IS 9121: Inspection Gauges for Checking Type 1 (Size 2) Taper Threads of Gas Cylinder Valves, Taper 1 in 16

2005·1.5 MB·English

by  Bureau of Indian Standards

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“The Right to Information, The Right to Live” “Step Out From the Old to the New”
IS 9121 (2005): Inspection Gauges for Checking Type 1 (Size
2) Taper Threads of Gas Cylinder Valves, Taper 1 in 16 [MED
16: Gas Cylinders]
“!ान $ एक न’ भारत का +नम-ण”
Satyanarayan Gangaram Pitroda
““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee””
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै”
Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”

‘“’
~
IS9121:2005

Indian Standard
INSPECTION GAUGES FOR CHECKING
TYPE 1 (SIZE 2) TAPER THREADS OF
...— —
GAS CYLINDER VALVES, TAPER 1 IN 16 —
SPECIFICATION
(First Revision)
ICS 17.040.01:23.020.30

0 BIS2005
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002

March 2005 Price Group 8
GasCylinders Sectional Committee, ME 16
FOREWORD
This Indian Standard (First Revision) was adopted by Bureau ofIndian Standards, afterthe draft finalized bythe
Gas Cylinders Sectional Committee had been approved by the Mechanical Engineering Division Council.
Inthisstandard,changeshavebeenincorporated inthelightoftheexperiencegainedbytheindustry andconsumers
over the years. The requirement of limits ontaper of both internal and external threads provided inthe standard
for the NGT threads ANSI/CSA/ STANDARD V-1-1987 ‘Compressed gas cylinder valve outlet and inlet
connection’ issued by the American National Standard Institute and Compressed Gas Association, Inc., this
being the standard forming the basis ofthese threads. Relevant portions ofthe specification ofthe threads have
been reproduced in this revision. With this requirement to inspect the taper of the threads, the method of
checking relative engagement of the product threads in the threaded and plain taper ring and plug gauges has
been included inthis revision.
The composition of the Committee responsible for formulation of this standard isgiven in Annex B.
For the purpose of deciding whether aparticular requirement of this standard iscompiled with, the final value,
observed or calculated, expressing the result of a test or analysis, shall be rounded off in a accordance with
IS2: 1960‘Rules for rounding off numerical values (revise@’. Thenumber ofsignificant places retained inthe
rounded off value should bethe sameasthat ofthe specified value inthis standard.
IS 9121:2005
Indian Standard
INSPECTION GAUGES FOR CHECKING
TYPE 1 (SIZE 2) TAPER THREADS OF
GAS CYLINDER VALVES, TAPER 1 IN 16 —
SPECIFICATION
(First Revision)
1SCOPE 4.2 Principal Dimensions (see Fig. 2)
This standard prescribes dimensions, tolerances 4.3 Limits on Crest and Root Truncations (see
and material requirement of inspection gauges Fig. 3)
recommended for checking the taper threads on the
4.4 Limits onSize
valvestemsandthetaperthreads onthecylinder necks
ofcompressed gascylinders—thethreadsconforming Final inspection limitsonsize(pitch diameter) ofboth
to Type 1 (size 2) covered in IS 3224 and Type 1 external and internal threads are * 1turn from basic
covered in IS 8737. althoughthepreferredworking limitsare* %turn from
basic.
2 REFERENCES
4.5 Limits onTaper
The standards listed below contain provisions, which
through reference inthis text, constitute provisions of
If there is an unintentional difference in taper at
this standard. At the time of publication, the editions
the pitch elements of the valve and of the cylinder
indicated were valid. All standards are subject to
threads, it is preferred to have greater tightness at
revision, and parties to agreements based on this
the bottom of the valve. The limits in gauging shall
standard are encouraged to investigate the possibility
be:
of applying the most receht editions of the standards
a) Taper on pitch elements of external threads
indicated below.
shall be 1 in 16 on diameter, with a minus
1sNo. Title
tolerance of one turn, but no plus tolerance in
1570(Part 2): 1979 Schedulesforwroughtsteels Part gauging.
2Carbonsteels(unalloyedsteels)
b) Taper on pitch elements of internal threads
(first revision)
shall be 1 in 16 on diameter, with a plus
1586:2000 Method fo r Rockwell Hardness tolerance ofoneturn, butno minus tolerance in
test for metall i c material (Scales gauging.
A-B-C-D-E-F-G-H-K 15N,30N,
45N, 15T, 30T and 45T) (fhird 4.6 The tolerance on 60° angle of threads shall be
revision) i 2“.
3224:2002 Valvefittingsforcompressedgas
4.7 The maximum taper on pitch line per millimetre
cylinders excluding liquefied
shallbe 0.0729 andtheminimum 0.0573.
petroleumgas(LPG)cylinders—
Specification (third revision) 5 DIMENSIONS AND TOLERANCES OF
8737:1995 Valve fittings for use with GAUGES FOR CHECKING THREADS IN
liquefied petroleum gas (LPG) CYLINDER NECK (INTERNAL THREADS)
cylinders of more than 5 litre
5.1 Taper Thread Plug Gauge for Checking
water capacity — Specification
Pitch Diameter in Cylinder Neck L,, Gauge A
(first revision)
(see Fig. 4)
3 MATERIAL
5.2 Full Form Taper Thread Plug Gauge for
Suitable wear resisting, steel, for example, 435C6of Checking Thread in Cylinder Neck L9,Gauge B
1S1570(Part 2)may beused.
(see Fig. 5)
4 DIMENSIONS OF THREADS ON VALVE
5.3 Plain Taper Plug Gauge for Checking Crest
STEMS AND IN CYLINDER NECKS
Truncations of Internal Thread, Gauge C
4.1 Basic Thread Form (see Fig. 1) (see Fig. 6)

