1. ______________________________
1
Mechanical Engineer - PETROBRAS
2
MSc, Materials Engineer – PETROBRAS
3
DSc, Materials Engineer – WOOD GROUP KENNY
IBP1094_15
STANDARDIZATION OF C-MN, LINED AND CLAD
LINEPIPES FOR RIGID SUBSEA RISER AND PIPELINE
PROJECTS
Guilherme E. Haverroth1
, Bruno R. M. da Cunha 2
,
Mônica C. R. Ribeiro3
Copyright 2015, Brazilian Petroleum, Gas and Biofuels Institute - IBP
This Technical Paper was prepared for presentation at the Rio Pipeline Conference & Exposition 2015, held between September,
22-24, 2015, in Rio de Janeiro. This Technical Paper was selected for presentation by the Technical Committee of the event. The
material as it is presented, does not necessarily represent Brazilian Petroleum, Gas and Biofuels Institute’ opinion or that of its
Members or Representatives. Authors consent to the publication of this Technical Paper in the Rio Pipeline Conference &
Exposition 2015.
Abstract
Subsea pipelines and risers are designed in accordance with several design codes standards, e.g. DNV-OS-
F101, DNV-OS-F201, API RP 2RD and API RP 1111. According to these codes, designers are responsible for selecting
the most suitable material for pipeline and riser considering operational and installation requirements like required
design life, fluid corrosiveness, integrity management and others. Dimensions of pipelines and risers, e.g. inner
diameter, outer diameter and wall thickness, are defined as a function of flow assurance analyses, loadings to which the
pipe will be subjected to during installation and operation and the availability of materials on supplying market. As the
number of possible scenarios is virtually infinite, standardization of variables allow manufacturers and suppliers to be
prepared in order to supply pipes in a shorter time than the usual as necessity arises from the client. However, variables
like pipe dimensions and material properties must be established by pipeline and riser designer (and consequently pipe
purchaser) in earlier stages of pipeline/risers projects, sometimes without all required information available. This paper
addresses the selection and standardization of material properties, dimensions and manufacturing tolerances of pipes
recently performed in order to define the specific requirements to be used on subsea pipelines and risers for the
development of PETROBRAS deep and ultra-deep water oil and gas fields. As a result of the standardization process,
four technical specifications have been developed based on actual revision of DNV-OS-F101. The specifications modify
or add requirements from DNV-OS-F101 as discussed with main pipe manufacturers in Brazil and main installation
contractors who have been working with PETROBRAS in the last decade.
1. Introduction
The development of offshore oil and gas fields is based on a subsea field layout which allows the exploitation
of the reservoir optimizing time and cost. In general, the subsea layouts consider the use of flexible or rigid pipelines to
connect the wellhead to the production unit and the use of rigid pipelines to export fluids after processing. The system
complexity rapidly increases when large fields at ultra-deep water and far from the shore are to be developed. As a
direct consequence, costs and time also increase and the field exploitation may become not so economic attractive.
Aiming to reduce time and costs of field layout implementation, PETROBRAS has decided to perform a
workshop involving the major rigid pipe manufactures and pipelaying contractors which have been in Brazil. The
workshop happened on first semester of 2014 and as a total three pipe manufactures and six pipelaying contractors were
involved. The main goal of the workshop was to develop a solution to subsea layouts considering the use of rigid
pipelines and risers in order to reduce the timing and costs of field development.
After initial discussions, an action plan was created with thirty specific subjects to be studied, agreed and
implemented. Workgroups were created joining representatives of each company and a schedule was defined. Two of
the subjects were directly related to pipeline standardization:
• Standardization of pipe diameter, wall thickness and material properties (seamless and welded pipes);
• Standardization of clad pipes and lined pipes.
For each subject a set of deliverables was defined, corresponding four technical specifications in total:

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• One technical specification for C-Mn seamless pipes and another technical specification for C-Mn SAWL
pipes;
• One technical specification for lined pipes and another technical specification for clad pipes.
