Germanischer Lloyd – Service/Product Description
Plant Integrity Management Contents
Service Title: Asset Management Services Page 3 Service Description and Values Generated
Lead Practice: GL Asset Management (UK) Pages 4 - 12 Detailed Method Statement
a: Plant Integrity Management System Audits
b: Corrosion Management
c: Material Defect and Component Failure
d: Fitness for Service Assessment
e: Written Schemes of Examination
f: Coatings Services
g: Welding Services
h: Risk Based Inspection
i: Pipework Vibration Services
Pages 12 - 22 Case Studies and Examples
a: Corrosion Management of LNG Storage Facilities
b: Integrity Management Review
c: Fracture of Thermowell
d: Failure of Impulse Pipework Compression Fitting
e: Fitness-for-Purpose Assessment of Pressure Vessels
f: Fracture Mechanics Assessment of a Defective Pig Trap
g: Defect Assessment of Corroded Pipework
h: Review of Integrity Management Framework
i: Safety Management Audit
j: Fitness for Service Assessment
k: Repair of Amine Stripper
l: Investigation of Coating Failure on Oil Storage Tank
and Values Generated:
Pages 23 - 32 Case Studies and Examples Germanischer Lloyd (GL) provides a range of Plant Integrity
Management services to assist Operators in managing their assets in
m: Corrosion Management Study a safe and efficient manner, as well as complying with all prevailing
regulations and legislation.
n: Weldability Testing of 48” Diameter X80
Europipe Production GL are able to tailor their services to meet client needs and can
generally provide support & solutions to a range of Integrity
o: Design and Qualification of Repair Management problems.
Procedures for Bellows Attachment Welding
Supporting each of the core services are experts with many years
p: Evaluation of RBI Software experience in integrity management.
q: T-OCR Risk Based Inspection
r: Investigation of Double Block and Bleed
Valve Vibration at a Gas Processing Facility
s: Long Term Monitoring of Pipework
Vibration at Gas Compressor Stations
t: Assessment of Risk of Pipework Failure Due
to Vibration During Offshore Plant Uprating
u: Vibration Screening at an Onshore Gas
DETAILED METHOD STATEMENT
a. Plant Integrity Management System Audits b. Corrosion Management
In general, an audit or review of an Integrity Management System will GL’s approach to corrosion management is to consider the process,
begin with a Gap Analysis. This entails a thorough review of the materials and safety aspects as an integrated whole. In most respects
Operator’s activities from corporate policy and organisation through the process dictates the materials and corrosion control methods used
to company procedures and work instructions, including the on plant while occasionally the materials technology available will
following: shape the feasible process solutions. Ultimately, the objective is to
produce a system that assures the safety of plant operations. Thus, all
Compliance with national legislation and local have to be addressed when considering corrosion management.
The production of a corrosion management system would
Integrity threats and mitigations in place generally involve the following stages:
- Onshore – mechanical damage, corrosion, ground 1. Gather process data e.g. temperatures, pressures and
movement etc fluid compositions during both normal operation and
- Offshore – mechanical damage, stress/fatigue type upset conditions
material failures, internal and external corrosion etc
Quantitative risk assessments undertaken 2. Consider the safety risk assessment in order to:
Engineering documentation Identify pressurised systems
Plant records and fault data Identify major hazards
Quality, health, safety and environmental issues Identify HAZOP actions related to corrosion and
Plant Operations and Maintenance
- Work scheduling 3. Conduct corrosion risk assessment including:
- Record keeping
- Routine and non routine activities Calculation of internal corrosion rates
Plant Inspection Assessment of stress corrosion cracking threat
Modification and repair process Assessment of erosion threat
Emergency management Assessment of external corrosion including under
Defect assessment and repair methods
Training and competency of staff
Safe control of operations
Continuous improvement processes in place
The Integrity Management System under review can then be assessed
for compliance with prevailing regulations and compared to
international “best practice”. Recommendations can be made to the
Operator as to how they can improve their processes and systems.
Generally in such a project there will be a Phase 2 which comprises
gap closure actions. Depending on the results from the gap analysis
this might entail a complete overhaul of an Operator’s Engineering
Documentation System or it may involve some rationalisation and
repackaging to ensure that the IMS is clear and coherent.
DETAILED METHOD STATEMENT
4. Produce corrosion management scheme c. Material Defect and Component Failure Investigation
Select materials (corrosion resistant alloys or carbon GL’s approach to failure investigations is not only to use state of the
steel with corrosion allowance) art methods to determine the immediate cause of the failure, but also
to identify the root cause and propose solutions for eliminating the
Select corrosion control methods (e.g. inhibition, problem in future.
coatings, cathodic protection)
There are many reasons why a material defect or failure may arise; for
Select corrosion monitoring methods and locations example:-
Produce corrosion data management strategy and Incorrect materials selection,
Materials quality issues,
Devise suitable key performance indicators (KPI) for
corrosion management Fabrication issues,
Document change procedure for revising scheme if Operating conditions outside original design parameters,
process parameters are altered (e.g. after
debottlenecking) Environmental factors,
Produce plant/field corrosion management guide/ Maintenance and protection issues,
Human and procedural factors,
5. Feed back the corrosion management activities into the Third party damage.
field safety case and risk assessment as mitigating factors
The scope of a failure investigation depends upon the nature of the
failure and also upon the results obtained as the investigation
An important first step is to ensure the failure is preserved for future
examination, particularly where this may be used as evidence for
litigation purposes. This may involve visits to site to assist in
identifying, examining and collecting all relevant material, and
stabilising and protecting as necessary for transport to the laboratory.