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1S 9121:2005
6 DIMENSIONS AND TOLERANCES OF agreement between themanufacturer andthe supplier.
GAUGES FOR CHECKING THREADS ON Surfaces other than the gauging surfaces shall be
VALVE STEMS (EXTERNAL THREADS) fimished smooth.
6.1 Taper Screw Ring Gauge forChecking Thread 10 DESIGNATION
of Taper Stem L,,Gauge D (see Fig. 7)
The gauges shall be designated by:
6.2 Full Form Taper Screw Ring Gauge for
Gauge type and number of this standard
Checking Thread of Taper Stem L,,Gauge E (see
Example:
Fig. 8)
A taper screw ring gauge for checking pitch
6.3 Plain Taper Ring Gauge for Checking Crest
diameter of taper stem at length L1shall be
Truncations of External Threads, Gauge F (see
designated by:
Fig. 9)
Gauge D, 1S9121
7 DIMENSIONS AND TOLERANCES OF
MASTER PLUG GAUGES 11CORROSION PROTECTION ANDPACKING
7.1 Master Taper Screw Ring Gauge (Gauge Gauges shall be protected against climatic conditions
M-INT), to Check L,(Gauge A) and L,(Gauge B) by application of anyanti-corrosive coating. Packing
(see Fig. 10) shouldbesuitabletoprevent damage intransit.
12 MARKING
7.2 Master Taper Thread Plug Gauge (Gauge
M-EXT), to Check L,(Gauge D) andL,(Gauge E)
12.1 Thegaugeshallbemarkedwithmefollowing
(see Fig. 11)
a) Designation,
8 USAGE OF GAUGES b) Manufacturer’snameortrade-mark,and
c) Serialnumber.
Usage of gauges isgiven inAnnex A.
12.2 BISCertification Marking
9 GENERAL REQUIREMENTS OF GAUGING
SURFACES The gauge may also be marked with the Standard
Mark.
9.1 Hardness
12.2.1 Theuse of the Standard Mark isgoverned by
Minimum 60 to 62 HRC (Rockwell, Scale C) when
the provisions oftheBureau ofIndian Standards Act,
determined according to IS 1586.
1986andtheRulesandRegulations made thereunder.
The details of conditions under which a Iicence for
9.2 Finish
the use of the Standard Mark may be granted to

Gauging surfaces shallbe ground, l apped andsuitably manufacturers or producers may be obtained from

stabilized. The method of stabilizing shall be as per Bureau of Indian Standards.

2
mkw--.,,.. —— ‘-’-q
lS 9121:2005
f~
H
f- 1
Fc
{
I
.... —
90°
-b=
I I---@’””
AXIS

EXTERNALTHR EAD INTERNALTHREAD
Pitch measured parallel toaxis, p= 1.814
Thread angle 60° normal totheaxis
Taper 1in16 measured onthe diameter alongthe axis
H = 0.866025p-height of60° sharp Vthread =1.57122
h = 0.800000p= heightofthreadonproduct= 1.45143
f‘c) = Depthoftruncation atcrest, ~) =Depthoftruncationatroot
f:) = Widthofflatatcrest, ~’) =Width offlatatroot
1)Forlimits~ee4C3.
NOTE — The thread issameas%“—14 National GasTaper (NGT) threadsofANSVCSWCGA
STANDARD V-1—1987.
All dimensions inmillimetres.
FIG.1 BASICTHREADFORN
IS 9121:2005
CLEARANCE =2p
Y/////A I I“RELIEF GROOVE-OPTIONAL”
REFERENCE PLANE
INTERNAL THREADS w////
I 6+HD 1! REFERENCE PLANE
0 1=, FOR GAUGING
I EXTERNAL THREADS
IDo 7
.—
Lg -1 I
) +
!.0K3
@E3
I
I SIVLE B
i TYPICAL LOW
PRESSURE CYLINDER NECK
STYLE A
TYPICAL NECK OF
DRAWN CYLINDER
D= Major diameter
Do = 26.03
D,. = 27.42
E= Pitchdiameter
E. = 24.58
El = 25.118
E% = 24.24
E, = 25.798
K= Minordiameter
K, = 22.79
L, = Standard handtightengagement= 8.611

~. 3threads (forwrenching)

L,+L3 = 1 4.05
L, = Lengthoffullexternal threads= 19.497
L, = Lengthoffullroots(minimum)oninternalthreads= 17.681
L,. = Overall lengthofexternalthreads (approx)=23
Diameter atsmall endofthevalve afterchamfer= 23
Alldimensions inmillimetres.
FIG.2 PIUNCIPADLIMENSIONS

4
IS 9121:2005
INTERNAL THREAD
N
. \.
TRUNCATION ‘
EXTERNAL THREAD
P= Pitch= 1.814
H= Heightofsharp Vthread =0.866 025p= 1.57122
h= Heightofthread onproduct=1.4514, Max/l .2880, Mirr
f= Truncationoncrestandroot
f.,n= 0.033P = 0.05987
f~.x= 0 .0 78p = 0.14151 l

Tolerance = 0.08164
F= Equivalent widthofflat
Fw,n=0.038p = 0.06894
F.W=0.090p = 0.16329
Tolerance = 0.09435
Alldimensions inmillimetres.
FIG.3 LIMITSONCRESTANDROOTTRUNCATIONS

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