SIST EN ISO 13625:2004

Petroleum and natural gas industries - Drilling and production equipment - Marine drilling riser couplings (ISO 13625:2002)

ISO 13625:2002 specifies requirements and gives recommendations for the design, rating, manufacturing and testing of marine drilling riser couplings. Coupling capacity ratings are established to enable the grouping of coupling models according to their maximum stresses developed under specific levels of loading, regardless of manufacturer or method of make-up.

Erdöl-, und Erdgasindustrie - Bohr- und Förderanlagen - Auslegung, Leistungeinstufung und Prüfung von Kupplungen für Bohrförderanlagen auf See (ISO 13625:2002)

Industries du pétrole et du gaz naturel - Equipement de forage et de production - Connecteurs de tubes prolongateurs pour forages en mer (ISO 13625:2002)

Petroleum and natural gas industries - Drilling and production equipment - Marine drilling riser couplings (ISO 13625:2002)

General Information

• Status: Published
• Publication Date: 30-Apr-2004
• ICS: 75.180.10 - Exploratory, drilling and extraction equipment
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-May-2004
• Due Date: 01-May-2004
• Completion Date: 01-May-2004
• Ref Project: EN ISO 13625:2002 - Petroleum and natural gas industries - Drilling and production equipment - Marine drilling riser couplings (ISO 13625:2002)

Overview

EN ISO 13625:2002 (ISO 13625:2002) specifies requirements and provides recommendations for the design, rating, manufacture and testing of marine drilling riser couplings used in petroleum and natural gas offshore operations. The standard establishes coupling capacity ratings to group coupling models by maximum stresses under defined loading conditions regardless of manufacturer or make-up method. EN ISO 13625:2002 is the CEN-adopted version of the ISO document and aligns with related industry guidance such as API RP 16Q and builds on API Specification 16R.

Key topics and technical requirements

The standard covers the full product lifecycle and quality assurance aspects for marine drilling riser couplings:

• Design and analysis
  • Service classifications and riser loading scenarios
  • Determination of stresses by analytical methods
  • Stress distribution verification tests and static loading design considerations
  • Stress amplification factors and required design documentation
• Materials and welding
  • Material selection guidance and welding requirements
  • References to mechanical testing and toughness standards (e.g., ISO 148, ISO 6892)
• Dimensions, weights and marking
  • Dimensional and mass requirements to support handling and interchangeability
  • Mandatory marking and stamping information for traceability
• Quality control and testing
  • Raw material and manufacturing conformance checks
  • Design qualification tests, non‑destructive examinations (liquid penetrant, magnetic particle, radiography)
  • Optional qualification tests and annexed test methods
• Operation and maintenance
  • Required documentation: operation and maintenance manuals, coupling usage guidelines, and maintenance instructions
• Normative and informative annexes
  • Annex A: stress analysis guidance
  • Annex B: optional qualification tests
  • Annex C: static loading design methodology

Practical applications and users

EN ISO 13625:2002 is essential for organizations involved in offshore riser systems, including:

• Riser coupling manufacturers - to design and certify couplings to international rating schemes
• Drilling and production engineers - to specify couplings compatible with riser system design and load cases
• Procurement and QA/QC teams - to verify material, welding and testing conformance
• Inspection bodies and class societies - to assess compliance during manufacture and field operations
• Operators and maintenance crews - to follow marking, operation and maintenance instructions for safe riser handling

Using EN ISO 13625:2002 helps ensure interoperability, safety and predictable performance of riser couplings in offshore drilling operations.