In the event of a dynamic failure, such as an explosion resulting in
extensive damage, this may be a difficult and arduous task as the
majority of the failures evident will be ‘effect’ and not necessarily
directly relevant to identifying the cause. In these circumstances
detailed photography is essential before any material is removed from
the site of the failure. It is also important to talk to site personnel to
establish the circumstances surrounding the failure and operating
conditions at the time.
Where the failure involves a defect in a component or structure it is
important that NDT (Non Destructive Testing) is carried out to
determine the extent of the failure and any associated damage prior
to extraction for detailed analysis. GL NDT experts offer a range of
techniques, both on-site and in the laboratory, including: magnetic
particle inspection (MPI), dye penetrant testing (DP), manual
ultrasonic testing (MUT), alternating current potential drop (ACPD),
and mechanical measurements.
For characterising the defect or failure a metallurgical examination
and materials testing programme is carried out.
DETAILED METHOD STATEMENT
A metallurgical examination of a defect or failure would typically d. Fitness for Service Assessment
GL routinely undertakes assessments of damaged pressure vessels and
Visual examination by eye and using a stereo optical pressure systems for an international clientele of asset owners/
microscope operators worldwide. We have in-depth knowledge and experience in
the use of industry recognised assessment methods such as:
Detailed fractography using a scanning electron
microsope (SEM) API 579
Surface compositional analysis by semi-quantitative X-ray RSTRENG
energy dispersive micro-analysis (EDX) in the SEM
Preparation of weld sections for macro-examination and
hardness surveys BS7910
Preparation of mounted and polished sections for ASME VIII
microstructural analysis and to confirm crack path
Materials testing, to establish compliance with relevant standards and BS EN13445
to generate mechanical property data for supporting engineering
analysis assessments, would typically involve:-
GL therefore have the capability to assess the integrity of pipework
Chemical composition and pressure vessels and routinely use advanced numerical techniques
such as the finite element (FE) method and pipe stress analysis to
Tensile testing (e.g. yield strength, ultimate tensile strength, undertake fitness for service assessments. We have excellent
elongation etc, and specific tests for threaded fasteners) knowledge of the UK Pressure Systems Safety Regulations, 2000
(PSSR) and relevant US Code of Federal Regulations (e.g. CFR 192 and
Hardness testing 195).
Charpy impact testing For any fitness-for-purpose assessment, assumptions are required on
the input parameters. These assumptions include:
Fracture mechanics testing (such as CTOD and J-integral)
Original equipment design data
The output from the metallurgical analysis and materials testing Operational and maintenance history
programme would offer the customer an opinion on the mode and likely
cause of failure, and an understanding of the contribution of material Expected future service
related factors. It is usual to complement the metallurgical examination
and materials testing programmes with an engineering analysis to Information specific to the assessment such as defect
identify and understand the contribution of mechanical factors. sizes, stress state, location of flaws, and material
properties such as tensile strength and fracture
Depending upon the nature and scope of the investigation further toughness.
analysis may be carried out to understand the wider implications of
the failure and to ensure that recommendations for preventing further Fitness for Service can be demonstrated using methods such as stress
failures are implemented, for example:- analysis, defects assessment and fracture mechanics approaches.
These are described as follows:
Detailed fracture mechanics analysis to determine safe
Fitness for purpose assessments
Remaining life analysis
Review and update of operating procedures
Review of asset integrity and inspection programmes
(such as RBI)
DETAILED METHOD STATEMENT
Stress Analysis Defect Assessment
Fitness for service can be demonstrated using higher level assessment Defect assessment is a deterministic approach used to assess the
methods such as FE (Finite Element Analysis). GL can undertake work integrity and fitness for service of defects found on pressure vessels or
ranging from the stress analysis of individual structural components piping. Defects are features that affect the structural integrity of
such as pressure vessel nozzles, full pressure vessel models to vessels, pipelines or piping, and may be located on the surface of the
complete piping systems. GL consultants have the capabilities to pipe wall or actually inside the material of the pipe or shell. There are
undertake advanced non-linear, static/dynamic analysis, vibration, numerous codes that can be used to assess defects and are
thermal and fatigue analyses. We use these capabilities to undertake summarised in documents such as the Pipeline Defect Assessment
fitness-for-service assessments of pressure systems and in conjunction Manual used for pipelines, which our consultants understand the best
with full scale testing facilities to develop defect assessment methods methods to use. In addition, GL has experience in conducting
for pipelines and pressure vessels. GL uses an extensive range of FE assessments to API 579 and BS 7910 used for pressure vessels and
and associated software tools that are mounted on both SUN Unix piping.
network and PC based Windows system. The software tools we use
include: Sources for defect data include NDT methods. Using in-house
expertise, appropriate assessment methods can then be chosen and
ABAQUS (Standard and Explicit) FE analysis program applied to demonstrate fitness-for-service in order to satisfy regulatory
requirements and operators’ integrity management strategy.
MSC/PATRAN and ABAQUS CAE FE pre and post
processor programs Damage assessment capabilities include the following;
PC based software such as MathCad and MATLAB i) Manufacturing Damage, Manufacturing features are
often a discontinuity in the geometry of the pipe or shell
In addition to the above, our consultants can write customised such as a reduction in wall thickness or in the material
programs, user subroutines, etc. in order to overcome the limitations itself.
in proprietary software. Areas of expertise include;
ii) Construction Damage, Construction defects may
Linear and non-linear analysis. Where necessary, include girth weld defects or seam weld defects caused by
non-linear effects can be included in the analysis; this can lack of fill or misalignment, and in the most severe case,
be through the modelling of non-linear material cracking. Also, other forms of damage may occur such as
behaviour, geometric non-linearity and contact indentation damage, corrosion at the girth weld, or even
damage to the external coating.
