ISO 10420:1994

Petroleum and natural gas industries - Flexible pipe systems for subsea and marine riser applications

Provides guidelines for the design, analysis, testing, storage, handling and installation of flexible pipe systems used in a variety of offshore oil production applications. Requirements are specified in API Recommended Practice 17B (API RP 17B), first edition, June 1 1988, which is adopted as ISO 10420. For the purposes of international standardization, however, modifications shall apply to specific clauses and paragraphs of publication API RP 17B. These modifications are outlined.

Industries du pétrole et du gaz naturel — Systèmes de canalisations flexibles pour applications sous-marines et en milieu marin

General Information

• Status: Withdrawn
• Publication Date: 20-Apr-1994
• Withdrawal Date: 20-Apr-1994
• ICS: 75.200 - Petroleum products and natural gas handling equipment
• Technical Committee: ISO/TC 67/SC 4 - Drilling and production equipment
• Drafting Committee: ISO/TC 67/SC 4/WG 6 - Subsea equipment
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 13-Sep-2007
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 13628-11:2007 - Petroleum and natural gas industries - Design and operation of subsea production systems - Part 11: Flexible pipe systems for subsea and marine applications
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 10420
First edition
1994-04-15
Petroleum and natura1 gas industries -
Flexible pipe Systems for subsea and
marine riser applications
Industries du phrole et du gaz naturel - Systemes de canalisations
flexibles pour applications sous-marines et en milieu marin
Reference number
ISO 10420: 1994(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. Esch 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.
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.
International Standard ISO 10420 was prepared by the American Petro-
leum Institute (API) (as RP 17B, 1st edition) and was adopted, under a
by Technical Committee ISO/TC 67, Ma-
special “fast-track procedure ”,
terials, equipment and offshore structures for Petroleum and natura/ gas
industries, in parallel with its approval by the ISO member bodies.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
Q ISO
Introduction
International Standard ISO 10420:1994 reproduces the content of API
RP 17B, 1st edition, 1988. ISO, in endorsing this API document, recog-
nizes that in certain respects the latter does not comply with all current
ISO rules on the presentation and content of an International Standard.
Therefore, the relevant technical body, within lSO/lC 67, will review
these rules.
This Standard is not intended to obviate the need for Sound engineering
judgement as to when and where this Standard should be utilized and
users of this Standard should be aware that additional or differing require-
ments may be needed to meet the needs for the particular Service in-
tended.
Standards referenced herein may be replaced by other international or
national Standards that tan be shown to meet or exceed the requirements
of the referenced Standards.
This page intentionally left blank

INTERNATIONAL STANDARD 0 ISO ISO 10420:1994(E)
- Flexible pipe
Petroleum and natura1 gas industries
Systems for subsea and marine riser applications
1 Scope
This International Standard provides guidelines for the design, analysis, testing, storage, handling and installation
of flexible pipe Systems used in a variety of offshore oil production applications.
2 Requirements
Requirements are specified in:
“API Recommended Practice 17B (RP 17B), 1st edition, June 1, 1988 - Recommended Practice for Flexible
Pipe”
which is adopted as ISO 10420.
For the purposes of international standardization, however, modifications shall apply to specific clauses and para-
graphs of publication API RP 17B. These modifications are outlined below.
Page 9
Information given in the POLICY is relevant to the API publication only.
Page 10
Subclause 1.2, Applicable Standards
API Standards referenced in subclause 1.2 and listed hereafter are available under the following ISO references:
API BUL 5C3 as ISO 10400
API RP 6G as ISO 10406
Page 41
Section 8, References
This section is informative. The documents listed therein constitute a bibliography.

(Blank Page)
Recommended Practice for
Flexible Pipe
API RECOMMENDED PRACTICE 17B (RP 17B)
FIRST EDITION, JUNE 1,1988
American Petroleum Institute
1220 L Street, Northwest
Washington, DC 20005
!YP
ISO 40420:1994(E)
Issued by
AMERICAN PETROLEUM INSTITUTE
Production Department
FOR INFORMATION CONCERNING TECHNICAL CONTENTS OF
THIS PUBLICATION CONTACT THE API PRODUCTION DEPARTMENT,
211 N. ERVAY, SUITE 1700, DALLAS, TX 75201 - [phone].
SEE BACK SIDE FOR INFORMATION CONCERNING HOW TO OBTAIN
ADDITIONAL COPIES OF THIS PUBLICATION.
Users of this pubiication shouid become famiiiar with its scope
and content. This pubiication is intended to Supplement rather
than repiace individual engineering judgment.
Copyright @ 1988 American Petroleum Institute

2 American Petroleum Institute
TABLE OF CONTENTS
Page
FOREWORD . . . . . . . . . . e . . . . . . . . . . . . . . e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
POLICY . . . . . . . . . . . . . . . . . . . . . ~ . . . . 0 rn.,.
