ISO 21329:2004

INTERNATIONAL ISO
STANDARD 21329
First edition
2004-10-01
Petroleum and natural gas industries —
Pipeline transportation systems — Test
procedures for mechanical connectors
Industries du pétrole et du gaz naturel — Systèmes de transport par
conduites — Modes opératoires d'essai des connecteurs mécaniques

Reference number
©
ISO 2004
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ii © ISO 2004 – All rights reserved

Contents Page
Foreword. v
Introduction . vi
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 2
4 Symbols and abbreviated terms. 4
4.1 Symbols. 4
4.2 Abbreviated terms. 6
5 Test categories. 6
5.1 General. 6
5.2 Pressure, temperature and depth ratings. 7
5.3 Application levels. 7
5.4 Confidence levels. 7
6 Test requirements. 9
6.1 General. 9
6.2 Purpose of tests . 10
6.3 Basis for mechanical loads. 10
6.4 Test-house selection. 11
6.5 Selection of tests and number of test samples .11
6.6 Additional tests. 12
6.7 Prior test results. 12
7 Connector manufacturer requirements. 14
7.1 General. 14
7.2 Quality control. 14
7.3 Connector geometry and performance data . 14
7.4 Selection of diameter. 14
7.5 Setting tolerances. 14
7.6 Connector material requirements . 16
7.7 Preparation of test samples. 17
7.8 Ports. 20
7.9 Replacement test samples. 20
7.10 Test record retention . 20
8 Test-house preparations. 20
8.1 General. 20
8.2 Calibration requirements. 21
8.3 Pressurization media. 22
9 Leak detection. 22
9.1 Leak-detection methods. 22
9.2 Leak-detection sensitivity. 22
9.3 External pressure leak detection. 22
10 Make-and-break testing. 23
10.1 General requirements. 23
10.2 Make-up method. 24
10.3 Repeated make-up and breakout . 26
10.4 Final make-up. 26
10.5 Reverse-torque tests of non-rotational make-up connectors . 26
10.6 Acceptance criteria. 26
11 Service-load test.27
11.1 Set-up.27
11.2 Confirmation of seal integrity .29
11.3 Selection of test pressures and temperatures .29
11.4 Installation tests.31
11.5 Hydrostatic pressure tests .33
11.6 Operational unrestrained tests.34
11.7 Operational restrained tests.36
12 Limit-load tests.38
12.1 General.38
12.2 Tension-to-failure test.39
12.3 Compression-to-failure test.40
12.4 Pressure-to-failure test.41
12.5 Bending-to-failure test.41
13 Bending-fatigue test procedures .42
13.1 General.42
13.2 Setting stress ranges for the test .42
13.3 Bending-fatigue test set-up.43
13.4 Bending-fatigue test procedure .43
13.5 Interpretation of fatigue results .44
Annex A (normative) Application levels.45
Annex B (normative) Connector geometry and performance data .48
Annex C (normative) Calculation of connector service loads .51
Annex D (normative) Test data tables .55
Annex E (normative) Connector test reports — Content.63
Annex F (informative) Test sizes and data extrapolation considerations.66
Annex G (informative) Additional testing for special applications.68
Annex H (informative) Additional information on fatigue.76
Bibliography.81

iv © ISO 2004 – All rights reserved

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 21329 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries, Subcommittee SC 2, Pipeline transportation systems.