Buckling, postbuckling and collapse analysis of pipelines
iii) 3rd party interference, 3rd party damage is often the
Soil structure interaction most severe form of damage resulting in failure of the
pipe or requiring immediate repair. Often this involves
Steady state and transient heat transfer analysis mechanical damage such as a gouge resulting in metal
loss of the pipe wall, or distortion of the pipe wall such as
Fatigue and fracture mechanics; cracked body analysis a dent.
Design by analysis iv) Operational damage. Defects arising from operational
usage include external corrosion caused by damaged or
disbonded coating where the Cathodic Protection System
is not effective. Also internal corrosion caused by water in
the product, and even other forms of corrosion namely
‘Sweet Corrosion’ and ‘Sour Corrosion’ may occur in
Windows is a trademark of MicrosoftTM corporation
DETAILED METHOD STATEMENT
Fracture Mechanics e. Written Schemes of Examination
BS7910 and similar codes such as the UK nuclear industry code R6 The Written Schemes of Examination (WSoEs) will be logically
and API 579, carry out fracture assessments using the Failure structured to allow for effective monitoring and control and will show
Assessment Diagram (FAD). This provides a graphical method for individual pressure systems within each of the major systems. The
assessing the proximity of a loaded structure containing a defect to components that require periodic inspection in order to ensure
failure by fracture and plastic collapse mechanisms. Proximity to continued fitness for purpose will be identified.
fracture is characterised by the fracture ratio parameter Kr and
proximity to plastic collapse is characterised by the parameter Lr. A The WSoE will ensure that all components within the plant are
loaded structure can therefore be represented as an assessment point sufficiently inspected to ensure that any defects are detected at an
on the FAD following calculation of Lr and Kr. early stage to prevent inoperability of the asset. Such inspections may
not be limited to pressure containing components, but may also
This diagram is used in levels 1 to 3 of BS7910 to determine the include access ladders, gantries, foundations, whose failure may limit
acceptability of cracks by plotting a point on the diagram. When the operability of the plant or equipment.
deciding which level to use, this depends on the input data available
and conservatism required. These levels can be summarised as; The WSoE will be structured in such a way that will allow the User to
determine the future inspection requirements for at least a 5-year
Level 1 is a simplified assessment method when there is period, however, it is more likely that future inspection requirements
limited data on material properties for circa 10 years will be attained.
Level 2 is the normal assessment route The items of equipment covered will generally cover the following:
Level 3 is based a ductile tearing resistance analysis Pressure vessels, drums, tanks etc.
Using the fracture mechanics approach our consultants can determine
whether a defect is SAFE or UNSAFE based on the Failure Assessment Compressors
Diagram. Using the fatigue assessment approaches described in
BS7910, we can then determine the remaining fatigue life and future Filters
integrity of the structure if subjected to cyclic loading.
Pressure safety valves
Fire systems components
Compressed air and nitrogen systems
DETAILED METHOD STATEMENT
The WSoEs will be developed by:- GL will nominate competent, technical engineers, with long term
experience in compiling WSoEs for major gas transporters, to
Reviewing existing documentation pertaining to design, undertake this work. The WSoEs will be generated on Microsoft Word
manufacture, construction, testing, modifications and and Excel and be provided on CDs and hard copy. The WSoEs will be
repairs, past inspection reports, etc. and plant operation based on UK best practice and will not include any other national
records. requirements, unless otherwise stated.
Establishing safe operating limits and their protective The WSoE will be submitted to the Independent Competent Person
devices. for review and/or approval.
Identifying individual pressure systems.
Developing examination specifications from each
Identifying examination frequencies on fixed time
intervals for major items of equipment based upon
industry practices, GL experience and information as
supplied from the Client.
Liaising with the system User.
The WSoEs will typically include :-
Safe Operating Limits.
Equipment to be inspected.
Identification references of each item of equipment.
Nature and type of inspection required (visual, NDT etc.)
Functional testing requirements for protective devices.
Preparatory work required prior to inspection.
Frequency of inspection.
Detailed written inspection procedures for each item of
equipment, based on current inspection methodologies,
based upon the generic examination specifications.
Competencies/qualifications required by inspectors.
Standard report formats for recording examinations.
Identification of applicable international / national codes,
specs, procedures etc.
Applicability and adaptability to utilise the most up to
date inspection techniques for the examination of plant in
the most cost effective manner.
DETAILED METHOD STATEMENT
f. Coatings Services g. Welding Services
Many factors dictate the protection being afforded to plant and GL staff have been involved, in many cases, in the development and
equipment and these must be considered when selecting paint and qualification testing of procedures and consumables for the
coating systems for providing corrosion, erosion and chemical construction of pipelines, process plant and ancillary high pressure
resistance. Long term corrosion protection will generally require: equipment. GL carries out weldability studies on all candidate linepipe
and components used in the UK National Transmission system in
1. Identification of appropriate coating systems accordance with the requirements of National Grid specification
T/SP/MPQ/1. For line pipe this involves the production of a full scale
Identify substrate type, method of preparation, girth weld under simulated field conditions, to an approved
operating temperature, requirements for insulation, procedure and including such factors as lifting and manipulation to
contents being processed or stored etc simulate movement of the line-up clamps following deposition of the
2. Small-scale performance evaluation to ensure long-term
protection at the new construction and maintenance Additionally, repair special procedures are tested and qualified before
stage being putting into service.