SECTION 1- GENERAL
. Scope. 6
.
12 Applicable Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
SECTION 2 - DEFINITIONS AND ABBREVIATIONS
21 . Definitions.,,,,. 7
22 . Abbreviations. 8
SECTION 3 - SYSTEM DESCRIPTION
31 . Scope.~ .
32 . Applications .
33 Construction Types
................................... 9
3 ’3 . 1 Non-bonded Construction
............................. 9
3 ’. 3 . 2 Bonded Construction
................................. 9
34 . EndFittings .
35 . BendLimiters .
36 . Bend Stiffeners
...................................... 9
37 . Buoyancy Devices
.................................... 10
SECTION 4 OPERATIONAL REQUIREMENTS AND DESIGN
CONSIDERATIONS
41 . Scope .
42 .
General.~ .
Mechanical Considerations.
........................... 14
. Dimensional
4 ’3 1
......................................... 14
4 ’3 . 2
Internal Pressure
.................................... 14
.
4 ’3 3 Collapse .
4 ’3 . 4
Tensile Load
......................................... 14
.
4 ’3 5 Flexibility .
.
4 ’3 6 Minimum Bend Radius
............................... 15
4 ’3 . 7 Weight and Buoyancy
................................ 15
4 ’3 . 8 Torsion. .
4 ’. 3 . 9 Rapid Decompression
................................. 15
44 Transported Fluid Considerations
..................... 15
4 ’4 . 1 Temperature Limits
.................................. 15
4 ’4 . 2 Fluid Properties
..................................... 15
4 ’4 . 3 FluidVelocity .
4 ’. 4 . 4 Pipe Roughness
...................................... 16
45 External Environment Considerations.
................ 16
4 ’5 . 1 Temperature Limits
.................................. 16
4 ’5 . 2 Fire Resistance
...................................... 16
4 ’5 . 3 External Protection
.................................. 16
4 ’5 . 4 Anti-fouling
.......................................... 16
4 ’. 5 . 5 Environmental Conditions
............................ 16

RP 17B: Flexible Pipe
TABLE OF CONTENTS (continued)
Page
.................................
46 Other Considerations
........................
4 ’6 . 1 Static or Dynamit Application
. .
4 ’6 2 Thermal Insulation
..................................
4 ’6 . 3 On-Bottom Behavior
...........................................
4 ’6 . 4 Trenching
........ :. ................
4 ’6 . 5 Pigging/TFL Requirements
..........................................
4 ’6 . 6 ServiceLife
..........................................
4 ’6 . 7 End Fitting
...............................
4 ’6 . 8 Bend Limiter/Stiffener
.........................................
4 ’6 . 9 Permeability
.................................
4 ’6 . 10 Electrical Continuity
..................................
4 ’6 . 11 Structural Damping
..................... .* ................
4 ’. 6 . 12 Appurtenanees
SECTION 5 ANALYSIS CONSIDERATIONS
51 . Scope .
...................................
52 . Analysis Objectives
.................................
53 Analysis Parameters
..................................
5 ’3 . 1 Pipe Characteristics
.....................................
5 ’. 3 . 2 Operational Data
..................................
54 Analysis Procedures
5 ’4 . 1 General .
............................... 19
5 ’4 . 2 System Static Analysis
............................ 19
5 ’4 . 3 System Dynamit Analysis
................................. 20
5 ’4 . 4 Local Stress Analysis
.................................. 20
5 ’4 . 5 Component Analysis
........................ 20
5 ’4 . 6 Flow-Induced Motion Analysis
5 ’. 4 . 7 Service Life Analysis .
SECTION 6 QUALITY ASSURANCE AND QUALITY CONTROL
Zl
61 . General .
.......................... 21
. Quality Assurance of Design
.................... 21
. Quality Assurance of Procurement
...................... Zl
Quality Assurance of Processing
6 ’4 . 1 Welding .
. Repair of Defects .
6 ’4 2
. . Marking of Pipe. .
6 ’4 3
User Inspection .
. .
6 ’5 1 Scope
. .
6 ’5 2 General
.......................................
6 ’5 . 3 Documentation
....................................
6 ’5 . 4 Acceptance Tests.
.....................................
6 ’. 5 . 5 Test Certificates.
66 Testing .
6 ’6 . 1 General .
6 ’6 . 2 Prototype Tests .
6 ’6 . 3 Acceptance Tests .
6 ’. 6 . 4 Special Tests .

American Petroleum Institute
TABLE OF CONTENTS (Continued)
Page
SECTION 7 STORAGE, HANDLING, TRANSPORTATION AND
INSTALLATION
71 . Scope . 34
72 Storage . 34
7 ’2 . 1 Reels . 34
7 ’2 . 2 Baskets . 34
. Crates/Pallets 34
7 ’2 3 .
