RINA Approach To The Offshore Enhancing Safety and Profitability

Stefano COPELLO RINA SERVICES S.p.A.

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

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

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

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?

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

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

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

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

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

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

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

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

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.

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.

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

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

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

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

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

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

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

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

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

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