Application, accelerated corrosion testing, Welding consultancy services are also required when new or difficult
performance assessment materials are involved, such as those employed for high temperature
or sour service environments and include materials such as Inconel,
3. Development of coating application specifications for duplex stainless steels or linepipe clad with these materials. In these
new construction and maintenance cases very specific welding procedure specifications are drawn up and
initial production welding is carried out under the supervision of
Surface preparation, application, inspection and GL expert staff.
GL also carries out welding prequalification of high pressure
4. Coating survey and technical audits to ensure successful components produced by new suppliers, and an investigation of the
application and compatibility with existing systems welding procedures and consumables employed by candidate
companies is an integral part of this. Site visits are carried out and
supervision of component production ensures that they meet the
GL has been involved in material selection, testing, specification relevant requirements for specific companies and individual projects
development and quality control issues to ensure long term protection and can be welded into the system without problems.
of plant and equipment.
GL also supplies expert assistance in the selection and application of
Where inappropriate coating systems have been specified, or coatings methods for weld repair of pipelines, process plant and high pressure
have been applied incorrectly, GL offer a consultancy service to help equipment. This is supplemented by expertise in inspection which
confirm the cause of failure. Laboratory test programmes help ensures that defective areas are professionally repaired and returned
establish the mechanism of failure, and to apportion blame where to service in fully reliable condition.
litigation is a likely outcome.
h. Risk Based Inspection
The main objectives of the RBI is to derive an inspection strategy that
ensures the maintenance of integrity of the plant.
To establish a minimised vessel inspection programme in
accordance with regulations
To optimise the inspection strategy for equipment
including the testing and maintenance of relief valves
To establish integrity management procedures for LNG
To reduce, and where possible, eliminate the need for full
vessel isolation and entry by utilising borescopic
DETAILED METHOD STATEMENT
The RBI methodology combines expert judgement and probabilistic A Plant Integrity Review (PIR) is then undertaken. The PIR re-evaluates
modelling. RBI software is used for the execution of criticality criticality assessments by examining process history, operating
assessments and generation of inspection plans. conditions and past inspection results. The initial risk assessment is
reviewed and verified against actual plant experience. This is an
The methodology includes procedures to define process fluids and essential step as it provides an opportunity for the degradation
systemise process streams. Within any process stream there may be mechanisms calculated by the software to be verified, by the ‘expert
changes in pressure and/or temperature of the contained fluid. A panel’ and any additional failure mechanisms to be added. Changes
system is defined as being that part of a process stream at similar to equipment criticality and confidence factors arising from the PIR
temperature and pressure; such changes may give rise to different will produce changes to the recommended inspection
corrosion regimes, or a different fluid state. Systemisation of sites is frequencies/tasks. PIR meetings should be formally recorded, using
carried out using the latest version hard copies of the piping & the appropriate PIR decision record template, with details of the key
instrumentation diagrams (P&IDs). decisions made and persons present.
As part of the RBI process, a qualitative assessment is carried out by The competent should either be present at the PIR or receive a
relevant members the RBI Project Team. This procedure uses process detailed report of any changes that are proposed, their reasons and
system information, in combination with the materials and contained the effect on periodicity for equipment covered by PSSR. Any changes
fluid properties to allocate specific operational consequence ratings that are made to the Written Schemes of Examination (WSoE) should
relating to standby, financial and location impact. This is also used to then be either made by the competent person or certified by the
highlight any particular areas of concern with respect to equipment competent person before they can take effect and job plans can be
i. Pipework Vibration Servicves
GL offers a broad range of vibration measurement and analysis
services with specialist skills and knowledge in the following areas to
determine and manage the risk of vibration-induced fatigue failure
of process pipework:
Troubleshooting service to resolve vibration related
Detailed screening of main pipe and small bore
Vibration measurement and assessment
Provision of advice and design guidance
Following data entry, an initial criticality (risk) assessment is carried
out using the current equipment design and process information. This Identification and development of optimum solutions
will generate an initial relative risk (or criticality rating) for each item
of equipment in the database, based on the probability and
consequence. Substantial experience has been gained in the investigation of
pipework vibration problems on process plant, including mechanical
The RBI software includes a module program that can be used and flow-related sources, and structural and acoustic transmission of
to develop detailed inspection plans. Although the RBI will determine vibration. This knowledge, coupled with an extensive range of
the recommended frequency of inspection, it cannot assign an experimental and theoretical techniques which can be employed,
inspection method. This must be manually selected from a list of enable a thorough investigation to be carried out. Any failure
methods. The RBI project team is responsible for populating the investigation can also draw on the substantial expertise in the
database with recommended inspection methods for each interim company regarding integrity issues on pipelines, pipework
inspection task. However, these may be amended by site once the RBI components, rotating machinery, pressure vessels and other
system is fully operational, depending on the views of site engineers, structures. In the event of a vibration related failure or identification
inspectors and the competent person. of a problem, GL are able to provide a timely response, depending
on the urgency of the request for support.
DETAILED METHOD STATEMENT
As part of a plant integrity management programme for onshore and GL has also developed a measurement, data acquisition and analysis
offshore assets, it is essential to manage the risk of potential vibration system that performs ‘long term monitoring’ of a large number of
problems on piping systems and small bore tubing. This can be sensors over extended periods, for investigation of intermittent but
achieved through a structured screening methodology which aims to significant pipework vibration problems associated with compression
quickly identify pipework at risk, assess the relative risk, and prioritise facilities and process plant. Subsequent analysis of the data provides
effort on plant areas of most concern. in-depth understanding of the operator’s specific vibration problems
to enable the implementation of a cost-effective solution.