Related standards

• API RP 16Q (riser system guidelines)
• API Specification 16R (basis referenced in the ISO introduction)
• ISO 10423 (wellhead and christmas tree equipment)
• Material and testing standards: ISO 148, ISO 6892, ISO 6506/6507/6508 and relevant ASME/ASTM documents mentioned as normative references.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2004
Petroleum and natural gas industries - Drilling and production equipment - Marine
drilling riser couplings (ISO 13625:2002)
Petroleum and natural gas industries - Drilling and production equipment - Marine drilling
riser couplings (ISO 13625:2002)
Erdöl-, und Erdgasindustrie - Bohr- und Förderanlagen - Auslegung, Leistungeinstufung
und Prüfung von Kupplungen für Bohrförderanlagen auf See (ISO 13625:2002)
Industries du pétrole et du gaz naturel - Equipement de forage et de production -
Connecteurs de tubes prolongateurs pour forages en mer (ISO 13625:2002)
Ta slovenski standard je istoveten z: EN ISO 13625:2002
ICS:
75.180.10 Oprema za raziskovanje in Exploratory and extraction
odkopavanje equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 13625
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2002
ICS 75.180.10
English version
Petroleum and natural gas industries - Drilling and production
equipment - Marine drilling riser couplings (ISO 13625:2002)
Industries du pétrole et du gaz naturel - Equipement de
forage et de production - Connecteurs de tubes
prolongateurs pour forages en mer (ISO 13625:2002)
This European Standard was approved by CEN on 27 November 2002.
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 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 Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13625:2002 E
worldwide for CEN national Members.

Foreword
This document (EN ISO 13625:2002) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum and natural gas industries" in
collaboration with Technical Committee CEN/TC 12 "Materials, equipment and offshore
structures for petroleum and natural gas industries", 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 June 2003, and conflicting national
standards shall be withdrawn at the latest by June 2003.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg,
Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.
NOTE FROM CMC  The foreword is susceptible to be amended on reception of the German
language version. The confirmed or amended foreword, and when appropriate, the normative
annex ZA for the references to international publications with their relevant European
publications will be circulated with the German version.
Endorsement notice
The text of ISO 13625:2002 has been approved by CEN as EN ISO 13625:2002 without any
modifications.
INTERNATIONAL ISO
STANDARD 13625
First edition
2002-12-01
Corrected version
2003-06-15
Petroleum and natural gas industries —
Drilling and production equipment —
Marine drilling riser couplings
Industries du pétrole et du gaz naturel — Équipement de forage et de
production — Connecteurs de tubes prolongateurs pour forages en mer

Reference number
ISO 13625:2002(E)
©
ISO 2002
ISO 13625:2002(E)
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ii © ISO 2002 – All rights reserved

ISO 13625:2002(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references. 1
3 Terms, definitions and abbreviations . 2
3.1 Terms and definitions. 2
3.2 Abbreviations. 4
4 Design. 4
4.1 Service classifications. 4
4.2 Riser loading. 5
4.3 Determination of stresses by analysis . 5
4.4 Stress distribution verification test. 6
4.5 Coupling design load. 6
4.6 Design for static loading . 7
4.7 Stress amplification factor. 7
4.8 Design documentation. 8
5 Material selection and welding . 8
5.1 Material selection. 8
5.2 Welding. 10
6 Dimensions and weights. 11
6.1 Coupling dimensions. 11
6.2 Coupling weight. 12
7 Quality control. 12
7.1 General. 12
7.2 Raw material conformance. 12
7.3 Manufacturing conformance. 12
8 Testing. 16
8.1 Purpose. 16
8.2 Design qualification tests . 16
9 Marking. 16
9.1 Stamping. 16
9.2 Required information. 16
10 Operation and maintenance manuals. 17
10.1 General. 17
10.2 Equipment description. 17
10.3 Guidelines for coupling usage . 17
10.4 Maintenance instructions. 17
Annex A (informative) Stress analysis . 18
Annex B (informative) Optional qualification tests . 19
Annex C (normative) Design for static loading . 20
Bibliography . 25

ISO 13625:2002(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.
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 13625 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries, Subcommittee SC 4, Drilling and production
equipment.
This corrected version of ISO 13625:2002 incorporates correction of the French title.

iv © ISO 2002 – All rights reserved

ISO 13625:2002(E)
Introduction
1) [1]
This International Standard is based upon API Specification 16R, first edition, January 1997 .
Users of this International Standard should be aware that further or differing requirements could be needed for
individual applications. This International Standard is not intended to inhibit a vendor from offering, or the
purchaser from accepting, alternative equipment or engineering solutions for the individual application. This
can be particularly applicable where there is innovative or developing technology. Where an alternative is
offered, the vendor will need to identify any variations from this International Standard and provide details.

