EN ISO 15848-1:2015

SLOVENSKI STANDARD
01-september-2015
1DGRPHãþD
SIST EN ISO 15848-1:2006
Industrijski ventili - Meritve, preskusi in postopki kvalificiranja pobeglih emisij - 1.
del: Klasifikacijski sistem in kvalifikacijski postopki za preskušanje tipa ventilov
(ISO 15848-1:2015)
Industrial valves - Measurement, test and qualification procedures for fugitive emissions -
Part 1: Classification system and qualification procedures for type testing of valves (ISO
15848-1:2015)
Industriearmaturen - Mess-, Prüf- und Qualifikationsverfahren für flüchtige Emissionen -
Teil 1: Klassifizierungssystem und Qualifikationsverfahren für die Bauartprüfung von
Armaturen (ISO 15848-1:2015)
Robinetterie industrielle - Mesurage, essais et modes opératoires de qualification pour
émissions fugitives - Partie 1: Système de classification et modes opératoires de
qualification pour les essais de type des appareils de robinetterie (ISO 15848-1:2015)
Ta slovenski standard je istoveten z: EN ISO 15848-1:2015
ICS:
23.060.01 Ventili na splošno Valves in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 15848-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2015
ICS 23.060.01 Supersedes EN ISO 15848-1:2006
English Version
Industrial valves - Measurement, test and qualification
procedures for fugitive emissions - Part 1: Classification system
and qualification procedures for type testing of valves (ISO
15848-1:2015)
Robinetterie industrielle - Mesurage, essais et modes Industriearmaturen - Mess-, Prüf- und
opératoires de qualification pour émissions fugitives - Partie Qualifikationsverfahren für flüchtige Emissionen - Teil 1:
1: Système de classification et modes opératoires de Klassifizierungssystem und Qualifikationsverfahren für die
qualification pour les essais de type des appareils de Bauartprüfung von Armaturen (ISO 15848-1:2015)
robinetterie (ISO 15848-1:2015)
This European Standard was approved by CEN on 7 February 2015.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15848-1:2015 E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 15848-1:2015) has been prepared by Technical Committee ISO/TC 153 “Valves” in
collaboration with Technical Committee CEN/TC 69 “Industrial valves” the secretariat of which is held by
AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2015, and conflicting national standards shall be withdrawn
at the latest by December 2015.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 15848-1:2006.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 15848-1:2015 has been approved by CEN as EN ISO 15848-1:2015 without any modification.
INTERNATIONAL ISO
STANDARD 15848-1
Second edition
2015-06-01
Industrial valves — Measurement,
test and qualification procedures for
fugitive emissions —
Part 1:
Classification system and qualification
procedures for type testing of valves
Robinetterie industrielle — Mesurage, essais et modes opératoires de
qualification pour émissions fugitives —
Partie 1: Système de classification et modes opératoires de
qualification pour les essais de type des appareils de robinetterie
Reference number
ISO 15848-1:2015(E)
©
ISO 2015
ISO 15848-1:2015(E)
© ISO 2015
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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the requester.
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Published in Switzerland
ii © ISO 2015 – All rights reserved

ISO 15848-1:2015(E)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 3
5 Type test . 4
5.1 Test conditions . 4
5.1.1 Preparation of a valve to be tested . 4
5.1.2 Test fluid . 4
5.1.3 Test temperature . 4
5.1.4 Measurement of test valve temperature. 4
5.1.5 Leakage measurement . 7
5.2 Test procedures . 8
5.2.1 Safety rules. 8
5.2.2 Test equipment . 8
5.2.3 Stem (or shaft) seal adjustment (SSA) . 8
5.2.4 Test description . 9
6 Performance classes .11
6.1 Classification criteria .11
6.2 Tightness classes .11
6.2.1 Definition .11
6.2.2 Helium as test fluid .12
6.2.3 Methane as test fluid .12
6.2.4 Correlations .12
6.3 Endurance classes .12
6.3.1 Mechanical-cycle classes for isolating valves .12
6.3.2 Mechanical-cycle classes for control valves.14
6.4 Temperature classes .15
6.5 Examples of class designation .16
6.6 Marking .16
7 Reporting .16
8 Extension of qualification to untested valves .17
Annex A (normative) Total leak rate measurement .19
Annex B (normative) Leak measurement using the sniffing method .32
Annex C (informative) Leak rate conversion (helium) .41
Bibliography .43
ISO 15848-1:2015(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 153, Valves, Subcommittee SC 1, Design,
manufacture, marking and testing.