Introduction
In some circumstances mechanical connectors provide a lower cost and/or enabling advantage to welded
connectors usually used for pipelines. However, use of mechanical connectors has raised concerns about
pipeline integrity due to the potential for leak paths and absence of a direct method of inspection. In the past,
reassurance of the integrity of mechanical pipeline connectors has relied upon design information provided by
the manufacturer, the results of finite element analysis and past experience.
This International Standard is primarily applicable to connectors to be used in a large number, and hence
there is a significant burden in the number of connectors that need to be tested. However, it is recognized that
the test burden can be reduced in project-specific cases, for example if there is no concern about fatigue, if
the connector will not be subjected to fully restrained forces and/or if the connector design is less sensitive to
accuracy of tolerance matching of components at assembly.
The tests specified in this International Standard provide a physical demonstration of the integrity of the
pipeline connector. This International Standard has been developed from three main sources.
[14]
The first is the Low cost pipeline connector systems joint industry project (JIP), (1995-1997) , which defined
the load envelopes for pipelines, identified the practical issues of installation, and conducted demonstration
physical tests on three types of mechanical connectors.
The second source is ISO 13679, which has a parallel function for downhole connections.
[15]
The third is the Connection testing specification JIP, (1999-2000) . The JIP was sponsored by oil companies,
connector suppliers, pipeline construction contractors and design consultants.

vi © ISO 2004 – All rights reserved

INTERNATIONAL STANDARD ISO 21329:2004(E)

Petroleum and natural gas industries — Pipeline transportation
systems — Test procedures for mechanical connectors
1 Scope
This International Standard specifies requirements and provides guidance for the testing of mechanical
connectors for use in pipeline transportation systems for the petroleum and natural gas industries as defined
in ISO 13623.
The tests specified in this International Standard are intended to form part of the design verification process
for connectors. They provide objective evidence that connectors conform to a defined performance envelope.
This International Standard does not cover the use of design procedures as part of the qualification process
for mechanical connectors, nor does it address fabrication and quality control. However, it can be used as
input to a qualification procedure.
Although its principles can be applied, this International Standard does not address
a) connectors that are designed to rotate in use,
b) manifolds,
c) topsides pipework or piping,
d) flanges,
e) connectors used in pipelines installed by reeling or J-tube pulls,
f) factory acceptance testing,
g) statistical bases for risk analysis.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method
ISO 783:1999, Metallic materials — Tensile testing at elevated temperature
ISO 3183-1, Petroleum and natural gas industries — Steel pipe for pipelines — Technical delivery conditions —
Part 1: Pipes of requirement class A
ISO 3183-2, Petroleum and natural gas industries — Steel pipe for pipelines — Technical delivery conditions —
Part 2: Pipes of requirement class B
ISO 3183-3, Petroleum and natural gas industries — Steel pipe for pipelines — Technical delivery conditions —
Part 3: Pipes of requirement class C
ISO 6892:1998, Metallic materials — Tensile testing at ambient temperature
ISO 9327, Steel forgings and rolled or forged bars for pressure purposes — Technical delivery conditions
ISO 13623, Petroleum and natural gas industries — Pipeline transportation systems
ISO 13679:2002, Petroleum and natural gas industries — Procedures for testing casing and tubing
connections
EN 10213, Technical delivery conditions for steel castings for pressure purposes
EN 10222-1, Steel forgings for pressure purposes – Part 1: General requirements for open die forgings
1)
ASTM A 370 , Standard Test Methods and Definitions for Mechanical Testing of Steel Products
ASTM A 487/A 487M, Standard Specification for Steel Castings Suitable for Pressure Service
ASTM A 694/A 694M, Standard Specification for Carbon and Alloy Steel Forgings for Pipe Flanges, Fittings,
Valves, and Parts for High-Pressure Transmission Service
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
actual yield strength
yield strength of material determined from specimens directly related to components used in construction of
the test samples
3.2
application level
service loading envelope encompassing a group of pipeline and riser applications
3.3
batch
group of items manufactured or machined under controlled conditions to ensure consistent chemical
composition, processing and heat treatment such that the group can be considered as a single population
3.4
by agreement
unless otherwise indicated, agreement between the manufacturer and purchaser at the time of enquiry and
order
NOTE Adapted from ISO 3183-2:1996.
3.5
connector
mechanical device used to connect adjacent components in the pipeline

1) American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, USA
2 © ISO 2004 – All rights reserved

