ASME B1.1-2019 pdf download
ASME B1.1-2019 pdf download.Unified Inch Screw Threads (UN, UNR, and UNJ Thread Forms).
1.4 InterchangeabiLity
1.4.1 UN and UNR. Unified (UN/UNR) and its predecessor American National (N) screw threads have substantially the same thread form, and threads of both standards having the same diameter and pitch are mechanically interchangeable. The principal differences between these standards relate to the application of allowances, the variation of tolerances with size, differences in the amounts of pitch diameter tolerances for external and internal threads, and differences in thread designations. Unified inch and ISO metric screw threads are not mechanically interchangeable.
1.4.2 UNJ. UN and UNJ threads are interchangeable with the exception of UNJ-3A external threads, which at maximum material condition will not assemble with a UN internal thread of any class at maximum material condition (see Figure 1).
1.5 Designations
Unified thread sizes (specific combinations of diameter and pitch shown in Table 1) are identified by the letter combination “UN” in the thread symbol. In the unified standards, the pitch diameter tolerances for external threads differ from those for internal threads; for this reason the letter “A” is used in the thread symbol to denote an external thread and the letter “B,” an internal thread. Where the letters “U,”“A,” or “B” do not appear in the thread designation, the threads conform to the outdated American National screw threads. Details regarding thread designations are given in section 6.
1.6 References
The following is a list of publications referenced in this Standard. Unless otherwise specified, the latest edition shall apply. The following documents form a part of this Standard to the extent specified herein.
ASME 81.2, Gages and Gaging for Unified Inch Screw Threads
ASME B1.3, Screw Thread Gaging Systems for Acceptability: Inch and Metric Screw Threads
For reference, the basic profile for UN and UNR screw threads is identical to that for ISO metric screw threads shown in Iso 68.
2.2.2 UNJ. The basic profile for UNJ screw threads is shown in Figure 3. It is the theoretical profile corresponding to the basic dimensions of the thread major diameter, pitch diameter, and minor diameter. This profile includes a O.15011107P to O.18042196P radius at the root of the external thread as shown in Figure
4. This also requires that the minor diameter of the external and internal threads be larger than the UN and UNR thread forms to accommodate the external thread maximum root radius. It is similar to but not the same as the profile for UN and UNR.
2.3 Design ProfiLes
The design profiles define the maximum material conditions for external and internal threads with no allowance and are derived from the basic profile. The design profiles of both external and internal screw threads vary from the basic profile.
