thread281-92960 (pdybeck) on NS Threads 1

[ataurino916]

Some helpful info on NS threads.

Since I'm in the nuclear manufacturing end of this business, I have some info to share.

Reference Specifications:
ANSI B1.1-1989 Unified Inch Screw Threads (UN and UNR Thread Form)

FED-STD-H28A Notice 1 dated 09/10/01 Screw-Thread Standards for Federal Services

The term "NS" is derived as American National-Special.
Per FED-STD-H28, American National threads are obsolete and are carried over to the Unified series.

Per H28:

Replacements for obsolete American National thread classes

American National class 1 coarse thread sizes (NC-1) is approximately equivalent to Unified class 1A/1B series. Class 1 fine thread series (NF-1) is approximately equivalent dimensionally to Unified class 2A/2B series. Standard Unified series threads should be considered prior to approval or replacement by non-standard threads.

American National class 2 coarse thread sizes (NC-2). 8 thread series (8N-2), 12 thread series (12N-2), 16 thread series (16N-2), and extra fine thread series (NEF-2) are most nearly equivalent to Unified series UNC-2A/2B, 8UN-2A/2B, 12UN-2A/2B, 16UN-2A/2B and UNEF-2A/2B, respectively. Class 2 fine thread series (NF-2) is approximately equivalent dimensionally to Unified class 3A/3B series, but the use of class 2A/2B series should be considered prior to approval of replacement by class 3A/3B.

American National class 3 series NC-3, NF-3, NEF-3, 8N-3, 12N-3 and 16N-3 are most nearly equivalent to Unified class 3 series UNC-3A/3B, UNF-3A/3B, UNEF-3A/3B, 8UN-3A/3B, 12UN-3A/3B and 16UN-3A/3B, respectively.

There is no Unified thread class equivalent to the old American National class 4 which required selective fit of parts due to the possibility of interference
---------------------------------------------------------
Old "NS" - New "UNS"

ANSI B1.1-1989

Designation of Unified screw threads is in accordance with section 6 of ASME B1.1-1989. Nominal size shall be stated in decimals. The symbol UNS is applicable to any thread:

having the basic Unified thread form and
with limits based upon Unified formulations and
which is not in the standard series listed in Table 3A of ASME B1.1-1989.

Now since your 1 9/16-18 NS-3 thread is obsolete, it should be considered in manufacturing as 1 9/16"-18 UNEF-3A, since it is listed in Table 3A. You can inspect your thread with a threaded GO/NO-GO ring gage for functional,pitch micrometer (if a NO-GO is not available)for actual and major diameter for System 21 acceptability. Ref: ANSI B1.3 - Screw thread gaging requirements for Unified inch screw threads.

Any other info is appreciated.

 

[KENAT]

I think maybe you meant to link that other thread

thread281-92960

Thanks for the info.

KENAT, probably the least qualified checker you'll ever meet...