3.6
galling
localized damage to material surfaces resulting from contact conditions
NOTE Galling can be caused by cold welding of contacting material surfaces followed by tearing of the weld during
further sliding or rotation.
3.7
heat, noun
batch of steel prepared in one steel-making operation
[ISO 15590-1:2001]
3.8
liner
internal layer of a material different to that of the pipe body
NOTE The liner material may be, for example, plastic or non-ferrous.
3.9
load envelope
limit of loads (axial, pressure, torsion, bending, fatigue and temperature) within which a connector operates
during service or is tested
3.10
manufacturer
organization responsible for the design and manufacture of the equipment
NOTE 1 The manufacturer is not necessarily the vendor.
NOTE 2 Adapted from ISO 13707:2000.
3.11
operational restrained test
simulation of the loads due to operational cycling on a section of pipeline that is fully axially constrained
3.12
operational unrestrained test
simulation of the loads due to operational cycling on a section of pipeline or riser that is not axially constrained
and may have axial tension due to self-weight or externally applied tension
3.13
pipeline
those facilities through which fluids are conveyed, including pipe, pig traps, components and appurtenances
up to and including the isolating valves
[ISO 13623:2000]
3.14
purchaser
individual or organization that issues the order and specification to the vendor
NOTE The purchaser may be the owner or the owner's agent.
[ISO 13707:2000]
3.15
reverse torque
Z
torque applied during tests to simulate loads that might cause the connector to rotate or unscrew, if applicable
3.16
riser
that part of an offshore pipeline, including subsea spool pieces, which extends from the seabed to the pipeline
termination on an offshore installation
[ISO 13623:2000]
3.17
seal
barrier that resists the passage of fluids
[ISO 13678:2000]
3.18
multiple seals
sealing system that consists of more than one independent barrier and of which each barrier forms a seal
itself
3.19
specified minimum yield strength
minimum yield strength required by the specification or standard under which the material is purchased
[ISO 13623:2000]
3.20
test sample
assembly of a connector and two pieces of pipe specifically for testing
4 Symbols and abbreviated terms
4.1 Symbols
A operational unrestrained axial factor
F,un
A specified cross-sectional area of pipe
s
B bending factor for hydrostatic pressure test
F,hy
B bending factor for installation
F,in
B bending factor for unrestrained operation tests
F,un
D specified pipe inside diameter
i
D specified pipe outside diameter
o
E Young’s modulus of pipe
p
F axial force for restrained operation
re
F axial force for unrestrained operation
un
f von Mises' factor
vM
H depth rating
r
K load multiplication factor
4 © ISO 2004 – All rights reserved

K torque factor
F
K  ratio of actual to specified minimum yield stress of the critical connector component material
cc
K  ratio of actual to specified minimum yield stress of the pipe body material
p
K stress concentration factor
SCF
L length of test sample between inner supports
L grip length of pipe
g
L unsupported pipe length for test sample
p
L length between scribe mark and coupling on test sample
s
M bending moment for installation
in
M bending moment for hydrostatic pressure test
hy
M bending moment for unrestrained operation
un
N total number of cycles
c
p design pressure
d
p external hydrostatic pressure
ex
p internal pressure value to be used for testing
H
p operating pressure based on MAOP at the connector
op
p
r manufacturer's rated pressure
p hydrostatic test pressure
t
S lowest fatigue stress range
L
S middle fatigue stress range
M
S highest fatigue stress range
H
S-N stress versus number of cycles in fatigue curve
σ restrained axial stress
ax,re
σ actual yield stress of the connector critical component
ayc
σ actual yield stress of the pipe body material
ayp
σ specified minimum yield stress of the connector critical component
syc
σ specified minimum yield stress of the pipe body material
syp
T maximum design temperature
d.max
T minimum design temperature
d.min
T maximum test temperature
HT
T minimum test temperature
LT
T maximum rated temperature
max
T minimum rated temperature
min
T maximum operating temperature
op,max
T minimum operating temperature
op,min
t specified wall thickness
t minimum wall thickness accounting for manufacturing tolerances
min
υ Poisson ratio of the pipe body
Z reverse torque
Z make-up torque
mu
4.2 Abbreviated terms
CRA corrosion-resistant alloy
FEA finite element analysis
ID inside diameter
MAOP maximum allowable operating pressure
OD outside diameter
5 Test categories
5.1 General
Connectors shall be tested according to the
 pressure, temperature and depth ratings, as defined in 5.2,
 intended application level, as defined in 5.3,
 confidence level as defined in 5.4.
The application level sets the loading and the confidence level the number of test samples. The general
intention of the test is to demonstrate that the connector is stronger than the associated pipe under all
applicable conditions of static and fatigue loadings, and remains leak-tight.
It is recommended that the connectors be tested to the highest application and confidence levels for which
they are suitable. If the loading exceeds that defined in application level 4, the loading to be applied in the test
shall be increased accordingly and recorded in the test report.
6 © ISO 2004 – All rights reserved