This second edition cancels and replaces the first edition (ISO 15848-1:2006) which has been technically
revised. The main changes are the following:
−1
— leak rate at the stem seal (Table 1) is expressed in mbar∙l∙s per mm stem diameter;
— flushing method is replaced by accumulation or suck through method to measure leak rate from
stem seal with Helium (Annex A);
— leakage is expressed in ppmv; leakage with methane is measured by sniffing;
−7 −1 −1 −5 −1 −1
— for tightness Class AH, leak rate ≤ 1,78·10 mbar∙l∙s ∙mm (10 mg∙s ∙m );
— the appropriate leak rate is given for Classes BH and CH;
— addition of Table 3 which gives tightness classes for stem (or shaft) seals with methane;
— there is no correlation intended between the tightness classes when the test fluid is helium (Classes
AH, BH, CH) and when the test fluid is methane (Classes AM, BM, CM);
— modification of the number of mechanical cycles for isolating valves;
— addition of Table 4;
— addition of Figures 3, 4, and 5;
— addition of type leak (A.1.3.4, B.1.4.2, B.1.6.1);
— modification of Figure B.2;
— modification of B.1.6.1 on calibration procedures;
— deletion of Figure B.3;
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ISO 15848-1:2015(E)
— addition of Table C.1 and modification of Table C.2.
ISO 15848 consists of the following parts, under the general title Industrial valves — Measurement, test
and qualification procedures for fugitive emissions:
— Part 1: Classification system and qualification procedures for type testing of valves
— Part 2: Production acceptance test of valves
ISO 15848-1:2015(E)
Introduction
The objective of this part of ISO 15848 is to enable classification of performance of different designs and
constructions of valves to reduce fugitive emissions.
This part of ISO 15848 defines type test for evaluation and qualification of valves where fugitive
emissions standards are specified.
The procedures of this part of ISO 15848 can only be used with the application of necessary precautions
for testing with flammable or inert gas at temperature and under pressure.
vi © ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 15848-1:2015(E)
Industrial valves — Measurement, test and qualification
procedures for fugitive emissions —
Part 1:
Classification system and qualification procedures for type
testing of valves
1 Scope
This part of ISO 15848 specifies testing procedures for evaluation of external leakage of valve stem
seals (or shaft) and body joints of isolating valves and control valves intended for application in volatile
air pollutants and hazardous fluids. End connection joints, vacuum application, effects of corrosion, and
radiation are excluded from this part of ISO 15848.
This part of ISO 15848 concerns classification system and qualification procedures for type testing of
valves.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 5208, Industrial valves — Pressure testing of metallic valves
EN 13185:2001, Non-destructive testing — Leak testing — Tracer gas method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
body seals
any seal in pressure containing part except stem (or shaft) seals
3.2
Class
convenient round number used to designate pressure-temperature ratings
Note 1 to entry: It is designated by the word “Class” followed by the appropriate reference number from the
following series: Class 125, Class 150, Class 250, Class 300, Class 600, Class 900, Class 1 500, Class 2 500.
3.3
concentration
ratio of test fluid volume to the gas mixture volume measured at the leak source(s) of the test valve
1)
Note 1 to entry: The concentration is expressed in ppmv .
3 3 3
1)  Parts per million volume is a unit deprecated by ISO. 1 ppmv = 1 ml/m = 1 cm /m .