GL have been active in developing strategies for reducing the threat
of vibration related failures in order to target potential problems and Following collection of the measurement data from a site, vibration and
demonstrate legislative compliance, resulting in a significant reduction fatigue assessment techniques are used, which have been developed
in the risk of failure at many sites. and independently validated to assess dynamic stress and vibration on
all aspects of pipework systems. Acceptance criteria have been derived
Typically a study of this type would cover the main pipework and small from BS 7608 (Fatigue design and assessment of steel structures) for a
bore connections through the following: range of common welded pipework and instrument stabbing
connections and used extensively in site surveys and assessments.
Finite element modelling is used in support of assessment and analysis
Basic vibration measurements activities, with detailed studies allowing pipe wall vibration modes
and stress concentration effects to be investigated in depth.
Assessment of risk of failure
To reduce the risk of failures occurring to acceptably low levels,
GL is able to provide advice on all aspects of pipework design related
The screening programme aims to identify issues from the site survey to dynamic behaviour, building on the experience gained in resolving
requiring immediate action, such as ineffective supports, poorly vibration related pipeline integrity issues. This advice can be applied
supported pipework and vulnerable small bore connections. at any stage of a plant’s design, construction and operation. For
Subsequent investigations, if required, can then focus on the highest example, specifications can be written for input to the design of an
risk areas which might include assessment of vulnerable connections, installation, design reviews can be carried out, and/or an as-built
monitoring of transient vibration events, and monitoring of plant over review of new or existing plant can be undertaken to identify areas of
an extended period to assess the behaviour over a full range of concern. Guidance can be provided on areas such as the following:
Main pipework configuration
This assessment methodology is consistent with the process industry
best practice, and has been used by operators to successfully Pipework supports
demonstrate to the UK HSE that appropriate steps have been taken
to manage the issue of pipework vibration on their assets. Small bore connections
An additional benefit of this type of project is an increased awareness Impulse pipework
of vibration issues for operational staff. This helps to avoid these
problems becoming significant in the future, through recognition of Valve selection
problems at an early stage, and implementation of best practice for
any maintenance and replacement activities. Thermowells
GL offers extensive experience of vibration surveys and on-site
measurements on operating plant pipework. Methodologies and Subsequent to the identification of pipework vibration problems, and
assessment methods have been developed for measuring and building on an increased understanding of the cause of the problem
assessing dynamic stress and vibration on all aspects of pipework from any on-site investigation, GL’s expertise is well placed to make
systems. Intrinsically safe instrumentation has been designed recommendations on the need for remedial measures to reduce the
specifically for these applications, allowing vibration measurements risk of failures occurring. A variety of solutions to reduce the risk of
to be carried out in hazardous areas using a combination of strain vibration-related failures are typically proposed for the client’s
gauges and accelerometers as required. This includes a friction strain consideration, taking into account issues of cost, effectiveness, ease
gauge for small bore pipework which was developed and patented by of implementation, operational restrictions and safety, depending on
GL, and which can be easily and rapidly installed to achieve accurate the nature of the problem and site under investigation.
dynamic strain measurement on most pipe sizes without the need for
significant surface preparation. Solutions can range from redesign and modification of pipework and
connections, and improvement of pipework supports, to identification
of preferred operating regimes and recommendations for
investigation of plant performance, and development of design
guidance documentation for future projects.
a. Corrosion Management of LNG Storage Facilities
Customer: National Grid
Savings: Improved corrosion management
GL has provided direct support and guidance for corrosion
management initiatives at five separate sites within the UK. In recent
years, this support has focused on the development of best-practice
corrosion management policies and guidelines.
GL assisted with the initial implementation of these guidelines by
raising the profile of corrosion issues in LNG processes, and by
promoting a corrosion awareness culture across the business.
Specific areas of support have included:
Fabric maintenance – Management and interpretation of
site surveys to determine requirements for maintenance
painting and insulation replacement. Definition of
site-specific workscopes for ongoing fabric maintenance.
Corrosion Management Policy – Drafting of policy to
reflect best-practice approach to corrosion control and
monitoring. Identification and definition of specific tasks
to enable integration with maintenance management
Cooling Water Treatments – Review of cooling water
systems and chemical treatment service provision at all
sites. Identified shortfalls in operational systems,
recommendations for improved monitoring and
opportunities for rationalisation of service contracts.
LNG Vaporiser Life Extension – Conducted studies at two
sites to confirm fitness-for-service of direct-fired vaporiser
units and identify operations and maintenance to achieve
required life extension.
b. Integrity Management Review
Customer: UK North Sea Oil Gas Operating Company
Savings: Improved systems integrity
GL was requested to carry out a review of integrity management The review of documentation was followed by a number of interviews
procedures relating to pressure systems, pipelines and subsea with key staff within the client organisation and the lead integrity
equipment ahead of an internal audit of the client company management contractor. The objective of the interviews was to
management systems. As part of this review GL was asked to consider address a series of questions that were developed based on the
the suitability of the following: relevant policies/procedures and integrity management
“best-practice” within the oil and gas industry.
Organisational relationships for delivery of effective
integrity management It was found that the integrity management systems for pressure
systems, subsea and pipelines were well structured and were, in
Corrosion risk assessments used as a basis for integrity general, providing highly effective services. Although there had been
management planning a number of relatively recent changes in terms of both staff and
supporting guidelines/procedures, it was considered that these were
The methods and frequency of inspection largely positive and should strengthen the understanding and control
of integrity management issues in the near future.