5.2 Pressure, temperature and depth ratings
5.2.1 Pressure rating
Connectors shall be tested according to the pressure defined in 11.3. The rated pressure shall take into
account any reduction in material strength at the rated temperature. For a specific pipeline or riser duty,
connectors may be de-rated to the pipeline/riser design pressure, p , or MAOP, p , at the connector location
d op
by agreement.
5.2.2 Temperature rating
Connectors shall be tested to the minimum and maximum temperatures as defined in 11.3. For a specific
pipeline or riser duty, connectors may be de-rated to the pipeline/riser design or operating temperature at the
connector location by agreement.
5.2.3 Depth rating
Connectors intended for use underwater shall be tested according to their rated depth, H . Connectors may be
r
de-rated to the pipeline/riser operating depth for a specific pipeline or riser duty at the connector location and
by agreement.
5.3 Application levels
A total of four application levels are defined, with increasing severity from application level 1 upwards. The
loading factors for each application level are detailed in Table 1. Testing to a given application level validates
connectors for lower application levels.
Annex A specifies application levels.
5.4 Confidence levels
The purchaser shall specify the required confidence level. Two confidence levels are defined in Table 2, with
increasing consequence of failure.
 Normal: for temporary conditions where failure implies risk of human injury, significant environmental
pollution or very high economic or political consequences. For this confidence level, no frequent human
activity is anticipated along the pipeline route.
 High: for operating conditions where failure implies high risk of human injury, significant environmental
pollution or very high economic or political consequences. This is the confidence level required for areas
with frequent human activity, e.g. those parts of the pipeline or riser near the platform or in areas
populated with more than 50 persons/km .

Table 1 — Test load factors
Load factor for application level
Test Subclause
1 2 3 4
Make, break and torque tests
Torque factor – K 10.5, C.1 0 0 0,05 0,05
F
a
Installation tests
11.4 0,3 0,85 0,95 0,95
Bending factor – B
F,in
Hydrostatic pressure tests
Bending factor – B 11.5 0 1,0 1,0 1,0
F,hy
Operational cycles unrestrained tests
Bending factor – B 11.6 0,3 0,3 0,9 0,9
F,un
b b b
0,2
Axial factor – A 0 0 0
F,un
Other
von Mises' factor – f C.2.2 NA 0,96 0,96 0,96
vM
a
In all cases, if the water depth H > 500 m the effect of external hydrostatic pressure shall be considered.
r
b
In the case of a suspended riser, the connector may have A > 0. Allowance should be made for this when defining an
F,un
application level within the range 1 to 3.

