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American National and Unified Form Threads

Class X Tolerance

For "GO" and "NOT GO" Thread Gages

TPI
LEAD
HALF ANGLE
MAJOR or MINOR DIAMETERS
PITCH DIAMETER

+
-
+
-
To and Incl. 4"
Above 4" Diam.
To and Incl. 11⁄2"
Above 11⁄2" to 4" Incl.
Above 4" to 8" Incl.
80
.0002
30 min.
.0003
--
.0002
--
--
72
.0002
30 min.
.0003
--
.0002
--
--
64
.0002
30 min.
.0004
--
.0002
--
--
56
.0002
30 min.
.0004
--
.0002
.0003
--

48
.0002
30 min
.0004
--
.0002
.0003
--
44
.0002
20 min
.0004
--
.0002
.0003
--
40
.0002
20 min
.0004
--
.0002
.0003
--
36
.0002
20 min
.0004
--
.0002
.0003
--

32
.0003
15 min
.0005
.0007
.0003
.0004
.0005
28
.0003
15 min
.0005
.0007
.0003
.0004
.0005
24
.0003
15 min
.0005
.0007
.0003
.0004
.0005
20
.0003
15 min
.0005
.0007
.0003
.0004
.0005

18
.0003
10 min.
--
.0007
.0003
.0004
.0005
16
.0003
10 min.
.0006
.0009
.0003
.0004
.0006
14
.0003
10 min.
.0006
.0009
.0003
.0004
.0006
13
.0003
10 min.
.0006
.0009
.0003
.0004
.0006

12
.0003
10 min
.0006
.0009
.0003
.0004
.0006
11
.0003
10 min
.0006
.0009
.0003
.0004
.0006
10
.0003
10 min
.0006
.0009
.0003
.0004
.0006
9
.0003
10 min
.0007
.0011
.0003
.0004
.0006

8
.0004
5 min.
.0007
.0011
.0004
.0005
.0006
7
.0004
5 min.
.0007
.0011
.0004
.0005
.0006
6
.0004
5 min.
.0008
.0013
.0004
.0005
.0006
5
.0004
5 min.
.0008
.0013
--
.0005
.0006

41⁄2
.0004
5 min.
.0008
.0013
--
.0005
.0006
4
.0004
5 min.
.0009
.0015
--
.0005
.0006
Thread Gages are made to Class X tolerances unless otherwise specified on orders or drawings.
Direction of Tolerances

MAJOR DIAMETER FULL FORM
MAJOR DIAMETER TRUNCATED SECTION
PITCH DIAMETER
MINOR DIAMETER
"GO" Work Plug
Plus
--
Plus
--
"NOT GO" Work Plug
Minus
--
Minus
--
"GO" Ring
--
--
Minus
Minus
"NOT GO" Ring
--
--
Plus
Plus
"GO" Set Plug
Plus
Minus
Minus
--
"NOT GO" Set Plug
Plus
Minus
Plus
--

RETURN TO TOLERANCE CHART INDEX