1) American Petroleum Institute, 1220 L Street NW, Washington D.C. 20005, USA.
INTERNATIONAL STANDARD ISO 13625:2002(E)

Petroleum and natural gas industries — Drilling and production
equipment — Marine drilling riser couplings
1 Scope
This International Standard specifies requirements and gives recommendations for the design, rating,
manufacturing and testing of marine drilling riser couplings. Coupling capacity ratings are established to
enable the grouping of coupling models according to their maximum stresses developed under specific levels
of loading, regardless of manufacturer or method of make-up. This International Standard relates directly to
API RP 16Q, which provides guidelines for the design, selection, and operation of the marine drilling riser
system as a whole.
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, Steel — Charpy impact test (V-notch)
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method (scales A, B, C, D, E, F, G,
H, K, N, T)
ISO 6892, Metallic materials — Tensile testing at ambient temperature
ISO 10423:2001, Petroleum and natural gas industries — Drilling and production equipment — Wellhead and
christmas tree equipment
2)
ASME , Boiler and Pressure Vessel Code, Section V
ASME, Boiler and Pressure Vessel Code, Section VIII
3)
ASTM E 94, Standard Guide for Radiographic Examination
ASTM E 165, Standard Test Method for Liquid Penetrant Examination
ASTM E 709, Standard Guide for Magnetic Particle Examination
ASTM E 747, Standard Practice for Design, Manufacture and Material Grouping Classification of Wire Image
Quality Indicators (IQI) Used for Radiology

2) American Society of Mechanical Engineers, 1950 Stemmons Freeway, Dallas, Texas 75207, USA.
3) American Society of Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103-1187, USA.
ISO 13625:2002(E)
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
[2]
NOTE A comprehensive list of definitions pertaining to marine drilling riser systems is contained in API RP 16Q .
3.1.1
auxiliary line
external conduit (excluding choke and kill lines) arranged parallel to the riser main tube for enabling fluid flow
EXAMPLE Control system fluid line, buoyancy control line, mud boost line.
3.1.2
breech-block coupling
coupling which is engaged by partial rotation of one member into an interlock with another
3.1.3
buoyancy
devices added to the riser joints to reduce their submerged weight
3.1.4
choke and kill lines
C&K lines
external conduits, arranged parallel to the main tube, used for circulation of fluids to control well pressure
NOTE Choke and kill lines are primary pressure-containing members.
3.1.5
collet-type coupling
coupling having a slotted cylindrical element joint mating coupling members
3.1.6
dog-type coupling
coupling having dogs which act as wedges mechanically driven between the box and pin for engagement
3.1.7
flange-type coupling
coupling having two flanges joined by bolts
3.1.8
indication
visual sign of cracks, pits, or other abnormalities found during liquid penetrant and magnetic particle
examination
3.1.8.1
linear indication
indication in which the length is equal to or greater than three times its width
3.1.8.2
relevant indication
any indication with a major dimension over 1,6 mm (1/16 in)
3.1.8.3
rounded indication
indication that is circular or elliptical with its length less than three times the width
2 © ISO 2002 – All rights reserved