Storage Conditions . 34
7 ’. 2 . 4
. Handling and Transportation
73 . 34
Installation . 34
. Installation Methods and Equipment
7 ’4 1 . 34
Installation Loads
7 ’4 . 2 . 35
7 ’4 . 3 Intermediate Connections . 36
7 ’. 4 . 4 Retrieval for Reuse . 36
SECTION 8 REFERENCES . 37
RECOMMENDED PRACTICE FOR FLEXIBLE PIPE
FOREWORD
This Recommended Practice (RP) is under the jurisdic- mended Practices are not intended to, in any way,
tion of the American Petroleum Institute (API) Com- inhibit anyone from using any other practices.
mittee on Standardization of Subsea Production
(3) Any Recommended Practice may be used by anyone
Systems.
desiring to do so, and a diligent effort has been made
by API to assure the accuracy and reliability of the
(1) American Petroleum Institute (API) Recommended
data contained herein. However, the Institute makes no
Practices are published to facilitate the broad availabil-
representation, warranty or guarantee in connection
ity of proven, Sound engineering and operating prac-
with the publication of any Recommended Practice and
tices. These Recommended Practices are not intended
hereby expressly disclaims any liability or responsibil-
to obviate the need for applying Sound judgment as to
ity for loss or darnage resulting from its use, for any
when and where these Recommended Practices should
Violation of any federal, state or municipal regulation
be utilized.
with which an API recommendation may conflict, or
for the infringement of any patent resulting from the
use of this publication.
(2) The formulation and publication of API Recom-

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REGULATIONS SHOULD BE REVIEWED.
GENERALLY, API STANDARDS ARE REVIEWED
AND REVISED, REAFFIRMED, OR WITHDRAWN
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PUBLICATION WILL NO LONGER BE IN EFFECT
POSED, CONCERNING HEALTH AND SAFETY
FIVE YEARS AFTER ITS PUBLICATION DATE
RISKS AND PRECAUTIONS, NOR UNDERTAKING
AS AN OPERATIVE API STANDARD OR, WHERE
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BY LETTERS PATENT. NEITHER SHOULD ANY-
WASHINGTON, D.C. 20005.
SECTION 1
GENERAL
ered as either all inclusive or exclusive of other stand-
1.1 Scope. This Recommended Practice provides
ards relating to topics covered in this RP.
guidelines for the design, analysis, quality assurance,
storage, handling, transportation, and installation of
American Petroleum Institute
flexible pipe Systems for subsea and marine riser appli-
cations. In general, flexible pipe is a custom-built prod- SPEC Ql
Quality Programs
uct which tan be manufactured in a variety of methods.
RP 2Q Design and Operation of Marine
It is not the intent of this document to discourage novel
Drilling Riser Systems
or new developments in the flexible pipe market. On I3UL 5c3
Formulas and Calculations for Cas-
the contrary, it is recognized that a variety of designs
ing, Tubing, Drill Pipe, and Line
and methods of analysis are possible. For this reason
Pipe Properties
some topics are presented in general terms, in a com-
SPEC 6FA Specification for Fire Test for Valves
mentary form, to provide guidance to the user while
RP 6G Through Flowline (TFL) Pump Down
still leaving the door open to alternative approaches.
Systems
RP 17A Design and Operation of Subsea Pro-
This Recommended Practice applies to flexible pipe
duction Systems
with a design pressure greater than 225 psi and used in
STD 1104 Welding Pipelines and Related Fa-
a variety of offshore oil production applications. Typical
cilities
applications include risers, pipelines, and pipeline/flow-
RP 1110 Pressure Testing of Liquid Petroleum
line tie-ins.
Pipelines
RP 1111 Design, Construction, Operation and
While the treatment of flexible pipe in this RP is
Maintenance of Offshore Hydrocar-
general and deals with a variety of applications, low
bon Pipelines
pressure (design pressure not greater than 225 psi)
hoses, flexible Choke and kill lines, and hydraulic con-
American Society for Testing and Materials
trol lines are beyond the scope of this RP. Flexible pipe
which will carry chemicals other than those expected in
ASTM-D-413 Adhesion to Flexible Substrate
an oil production application are also outside the scope
ASTM-D-2 143
Cyclic Pressure Strength of Rein-
of this RP. forced, Thermosetting Plastic Pipe
ASTM-D-Z924
External Pressure Resistance of Re-
Several factors justify the need for this Recommended
inforced Thermosetting Resin Pipe
Practice. Flexible pipe Systems are already used in a
variety of applications offshore, and as the industry
Lloyd ’s Register of Shipping
moves to frontier areas, such as deepwater, the number
ICE/FIRE, OSG 1000/499 Flexible Hoses on Offshore
of potential applications increases. While the number of
Installations (Fire Test)
so also are the number of
applications is growing,
manufacturers and the types of construction. In addi-
National Association of Corrosion Engineers
tion, the design and analysis of flexible pipe are made
MR-01-75 Sulfide Stress Cracking Resistant
difficult by its multilayered composite construction
Metallic Material for Oil Field
involving different materials.