ISO 15848-1:2015(E)
3.4
control valve
power operated device which changes the fluid flow rate in a process control system and which consists
of a valve connected to an actuator that is capable of changing the position of a closure member in the
valve in response to a signal from the controlling system
3.5
fugitive emission
chemical or mixture of chemicals, in any physical form, which represents an unanticipated or spurious
leak from equipment on an industrial site
3.6
leakage
loss of the test fluid through the stem (or shaft) seal or body seal(s) of a test valve under the specified
test conditions and which is expressed as a concentration or a leak rate
3.7
leak rate
−1
mass flow rate of the test fluid, expressed in mg·s per millimetre of stem diameter through stem seal
–1
system or volumic flow rate of the test fluid, expressed in mbar∙l∙s per millimetre of stem diameter
through stem seal system
3.8
local leakage
measurement of the test fluid leakage using a probe at the leak source point
3.9
mechanical cycle of control valves
for linear/rotary control valves, test cycles performed at 50 % of stroke/angle with an amplitude of
±10 % of full stroke/angle
3.10
mechanical cycle of isolating valves
motion of a valve obturator moving from fully closed position to fully opened position, and returning to
fully closed position
3.11
nominal size
DN
alphanumeric designation of size for components of a pipework system, which is used for reference
purposes, comprising the letters DN followed by a dimensionless whole number which is indirectly
related to physical size, in millimetres, of the bore or outside diameter of the end connections
Note 1 to entry: The nominal diameter is designated by the letters DN followed by a number from the following
series: 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200, 250, 300, 350, 400, etc.
Note 2 to entry: The number following the letters DN does not represent a measurable value and should not be
used for calculation purposes except where specified in the relevant standard.
Note 3 to entry: Adapted from ISO 6708:1995, definition 2.1.
3.12
nominal pressure
PN
numerical designation relating to pressure, which is a convenient rounded number for reference
purposes, comprising the letters PN followed by the appropriate reference number
Note 1 to entry: All equipment of the same nominal size (DN) designated by the same PN number have compatible
mating dimensions.
Note 2 to entry: The maximum allowable working pressure depends upon materials, design, and working
temperatures and is selected from the pressure/temperature rating tables in the appropriate standards.
2 © ISO 2015 – All rights reserved

ISO 15848-1:2015(E)
Note 3 to entry: The nominal pressure is designated by the letters PN followed by the appropriate reference
number from the following series: 2,5, 6, 10, 16, 20, 25, 40, 50, etc.
Note 4 to entry: Adapted from ISO 7268:1983, definition 2.1.
3.13
isolating valve
valve intended for use principally in the closed or open position which can be power actuated or manually
operated
3.14
performance class
level of the performance of a test valve
Note 1 to entry: The performance classes are defined in Clause 6.
3.15
room temperature
temperature in the range of −29 °C to +40 °C
3.16
stem
shaft
valve component extending into the valve shell to transmit the linear/rotary motion from the actuating
device to the valve obturator
3.17
stem seal
shaft seal
component(s) installed around the valve stem (or shaft) to avoid leakage of internal fluids to atmosphere
3.18
test pressure
pressure used for testing the valve which, unless otherwise specified, is the rated pressure specified at
the test temperature and the shell material of a test valve in the relevant standards
3.19
test temperature
fluid temperature selected for the test as measured inside the test valve
Note 1 to entry: The test temperature is given in Table 5.
3.20
thermal cycle
change of the temperature from the room temperature to the specified test temperature and return to
the room temperature
3.21
total leakage
collection of leakage of the test fluid at the leak source using an encapsulation method
3.22
type test
a test conducted to establish the performance class of a valve
4 Symbols and abbreviations
M predicted maximum leakage
alr
SSA stem (or shaft) seal adjustment
ISO 15848-1:2015(E)
OD stem outside diameter
stem
RT room temperature
NOTE The abbreviation SSA corresponds to the abbreviation of “Stem Seal Adjustment”.
5 Type test
5.1 Test conditions
5.1.1 Preparation of a valve to be tested
Only a fully assembled valve shall be used for the test.
A valve shall be selected from standard production at random. The valve shall have been tested and
accepted in accordance with ISO 5208 or any other applicable standard and no subsequent protective
coating shall have been applied.
Additional seal arrangements to allow the stem sealing system leakage measurement is permitted and
shall not affect the sealing performance of the valve.
The test valve interior shall be dried and lubricants (if any) shall be removed. The valve and test
equipment shall be clean and free of water, oil, and dust and the packing may be changed prior to the
test. If the valve packing is changed prior to the test, it should be done under the supervision of the valve
manufacturer.