ISO 13625:2002(E)
3.1.9
marine riser coupling
means of quickly connecting and disconnecting riser joints
NOTE The coupling box or pin (depending on design type) provides a support for transmitting loads from the
suspended riser string to the riser-handling spider while running or retrieving the riser. Additionally, the coupling can
provide support for choke and kill and auxiliary lines, and load reaction for buoyancy.
3.1.10
marine drilling riser
tubular conduit serving as an extension of the well bore from the well control equipment on the wellhead at the
seafloor to a floating drilling rig
3.1.11
preload
compressive bearing load developed between box and pin members at their interface; this is accomplished by
elastic deformation induced during make-up of the coupling
3.1.12
rated load
nominal applied loading condition used during coupling design, analysis and testing, based on a maximum
anticipated service loading
NOTE Under the rated working load, no average section stress in the riser coupling exceeds allowable limits
established in this International Standard.
3.1.13
riser coupling box
female coupling member
3.1.14
riser joint
section of riser pipe having ends fitted with a box and a pin, typically including integral choke and kill and
auxiliary lines
3.1.15
riser main tube
basic pipe from which riser joints are fabricated
3.1.16
riser coupling pin
male coupling member
3.1.17
stress amplification factor
SAF
K
SAF
factor equal to the local peak alternating stress in a component (including welds) divided by the nominal
alternating stress in the pipe wall at the location of the component
NOTE This factor is used to account for the increase in the stresses caused by geometric stress amplifiers which
occur in riser components.
3.1.18
threaded coupling
coupling having matching threaded members to form engagement
ISO 13625:2002(E)
3.2 Abbreviations
The following abbreviations are used in this International Standard.
BOP Blowout preventer
C&K Choke and kill
LP Liquid penetrant
MP Magnetic particle
NDE Non-destructive examination
QTC Qualified test coupon
SAF Stress amplification factor
4 Design
4.1 Service classifications
4.1.1 Design information
The coupling manufacturer shall provide design information for each coupling size and model which defines
load capacity rating. These data are to be based on design load (see 4.5) and verified by testing (see 8.2).
4.1.2 Size
Riser couplings are categorized by riser main tube size . The riser pipe outer diameter and wall thickness
(or wall thickness range) for which the coupling is designed shall be documented.
4.1.3 Rated load
The rated loads listed in here provide a means of general classification of coupling models based on stress
magnitude caused by applied load. To qualify for a particular rated load, neither calculated nor measured
stresses in a coupling shall exceed the allowable stress limits of the coupling material when subjected to the
rated load. The allowable material stresses are established in 4.6.
The rated loads are as follows:
a) 2 220 kN (500 000 lbf);
b) 4 450 kN (1 000 000 lbf);
c) 5 560 kN (1 250 000 lbf);
d) 6 670 kN (1 500 000 lbf);
e) 8 900 kN (2 000 000 lbf);
f) 11 120 kN (2 500 000 lbf);
g) 13 350 kN (3 000 000 lbf);
h) 15 570 kN (3 500 000 lbf).
4 © ISO 2002 – All rights reserved