Equipment
This document is not intended to offer a comprehensive
RP 01-75 Control of Internal Corrosion in Steel
treatment of flexible Pipe. It will be revised as new
Pipelines and Piping Systems
information becomes available.
Oil Companies International Marine Forum
1.2 Applicable Standards. The following Standards
Hose Standards: Specification for Rubber, Reinforced,
are referenced in part or in whole in this Recom-
Smooth Bore, Oil Suction and Discharge Hoses for Off-
mended Practice. It is recognized that additional stand-
shore Moorings (Including Purchaser ’s Inspection
ards have been developed by other bodies. Therefore
Guide), 3rd Edition, 1 September 1978.
this listing is representative and should not be consid-
RP 17B: Flexible Pipe
SECTION 2
DEFINITIONS AND ABBREVIATIONS
2.1 Definitions LAY ANGLE: In flexible Pipe fabrication this is the
angle between the axis of the armor wire and a line
BEND LIMITER: A mechanical device that functions
parallel to the flexible pipe axis.
as a mechanical stop and limits the local radius of cur-
vature of the flexible pipe to a minimum value. Can LAZY S CONFIGURATION: A double catenary shape
also be called bend restricter. taken by a flexible pipe riser when the riser runs from
the surface to the seafloor over a midwater pipe tray
BEND RESTRICTER: See bend limiter.
supported by a subsurface buoy. The buoy may be kept
in Position by a chain or cable attached to a deadweight
BEND STIFFENER: Flexible pipe construction aimed
anchor positioned on the seafloor. See Figure 2.1.
at increasing the bending stiffness in a localized region
to reduce maximum Stresses when large bending
LAZY WAVE CONFIGURATION: Similar to the
moments are expected. Can also be called strain relief
Lazy S configuration with the pipe tray and the subsur-
unit.
face buoy replaced by an appropriate distribution of
smaller buoyancy modules along a section of the riser.
BENDING STIFFNESS: Bending stiffness in a flexi-
Also, the lazy wave configuration does not require a
ble pipe is analogous to the structural stiffness of a
deadweight anchor. See Figure 2.1.
rigid beam or pipe (modulus of elasticity times the
second area moment of inertia), except that it tan vary
to a larger extent with temperature and pressure. It is
MINIMUM BEND RADIUS (MBR): The minimum
often quantified as the product of an applied bending
radius of curvature, measured from the pipe centerline,
moment times the resultant bend radius of the Pipe.
that the flexible pipe tan sustain without darnage.
Darnage caused by excessive bending tan take several
CARCASS: An interlocked metallic construction that
forms, such as crushing of the interlocked steel carcass,
tan be used as one of the flexible pipe component
local buckling, permanent deformation, or loss of bond-
layers.
ing between adjacent layers. Different values may be
CHINESE LANTERN CONFIGURATION: A quasi- applicable for the minimum bend radius for different
vertical shape for a riser supported by distributed or conditions, such as storage, installation and Operation.
Also, the minimum bend radius may be different for
continuous buoyancy. See Figure 2.1.
static and dynamic applications.
CONNECTOR: A device used to provide a leak-free
MULTIBORE FLEXIBLE PIPE CONSTRUCTION:
structural connection at the end of a length of flexible
See integral flexible pipe construction.
Pipe. Connectors include bolted flanges, clamped hubs,
and proprietary connectors. They may be designed for
diver-assisted makeup or for diverless Operation using
NON-INTEGRAL FLEXIBLE PIPE CONSTRUC-
either mechanical or hydraulic apparatus.
TION: An assembly of individual flexible lines installed
in parallel and constrained together at one or more
END FITTING: The flexible pipe end construction,
intermediate Points along their length. These con-
including the termination of the different flexible Pipe
straints may be a pipe tray, a common flotation device,
layers and the connector. See termination or connector.
or spacer bars.
END-CUT: Open section of flexible pipe which has
been tut for future installation but did not receive an
PERMEABILITY: The characteristic of a material to
end fitting.
allow a fluid (liquid or gas) to pass through it. In flexi-
ble Pipe, permeability may allow gases to pass through
FLEXIBLE PIPE: A pipe that tan perform functions
the primary fluid-containing layer and build up in the
similar to rigid Pipe, and which tan also withstand
interplay region.
large curvature without adverse effects.