8 © ISO 2004 – All rights reserved

Table 2 — Test requirements, test sample numbers and confidence levels
Subclause Confidence level
Requirements
reference normal high
Connector geometry and performance data 7.3 In all cases
8 12
Number of test samples to prepare 6.5 numbered 1 to 4 and numbered 1 to 12
9 to 12
Test sample number(s)
Make, Repeated make-up and breakout 10.3 1 to 4 1 to 8
break and
Final make-up 10.4 All All
torque
tests
Reverse torque 10.5 1 to 4 1 to 8
Installation tests 11.4 1 to 4 1 to 8
Hydrostatic pressure tests 11.5 1 to 4 1 to 8
Operational unrestrained tests 11.6 1, 3 1, 3, 5, 7
Service
load tests
Total number of cycles, N 20 100
c
Operational restrained tests 11.7 2, 4 2, 4, 6, 8
Total number of cycles, N 20 100
c
Pressure-to-failure test 12.4 1 1
Compression-to-failure test 12.3 NA 5
Limit load
tests
Bending-to-failure test 12.5 4 4
Tension-to-failure test 12.2 NA 7
Bending fatigue-to-failure test 13
S , see 13.2.4 2, 9 2, 6, 9
L
Fatigue
10, 11 10, 11 (see NOTE)
tests
S , see 13.2.4
M
3, 12 3, 8, 12
S , see 13.2.4
H
'All' signifies all test samples shall undergo the specific test.
NOTE In many applications some modes of testing may not be necessary, e.g. where fully restrained conditions cannot occur,
and where it may not be necessary to conduct limit compression tests to failure. This would make the third connector available for
fatigue testing.
6 Test requirements
6.1 General
Connectors intended for a specific application level shall be tested according to the sequence shown in
Table 2.
6.2 Purpose of tests
6.2.1 Introduction
The purpose of the tests is to simulate conditions that can occur during installation, commissioning and
operation. The test requirements comprise four sets of procedures as outlined below. The tests shall be
witnessed either by an inspector appointed by the purchaser or an independent third party. The fatigue-
loading test is optional, and for a specific project it is the responsibility of the purchaser to define the fatigue
loading.
6.2.2 Make, break and torque tests
The make-and-break procedures determine the ability of the connectors to resist wear and galling during
repeated make-up, if applicable. The torque procedures assess the ability of the connector to resist torque,
which could cause the connector to become undone or else cause loss of sealing integrity.
6.2.3 Service-load tests
The service-load tests simulate the installation loads, the hydrostatic pressure test loads, and the operational
loads on a connector. For example, operational unrestrained tests simulate the loads due to operational
cycling on a portion of pipeline or riser that is not axially constrained and may have axial tension due to self-
weight or externally applied tension. Operational restrained tests simulate the loads due to operational cycling
on a portion of pipeline that is fully axially constrained.
6.2.4 Limit-load tests
Limit-load tests are conducted to establish the structural and sealing limits of the connector. These limits are
important for establishing the reliability limits of connectors under field conditions, and are also useful for
correlating with strain gauge and finite element analysis results. Procedures are given for the following:
 tension-to-failure test, which applies to pipelines where there is a risk of inducing a high tensile load
during operation;
 compression-to-failure test, which applies to pipelines where there is a credible risk of high compressive
loads during operation, particularly if used with axial strains beyond yield, or where there is a risk of local
buckling of the pipe;
 pressure-to-failure test, which applies to pipelines where there is a credible risk of high internal or external
pressure loads during operation. These tests give a measure of the margin of safety against internal and
external overpressurization, the latter only being required for deep-water pipelines and risers.
6.2.5 Bending-fatigue tests
The fatigue test is a full-scale design verification test requiring the connector to achieve without failure the
minimum number of stress cycles predicted by the manufacturer.
The purposes of the fatigue test are to
a) verify the manufacturer’s prediction of the fatigue performance,
b) allow the purchaser to select a connector with sufficient fatigue strength for the required duty.
6.3 Basis for mechanical loads
The performance of the connector as determined in this International Standard shall be related to actual yield
values, σ rather than to specified minimum yield values, σ .
ayc syc
10 © ISO 2004 – All rights reserved

