RINA Rules for the Classification or Certification of Steel Fixed Offshore Platforms – 2015 Edition

1. RINA Approach To The Offshore
Enhancing Safety and Profitability
Stefano COPELLO
RINA SERVICES S.p.A.

2. RINA, the former Italian Register of Shipping, is a multi-national group
dedicated to support its clients in the development and management of the
various phases of their activities, offering through dedicated companies
consulting engineering, certification services, testing and inspections
 Over 150 years of experience
 Tailored high innovative solutions
 Specialized skills coverage throughout project life cycle
 Prompt responses
 Global network

3.  IACS Founding Member
 1st Italian certification body
 Global Network
 + 30 years of experience in
offshore platform
certification
Classification
Native Marine Business
Certification
System, Product, Personnel and
Project Certification
Testing & Inspection
Inspection, Site Supervision and
Testing for O&G and T&I Clients
Certification of Fixed
Offshore Platforms

4. Since 70s RINA offers certification services for design, construction and
installation of offshore platforms aimed to oil and gas production from the
offshore reservoir
150+ offshore platforms certified
(Mediterranean, West Africa,
Caspian Sea, …)
Certification is aimed to ensure
the compliance of the structure
and equipment with internationally
recognized industrial standards
(such as API or ISO)
or Applicable National Regulations
(ref. to Territorial waters)
Certification of Fixed
Offshore Platforms

5.  In today's increasingly more attentive and demanding market, the
certification procedure, in which a third party gives written assurance that
a product complies with specified requirements, is a tool of great economic
and social utility
 Certification of an offshore platform has the main purpose to ensure, by
performing a third party independent review of the project, that the
industrial plant going to be installed in a socially sensitive scenario, will
respect objective parameters of safety in order to reduce as low as
reasonably possible the risk to human life and environment, eventually
allowing the owner to be facilitated in the permission and insurance
processes
Why Certification?

6.  Offshore platforms are to be designed and
constructed so as:
 To ensure an acceptable standard with regard to
the safety of life at sea and to the prevention of
environmental pollution
 To prevent possible major economic losses during
all phases of the design life
 The certification covers all phases of an offshore
project after its preparation and throughout all
stages of construction and operation (up to removal
or reuse):
 Design (3rd Party Independent Verification)
 Fabrication at onshore yard (Survey)
 Offshore installation operations (Survey)
 Service Life (Periodical follow-up surveys)
Certification
Requirements

7.  Initial design and construction appraisal
SAFETY and OPTIMIZATION OF CAPEX
 Modern design codes (ISO 19900 series)
 Risk Exposue Categories
 LRFD Format
 Platform Dynamics (Seismic/Fatigue)
 Foundation model
 Modern technologies for fabrication /NDT
 Service life (20-25 years design target)
MAINTENANCE COST REDUCTION (OPEX)
 Reliability based inspection and maintenance plan
NEW RULES
FOR
CERTIFICATION
Certification
Drivers / Benefits

8. The number of existing fixed
offshore platforms nearing the end of
their design life is increasing
The regulatory framework
for offshore platforms is changing
(new European Directive
2013/30/EU)
Pressure on platforms operators and designer of new units
Business Challenge

9. The existing structure is fit-for-
purpose when the risk of structural
failure leading to unacceptable
consequences is adequately low
Due to a change in economic conditions - and an increase in oil & gas recovery
possibilities - operators often want to continue exploiting platforms beyond
their 20-25-year designed lifecycle instead of investing in a new platform
 The challenge is to continue to use, in safety conditions, offshore
platforms that have reached the end of their designed lifetime and have
this extended use approved by statutory authorities
Safety and environment are still
essential but focus shall be also on
cost reduction and production
optimization
NEW RINA RULES
Platforms life extension

