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ISO
METRIC THREAD SERIES
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| SPECIFICATION |
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Basic
Dimensions :
I.S. 4218 – 1976
I.S.O 724 – 1978 (E) & I.S.O 965/1-1980 (E)
B.S. 3643 Part II
Gauging Practice :
I.S 2334 – 1975
I.S.O 1502 – 1978 (E).
B.S 919 Part III - 1968
DIN 13 - 1987
ANSI / ASME B 1.16 M – 1984
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| STANDARD
DIAMETER-PITCH
COMBINATION |
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Dia
in mm
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Coarse
Pitch
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1,
1.1, 1.2
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0.25
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1.4
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0.3
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1.6,
1.8
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0.35
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2
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0.4
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2.2,
2.5
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0.45
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3
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0.5
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3.5
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0.6
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4
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0.7
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4.5
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0.75
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5
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0.8
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6,
7
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1
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8,
9
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1.25
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10,
11
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1.5
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12
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1.75
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14,
16
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2
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18,
20, 22
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2.5
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24,
27
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3
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30,
33
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3.5
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36,
39
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4
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42,
45
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4.5
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48,
52
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5
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56,
60
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5.5
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64,
68
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6
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| CLASS
OF FIT |
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Classes
above '6' are coarse classes i.e. 7,8 etc.
Classes below '6' are close classes i.e. 5,4 etc.
'6H' for plugs and '6g' for rings represent medium class.
Class of fit for rings is always denoted by small letters,
while for plugs by capital letters.
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| COATED
& UNCOATED THREADS |
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Type
of Gauge
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Before
Coating
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After
Coating/Uncoated finish
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Plug
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'G'
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'H'
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Ring
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'g'
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'h'
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Ring
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'e'
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| APPLICATION |
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General purpose fasteners.
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| THE
STANDARD DIAMETER PITCH COMBINATION IS GIVEN IN CHART |
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For
metric gauges of coarse diameter pitch combination,
pitch is not to be written after diameter as per specification.
Example M8x1.25 6H, only M8 – 6H designation to be used.
The chart giving coarse pitch diameter combination is
given above. For marking gauges above system should
be followed. M6 – 6H (means Plug gauge of coarse
pitch of 1mm and 6H class of fit) M6x0.75 5H
(means Plug gauge of fine pitch and 5H class of fit).
M4 – 6g LH (means Ring gauge of coarse pitch
of 0.7mm 6g class of fit and Left Hand threading) M14x1.5
6g CP Go Ring (means Check Plug for GO ring of 1.5mm
pitch and 6g class of fit) M24 5g WCP NOGO Ring
(means Wear Check Plug for NOGO ring of 3mm pitch and
5g class of fit)
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