ISO/R 228:1961

m
Ref. No.: ISO/R 228 - 1961 (E)
UDC 621.643
IS0
I NT ERN AT I ON AL O RG A N I Z AT I O N F O R STAND A RD IZ AT I O N
IS0 RECOMMENDATION
I
R 228
PIPE THREADS WHERE PRESSURE-TIGHT JOINTS
ARE NbT MADE ON THE THREADS
(1/8 INCH TO 6 INCHES)
1st EDITION
December 1961
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.

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BRIEF HISTORY
The IS0 Recommendation R 228, Pipe Threads where Pressure-Tight Joints are not made
on the Threads (118 inch to 6 inches), was drawn up by Technical Committee ISO/TC 5, Pipes
and Fittings, the Secretariat of which is held by the Association Suisse de Normalisation (SNV).
Work on this question by the Technical Committee began in 1953 and led, in 1959, to the
adoption of a Draft IS0 Recommendation.
In November 1959, this Draft IS0 Recommendation (No. 332) was circulated to all the
IS0 Member Bodies for enquiry. It was approved by the following Member Bodies:
Belgium France Italy
Burma Germany Netherlands
Chile Greece Norway
Czechoslovakia Hungary Portugal
Denmark India Romania
Finland Israel Spain
Switzerland
Five Member Bodies opposed the approval of the Draft:
Australia, New Zealand, Sweden, United Kingdom, U.S.S.R.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in December 1961, to accept it as an IS0 RECOMMENDATION.
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ISO/R 228-1961 (E) '
IS0 Recommendation R 228 December 1961
PIPE THREADS WHERE PRESSURE-TIGHT JOINTS
ARE NOT MADE ON THE THREADS
(il8 INCH TO 6 INCHES)
1. SCOPE
The threads covered by this IS0 Recommendation are intended for the mechanical assembly of
the component parts of fittings, cocks and valves, etc.
2. PROFILE
The profile of the thread specified in this IS0 Recommendation is identical with that of the parallel
thread specified in IS0 Recommendation R 7. The internal and external threads covered by
this IS0 Recommendation are both parallel.
The crests of the threads may be truncated to the limits of tolerance, as given in columns 11,
12, 13 and 14, except on the internal threads, when they are likely to be assembled with external
threads conforming to IS0 Recommendation R 7.
3. SIZES
This IS0 Recommendation provides for a range of diameters which are considered to be necessary
to fulfil general requirements. It is recommended to use the diameters in bold type in the first
column of the table wherever possible. *
4. TOLERANCES
4.1
For internal threads, the tolerances on the effective diameter, specified in columns 6 and 7
of the table, correspond to the positive deviation of the tolerances on the diameter according
to the IS0 Recommendation R7,** with the exception of those of the diameters 1/4 and
3/s in, for which slightly higher values have been specified.
4.2 For external threads, two classes of deviations on the effective diameter have been established:
Class A deviation (col. 8): entirely negative, equivalent to the deviation for the internal
thread.
Class B deviation (col. 9): entirely negative, value twice that of Class A.
The choice between Class A or Class B depends on the conditions of application.
5. TABLES
The following tables give the values in inches and millimetres established by starting from the
fundamental dimensions, i.e. major diameter and number of threads per inch.
In principle, the values given in the tables are calculated to 0.0001 mm (or to 0.000 O1 in)
and rounded off to 0.001 mm (or to O.OOO1 in). The effective diameter d2 and the minor
diameter dl have been obtained by subtracting once, respectively twice, the value h (depth of
thread) from the major diameter d.
* These sizes correspond with those in the following IS0 Recommendations:
ISOIR 7, Pipe threads for gas lirt tubes and screwedfiitings where pressure-tight joints are made on the threads (Il8 inch io 6inches) ;
ISOIR 49, Malleable cast iron pipefiftings screwed in accordance with IS0 Recommendation R 7;
ISO/R 50, Steel sockets screwed in accordance with IS0 Recommendation R 7. Minimum lengths;
ISOIR 65, Sieel tubes suitable for screwing in accordance with IS0 Recommendation R 7.
** 1/16 of the tolerances on length (IS0 Recommendation R 7, col. 13).
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I
PIPE THREADS WHERE PRESSURETIGI'iT JOINTS
(1/8 IN( H TO 6 INCH
H = 0.960 491 x p
h = 0.640 327 x p
r = 0.137 329 x p
2 6 7 l I
3 I 4 l 5
Pmissibie tolerances
Basic diameters
Number
Internal thread
of threads
major effective minor
TI
per inch
d Lower c
4 dl
Lower deviation Upper dedon
Cla:
in in in in ir
in-
28 0.3830 0.3601 0.3312 O + 0.042 - O.(
+ 0.049 - O.(
19 0.5180 0.4843 0.4506 O
19 0.6560 0.6223 0.5886 O + 0.019 - O.(
- O.(
14 0.8250 0.7793 0.7336 O + 0.0'56
- O.(
14 0.9020 0.8563 0.8106 O + 0.056
14 1.0410 0.9953 0.9496 O + 0.056 - O.(
- O.(
...