1.1. Abbreviations
CRA - Corrosion Resistant Alloy
CTOD - Crack Tip Opening Displacement
DNV GL - Det Norske Veritas
ID - Internal Diameter
NDT - Non-destructive Testing
SAWL - Submerged Arc-welding Longitudinal
SMYS - Specified Minimum Yield Stress
2. Scenarios for Standardization
Prior to discuss any standardization of material properties, manufacturing parameters and construction
requirements, the workgroup agreed to define a typical scenario where the unification would be useful. As the main goal
was to develop a solution to subsea layouts at deep and ultra-deep waters, the Brazilian pre-salt area was a natural
choice.
The pre-salt area contains several fields at Santos Basin and Campos Basin, both located at offshore southeast
region in Brazil. Water depths of 2200m were already studied and the production is ongoing. Fields located at deeper
waters, 2500m for instance, are a possibility for future projects. Flow rates were estimated based on reservoir data which
are already in production and on fields that are still being studied. Production pipelines (oil, gas and multiphase streams
from well to production unit), water and gas injection pipelines and service pipelines (gas lift) also were considered. In
order to take advantage of all knowledge within workgroup, it was decided to study and also to define scenarios for
export pipelines. As a consequence, not only scenarios considering the use of seamless pipes were defined but also
scenarios considering the use of SAWL pipes.
In order to fulfill Brazilian regulation, an international and recognized design standard was selected. The
natural choice was the DNV-OS-F101 (2013) standard once this is the most common subsea pipeline design standard
adopted worldwide. The material selected for wall thickness assessment was steel pipe with 450MPa (SMYS),
fabrication factor 0.85 for SAWL pipes and 1.00 for seamless pipes. Wall thicknesses were calculated considering
pressure loads only (internal and external typical values observed for pre-salt fields). Loads due to fatigue during
installation and operation and also localized loads induced during pipeline installation were not considered (these checks
shall be performed case by case. The selection of a representative case may be a tricky situation since environmental
conditions and other factors should be considered). Safety classes were defined in accordance with DNV-OS-F101
(2013).
2.1. Scenarios for Production, Water and Gas Injection and Service Pipelines
Production and water injection scenarios were defined considering the use of clad/lined pipes due to the
corrosiveness of the fluids. In addition, for water injection pipes the requirement of purity of the fluid was considered in
order to avoid the injection of solid particles within the reservoir which could block the porous media. The defined
scenarios for production and water injection are shown in Table 1. Dimensions shown on Table 1 consider the backing
steel only (corrosion resistant alloy thickness is not considered).
Table 1. Scenarios for production and water injection pipelines.
Nominal Diameter (in) Nominal Thickness (mm) Outer Diameter (mm)
6.5
14.3 199.7
20.6 212.3
25.0 221.1
8.0
16.7 242.6
23.6 256.4
30.0 269.2
8.5
17.8 257.5
25.1 272.1
32.0 285.9
10.0
20.9 301.8
29.5 319.0

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38.0 336.0
12.0
25.0 360.8
35.4 381.6
40.0 390.8
16.0
33.4 479.2
39.0 490.4
47.2 506.8
2.2. Scenarios for Gas Injection and Service Pipelines
Scenarios for gas injection and service pipelines were defined considering the use of C-Mn pipes without any
corrosion resistant alloy. The dimensions selected are shown in Table 2.
Table 2. Scenarios for gas injection and service pipelines.
Nominal Diameter (in) Nominal Thickness (mm) Outer Diameter (mm)
4.0
12.7 127.0
20.0 141.6
6.0
16.2 184.8
25.4 203.2
28.0 208.4
8.0
21.0 245.2
37.0 277.2
10.0
25.4 304.8
32.5 319.0
44.5 343.0
12.0
29.3 363.4
37.0 378.8
52.5 409.8
2.3. Scenarios for Export Pipelines
Similarly to gas injection and service pipelines, scenarios for export pipelines were defined considering the use
of C-Mn steel pipes. As export pipelines may have large diameters, both seamless and SAWL pipes were considered.
The boundary for each manufacturing method was defined in accordance with local suppliers’ capabilities. The
dimensions selected are shown in Table 3.
Table 3. Scenarios for export pipelines.
