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ASME B1.3-2017 pdf download

ASME B1.3-2017 pdf download.Screw Thread Gaging Systems for Acceptability: Inch and Metric Screw Threads (UN, UNR, UNJ, M, and MJ).
(1 ) System 21 . Provides for interchangeable assem- bly with functional size inspection/evaluation at the maximum material limit within the length of standard gaging elements, and also inspection/evaluation of characteristics identified as NOT GO functional diame- ters or as HI (internal) and LO (external) functional diameters. (2) System 22. Provides for interchangeable assem- bly with functional size inspection/evaluation at the maximum material limit within the length of standard gaging elements, and also inspection/evaluation of the minimum material size pitch diameter or thread groove diameter over the length of the full thread. The cumula- tive effects of all other thread characteristics such as lead, flank angle, taper, and roundness variations are confined within product tolerance limits with no specific inspection/evaluation of their magnitudes. (3) System 23. Provides for interchangeable assem- bly with functional size inspection/evaluation at the maximum material limit within the length of standard gaging elements, and also inspection/evaluation of the minimum material size pitch diameter or thread groove diameter over the length of the full thread. The magni- tude of other thread characteristics such as lead, flank angle, taper, and roundness are further inspected/evalu- because of gage design. Tables 1 and 2 provide a selection of gages which in combination may be needed to assure that diameter size variations caused by out-of-round- ness are contained within product tolerance limits. 5 GAGING REQUIREMENTS (a) Screw threads of threaded products are defined by the applicable thread document. Appropriate standards are listed in section 2. (b) The gaging system used to inspect/evaluate the screw thread of a threaded product shall be as specified in the product standard, procurement drawing, or pur- chase inquiry and order. In the absence of a specified gaging system on the purchase order, product drawing, or other applicable documentation, the supplier and cus- tomer must agree upon a suitable gaging system. There is no implied default gaging system. (c) Each of the thread characteristics specified in the gaging system shall be inspected/evaluated using the gage (or one of the gages) specified for that characteris- tic. Gages shall be in conformance with the applicable gaging documents. Use appropriate standards listed in section 2 unless otherwise specified. (d) The use of any gage or measuring device is not precluded if the results given by such gage or measuring device correlate with a gage or measuring device listed in this Standard. (e) All measurement results are not necessarily equal to a characteristic’s true size. The environment, the instruments, and the operator are factors influencing measurement results. The sum of these factors may be cumulative, making the measurement results further from the characteristic’s true size, or the factors may cancel each other out, making the measurement results closer to the characteristic’s true size. ated, as specified within the pitch diameter limits. Only thread characteristics in System 23 for which require- 6 ACCEPTABILITY ments or limitations are specified must be inspected/ evaluated for System 23 compliance. For example, if the product thread has no surface texture requirement nor major-to-pitch runout limitation, then System 23 does not require that these two characteristics be checked. (d) For special applications, the screw thread on a threaded product may require inspection/evaluation not consistent with any of the standard gaging systems. In such cases, one of the standard gaging systems should be selected and modified by specifying, in accordance with para. 7(b), the addition or the reduction of thread characteristic(s) and gage(s) as selected from Table 1 or 2, as applicable. (e) Product threads affected by roundness variations may be even-lobed (1 80 deg contact) or odd-lobed (120 deg contact). Product thread acceptance or rejection can be influenced by thread gages and measuring equip- ment having the ability to detect one, but not both, 2 (a) The screw thread of a threaded product shall be acceptable when each of the thread characteristics speci- fied in the designated gaging system is found to be acceptable. (b) Within each gaging system, a choice of gages is specified for each characteristic. Acceptance by any one gage in current calibration specified for a characteristic shall be the criterion for acceptance of that characteristic. (c) All threaded products are subject to visual inspec- tion/evaluation for gross defects. This visual inspec- tion/evaluation shall be made without magnification and is intended to detect such gross defects as missing or incomplete threads, defective thread profile, torn or ruptured surfaces and cracks, etc. Surface texture of threaded products, when required, will be inspected/ evaluated by visual or tactile comparison with texture specimens or surface measurement equipment.

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