PIPE TRAY: The support of the flexible Pipe when a
FREE HANGING CONFIGURATION: The shape,
riser is set in a Lazy S or Steep S configuration. It
typically a catenary, that a flexible pipe takes when
transmits the buoyancy forte to the flexible pipe while
suspended between two Points and acted upon only by
keeping it at an acceptable curvature.
its own weight. See Figure 2.1.
PRESSURE: See Section 4.3.2 for definitions of design,
H$3 SERVICE: H$ Service is defined as fluid Service
operating, test, and burst pressures.
conditions containing above 0.05 psi partial pressure of
hydrogen sulfide calculated at working pressure.
QUALITY: Conformance to specified requirements.
INTEGRAL FLEXIBLE PIPE CONSTRUCTION:
An assembly of individual flexible pipelines, electrical
QUALITY ASSURANCE: Those planned, systematic,
cable, Optical fibers, etc., constrained by a common con-
and preventive actions which are required to ensure
tinuous outer jacket. Can also be called multibore
that materials, products, or Services will meet specified
construction.
requirements.
8 American Petroleum Institute
STRAIN RELIEF UNIT: See bend stiffener.
QUALITY CONTROL: Inspection, test or examination
to ensure that materials, products, or Services conform
to specified requirements.
TERMINATION: A part of the end fitting which
QUALITY PROGRAM: An established documented
forms the transition between regular flexible pipe con-
System to ensure quality.
struction and the connector. The different pipe layers
are terminated in such a way as to transfer the load
RISER BASE: The riser base anchors the flexible Pipe
between the flexible pipe and the connector, without
at the seabed to prevent vertical or lateral movement.
any reduction in mechanical properties.
SPOOL: A short flexible pipe Segment commonly used
in connecting pipelines. A spool typically includes a
2.2 Abbreviations
connector at each end.
ANSI American National Standards Institute
STEEP S CONFIGURATION: A riser shape similar
API
American Petroleum Institute
to the Lazy S configuration, except that the lower sec-
ASME
American Society of Mechanical Engineers
tion of the flexible pipe between the buoy and the riser
ASTM
American Society for Testing and Materials
base is vertical and serves as a tension member. See
FPS Floating Production System
Figure 2.1.
I.D. Inside Diameter
STEEP WAVE CONFIGURATION: Similar to the MBR Minimum Bend Radius
NACE National Association of Corrosion Engineers
Steep S configuration with the pipe tray and the sub-
OCIMF Oil Companies International Marine Forum
surface buoy replaced by an appropriate distribution of
small buoyancy modules along a section of the riser. 1 O.D. Outside Diameter
TFL T hrough Flowline
See Figure 2.1.
I
FREE HANGING LAZY S
STEEP S
LAZY WAVE STEEP WAVE
CHINESE LANTERN
FIG. 2.1
RP 17B: Flexible Pipe 9
SECTION 3
SYSTEM DESCRIPTION
tile reinforcement to provide axial and radial strength,
3.1 Scope. This Section describes the different possible
and may incorporate a spiral or helical structure to
applications and the main components of flexible pipe
provide collapse resistance. Fluids and gases are con-
Systems, including the end fittings, bend limiters, bend
tained by a layer principally made from polymeric
stiffeners, and buoyancy devices. The main construction
materials. The number and angle of the reinforcement
types are also described.
materials, the thickness and material choice of layers,
3.2 Applications. Applications of flexible pipe in off-
and the Order of layers and reinforcement in the pipe
shore oil and gas production tan be grouped into two
construction are governed by Service and installation
categories: static and dynamic. Examples of flexible
requirements.
pipe applications include those illustrated in Figures
3.3.1 Non-Bonded Construction. Non-bonded flexible
3.1 and 3.2.
pipe consists of several individual and separate layers
The use of flexible pipe for static applications is pri-
having no adhesion between them. Esch succeeding
marily for Pipeline and platform riser Service. In these
layer is wrapped or extruded over the previous layer in
applications, flexible pipe is used to simplify design or
a continuous process along the entire length.
installation procedures. In addition, reduction of instal-
lation and end connection loads and moments may be 3.3.2 Bonded Construction. Bonded layer flexible pipe
achieved using flexible Pipe. Examples where the use consists of several layers wrapped or extruded individ-
of flexible pipe results in simplified Pipeline design or ually and then bonded together through the use of
installation include: adhesives or by applying heat and/or pressure (such as
vulcanizing) to fuse the layers into a Single construc-
l Subsea Pipeline end connections where expensive or
tion. In some constructions there is an inner steel car-
difficult operations, such as exact orientation meas-
cass which is not bonded to the adjacent layer.
urements for spool pieces or the use of large align-
ment equipment to re-Position the Pipeline, tan be 3.4 End Fittings. At the two ends of a length of flexi-
eliminated. ble pipe are end fittings. An end fitting consists of an
end termination and end connector, as illustrated in
l Situations where gross movements and darnage to
Figure 3.4. End fittings may be built in during pipe
pipelines due to mudslides tan be reduced through
manufacture or installed in the field. The purpose of a
the use of slack sections of flexible Pipe.