ISO 13625:2002(E)
4.1.4 Stress amplification factor
The calculated SAF values for the coupling shall be documented at the pipe-to-coupling weld and at the
locations of highest stress in the pin and box. SAF is a function of pipe size, and wall thickness. It is calculated
as follows:
σ
LPA
K =
SAF
σ
NAS
where
σ is local peak alternating stress;
LPA
σ is nominal alternating stress in pipe.
NAS
4.1.5 Rated working pressure
Riser couplings shall be designed to provide a pressure seal between joints. The manufacturer shall
document the rated internal working pressure for the coupling design.
4.2 Riser loading
4.2.1 General
A drilling riser's ability to resist environmental loading depends primarily on tension. Environmental loading
includes the hydrodynamic forces of current and waves and the motions induced by the floating vessel's
dynamic response to waves and wind.
The determination of a riser's response to the environmental loading and determination of the mechanical
loads acting upon, and developed within, the riser require specialized computer modelling and analysis. (For
[2]
the general procedure used to determine riser system design loads and responses, see API RP 16Q .
Additional sources of applied load that are not included in the rated load may significantly affect the coupling
design and shall be included in design calculations.
4.2.2 Loads induced by choke and kill and auxiliary lines
Riser couplings typically provide support for choke and kill and auxiliary lines. This support constrains the lines
to approximate the curvature of the riser pipe. Loads can be induced on the coupling from pressure in the
lines, imposed deflections on the lines and the weight of the lines. The manufacturer shall document those
loads induced by choke and kill and auxiliary lines for which the coupling has been designed.
4.2.3 Loads induced by buoyancy
Riser couplings may provide support for buoyancy, which induces loads on the couplings. The manufacturer
shall document the buoyancy thrust loads for which the coupling has been designed.
4.2.4 Loads induced during handling
Temporary loads are induced by suspending the riser from the handling tool or spider or both. The
manufacturer shall document the riser handling loads for which the coupling is designed and how these loads
are applied.
4.3 Determination of stresses by analysis
Design of riser couplings for static loading (see 4.6) and determination of the stress amplification factors (see
4.7) require detailed knowledge of the stress distribution in the coupling. This information is acquired by finite
element analysis and subsequently validated by prototype strain gauge testing. A finite element analysis of the
ISO 13625:2002(E)
riser coupling shall be performed and documented. The analysis shall provide accurate or conservative peak
stresses, and shall include any deleterious effects of loss of preload from wear, friction and manufacturing
tolerances. Suggestions for the analysis can be found in Annex A. The following shall be documented and
included in the analysis:
a) hardware and software used to perform the analysis;
b) grid size;
c) applied loads;
d) preload losses;
e) material considerations.
4.4 Stress distribution verification test
After completion of the design studies, a prototype (or multiple prototypes) of the riser coupling shall be tested
to verify the stress analysis. The testing has two primary objectives: to verify any assumptions which were
made about preloading, separation behaviour and friction coefficients, and to substantiate the analytical stress
predictions.
Strain gauge data shall be used to measure preload stresses as they relate to make-up load or displacement.
Friction coefficients shall be varied (including at least two values) in order to establish sensitivity.
The coupling design load shall be applied in order to verify any assumption made in the analysis regarding
separation.
Strain gauges shall be placed as near as physically possible to at least five of the most highly stressed
regions, as predicted by the finite element analyses performed in accordance with 4.3, and in five locations
away from stress concentrations. Rosettes shall be used. All strain gauge readings and the associated loading
conditions shall be recorded such that they may be retained as part of the coupling design documentation.
Normal design qualification tests may be performed simultaneously with this stress distribution verification
testing (see 8.2).
NOTE It is often difficult to acquire sufficient strain data to totally correlate with the analytical results. High-stress
areas may be inaccessible and are sometimes so small that a strain gauge gives an average rather than the peak value.
The testing serves to verify the pattern of strain in regions surrounding the critical points.
4.5 Coupling design load
The coupling design load represents the maximum load-carrying capacity of the coupling. The manufacturer
shall establish the design load for each coupling design, based on the methods and criteria given in this
International Standard. Neither calculated nor measured stresses in a coupling shall exceed the allowable
stress limits of the coupling material when subjected to the design load. The allowable material stresses are
established in 4.6. The coupling’s rated load (see 4.1.3) shall be less than or equal to the coupling’s design
load.
For simplicity, the design loading condition is taken to be axisymmetric tension. In using this simplification,
riser bending moment is converted to equivalent tension, T . The coupling design load can be specified
EQ
either as an axisymmetric tension of magnitude, T , or it may be considered to be any combination of
design
tension (T) and bending moment (M) so that
32td( −t)
Mc
o
TA+=T+M =T+T=T (2)
EQ design
I
dd−−(2t)
oo
6 © ISO 2002 – All rights reserved