10. When the platform is ageing, and is planned to remain in service longer than its
original design lifetime, a comprehensive reassessment of the platform
conditions is to be carried out before any life extension
The reassessment takes into account:
 Actual conditions of the structure
 Recent metocean data and updated calculation methods for the re-analysis
 Platform history data
Key benefits
 A new or continued License to Operate
 Reduction in amount of repairs and reinforcements required
 Confidence for the operator, regulatory agencies and surrounding
community that the platform is safe and reliable
Life extension target

11. The required safety target shall be demonstrated for the specific site
conditions and given operational requirements
The original design target was ensured (typically with respect to the extreme
environmental event, related in turn to a prescribed design life) introducing
some conservativisms
 Uncertianties in platform actual response (still to be realized)
Reassessment is possible by taking into account the new information and
measurements due to the actual behaviour of the platform and its history
 Platform as its own Full Scale Model
 Reduced Uncertianties
 Margin for Design Life Extension
Design life extension
principle

12.  More than 80 platforms verified (mainly in last 15 years) for various
operators:
 ENI/Petrobel/Eni Congo/Edison/DOTL/ONGC
 Adriatic Sea (28)
 Sicily Channel (3)
 Mediterranean (Egypt) (2)
 Red Sea (11)
 Offshore Congo (13)
 Offshore Nigeria (2)
 Caspian Sea (9)
 Indian Ocean (22)
 Jacket engineering reassessment (main issue):
 Fatigue & Corrosion
 Life extension based on inspections/maintenance records
 Future IMR Planning
RINA experience in certification
of existing platforms

13.  A cradle-to-grave framework for the structural and process safety of the
platform
 Design, fabrication, installation, life extension assessment and de-
commissioning are all covered
 Platform designers and operators can choose from and mix three
approaches:
 Classification
 allows the platform to be built and maintained against a set of rules
covering the whole service life
 Certification
 measures the platform structure and topside process against set
international or local standards
 Verification
 is the new risk-based Safety Case, regulatory system to the entire EU
from 2015, in increasing use globally, with the aim of significantly
reducing the risk of accidents and environmental damage
New RINA Rules

14. RINA Rules for Classification and Certification of Fixed Offshore Platforms – 2015 Ed.
 PART A
– APPLICATION AND GENERAL
– CLASSIFICATION CERTIFICATION AND INDIPENDENT VERIFICATION
– MAINTENANCE OF CLASS OR EXTENSION OF THE CERTIFICATION
 PART B
– GENERAL PRINCIPLES
– ENVIRONMENTAL CONDITIONS
– DESIGN LOADS
– STRUCTURAL ANALYSIS
– FOUNDATIONS
– ASSESSMENT OF EXISTING STRUCTURES
 PART C
– GENERAL REQUIREMENTS
– PRODUCTION, PROCESS AND ANCILLARY PIPING SYSTEMS
 PART D
– MATERIALS FOR STRUCTURES
– MATERIALS FOR PROCESS PIPING SYSTEMS
– STRUCTURE FABRICATION
– PIPING FABRICATION
– QUALITY ASSURANCE / QUALITY CONTROL
– PROTECTION AGAINST CORROSION
 PART E
– MARINE OPERATIONS
RINA Rules - 2015 Ed.

15. PART B CHAPTER 6 – ASSESSMENT OF EXISTING STRUCTURES
1 General
2 Assessment Process
2.1 Assessment data gathering
2.2 Inspection on the current platform status
2.2.1 General requirements
2.2.2 Requirements for submarine survey
2.2.3 Level I
2.2.4 Level II
2.2.5 Level III
2.2.6 Level IV
2.2.7 Survey Specification
2.2.8 Survey Procedure
2.3 Definition of the up-to-date platform model
2.4 Definition of the loads
2.5 Verification of the platform structure
2.5.1 Resistance assessment
2.5.2 Fatigue assessment
2.5.3 System assessment
2.5.4 Reference values for the Reserve Strength Ratio
RINA Rules for the Classification
or Certification
of Steel Fixed Offshore Platforms – 2015 Ed.