flexible pipe end.fitting is twofold:
l Applications where field hardware and Pipeline loca-
0 the end termination Portion of the fitting should be
tion Change with the field ’s production characteris-
able to terminate all the strength members in the
tics, which may necessitate the recovery and reuse of
pipe ’s construction so that axial loads and bending
flexible pipe pipelines.
moments tan be transmitted into the end connector
without adversely affecting the fluid-containing
Dynamit applications use flexible pipe between supply
layers,
and delivery Points where there is relative movement
between these two Points while in Service. These types
l the end fitting should provide a pressure tight transi-
of applications usually involve an offshore floating pro-
tion between the pipe body and the connection Point.
duction facility or terminal connected to another float-
End connectors may be an integral part of, or attached
ing facility, fixed structure, or fixed base. Examples of
to, the end termination to complete the end fitting. A
dynamic applications include:
variety of end connectors exist, such as bolted flanges,
@ flexible pipe risers for tanker/terminal moorings,
clamp hubs, proprietary connectors, and welded joints
(two end terminations welded together to join Pipe
l flexible pipe riser connections between floating pro-
Segments into a longer Segment). The selection of end
duction facilities and subsea equipment.
connector depends on operational and Service require-
Static and dynamic applications place different physi-
ments.
cal demands on flexible Pipe. Static applications require
3.5 Bend Limiters. Bend limiters (or bend restricters)
long life, good strength, darnage resistance, and min-
are designed either to restriet mechanically the flexible
imal maintenance while in Service. In addition to the
pipe from bending beyond its MBR or to meet opera-
static requirements, dynamic applications require in-
tional requirements. For example, a bend limiter may
Service pliancy and long-term cyclic Service life while
be used on the end of a flexible pipe to protect it from
maintaining pressure integrity.
the unusual loading associated with a diverless in-
3.3 Construction Types. Flexible pipe may be divided
stallation.
into two basic types depending on the construction: non-
bonded layer and bonded layer, as illustrated in Figure
3.6 Bend Stiffeners. Whereas bend limiters mechani-
3.3. Flexible pipe principally relies on steel and/or tex-
cally prevent overbending, bend stiffeners are used to
American Petroleum Institute
increase the pipe ’s bending stiffness in localized areas. shape, Chinese lantern). In addition, some applications
The increased stiffness reduces Stresses in the pipe lay- may require additional buoyancy to control riser shape
ers when subjected to anticipated bending moments or descent Speed when the riser top is disconnected.
that would otherwise be unacceptable. While buoyancy devices may be incorporated in the
flexible pipe ’s construction, they are more commonly
external foam modules or closed air cans which are
3.7 Buoyancy Devices. Buoyancy may be added to the
flexible pipe design for many reasons, such as to reduce clamped directly to the pipe or connected through a
topside riser pipe loads, reduce Pipeline soil friction or pipe tray. If the buoyancy devices are clamped to the
tension loads during Pipeline installation, or achieve a Pipe, care should be taken to ensure that they neither
particular flexible pipe configuration (S-shape, wave slide along nor darnage the Pipe.
FLOWLBES REPOSTKMED FOR
MA- FELD PmDucnON
SCHEME
SPOOL PIECE
SUBSEA FACILITY
(TOP VIEW)
FLEXIBLE PIPE
RIGID PIPE
FIG. 3.1
EXAMPLES OF STATIC APPLICATIONS
FOR FLEXIBLE PIPE
RP 17B: Flexible Pipe 11
FLEXIBLE
RISER
@-dz, -s--y &lGID PIPE cc -
w
FLOATING PRODUCTION
SYSTEM (FPS)
FLOATING PRODUCflON
SYSTEM (FPS)
ANCHOR CHAIN
FLEXIBLE RISER
FLOATING TANKER/TERMINAL MOORING
FIG. 3.2
EXAMPLES OF DYNAMIC APPLICATIONS
FOR FLEXIBLE PIPE
ISO “10420:1994(E)
American Petroleum Institute
NON-BONDED FLEXIBLE PIPE
END TERMINATION
f
FLEXIBLE PIPE
BONDED FLEXIBLE PIPE
A ElwoRcwENTwIFD(NGs
B FLUD CONTAIMNG IJfER
END CONNECTOR
c OUTERJACKET
D STRUCTURAL MEMBERS
FIG. 3.4
FIG. 3.3
FLEXIBLE PIPE END FITTING
EXAMPLES OF CONSTRUCTION FOR
FLEXIBLE PIPE DESIGNS
RP 17B: Flexible Pipe 13
SECTION 4
OPERATIONAL REQUIREMENTS AND DESIGN CONSIDERATIONS
TABLE 4.1
4.1 Scope. The purpose of this Section is to provide
CONSIDERATIONS
guidelines for the user when defining flexible pipe for a
given application and set of operational requirements. WHEN SPECIFYING FLEXIBLE PIPE
Same guidance on minimum factors of safety are given
(may not be totally inclusive)
where appropriate. Also, this Section provides informa-
MECHANICAL CONSIDERATIONS
tion concerning the effect of varying criteria, conditions
Dimensional
of Service, and combined load conditions on the design
Inside Diameter (I.D.)
and construction of flexible Pipe. When appropriate,
Outside Diameter (O.D.)