ISO 13625:2002(E)
where
c is the mean radius of riser pipe;
I is the moment of inertia of riser pipe;
A is the cross-sectional area of riser pipe;
d is the outside diameter of riser pipe;
o
t is the wall thickness of riser pipe.
Using this relationship, the maximum calculated riser pipe stress at the middle of the pipe wall caused by pure
bending is treated in the same manner as that caused by pure tension. To classify a particular coupling
design, only the axisymmetric tensile load (T ) case need be considered.
design
While the coupling design load provides a means of grouping coupling models regardless of manufacturer or
method of make-up, it does not include all loads affecting coupling design. Additional loads (see 4.2) shall also
be included in the evaluation of coupling designs.
4.6 Design for static loading
4.6.1 General
The design of a riser coupling for static loading requires that it support the design load and preload, if any,
while keeping the maximum cross-sectional stresses within specified allowable limits.
4.6.2 Riser coupling stresses
For all riser coupling components except bolts, stress levels shall be kept below the values provided in
Annex C.
For load-carrying bolts in bolted-flange couplings, the manufacturer shall document the design-allowable
stress levels in the bolts. Acceptance criteria for these bolt stresses shall be based on recognized codes and
standards.
4.7 Stress amplification factor
Field experience suggests that the most likely cause of a riser coupling failure is propagation of a fatigue crack
that has been initiated at a point of stress concentration. It is, therefore, incumbent upon the designer to
endeavour to minimize the conditions leading to the initiation and propagation of fatigue cracks. The SAF is
intended to provide the coupling user with information needed to estimate fatigue damage for a particular
application, without extensive fatigue testing of the coupling. The SAF is a function of the double amplitude
range of alternating stress.
It is important to note that the SAF value depends largely on the exhaustiveness of the finite element analysis
and the validity of assumptions in the analysis. Assumptions such as load distribution, the correctness of
preloading in field service and finite element size at critically stressed points necessitate individual evaluation
for each design case.
The following procedure shall be used for an individual coupling design:
a) select the rated load from 4.1.3;
b) perform finite element analysis in accordance with 4.3 to determine maximum equivalent combined
stresses for the loads
1) L = nominal preload plus 0,2 × rated load,
2) L = nominal preload plus 0,4 × rated load,
ISO 13625:2002(E)
3) L = nominal preload plus 0,6 × rated load,
4) L = nominal preload plus 0,8 × rated load,
5) L = minimum preload plus 0,2 × rated load,
6) L = minimum preload plus 0,4 × rated load,
7) L = minimum preload plus 0,6 × rated load, and
8) L = minimum preload plus 0,8 × rated load;
c) verify the finite element analysis by strain gauge test of prototype in accordance with 4.4;
d) identify high-stress points in the structure and the pipe–to–coupling weld. For each, record the local peak
stresses L to L (using von Mises' theory, explained in more detail in Annex C) for loading conditions L
1 8 1
to L ;
e) calculate the SAFs for the pin and for the box of the coupling. If SAF varies with load or preload,
document this variation.
4.8 Design documentation
For each size, model and service classification, the following documentation shall be retained by the
manufacturer for a period of at least ten years after the manufacture of the last unit of that size, model and
service classification:
a) design loads (tensile, bending, loads from auxiliary lines and others) in accordance with 4.2;
b) finite element analysis performed in accordance with 4.3;
c) results of tests performed in accordance with 4.4 and 8.2;
d) results of SAF and peak stress calculations in accordance with 4.7.
5 Material selection and welding
5.1 Material selection
5.1.1 General
Material selection for each component of the riser coupling shall include consideration of the type of loading,
the temperature range, the corrosive conditions, strength requirements, durability, toughness and the
consequences of failure. Documentation of these design parameters shall be retained by the riser system
manufacturer throughout the design life of the riser system. All materials used shall conform to a written
specification covering chemical composition, physical and mechanical properties, method and process of
manufacture, heat treatment, weldability, and quality control. Such written specification may be either a
published or manufacturer's proprietary document.
All materials for primary load-carrying components, including weld metals, shall be low alloy steels having
properties as represented by test coupons conforming to the specifications of 5.1.5. Test coupons shall be cut
from a separate or attached block, taken from the same heat and, when applicable, formed similarly and given
the same heat treatment as the product material they represent.
8 © ISO 2002 – All rights reserved