If a test valve is equipped with a manually adjustable stem (or shaft) seal(s), it shall be initially adjusted
according to the manufacturer’s instructions and recorded in the test report as provided in Clause 7.
The valve manufacturer shall select the appropriate actuating device.
5.1.2 Test fluid
The test fluid shall be helium gas of 97 % minimum purity or methane of 97 % minimum purity. The
same test fluid shall be used throughout the test.
5.1.3 Test temperature
Valve mechanical cycling is carried out at the room temperature or in the steps of the room temperature
and the selected test temperature other than the room temperature (see 5.2.4.1).
The test temperature shall be recorded for each leakage measurement.
5.1.4 Measurement of test valve temperature
The temperature of the test valve shall be measured at three locations, as shown in Figure 1, and
recorded in a test report.
a) Measurement at location 1 shall be used to determine the test temperature.
b) Measurement at location 2 is also made for information. Any use of insulation shall be detailed in
the test report.
c) Measurement at location 3 is used to determine the external valve temperature adjacent to the stem
(or shaft) seal(s) for information.
d) Measurement at location 4 is an option if measurement location 1 is not possible (except in the case
where heating elements penetrate the blind flanges).
4 © ISO 2015 – All rights reserved

ISO 15848-1:2015(E)
All temperatures at location 1, 2, and 3 (and 4) shall be stabilized before leakage is measured (see
Figures 2 and 3). Temperature at location 3 shall be stabilized for minimum 10 min prior to leakage
measurement.
Check if the temperature variation is within ±5 %.
Key
1 location 1: flow path (temperature T )
2 location 2: valve body (temperature T )
3 location 3: stuffing box (temperature T )
4 location 4: optional for flow path (temperature T )
Figure 1 — Measurements of temperature
ISO 15848-1:2015(E)
Key
T test temperature, °C
test
T stabilization temperature at location 1 (flow path)
T stabilization temperature at location 2 (valve body)
T stabilization temperature at location 3 (stuffing box)
t time
t stabilization of temperature at location 3 (stuffing box)
t + 10 min start of mechanical cycles
Figure 2 — Stabilization of temperatures (when the valve is internally heated or cooled)
6 © ISO 2015 – All rights reserved

ISO 15848-1:2015(E)
Key
T test temperature, °C
test
T stabilization temperature at location 1 (flow path)
T stabilization temperature at location 2 (valve body)
T stabilization temperature at location 3 (stuffing box)
t time
t stabilization of temperature at location 3 (stuffing box)
t + 10 min start of mechanical cycles
Figure 3 — Stabilization of temperatures (when the valve is externally heated or cooled)
5.1.5 Leakage measurement
5.1.5.1 Stem (or shaft) leakage measurement
Leakage shall be measured from a test valve at rest in the partly open position.
The leakage measurement shall be performed
— by the global method (vacuum or bagging) according to the procedures described in Annex A, or
— by the local leakage measurement (sniffing) according to the procedures described in B.2.
5.1.5.2 Body seal leakage measurement
The local leakage shall be measured by sniffing method according to the procedure described in Annex B.
Evaluation of the end connections should be done to ensure that they do not affect the results of the
evaluation of the body seals.
ISO 15848-1:2015(E)
5.1.5.3 Leakage-measurement records
All results of leakage measurements shall be recorded in a test report as specified in Clause 7.
5.2 Test procedures
5.2.1 Safety rules
Testing with high pressure gas is potentially hazardous and thus all applicable local safety rules and
adequate safety measures shall be followed. If methane (CH ) is used, the combination of the test
pressure and temperature shall be reviewed for possible combustion concerns.
5.2.2 Test equipment
The test equipment shall be appropriately selected to
a) apply and maintain the test pressure within a range of ±5 % of the nominal value,
b) apply valve mechanical cycles,
c) heat or cool the test valve to the selected test temperature and maintain it within a range of ±5 %
but not exceeding 15 °C; no mechanical cycling is permitted during temperature change,
d) measure and record time, pressure, temperature, leakage, and duration of a valve mechanical cycle,
e) measure and record actuation forces or torques to operate a test valve, and
f) measure and record the stem sealing system loading, if applicable.
