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The company reserves the right to vary models and dimensions without notice.
These products are designed for industrial applications and are not suitable for sale to the general public.
TECHNICAL DATA
Technical Data
10
NORTH AMERICAN FITTINGS & FLOW CONTROL VALVE CATALOG
>
Release 8.6
UTS PREFERRED SIZES
Major
diameter
[in]
Pitch
[1/in]
Major
diameter
[mm]
Coarse
UNC
Fine
UNF
#0 =
0.0600
–
80 1.5240
#1 =
0.0730
64 72 1.8542
#2 =
0.0860
56 64 2.1844
#3 =
0.0990
48 56 2.5146
#4 =
0.1120
40 48 2.8448
#5 =
0.1250
40 44 3.1750
#6 =
0.1380
32 40 3.5052
#8 =
0.1640
32 36 4.1656
#10 =
0.1900
24 32 4.8260
#12 =
0.2160
24 28 5.4864
1/4
20 28 6.3500
5/16
18 24 7.9375
3/8
16 24 9.5250
7/16
14 20 11.1125
1/2
13 20 12.7000
9/16
12 18 14.2875
5/8
11 18 15.8750
3/4
10 16 19.0500
7/8
9
14 22.2250
1
8
12 25.4000
Tolerance classes
A classification system exists for ease of manufacture and interchangeability of fabricated threaded
items. Most (but certainly not all) threaded items are made to a classification standard called the
Unified Screw Thread Standard Series. This system is analogous to the fits used with assembled
parts.
Classes 1A, 2A, 3A
apply to external threads; Classes 1B, 2B, 3B apply to internal threads.
Class 1
threads are loosely fitting threads intended for ease of assembly or use in a dirty environ-
ment.
Class 2
threads are the most common. They are designed to maximize strength considering typi-
cal machine shop capability and machine practice.
Class 3
threads are used for closer tolerances.
Thread class
refers to the acceptable range of pitch diameter for any given thread. The pitch
diameter is shown as d2 in figure 1 above. There are several methods that are used to measure
the pitch diameter. The most common method used in production is by way of a Go-NoGo gauge.
References
ASME/ANSI B1.1 – 2003 Unified Inch Screw Threads, UN & UNR Thread Form
ASME/ANSI B1.10M – 2004 Unified Miniature Screw Threads
ASME/ANSI B1.15 – 1995 Unified Inch Screw Threads, UNJ Thread Form
Unified Thread Standard
The Unified Thread Standard (UTS)
defines a standard thread
form and series—along with allowances, tolerances, and desig-
nations—for screw threads commonly used in the United States
and Canada. It has the same 60° profile as the ISO metric screw
thread used in the rest of the world, but the characteristic dimen-
sions of each UTS thread (outer diameter and pitch) were cho-
sen as an inch fraction rather than a round millimeter value. The
UTS is currently controlled by ASME/ANSI in the United States.
Designation
The standard designation for a UTS thread is a number indicat-
ing the nominal (major) diameter of the thread, followed by the
pitch measured in threads per inch. For diameters smaller than
¼ inch, an integer number defined in the standard indicates the
diameter. For all other diameters, the inch figure is given.
This number pair is optionally followed by the letters UNC and
UNF if the diameter-pitch combination is from the “coarse" or
“fine" series, and may also be followed by a tolerance class.
Example:
6-32 UNC 2B (major diameter: 0.1380 inch, pitch:
32 tpi)