ISO 13625:2002(E)
5.1.2 Chemical composition
All materials shall conform to the chemical composition provided in the manufacturer's written specification.
Conformance with the manufacturer's composition specification shall be demonstrated by mill analysis or test
sample verification.
5.1.3 Mechanical properties
All materials shall meet the minimum and maximum mechanical properties specified in the manufacturer's
written specification. Materials for primary load-carrying components, including weldments, shall additionally
meet the minimum mechanical properties in Table 1.
Tensile testing shall be performed in accordance with ISO 6892 after all heat treatment for mechanical
properties and using representative test coupons conforming to the specifications of 5.1.5.
Table 1 — Minimum mechanical properties
Property Minimum value
Elongation 18 %
Reduction of area 35 %
5.1.4 Impact testing
Materials for components that are in the load path, including weldments, shall meet the following minimum
Charpy V-notch impact values:
a) average for three specimens: 41 J @ −20 °C (30 ft-lbf @ −4 °F);
b) minimum single value: 28 J @ −20 °C (21 ft-lbf @ −4 °F).
Charpy impact testing shall be performed in accordance with ISO 148 after all heat treatment for mechanical
properties and shall use representative test coupons. Notch impact tests shall be performed with the test
specimens oriented longitudinally to the grain orientation of the parent metal.
5.1.5 Test specimens
5.1.5.1 General
Test specimens shall be taken from a qualified test coupon (QTC) in accordance with ISO 10423:2001, 5.7
and 5.7.4.1.
5.1.5.2 Tensile and impact testing
Tensile and impact test specimens shall be removed from the same QTC after the final QTC heat treatment
cycle.
Tensile and impact specimens shall be removed from the QTC so that their longitudinal centreline axis is
wholly within the centre core 1/4 “t” envelope for a solid QTC or within 6 mm (1/4 in) of the mid-thickness of
the thickest section of a hollow QTC (see Figure 1).
When a sacrificial production part is used as a QTC, the impact and tensile test specimens shall be removed
from the 1/4 “t” location of the thickest section in that part.
ISO 13625:2002(E)
5.1.5.3 Hardness testing
The following steps apply to hardness testing:
a) a minimum of two Brinell hardness tests shall be performed on the QTC after the final heat treatment
cycle;
b) hardness testing shall be performed in accordance with ISO 6506-1;
c) the hardness of the QTC shall meet the manufacturer's written specification.
5.2 Welding
Welding procedures and processes shall be in accordance with ISO 10423:2001, 6.3 and 6.3.4.

a)  Simple geometric equivalent round sections/shapes having length l
10 © ISO 2002 – All rights reserved

ISO 13625:2002(E)
b)  Keel block configuration (ER = 2,3R)
When l is less than t, consider the section as a plate of l thickness.
When l is less than d, consider the section as a plate of t thickness.
NOTE Area inside dashed lines in a) is 1/4t envelope for test specimen removal.
Key
1 1/4t envelope for test specimen removal
a Round
b Hexagon
c Square
d Rectangle or plate
e Simple hollow shape
Figure 1 — Equivalent round (ER) models
6 Dimensions and weights
6.1 Coupling dimensions
Riser couplings are categorized by mating riser pipe sizes. Riser pipe and the associated couplings are
generally sized to be compatible with a specific blowout preventer (BOP) stack size. Compatible BOP bore
and riser outer diameter combinations are shown in Table 2. The make-up length, butt weld-to-butt weld, shall
be documented.
ISO 13625:2002(E)
Table 2 — Compatible BOP bore and riser outer diameter combinations
BOP bore Riser outer diameter
346 mm (13 5/8 in) 406 mm (16 in) riser
425 mm (16 3/4 in) 473 mm (18 5/8 in) riser
476 mm (18 3/4 in) 508 mm (20 in) or 533 mm (21 in) riser
527 mm (20 3/4 in) 558 mm (22 in) or 609 mm (24 in) riser
539 mm (21 1/4 in) 609 mm (24 in) riser
NOTE A given coupling size may be used with a range of riser pipe outside diameters, wall
thicknesses, and material yield strengths.

6.2 Coupling weight
The coupling weight for each coupling size shall be documented. The weight of a riser coupling shall include
the sum of the in-air weights of the structural components of the coupling, the lock mechanisms and the
brackets or clamps that support the end extremities of auxiliary and choke and kill lines. The coupling weight
includes the in-air weight of any and all parts that contribute to the submerged, in-service weight of the
coupling.
7 Quality control
7.1 General
The manufacturer shall retain all records required by this International Standard for a period of ten years after
the manufacture of the last unit of that size, model, and service classification.
7.2 Raw material conformance
7.2.1 Traceability
Parts in the primary load path shall be traceable to the individual heat and heat treatment lot.
Identification shall be maintained on materials and parts to facilitate traceability, as required by documented
manufacturer's requirements.
Manufacturer's documented traceability requirements shall include provisions for maintenance or replacement
of identification marks and identification control records.
7.2.2 Chemical analysis
Chemical analysis shall be performed in accordance with a recognized industry standard.
The chemical composition shall be in accordance with the manufacturer's written specification.
7.3 Manufacturing conformance
7.3.1 General
The manufacturer shall retain drawings and documentation by serial number and part number regarding
material properties, heat numbers, riser tube dimensions, minimum through bore, service classifications and
date of manufacture, as well as design documentation in accordance with 4.8. In addition, the following steps
are required.
12 © ISO 2002 – All rights reserved