5.2.3 Stem (or shaft) seal adjustment (SSA)
5.2.3.1 Number of stem seal adjustment
Mechanical adjustments of stem (or shaft) sealing system during the type test shall be permitted only
once, as shown below, for each of qualification stage done according to Figures 4, 5, and 6, if stem
(or shaft) leakage has been measured in excess of the target tightness class selected from Tables 1 to 4.
The maximum retightening force (or torque) to apply shall be determined prior to the type test.
EXAMPLE
— A maximum of one adjustment is accepted for CC1 or CO1.
— A maximum of two adjustments is accepted for CC2 or CO2.
— A maximum of three adjustments is accepted for CC3 or CO3.
5.2.3.2 Test failure after stem seal adjustment
If a stem (or shaft) sealing arrangement fails to achieve the target tightness class, or it is not possible
to continue mechanical cycling, the test shall be considered terminated, and the test valve shall be
evaluated for qualification of lower tightness and endurance classes, if applicable.
5.2.3.3 Reporting the number of SSA
The total number of stem (or shaft) seal adjustment shall be recorded in the test report and indicated in
the designation of the valve classification as “SSA-1”, “SSA-2”, and “SSA-3”.
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ISO 15848-1:2015(E)
5.2.4 Test description
5.2.4.1 General
The test description is the following:
a) The test valve shall be mounted on a test rig, according to the instructions given by the manufacturer.
b) The valve mounting shall be principally made with a stem (or shaft) positioned vertical. A valve
intended for use in other positions shall be mounted with the stem (or shaft) positioned horizontally.
c) All sealing systems shall have been properly adjusted beforehand, according to the manufacturer’s
instructions. For valves using packings as a stem seal, the tightening torque of the gland boltings
shall be measured and recorded at the beginning of the test and after any stem seal adjustment.
d) The target number and combination of mechanical and thermal cycles shall be selected from the
endurance classes specified in Figures 4, 5, and 6.
e) Leakage from the stem (or shaft) seal and from the body seals shall be separately measured. If the
valve does not allow such a separate measurement, the total leakage of both stem (or shaft) and
body seals shall be measured at the same time according to Annex A and Annex B respectively.
f) Actual methods of mechanical cycles other than those specified in 5.2.4.2 and 5.2.4.3 shall be in
accordance with the manufacturer’s instructions, and opening, closing, and dwelling time shall be
recorded in the test report. Basically, they shall represent the intended operating conditions of a
test valve.
g) Valve opening and closing force (or torque) shall be measured and recorded at the start and at the
end of the test, following subsequent stem seal adjustments if applicable.
5.2.4.2 Mechanical cycles of isolating valves
Unless otherwise specified by the valve manufacturer, the valve seating force (or torque) required for
tightness under a differential pressure of 0,6 MPa (6 bar), air or inert gas shall be used as the minimum
force (or torque) for mechanical cycle of a test valve.
Fully back seating a test valve is not required.
5.2.4.3 Mechanical cycles of control valves
The stem motion of linear action valves shall be between 1 mm/s and 5 mm/s. The shaft motion of
rotary control valves shall be between 1°/s and 5°/s.
The actuator to operate a test valve shall withstand only the pressure and friction force (or torque)
acting on the valve stem, and these values shall be recorded.
NOTE Measurement of friction force (or torque) is principally intended to check the packing friction usually
expressed as the dead band.
5.2.4.4 Preliminary tests at the room temperature (test 1)
The tests are carried out as shown below.
a) Pressurize a test valve with the test fluid to the test pressure as specified in a relevant standard.
b) After the test pressure has been stabilized, measure leakages both from the stem (or shaft) seal and
from the body seals, in accordance with Annexes A and B, respectively.
c) Record the test result in a test report.
ISO 15848-1:2015(E)
5.2.4.5 Mechanical cycle test at the room temperature (test 2)
The tests are carried out as shown below.
a) Perform mechanical cycles at room temperature while the test valve is kept pressurized.
b) Measure the leakage from the stem (or shaft) seal only, in accordance with Annex A.
c) Record the test result in the test report.
d) Repeat the test in case of Class CO1 and CC1, as indicated in Figures 4 and 6.