In addition, the mechanical loads applied to the connector according to the requirements of this International
Standard are based on the specified minimum yield stress, σ and physical dimensions of the pipe body.
syp
Consequently, the test loads are adjusted up to take into account the actual material strength being greater
than the minimum. This is done by applying a load factor to the calculated loads based on the ratio between
actual and specified yield stress.
The tests carried out in accordance with this International Standard shall determine the
 actual yield strength of the critical connector component material, σ in accordance with 7.6.3,
ayc
actual yield stress σ , of the pipe body used in the test sample(s) in accordance with 7.6.3.
ayp

Factors shall be determined in accordance with Equations (1) and (2).
σ
ayc
K = (1)
cc
σ
syc
where
K is the ratio of actual to specified minimum yield stress of the critical connector component;
cc
σ is the actual yield stress of the critical connector component;
ayc
σ is the specified minimum yield stress of the critical connector component.
syc
σ
ayp
K = (2)
p
σ
syp
where
K is the ratio of actual to specified minimum yield stress of the pipe body material;
p
σ is the actual yield stress of the pipe body material;
ayp
σ is the specified minimum yield stress of the pipe body material.
syp
The mechanical loads applied in the test shall be multiplied by the factor K, which is the lesser of K or K for
p cc
the relevant materials.
The factor K is applied in the calculation of loads given in Annex C.
6.4 Test-house selection
The testing facilities shall satisfy the requirements in Clause 8. The testing shall be carried out either by a test
house independent of the manufacturer, or by the manufacturer with independent verification.
6.5 Selection of tests and number of test samples
The test samples shall be numbered as shown in Table 2 and shall retain their designated number throughout
the tests.
Table 1 defines the load factors to be applied during the tests for a given application level. The test shall take
into account external hydrostatic pressure if the specified depth exceeds 500 m. Tests to take into account
external pressure at shallower depths may also be carried out if specified.
Tests shall be carried out in the lifetime sequence of loading of the connector, as shown in Figure 1, for each
test sample, i.e. running from top to bottom of Table 2.
Tests on different samples may be run in parallel. If the same service-load test is required on multiple test
samples, a single assembly of those test samples may be used.
The number of tests and test samples may be reduced for a particular application level if it can be shown that
there is no need to carry out the tests.
EXAMPLE Tests to simulate high installation and operational restrained-loading conditions may not be applicable for
a connector intended for use on a spool piece. Similarly there is no need to test for bending fatigue if it can be shown that
fatigue loading, for example due to vortex-induced vibration, will not occur.
If tests are project-specific, pipe of the same dimensions, tolerances and material properties as the project
pipe shall be used for the tests.
NOTE Annex F provides guidance on the choice of sizes to be tested if multiple sizes of connectors are used in a
project. Annex F also indicates how the results of testing can be extended to other sizes and grades of connector.
6.6 Additional tests
The purchaser should consider the additional tests described in Annex G for connectors subject to special
applications. These applications can include, but are not limited to, the following:
a) connectors with elastomeric seals;
b) misalignment at make-up;
c) rapid cool-down conditions;
d) severe sour service;
e) fire exposure;
f) compression beyond yield;
g) crevice corrosion;
h) impact;
i) J-lay.
6.7 Prior test results
Prior connector test results meeting the requirements of this International Standard may be substituted for
repeat tests.
12 © ISO 2004 – All rights reserved