16. Limited failures of individual components are accepted if the reserve against
overall system failure remains acceptable.
The platform has shown appropriate performance via full-scale model, i.e. the
platform itself
Yielding or failure of individual components is acceptable, if the remaining
parts of the structural system have sufficient reserve strength to redistribute
the action
A pushover analysis is used to demonstrate that the safety factor against
failure of the whole structural system meets acceptable levels (RSR target)
Strength Assessment
The system approach

17. Ultimate strength analysis by elasto-plastic analysis.
Environmental loads increase up to the whole system collapse. The verification is considered satisfied
when the collapse load will result “appropriately” greater than the design load
Non-linear push-over
 Loads are applied in sequence:
 Dead and live loads are applied
to their nominal value
 100-year environmental load
vector (wave, current and wind)
is applied and increased until
the structural collapse of the
whole platform
 RSR: ratio between base shear
resistance and design load
(Rd/F100)
The system approach

18.  When it is not possible to show that the structure is acceptable even by RSR
 decreased reliability of the overall system could be acceptable, provided
that the consequences of failure are acceptable for both the life and the
environment
 e.g. de-manning the platform and provide for safety system to close the
wells in case of foreseen extreme environmental event
 Notional yearly probability of failure evaluation by SRA to determine
maximum extreme wave (return period) and relevant residual life
The system approach

19. Existing platform installed in the Caspian Sea, offshore Turkmenistan, in
about 27m w.d.
 several jacket modules with vertical legs
 topside lattice frames
 drilled and grouted piles
Reassessment analysis carried out in n 2011-2014 (9 platforms)
Target: life extension
Possible strengthening, also to support foreseen work-over rig
Push-over analysis considering the most critical environmental loading
Example of residual life
evaluation

20. Minimum RSR = 1.02
probability of collapse Pc = 2.75x10-2,
safety index b = F-1 (- Pc) = 1.919
Reference ‘target’ RSR = 1.2
‘target’ value of b = 2.253
design life of 20 years
Actual life 10 years
Allowable wave return period 85 years
maximum allowable wave height 10.2 m
Life extension
assessment results

21.  The platforms are characterized by an overall level of safety that can be
considered acceptable for a design life of about 10 years
 The platforms would be globally able to withstand a maximum wave height
characterized by 50 yrs return period, i.e. a maximum wave height of 10.2m
(wrt NW incoming direction)
 Conditional Certificates issued
– Required repairs and strengthening measures as identified by relevant
analysis and drawings are to be carried out
– The platforms are to be evacuated and consequently subject to a special
survey in the event where a sea state characterized by maximum wave
height of 10.2m occurs during the recognized 10 years of lifetime
Conclusions: conditional
certificates

22. By adopting a reliability based fatigue approach it is possible to account for a
new possibility, which is of paramount importance to the management of
structural safety:
 The results of the in situ inspections can be utilized to update, in
quantitative terms, the structural reliability evaluation
 The reliability index is evaluated as a function of the time passed since
installation, the expected endurance of the node at the design stage and
the results of the node inspection
Maintenace optimization example
Reliability based fatigue approach

23. b
T
bo
bup
Inspection outcomes combined with
fatigue predictions:
 Reliability approach to update fatigue
safety margin and to plan future
inspections
 Fatigue safey margin as b(t)
 Updating of b at a given time of
inspection
 Reducing uncertainty -> increasing
safety margin, particularly in case
that no cracks are detected
Optimal inspections
planning

24.  Optimal Inspection Planning
 When required
 Increase in safety
 Less frequent inspections when the
structure is new or well-manufactured,
increase in frequency when older
 Optimal Maintenance
 Cost Saving
 Less number of offshore campaign
wrt regular scheduling
RELIABILITY BASED
24
Optimal inspections
planning

25. RINA SERVICES S.p.A.
Via Corsica, 12
16128 Genoa - Italy
Ph. +39 010 53851
Fax +39 010 5351000
info@rina.org
www.rina.org
Stefano Copello
Ph. +39 010 5385872
Mob +39 335 8749142
stefano.copello@rina.org