5.2.4.6 Static test at the selected test temperature (test 3)
The tests are carried out as shown below.
a) Pressurize a test valve with the test fluid to the test pressure as specified in a relevant standard for
the selected test temperature selected from Table 5.
b) After the test pressure has been stabilized, adjust the valve temperature to the selected test
temperature, ensuring that the test pressure does not exceed the level specified in the relevant
standard.
c) After the valve temperature has been stabilized with an allowance of ±5 % with a maximum of
15 °C, measure the leakage from the stem (or shaft) seal only in accordance with Annex A.
d) Record the test result in the test report.
e) Repeat the test in case of Class CO1 and CC1, as indicated in Figures 4 and 6.
5.2.4.7 Mechanical cycle test at the selected test temperature (test 4)
The tests are carried out as shown below.
a) Perform mechanical cycles at the selected test temperature while the test valve is kept pressurized.
b) Measure the leakage from the stem (or shaft) seal only in accordance with Annex A.
c) Record the test result in a test report.
d) Repeat the test in case of Class CO1 and CC1, as indicated in Figures 4 and 6.
5.2.4.8 Intermediate static test at the room temperature (test 5)
The tests are carried out as shown below.
a) Allow a test valve to return to the room temperature, without artificial cooling (or heating).
b) After the valve temperature has been stabilized, measure the leakage from the stem (or shaft) seal
only in accordance with Annex A.
c) Record the test result in a test report.
5.2.4.9 Final test at the room temperature (test 6)
The tests are carried out as shown below.
a) Allow a test valve to return to the room temperature, without artificial measures.
b) After the valve temperature has been stabilized, measure the leakage from the stem (or shaft) seal
in accordance with Annex A and from body seals in accordance with Annex B.
c) Record the test results in the test report.
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ISO 15848-1:2015(E)
5.2.4.10 Post-test examination
After all the tests have been successfully completed, the test valve shall be disassembled and all sealing
components shall be visually examined to record notable wear and any other significant observations
for information.
5.2.4.11 Qualification
Tested valves shall be qualified when
— all steps of test procedures have been satisfactorily performed for the target performance class, and
— all leakage measurements are verified equal or lower than the values specified for the target
performance class.
6 Performance classes
6.1 Classification criteria
Valve operating conditions and hazards of the line fluid being handled can result in different levels of
valve emission performance.
The purpose of Clause 6 is to define classification criteria resulting from the type test.
A performance class is defined by the combination of the following criteria:
a) “tightness class”: see Tables 1 and 2 (helium as test fluid), Tables 3 and 4 (methane as test fluid);
b) “endurance class”: see Figures 4, 5, and 6;
c) “temperature class”: see Table 5.
6.2 Tightness classes
6.2.1 Definition
Tightness classes are defined only for stem (or shaft) sealing systems.
Table 1 — Tightness classes for stem (or shaft) seals with helium
Measured leak Measured leak Measured leak rate
rate (mass flow) rate (mass flow) (volumic flow)
−1
mbar∙l∙s per mm
Class Remarks
−1 −1 −1 −1
mg·s ·m stem mg·s ·mm stem
stem diameter
perimeter diameter through
through stem seal
(for information) stem seal system
system
Typically achieved with bellow seals
a −5 −8 −7
AH ≤10 ≤3,14∙10 ≤1,78∙10 or equivalent stem (shaft) sealing
system for quarter turn valves
Typically achieved with PTFE based
b −4 −7 −6
BH ≤10 ≤3,14∙10 ≤1,78∙10
packings or elastomeric seals
Typically achieved with flexible
b −2 −5 −4
CH ≤10 ≤3,14∙10 ≤1,78∙10
graphite based packings
a
Measured by the vacuum method as defined in Annex A.
b
Measured by the total leak rate measurement method (vacuum or bagging) as defined in Annex A.
ISO 15848-1:2015(E)
Table 2 — Leakage from body seals with helium
Measured leakage
ppmv
≤50
NOTE Measured by the sniffing method as defined in
Annex B.