ISO 13625:2002(E)
7.3.2 Visual examination
The requirements for visual examination are as follows.
a) Each part shall be visually examined.
b) Visual examinations of castings and forgings shall be performed in accordance with the manufacturer's
written specification.
c) Acceptance criteria shall be in accordance with the manufacturer's written specifications.
7.3.3 Surface non-destructive examination (NDE)
7.3.3.1 General
All surfaces of each finished part shall be inspected in accordance with 7.3.3.2 to 7.3.3.5.
7.3.3.2 Surface NDE ferromagnetic materials
Well fluid wetted surfaces and all accessible sealing surfaces of each finished part shall be inspected after
final heat treatment and after final machining operations by either magnetic particle (MP) or liquid penetrant
(LP) methods.
7.3.3.3 Surface NDE non-ferromagnetic materials
All accessible well fluid wetted surfaces of each finished part shall be inspected after final heat treatment and
after final machining operations using a liquid penetrant method.
7.3.3.4 Methods
MP inspection shall be in accordance with ASTM E 709. Yoke prods or contact prods are not permitted on
well fluid wetted surfaces or sealing surfaces and generally not on sensitive machined parts. The MP dry
method is also not allowed on machined parts or on parts where the magnetic powder, when imperfectly
removed after control, could lead to corrosion or remain trapped in areas where it might have adverse effects
(threads, etc.). In these cases the MP wet method shall be preferred to the MP dry method.
LP examination shall be in accordance with ASTM E 165.
7.3.3.5 MP and LP indications
Inherent indications not associated with a surface rupture (e.g. magnetic permeability variations and
non-metallic stringers) are considered non-relevant. If magnetic particle indications are believed to be
non-relevant, they shall be examined by LP surface NDE methods or removed and reinspected to prove their
non-relevancy.
7.3.3.6 Acceptance criteria for MP and LP
Acceptance criteria for surfaces other than pressure contact sealing surfaces are as follows:
a) no relevant indication with a major dimension equal to or greater than 4,8 mm (3/16 in);
2 2
b) no more than ten relevant indications in any continuous 39 cm (6 in ) area;
c) four or more relevant indications in a line separated by less than 1,6 mm (1/16 in) (edge-to-edge) are
unacceptable.
Acceptance criteria for pressure contact (metal-to-metal) sealing surfaces are that there shall be no relevant
indications in these surfaces.
ISO 13625:2002(E)
7.3.4 Weld NDE
7.3.4.1 General
When examination is required, essential welding variables and equipment shall be monitored. The entire weld,
including a minimum of 13 mm (1/2 in) of surrounding base metal, shall be examined in accordance with the
methods and acceptance criteria of 7.3.4.
7.3.4.2 Weld prep NDE — Visual
The totality (100 %) of all surfaces prepared for welding shall be visually examined prior to initiating welding.
Examinations shall include a minimum of 13 mm (1/2 in) of adjacent base metal on both sides of the weld.
Weld NDE surface preparation acceptance shall be in accordance with the manufacturer's written
specification.
7.3.4.3 Post weld visual examination
All welds shall be examined according to manufacturer's written specification.
All pressure-containing welds shall have complete joint penetration.
Undercut shall not reduce the thickness in the area (considering both sides) to below the minimum thickness.
Surface porosity and exposed slag are not permitted on or within surfaces.
7.3.4.4 Weld NDE — Surface (other than visual)
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