API RP l7A, RP 1110, and RP 1111 should also be con-
Length
sulted for additional guidance.
Dimensional Tolerantes
Internal Pressure
4.2 General. The user should inform the manufacturer
Design Pressure
of details concerning the application and configuration
Operating Pressure
for the flexible pipe so that proper considerations tan
Test Pressure
be given to design. Safety factors may be specified by
Burst Pressure
the user and these should be met or exceeded by the
Collapse
manufacturer.
Depth Rating
Crush Resistance
Operational requirements consist of functional require-
External Local Darnage
ments and Performance characteristics. Functional
Tensile Load
requirements are criteria to be specified by the user
Design Tensile Load
which the pipe must meet in a given application. It is
Ultimate Tensile Load
important that these be checked whenever Service con-
Flexibility
ditions are changed.
Minimum Bend Radius (MBR)
Performance characteristics are properties which char- Weight and Buoyancy
acterize the Performance of a given flexible Pipe, as Torsion
determined by the design, based on the functional Rapid Decompression
requirements specified by the User. They may be
TRANSPORTED FLUID CONSIDERATIONS
determined by the use of appropriate analytical and
Temperature Limits
testing procedures. Some recommended tests are out-
Fluid Properties
lined in Section 6.
Fluid Velocity
Pipe Roughness
The user should have an understanding of how the
EXTERNAL ENVIRONMENT CONSIDERATIONS
functional requirements of a specific application affect
Temperature Limits
the design of the flexible Pipe. Because of its composite
Fire Resistance
construction, the choice of design criteria for certain
External Protection
functional requirements may adversely affect the per-
Anti-fouling
formante characteristics of a flexible pipe in other
Environmental Conditions
areas of the design. For example, the allowable tensile
load for some pipe designs may decrease as the internal
OTHER CONSIDERATIONS
and external pressures increase.
Static or Dynamit Application
Thermal Insulation
In addition to the mechanical requirements, the choice
On-Bottom Behavior
of materials for the flexible pipe should be carefully
Trenching
considered. All pipe materials must be selected with
Pigging/TFL
regard to the physical and Chemical conditions to which
Service Life
the pipe will be exposed.
End Fitting
Table 4.1 lists areas needing consideration when speci- Bend Limi ter/S tiffener
fying flexible Pipe. These areas have been grouped into Permeability
mechanical considerations, transported fluid considera- Electrical Continuity
tions, external environment considerations, plus other Structural Damping
considerations. Esch area is discussed below. Appurtenances
American Petroleum Institute
4.3 Mechanical Considerations 4.3.3 Collapse. Collapse of a flexible pipe results in
permanent darnage to the Pipe. Collapse normally
4.3.1 Dimensional. The following dimensions are re-
involves a flattening of the Cross section and prevents
quired to define a flexible Pipe: inside diameter (I.D.),
the pipe from performing the functions for which it
outside diameter (O.D.) and length. Whereas the I.D.
was intended. Collapse tan be caused by a number of
and length should be specified by the User, the O.D. is
loading conditions acting separately or in combination.
generally a characteristic of the design. However, the
These include: (1) excessive external pressure, such as
user should notify the manufacturer if there are any
happens when the depth rating is exceeded; (2) exces-
restrictions to the O.D. or end fitting dimensions for the
sive axial or lateral compressive loads; (3) accidental
application considered.
external impact loads; (4) excessive tensile load; and
(5) bending of the pipe to a radius smaller than the
Tolerantes for these dimensions should be agreed
minimum bend radius.
between the user and manufacturer. In particular the
user should be aware that pipe elongations tan occur,
The user should be aware that tension in a flexible pipe
primarily as a result of internal pressure.
tan induce internally-generated collapse loads. These
loads result from the tendency of the helically-wound
Given a design pressure, as defined in Section 4.3.2.1,
structures to reduce their diameter as tension is ap-
the choice of the I.D. has an impact on the construction
plied. Tension-induced collapse loading may be a signif-
of the Pipe. In general, as the I.D. of the pipe is
icant combined load effect in flexible Pipe. Tensile load
increased for a given design pressure, the structure of
requirements are defined in Section 4.3.4. Tensile loads
the pipe must be changed to resist the increased hoop
during flexible pipe installation and their effect on pipe
stress developed. This may require the use of higher
crushing are discussed in Section 7.4.2.
strength materials, increased layer dimensions, addi-
tional layers, or increased lay angles for various wind-
If a flexible pipe is bent to a radius smaller than the
ings in the Pipe.
minimum bend radius, the Cross section tan flatten and
this tan lead to collapse. Minimum bend radius require-
4.32 Internal Pressure
ments are defined in Section 4.3.6.