Inspection records of lead integrity management
contractor The most pressing issue to be addressed concerned the fatigue of
topside process plant. It was considered that the existing risk based
The interpretation and analysis of inspection data inspection (RBI) plan could not be expected to manage this problem.
Although it was felt that the RBI process could assist with, through
Review feedback process from inspection findings into criticality assessments, the targeting of equipment a separate strategy
future inspection programmes was required to manage the problem effectively.
The impact of general fabric maintenance procedures on Further actions were recommended in the following areas:
Management of corrosion under insulation (CUI)
To carry out the review effectively, GL requested access to a number Incorporation of piping systems from vendor skids into
of client and integrity management contractor documents, including: inspection plans
Integrity Management Policy Consideration of performance targets or key performance
indicators for the Integrity Management Policy
Pressure Systems Integrity Management System
Clarification of the terms of engagement between the
Subsea and Pipeline Integrity Management (Draft) client and lead integrity management contractor
Fabric Maintenance Philosophy Consideration of weld corrosion in risk assessments
Pressure Systems Integrity Review Procedure
Monitoring, Inspection and Mitigation Procedures
Written Schemes of Examination (for relevant assets)
c. Fracture of Thermowell d. Failure of Impulse Pipework Compression Fitting
Date: 2005 Date: 2005
Customer: Transmission Pipeline Operator Customer: Compressor Station Operator
Savings: Improved use of thermowells Savings: Improved installation specifications
GL were asked to investigate the failure of a stainless steel thermowell GL were asked to investigate the failure of a compression fitting on a
which had been located in a dry gas transmission pipeline. A section of impulse pipework at a compressor station. The failure of
circumferential crack was found at the base of the thermowell. A the fitting had caused the shutdown of the compressor unit. A
metallurgical examination determined that the crack was consistent metallurgical examination determined that the failure was due to
with low stress, high cycle fatigue crack propagation. An assessment three circumferential low stress, high cycle fatigue cracks which had
of the process conditions indicated that the fracture was caused by initiated on the outer surface of the pipe at the point of contact with
flow induced vibration produced by vortex shedding around the the back ferrule of the compression fitting.
The root cause of the problem was identified as inadequate support
provided to the impulse pipework. GL suggested an improved
support arrangement and, as part of a larger programme of work,
GL monitored the vibration of the impulse pipework to ensure that
the new support arrangements were sufficient to prevent any future
failure of this pipework.
Fracture highlighted using dye penetrant
As a result of this failure the customer reviewed the use of
thermowells across its whole network. GL assisted by providing
further guidance on the susceptibility of thermowells to vortex
shedding, and by identifying appropriate alternatives.
Failed impulse pipework
Above – scanning electron microscope images of crack surface. Left
– low magnification, transgranular separation and ‘feathery’
appearance typical of austenitic stainless steel low stress high cycle Circumferential fracture
fatigue failures. Right – high magnification, fine striations, a
characteristic feature of low stress high cycle fatigue crack
e. Fitness-For-Purpose Assessment of Pressure Vessels
Savings: Cost savings to the client through a reduced frequency
for repair/replacement, reduced system downtime, and
life extension of high-pressure storage assets.
Fracture mechanics-based fitness for purpose (FFP) assessment
methods, such as those described in BS 7910, R6 and API 579 have
undergone rapid developments over the past 30 years. The FFS
(Fitness For Service) methodology has developed into a powerful tool
that enables the analyst to assess the significance of flaws in welded
Although comprehensive and applicable to a wide range of
engineering components, the methods contained within these
guidance documents are conservative. Furthermore, the methods can
be limited by, for example, the availability of stress intensity factor
and reference stress solutions for specific geometries. One such
limiting geometry is the nozzle, in particular the nozzle attachment
welds, which is a common feature on high-pressure gas storage
In the UK, operators must follow legislation given in the Pressure
Systems Safety Regulations (PSSR), which provides a regime with the Pressure Vessel Nozzle
aim of ensuring the safety of pressure systems. One of the regulations
requires that high-pressure gas storage systems must be subject to
periodic inspections followed by a FFS assessment to ensure the
integrity of the system.
Methodology & Results:
To ensure compliance with the requirements of the PSSR, GL has
developed an in-house procedure that enables an FFS assessment to
be undertaken for a flaw in a nozzle weld. This procedure was
developed to reduce the conservatism inherent in the assessment
procedures given in BS7910 while still maintaining an acceptable level
of safety. Using a combination of Finite Element analysis and fracture
mechanics techniques, a full FFS of pressure vessels was completed.
This has resulted in substantial cost savings to the client through a
reduced frequency for repair/replacement, reduced system downtime,
and life extension of high-pressure storage assets.
Finite Element Analysis of Pressure Vessel Nozzles
f. Fracture Mechanics Assessment of a Defective Pig Trap
Customer: United Utilities
Savings: Cost of temporary pig trap and system downtime
due to installation
GL were required to conduct a detailed assessment of a reported crack
indication found on the closure casting of a pig trap located at an
AGI facility in the UK. Following defect measurement in February
2007, this was recorded at approximately 3-4 mm. A number of pig
runs were then subsequently conducted. The defect was then
re-measured and reported to have a maximum depth of 5.3 mm.
Measurements suggested that the defect had therefore grown since
the pigging runs were conducted in 2007. The operator of the site
facility intended to conduct further pig runs in February 2008 and
hence required an assessment to determine whether the defect was
safe for the intended pig runs.