Nominal Diameter (in) Nominal Thickness (mm) Outer Diameter (mm)
24.0
35.3 539.1
32.8 544.0
30.4 548.7
28.2 553.3
25.8 558.0
23.3 563.0
20.0
33.5 441.1
31.1 445.9
28.7 450.5
25.9 456.3
23.0 462.0
20.7 466.6
18.0
30.6 396.0
27.7 401.8
25.4 406.4
22.5 412.3
20.0 417.2
18.6 420.0
14.0
25.5 317.3
23.2 321.9

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21.0 326.3
19.0 330.4
17.7 332.8
2.4. Standardization x Optimization x Special Cases
Standardization and optimization may be considered two different solutions which compete and cannot be
adopted simultaneously. Main advantages of each one may be summarized as follows:
• Standardization: variables and parameters are defined in an early stage of the project; changes are more
likely to happen. Number of possibilities to be considered are reduced, potential savings in time due to the
possibility of purchasing materials in advance are normally expected;
• Optimization: variables and parameters are defined in a later (more mature) stage of the project; changes are
less likely to happen. Comparing with the first condition above, the number of possibilities to be considered is
greater, nevertheless potential savings in cost due to the possibility of purchasing materials strictly as required
could be the major advantage for this solution.
As the main goal of the workshop is to obtain savings in time, standardization is clearly the option to be
adopted. However, due to early stages of development of pre-salt fields and consequently shortage of available data, the
defined scenarios shown in Tables 1 to 3 may be revised. Special cases may also occur, especially when considering the
development of fields outside the pre-salt fields located in Brazil’s southeast. For instance, the definition of a set of
scenarios is important in order to make evaluations from pipe manufactures more representatives when analyzing
subjects like dimensional tolerances, manufacturing capabilities, etc.
The scenarios defined do not consider pipe manufacturers limitations. Dimensions were also defined
considering standard values informed within suppliers’ catalogues, when convenient. Occasionally, pipe suppliers’
actual capabilities may not be sufficient. If this is the case, two options should be considered: spend time and money in
order to improve suppliers’ capabilities; or revise the scenarios.
3. Standardization of Requirements for C-Mn Steel Pipes
Requirements for C-Mn steel pipes were defined based on DNV-OS-F101 (2013). Available technical
specifications made by PETROBRAS engineers and which had been used on previous projects were considered as a
base case. Discussions were on main subjects as follows:
• Definition of dimensional tolerances: despite dimension tolerances (out-of-roundness, straightness,
thickness, etc.) defined by DNV-OS-F101 (2013), pipelaying contractors are interested in as less variation as
possible. This is due to welding timing offshore which impacts on daily laying rates and consequently on timing
and cost of the project. However, reducing acceptance ranges impacts directly on pipe manufacturing costs due
to the rejection rates, normally, increase (in re-process, for example). The goal was to achieve the dimensional
tolerances which are feasible for pipe manufacturing but also do not have a significant impact on offshore
activities. Achieving a consensus the next step is to adopt tolerances in accordance with DNV-OS-F101 (2013)
standard for flowlines and more stringent tolerances for risers. For this scenario, a case by case study shall be
performed.
• Definition of chemical composition: pipelaying contractors require a weldability test in order to reduce risks
during offshore activities. The proposal is to define the chemical composition of pipe material in advance in
order to allow contractors to develop welding procedures adequate to the supplied pipe material.
• Definition of mechanical parameters: mechanical properties such as yield to ultimate strength ratio,
hardness and toughness should be defined in order to standardize the pipes. Hardness, for example, as others
can influence the weldability of pipes. In this case, an agreement was achieved to follow DNV-OS-F101 (2013
requirements).
After achieving an agreement on all issues raised up by pipe’ manufacturers and pipelaying contractors, DNV
GL was officially involved in order to validate all definitions made by workgroup. Having DNV GL approval, the
technical specifications for seamless (Figure 1a) and SAWL (Figure 1b) C-Mn pipes were issued at the beginning of
2015.

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(a) Seamless pipes (image courtesy of Vallourec Tubos do Brasil S.A.)