Figure 1 — Flow diagram showing test sequence, with relevant subclause number
7 Connector manufacturer requirements
7.1 General
The manufacturer shall issue a declaration of conformity stating that the connectors manufactured for the
purpose of these tests are of the same design, temperature and pressure ratings and extremes of tolerances
(see 7.5) as those to be supplied for pipeline service.
NOTE ISO/IEC Guide 22 contains information on declaration of conformity.
7.2 Quality control
Quality control procedures for the manufacturing of test samples shall be documented and shall be consistent
with procedures used for connectors manufactured for pipeline service.
The manufacturer shall provide a quality plan. This shall include procedure or drawing numbers as well as
associated revision levels for all applicable sub-tier documents (e.g. manufacturing, gauge calibration,
gauging procedure, surface treatment, etc.).
7.3 Connector geometry and performance data
The manufacturer shall provide connector geometry and performance data (see Annex B) describing the
connector’s geometry and performance properties in terms of tension, compression, internal pressure,
external pressure, bending and torque. The data shall also specify the minimum failure loads for the connector
and identify the component that is the cause of failure.
The data shall specify the make-up torque or force and speed of make-up if appropriate. If the application of
pipeline torque can cause damage to the connector, e.g. screwed connector, the manufacturer shall specify
the torque rating of the connector.
The manufacturer shall identify the critical dimensions and tolerances in the data provided. In addition to the
data required herein, the manufacturer should document other data, e.g. seal material limitations, considered
pertinent to these tests.
The manufacturer shall develop a minimum failure load or load surface for load combinations. The actual
failure load can then be used to determine the safety factor.
7.4 Selection of diameter
The test connectors should be of the same size as intended for the pipeline service.
NOTE Guidance on test sizes and extrapolation of test data to other sizes is given in Annex F.
7.5 Setting tolerances
7.5.1 Worst-case performance objectives
For design verification, connectors shall be tested at the worst-case configuration and condition determined
from drawings, quality plan, running/doping procedures, make-up torques/forces, etc.
The manufacturer shall use analytical, computational [such as finite element analysis (FEA)], and/or
experimental techniques such as strain-gauge testing to provide objective evidence that the extreme
dimensional configurations of the product resulting in worst-case performance are tested.
To select worst-case performance objectives, the manufacturer shall take into account the minimum and
maximum extremes of local seal contact pressure, total seal load, and total active seal contact length as
influenced by machining parameters. For threaded and coupled connections, side A and side B shall be
machined to identical dimensional objectives.
14 © ISO 2004 – All rights reserved

NOTE The specific machining dimensions depend on the type of connector.
Machining tolerances shall be set by the manufacturer to produce the worst-case performance of the
connector, including, but not limited to, considerations of the tolerances on
 seal interferences,
 pin nose thickness,
 surface roughness,
 thread tapers,
 thread interferences.
7.5.2 Example of machining tolerances
As an example, for metal-to-metal sealing, tapered thread, connections with pin nose torque shoulders,
Table 3 shows combinations of seal and thread diameters, thread tapers and final make-up torques which
have been found to provide the worst-case performance extremes corresponding to the test objectives in
Table 2. For this type of connection, the manufacturer should machine the specimens to the extremes in
Table 4 unless the techniques described in 7.5.1 indicate other tolerances should be tested.
Table 3 — Example of test sample tolerances
Test sample Pin body Box body
Body Seal Torque Lubricant Misalignment
No. taper taper
a c c
1 High Low High Low Slow Fast None
b
2 Low High High Low Fast Slow None
3 Low Low Low Low Slow Fast Maximum
4 High High High High Nominal Nominal None
5 High Low High High Slow Fast None
6 Low High Low Low Fast Slow None
7 Low Low High Low Slow Fast None
8 High High Low High Nominal Nominal None
9-12 Nominal Nominal Nominal Nominal Nominal Nominal None
a
Tolerances test for body galling.
b
Tolerances test for seal galling.
c
“Fast” refers to a steep taper that enables rapid make-up; “slow” has a shallow taper and takes longer to make up.

Table 4 — Tolerance limits on machining objectives
Item Positive tolerance Negative tolerance
Maximum body tolerance No limit 0,025 mm (0,001 in)
Maximum seal tolerance No limit 0,025 mm (0,001 in)
Minimum
...