Methodology & Results:
The approach that GL used was based on a BS7910 level 2a fracture
mechanics assessment. Using fracture mechanics calculations and use
of the FAD (Failure Assessment Diagram), the aim was to determine
whether the current size of crack was safe under the current design
conditions and safe for the intended pig runs. Finally using a BS7910
fatigue assessment of the crack, fatigue calculations were then
conducted to determine the remaining fatigue life of the reported
defect and whether further pressure cycles can be tolerated due to
the intended pig runs. The fatigue assessment results showed that
the defective area was likely to endure a large number of cycles before
failure. Consequently it was concluded that the defect would endure
sufficient further pressure cycles to conduct the intended pigging
Ultimately, the operator would have had to install a temporary pig
trap to conduct the required pigging runs. Following this, the
temporary trap would have been removed and a new trap installed in
its place resulting in costly delays and system downtime. By
conducting a fracture mechanics assessment, GL have saved the client
costs associated with installing a temporary pig, inspection delays and
g. Defect Assessment of Corroded Pipework
Savings: Savings due to potential loss of containment and
ADMA-OPCO identified areas of general corrosion on the inlet
pipework to separators on one of their platforms. The corrosion had
occurred where clamps were fitted around vertically orientated 12”
pipework, just above the girth weld that connects the pipework to
90° elbows. ADMA-OPCO requested that GL undertake an assessment
of the defective area.
Methodology & Results:
Four assessment methodologies were used for the assessment, B31G,
RSTRENG, LPC-1 and API 579 Level 1. Predicted failure pressures and
safe operating pressures were calculated using the B31G, RSTRENG
and LPC-1 assessment methodologies. Results showed that all failure
pressures were well in excess of the design pressure, however the safe
operating pressures calculated using the B31G and RSTRENG
methodologies were considered to be unacceptable. In addition, the
defect area was assessed to the general and local metal loss Level 1
procedures of API 579. The defects had been found to be
unacceptable. These assessment results formed part of an overall
opinion regarding the safety of the reported defect.
Savings were made due to potential loss of containment and system
h. Review of Integrity Management Framework i. Safety Management Audit
Date: 2007 Date: 2006
Customer: Middle East Oil Producer Customer: UK LNG Terminal Operator
Savings: Improved integrity management Savings: Improved safety management system
A major operating company in the UAE were keen to ensure that their A UK LNG Terminal operator were expanding their storage capacity.
recently implemented Integrity Management Framework was Before they were able to commission the new phase, it was imperative
delivering what was intended. that a complete safety audit was undertaken to ensure that all
processes currently in place were operating correctly.
GL undertook a gap analysis of the current operating philosophy
against the IMF, and reported on where we felt the organisation was GL sent in a team of specialists in their field to undertake this review.
in relation to the IMF as well as benchmarking where we determined Interviews were undertaken with a cross section of staff, documents
the IMF was in relation to international best practice. were reviewed, and site inspections were undertaken to ensure that
the practice matched the document trail.
This project covered:-
The benefit to the client was that they were able to ensure that all
Pipelines deficiencies were actioned and lessons learned before the expansion
Critical Safety Systems
Once the gap analysis had been undertaken, a detailed list of
deficiencies was prepared, and suggested improvements identified to
bring the operations up to the desired level.
j. Fitness for Service Assessment
Customer: BG Tunisia
Savings: Improved monitoring and compliance
Regulatory conditions state that all pressure systems need to be
inspected to ensure they are fit for purpose, and examination
schedules needed to be produced. Therefore the client required an
inspection schedule to be developed to make sure their assets are fit
for purpose and operating within the design specifications.
Methodology & Results:
By working closely with the client and by taking reference from
Pressure Systems Safety Regulations, the contents of the WSoE’s were
agreed upon. An up to date inspection scheme was produced,
scheduling inspection work to be carried out during the plant
shutdown period. Inspections were identified with inspection dates
and times organised and a contingency for remedial work allocated.
A list of required inspection qualifications was produced and from
this a list of qualified engineering staff was assembled. A Competent
Person was assigned to define roles under the UK legislation that the
staff would take.
From the construction of the WSoE’s an extensive inspection of the
client’s assets were produced. The inspection identified areas of
remedial work that were required and helped setup monitoring
programmes on assets that were at greatest risk of failure. The
Written Scheme of Examination also provides the client with a means
to demonstrate compliance with the Pressure Systems Safety
k. Repair of Amine Stripper
Customer: BG Hannibal Gas Processing facility
Savings: Failure of processing vessel and plant shut down
The client had experienced up to 40% loss in wall thickness on an
amine stripper due to corrosion.
Methodology and Results:
The use of a coating system to isolate the vessel wall from the
corrosive environment inside the amine strippers was considered to be
the most cost effective solution. GL reviewed the properties of a range
of different generic coatings systems to identify a material that would
be compatible with the operating conditions within the amine
stripper. Having identified a suitable material, a technical review of
the proposed coating specification was performed and technical
assistance provided during the on-site coating application process.
Through wall corrosion failure and the requirement to shutdown the
plant to facilitate a vessel repair. The estimated cost of a shutdown
l. Investigation of Coating Failure on Oil Storage Tank
Customer: Major Exploration and Operating Company
Savings: Prevention of large-scale coating failure
The customer was experiencing cracking and disbonding of the
coating system applied to the external surfaces of a crude oil storage
tank. The customer required GL to establish the mechanism of
breakdown and to recommend methods of reparation.
Methodology and Results:
GL visited site to investigate the scale and nature of the failure. A
laboratory programme of work was initiated to reproduce the coating
failure under controlled conditions and to establish the failure
mechanism systems for reparation of the failed coating were
recommended and an application procedure prepared.
