ASME B18.16.6-2017 pdf – Prevailing Torque Locknuts(Inch Series)
ASME B18.16.6-2017 pdf – Prevailing Torque Locknuts(Inch Series).
11 TEST METHODS
11.1 Proof Load Test
The test sample nut shall be assembled on a test bolt (see para. 11.5.4) or on a hardened mandrel (see para. 11,5.5) with a minimum of three threads projecting through the nut. The proof load test may be performed prior to the prevailing torque tea Lure being added to the nut. For referee test purposes, the hardened mandrel shall be used and the prevailing torque feature present. The maximum prevailing torque occurring during the assembl’ of the nut on the test bolt or mandrel shall be recorded.
The specified proof load in Tables 12, 13, and 14 shall be applied in tension or compression through the test bolt or mandrel against the nut bearing surface in an axial direction and held for 10 sec. For referee purposes. the load shall be applied in tension, The nut shall resist this load without thread stripping or rupture. The prevailing torque necessafy to remove the nut from the test bolt or mandrel shall not exceed the maximum torque occurring during assembly.
11.2 Rockwell Hardness Test
Rockwell hardness tests shall be conducted in accordance with the procedures in ASTM F606/F606M.
11.3 PrevaIling Tocque Test
The prevailing torque test shall be conducted at roon temperature using a load-measuring device (see para. 11.5.2). A test bolt (see para. 11-5.4) and/or hardened mandrel (see para. 11.5.6) shall be inserted in the load-measuring device and hardened washer (see para. 11.5.3) placed on the bolt or mandrel and the tam- pie nut then assembled on the bolt or mandreL 11w nut shall be advanced until a minimum of three and a maximum of five full bolt or mandrel threads protrude through the top of the nut, At that time. th maximum torque shall be recorded. This torque shall not exceed the first installed prevailing torque value as specified for the applicable grade and thread series in Tables 12. 13. and 14. The torque-measuring device shall he in accordance with para. 11.5.1.
Tightening shall be continued until the nut is seated against the hardened washet The length of the test bolt or mandrel should be such that seating of the nut shall occur at or before a length equivalent to a maximum of nine thread pitches of the test bolt or mandrel protruding through the top of the nut. as mcasun.’d from the end of thc bolt or mandrel. The nut shall then he tightened until a tensile load equal to the clamp load, as specified for the applicable grade and thread series in Tables 12. 13. and 14. is developed in the bolt or mandrel. The hardened washer shall be presented front turning during nut tightening. The nut shall then be backed off by the application of reverse torque until the tensile load in the bolt or mandrel has been reduced to zero.
At no time during the two additional installations and removals should the prevailing torque exceed the masimum. first install prevailing torque value as spedfled for the applicable grade and thread series in Tables 12, 13, and 14. During the third removal, the minimum torque occurring while the nut is being backed off throughout the first 30 dcg of rotation shall be recorded, The minimum torque shall not be less than the third removal value as specified in Tables 12, 13, and 14. Sufficient time shall elapse between installation and removal cycles to prevent overheating of the test assembly.
The speed of installation and removal of the nut shall not e’ceed 30rpm and shall be continuous and uniform.
11.4 OptIonal Torque-Tension Test
When torque-tension data arc desired by the purcKmet . refer to IFI-lOl.
11.5 Test Devices, Washers. Bolts, and Mandrels
11.5.1 Torque-Measuring Device. The torquemeasuring device, handheld or automatic, shall be capable of measuring the torque while the test kxknut is rotating on a test bolt. The measuring devices and/or system shall be accurate within ±2% of the device scale from 20% through 100% of the full scale. Devices should not be used in the lower 20% of their full-scale capabilih
11.5.2 load-Measuring Device. The load-measuring device used in the prevailing torque test shall becapabk’ of measuring the actual tension induced in the test boll as the nut is tightened. The measuring devices and/or system shall be accurate within ±5% of the device scale from 20% through 100% of the full scale. The bolt clearance hole in the backing plate behind the washer shall have the same diameter and tolerance as the test washer.