Table 3 — Tightness classes for stem (or shaft) seals with methane
Class Measured leakage (sniffing
method as described in Annex B)
ppmv
AM ≤50
BM ≤100
CM ≤500
Table 4 — Leakage from body seals with methane
Measured leakage (sniffing method as described in
Annex B)
ppmv
≤50
6.2.2 Helium as test fluid
When the test fluid is helium, the tightness classes are identified as Class AH, Class BH, and Class CH.
6.2.3 Methane as test fluid
When the test fluid is methane, the tightness classes are identified as Class AM, Class BM, and Class CM.
6.2.4 Correlations
There is no correlation intended between measurements of total leak rate as described in Annex A and
local sniffed concentration as described in Annex B.
There is no correlation intended between the tightness classes when the test fluid is helium (Class AH,
Class BH, and Class CH) and when the test fluid is methane (Class AM, Class BM, and Class CM).
6.3 Endurance classes
6.3.1 Mechanical-cycle classes for isolating valves
The required minimum number of mechanical cycles for isolating valves shall be 205 cycles (full stroke)
with two thermal cycles (a total of 50 cycles at RT, 50 cycles at test temperature, 50 cycles at RT, 50 cycles
at test temperature and 5 cycles at RT). This classification stage shall be identified as CO1 (see Figure 4).
An extension to classification CO2 shall be accomplished by addition of 1 295 mechanical cycles with
one thermal cycle (795 cycles at RT followed by 500 cycles at test temperature). Further extension to
CO3, etc. shall be achieved by addition of 1 000 mechanical cycles with one thermal cycle (see Figure 5).
12 © ISO 2015 – All rights reserved

ISO 15848-1:2015(E)
Key
T test temperature, °C
test
L measurement of leakage of stem seal
L measurement of leakage of body seal
N number of mechanical cycles
P test fluid pressure
NOTE The numbers 1 to 6 refer to the test sequences test 1 to test 6 as defined in 5.2.4.4 to 5.2.4.9.
Figure 4 — Mechanical-cycle classes for isolating valves (endurance Class CO1)
ISO 15848-1:2015(E)
Key
T test temperature, °C
test
L measurement of leakage of stem seal
L measurement of leakage of body seal
N number of mechanical cycles
P test fluid pressure
NOTE The numbers 1 to 6 refer to the test sequences test 1 to test 6 as defined in 5.2.4.4 to 5.2.4.9.
Figure 5 — Mechanical-cycle classes for isolating valves (endurance Classes CO2 and CO3)
6.3.2 Mechanical-cycle classes for control valves
The required minimum number of mechanical cycles for control valves shall be 20 000 cycles having two
thermal cycles (a total of 10 000 cycles at RT and 10 000 cycles at test temperature). This classification
stage shall be identified as CC1. An extension to classification CC2 shall be accomplished by addition
of 40 000 mechanical cycles having one thermal cycle (a total of 20 000 cycles at RT followed by
20 000 cycles at test temperature). Further extension to CC3 etc. shall be achieved by repetition of the
requirement for CC2 (see Figure 6).
14 © ISO 2015 – All rights reserved

ISO 15848-1:2015(E)
Key
T test temperature, °C
test
L measurement of leakage of stem seal
L measurement of leakage of body seal
N number of mechanical cycles
P test fluid pressure
NOTE The numbers 1 to 6 refer to the test sequences test 1 to test 6 as defined in 5.2.4.4 to 5.2.4.9.
Figure 6 — Mechanical-cycle classes for control valves
6.4 Temperature classes
The target temperature class shall be selected from Table 5. If the test is carried out at any temperature
other than those specified in Table 5, the next lower class shall apply in case of the test temperature
being above zero, or the next higher class shall apply in case of the test temperature being below zero.
EXAMPLE If the test temperature is 405 °C, the value shall be classified as (t400 °C).
Table 5 — Temperature classes
(t-196 °C) (t-46 °C) (tRT) (t200 °C) (t400 °C)
−196 °C −46 °C Room temperature, °C 200 °C 400 °C
All test temperatures shall be recorded in the test report.
— Test at −196 °C qualifies the valve in the range −196 °C up to RT.
— Test at −46 °C qualifie
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