4.3.2.1 Design Pressure. The design pressure is
4.3.3.1 Depth Ratings. The design depth rating is
the maximum internal pressure to which the flexi-
the maximum depth in seawater for which a flexi-
ble pipe will be subjected during its life. It includes
ble Pipe, filled with air at atmospheric pressure,
operating pressure and allowances for surges or
has been designed. The depth of the pipe in Service
other factors affecting internal pressure of the Pipe.
should never be greater than the design depth.
The pipe should be able to withstand the internal
The ultimate depth rating is the depth at which the
design pressure with atmospheric external pressure.
pipe will experience collapse from hydrostatic pres-
The choice of design pressure for the flexible pipe
sure with atmospheric internal pressure. Typically
has a major impact on pipe construction. Internal
this should be at least 1.5 x the design depth rating.
design features, such as the lay angle of pressure
The user should be aware that axial loads in combi-
back-up and tensile armor wires, wire dimensions,
nation with internal pressure tan adversely affect
and number of layers, may be affected by the choice
of the design pressure. the flexible pipe ’s capability with respect to its
ultimate depth rating.
4.322 Operating Pressure. The operating pres-
Sure, or working pressure, is the typical pressure to 4.3.3.2 Crush Resistance. The resistance of a flex-
which the pipe will be subjected under normal ible pipe to crushing as a result of locally applied
operating conditions, excluding pressures which compressive loads is also a design consideration.
may result from intermittent effects such as surges. These loads may result from a variety of conditions,
such as pipe saddles, clamps and guides, and ten-
4.323 Test Pressures. Pressure testing includes
sioners, chutes and sheeves on installation equip-
acceptance tests and tests to be performed after
ment, as discussed further in Section 7.
installation of the flexible Pipe, as discussed in more
detail in Section 6. Typically the acceptance test 4.3.3.3 External Local Darnage. Excessive local
pressure should be 1.5 x the design pressure. There loading on the flexible pipe structure through
should be agreement between the user and manu- external concentrated loads caused by foreign
facturer as to the installed test pressure, but gener- objects (such as tools and equipment) tan Cause
ally it should not exceed 1.25 x the design pressure. failure. In some applications it may be advisable to
add external protection to the flexible Pipe.
4.3.2.4 Burst Pressure. The burst pressure for a
flexible pipe is a Performance characteristic result- 4.3.4 Tensile Load. The design tensile load is the max-
ing from the design pressure specified by the User. imum tension to which the flexible pipe will be sub-
Typically the burst pressure should be at least 2 x jected. The ultimate tensile load is the maximum axial
load to which the pipe tan be subjected without expe-
the design pressure.
(El
RP 17B: Flexible Pipe 15
riencing collapse or other darnage which will render it 4.42 Fluid Properties. Because all pipe materials
incapable of performing the intended Service. Typically should be selected with regard to the Chemical condi-
it should be at least 2 x the design tensile load. tions to which the pipe will be exposed, the User should
specify, by type and concentration, composition of the
The most adverse combination of internal and external
elements of any fluids to be carried by the flexible pipe
pressure and tensile loading on the flexible pipe should
during its life. It is important that any adverse ele-
be considered when the pipe is designed or selected.
ments found in produced fluids and Chemical treat-
ments, as well as batch treatment chemicals to be used
4.3.5 Flexibility. Flexibility is normally a Performance
in production well stimulation, be identified as they
characteristic of the flexible pipe for a given design, as
may affect the Service life of the Pipe. For example,
measured by the bending stiffness, axial stiffness and
Chemical action may accelerate the aging of the
torsional stiffness. However, the user should advise if
polymers.
there is a specific flexibility requirement.
Examples of adverse elements are H,S, COz, Sand,
4.3.6 Minimum Bend Radius (MBR). The minimum
water, and chloride.
bend radius is generally a Performance characteristic
of the flexible pipe for a given design. As such it is
a. H# Service. All pipe materials used in HZS Service
specified by the manufacturer to prevent darnage to the
should be capable of resisting degradation over the
pipe as a result of flexure during the conditions of stor-
life of the Pipe. Many Polymers are susceptible to
age, installation and Operation. Certain pipe construc-
degradation and blistering when in cont
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