than 40 HRC,and surface roughness of 63 microinches Ra. Nuts shall withstand 12 successive applications of the torque specified in Table 2 without destroying the wrenchability of the nut. Wrenches used for this test can be open ended type or socket type.
The locking feature torque shall be measured and recorded for not less than 10 new nuts, selected at random from the lot,for each of the tests required in 3.9.5. Loading and conditioning for the five-cycle test of 3.9.5.2, shall be in accordance with 3.9.3.1.Test bolts shall conform to 3. 10 or equivalent threaded parts. Test fixtures shall conform to 3.9.3.1.2. Tests shall be conducted at room temperature. The end of the bolt shall extend a minimum of 1.5 thread turns through the top of the nut at the start of the test. Test shall be run in such a manner that a dependable measure of torque will be obtained. The increase in temperature of the nuts during the test shall not exceed 74 °F. The maximum prevailing and minimum breakaway torque (see AS1310) shall not exceed the values specified in Table 3 as required by the reusability tests in 3.9.5.SAE AS 7251C pdf free download.