(b) SAWL pipes (image courtesy of TenarisConfab Industrial S.A.)
Figure 1. Seamless and SAWL pipes.
4. Standardization of Requirements for Clad Pipes
The clad pipe workgroup, through a series of meetings, has commented and discussed the requirements of
PETROBRAS technical specification for clad pipes (Figure 2). Besides PETROBRAS, the workgroup was formed by
pipe suppliers and pipelaying contractors. Several comments were issued by suppliers and contractors and were suitably
treated by PETROBRAS. The main changes made in the specification to comply with the comments of this workgroup
are described in the following paragraphs. It is also worth noting that the revised text was submitted to DNV GL for
comments and verification, in order to check the consistency of the whole specification requirements with DNV-OS-
F101 (2013) standard.
The major point in the referred specification was a specific indication of amendments to each item of DNV-OS-
F101 (2013), adopting [Addition] for additional requirement and [Modification] for modified requirements.
New tables were also included. All these changes were performed in order to have suppliers, PETROBRAS and
pipelaying contractors agreements and understanding of additional or modifications to DNV-OS-F101(2013) clauses.
Additional requirements to the following items were included:
• ID pipe roughness;
• Internal pipe end machining;
• Compression tests;
• Additional CTOD testing;
• Ring splitting residual stresses testing;
• Corrosion testing in accordance with ASTM G48;
• NDT acceptance criteria;
• Reel-Lay Installation;
• Strengthening effects of CRA layer.

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Figure 2. Clad pipes (layer of Corrosion Resistant Alloy is metallurgicaly bond) while the lined pipe is applied
through a mechanical bond between the CRA and the C-Mn pipe (image courtesy of TenarisConfab Industrial S.A.)
5. Standardization of Requirements for Lined Pipes
The same methodology performed on clad requirements was followed to discuss the lined additional
requirements to DNV-OS-F101.
Special discussions happened regarding the following items:
• Validity of Full scale tests;
• Fatigue full scale tests;
• Bending full scale tests;
• NDT Clad weld qualification tests;
• Utilization on fatigue sensitivity locations on rigid risers.
6. Final Considerations
In order to have a competitive solution considering the use of rigid pipelines and risers for subsea layouts of
fields located at deep and ultra-deep water, PETROBRAS performed a workshop with main pipes’ suppliers and
pipelaying contractors. The main goal was to standardize parameters and requirements to save time during project
implementation. Thirty subjects were studied, being two of them related to pipe standardization:
• Standardization of pipe diameter, wall thickness and material properties (seamless and welded pipes);
• Standardization of clad pipes and lined pipes.
Workgroups were defined and meetings happened in order to achieve a consensus regarding pipe suppliers,
pipelaying contractors and PETROBRAS interests. Four technical specifications were issued and approved by
certifying authority:
• Technical specification for C-Mn seamless pipes;
• Technical specification for C-Mn SAWL pipes;
• Technical specification for lined pipes;
• Technical specification for clad pipes.
Scenarios were defined in order to provide a forecast of future necessities of PETROBRAS regarding rigid
pipelines. However, defined scenarios may be revised when new data from pre-salt fields are available and/or in
accordance with pipe suppliers’ capability of manufacturing.
All companies involved agree that standardization is feasible and expectation is to reduce timing when
implementing new projects considering rigid pipelines and risers. Next steps (qualification programs, contractual
agreements, etc.) should be addressed this year.
7. Acknowledgements
The authors would like to thanks Petróleo Brasileiro S.A. and all pipe manufacturers and pipelaying contractors
who contributed to the workshop and consequently to this paper.

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8. References
API RP 1111. Design, Construction, Operation, and Maintenance of Offshore Hydrocarbon Pipelines (Limit State
Design). 2011.
API RP 2RD. Design of Risers for Floating Production Systems (FPSs) and Tension-Leg Platforms (TLPs). 2006.
ASTM G48. Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys
by Use of Ferric Chloride Solution. 2011.
DNV-OS-F101. Submarine Pipeline Systems. 2013.
DNV-OS-F201. Dynamic Risers. 2010.