This work identified the mechanism of coating failure and helped to
prevent similar failures occurring in the future.
m. Corrosion Management Study
Customer: National Grid
Savings: Development of a robust corrosion management
policy to maximise asset life
The client wanted to establish a robust corrosion management plan
for the above ground installations that were an integral part of the
high pressure gas transmission system.
Methodology & Results:
GL performed a review of the customer’s corrosion management
policy with a view to quantifying how much should be invested on
inspection and maintenance for corrosion control purposes. The
Inspection and maintenance policy
Future maintenance requirements to reflect best industry
The current inspection frequencies and those frequencies
required to maintain plant and equipment
A series of site visits were conducted to obtain an overview of the
current condition of the corrosion control systems, the general
requirements for maintenance painting and to identify and quantify
areas which would require regular inspection and maintenance.
Reduced unscheduled reductions and outages due to
corrosion related issues.
Reduced repair cost.
Maximisation of asset life.
n. Weldability Testing of 48” Diameter X80 Europipe
Customer: National Grid (Milford Haven extension)
Savings: Approved procedures of manufacturing
Weldability testing entails the production of a full-scale girth weld
between two 12m pipe joints under field conditions and including
the manipulation of the partially-completed weld to simulate the
removal and movement of the line-up clamp. Following production of
the complete girth weld, the joint is subjected to X-ray inspection and
must pass required codes (T/SP/P/2 or API 1104 requirements) and is
then subjected to a full suite of mechanical tests. Following
satisfactory results from these investigations, the welding procedure
and the linepipe manufacturing route are qualified for supply to
Girth welding of 48” X80 pipe Simulation lifting of 48” joint after
during weldability testing hot pass deposition.
Sample welding procedure qualification record from the
48” X80 trials, showing joint design, consumables,
pre-heat requirements, pass sequence and other details.
o. Design and Qualification of Repair Procedures for Bellows
Customer: Pipeline Operator
Savings: Improved welding procedure
A GL report on the bellows connection concluded that the bellows on
the pipeline required a weld repair to be undertaken on the cracked
fillet welds. The bellows configuration is shown in Figure A of that
report, reproduced below:
Proposed weld procedure for the repair. Qualification of this
procedure is in progress.
Weld Repair instructions:
Weld repairs to cracked fillet welds in bellows unit to be
carried out after qualification of the attached weld repair
procedure and following decommissioning and purging
Consequently, according to British Standard BS 6990, prior to welding of pipeline 2.
onto the live pipeline, it is necessary to qualify a procedure, simulating
the cooling effect of the gas which complicates the qualification. The Ensure all necessary risk assessments and safety checks
qualification set-up should simulate actual flow conditions. have been undertaken and procedures are followed,
including safe control of operations (non routine
The weld procedure has been developed to minimise the risk of operation) and entry into confined spaces.
lamellar tearing. For weld procedure qualification, plate material
representing the nearest equivalent currently available material is Prior to repair, determine chemical analysis of carrier pipe
used. and box material by on-site material sampling of the
carrier pipe and restraining box material in accordance
with T/PM/Q/10 (ref clause 12 and appendix B). Report
results to GL for assessment.
Remove the two fillet weld cracks in bellows 2 by grinding
in accordance with T/PM/P/11 appendix F.
Confirm defect removal by visual inspection and MPI.
Check carrier pipe for defects by UT & MPI below
intended area of weld repair prior to welding.
Perform weld repair in accordance with attached
procedure: WPS/A/Tinsley/01FR (subject to qualification).
Completed repair welds to be subjected to visual
inspection and MPI.
Cracking located in bellows attachment fillet welds.
p. Evaluation of RBI Softaware
Customer: Major Gas Operator
Savings: Company time understanding the issues with
different RBI software packages
The client was in the process of evaluating bidders for provision of
integrity management software (IMS) oriented risk based inspection
management of pressure systems, pipelines and structure of the
Miskar Assets. Five software products were evaluated: Tishuk T-OCA,
DNV Orbit, Lloyds Capstone, Aver Kvarner Coabis and Credosoft Credo
Pro. The client required a third party overview of the RBI systems
embedded in the software and to determine the merits of the five
different RBI systems.
Methodology & Results:
From GL experience with RBI systems, an evaluation of the RBI
software was produced. The main factors GL’s experienced personnel
believed to be important in determining an effective RBI system are:
Determine whether the RBI is qualitative, quantitative,
semi-quantitative or combination of both
Evaluate how the software derive Probability of Failure
Evaluate how the software derives Consequence of Failure
(CoF) and whether important consequence attributes
have been captured
Degradation mechanisms in the assessment and
comparison with degradation mechanism in country
Post RBI analysis activities (e.g. Inspection planning)
An impartial third party review of software was obtained, denoting
the merits and drawbacks to each system. Allows GL’s experienced
personnel to put forward the best system that meets the requirements
of the client, so that the investment into the system produces the best
result. Also saves personnel time in trialling all the software and
producing an evaluation of each.
q. T-OCR Risk Based Inspection
Customer: Major Natural Gas Company
Savings: Reduced equipment downtime and
costs due to failures
The client expressed an interest in adopting a risk based inspection Main saving is on the company time and finances on determining the
(RBI) scheme for integrity management of its offshore and onshore benefits and viability of implementing an RBI approach. Also identifies
process plant. A feasibility study was required to determine the to the client the long term benefits of a RBI approach, as shown
practicalities, outline implementation costs and potential benefits of below:
Reduced equipment downtime and costs due to failures
Methodology & Results: Reduced requirement for items to be taken offline to be
The initial part of the study included a review of the current integrity
management systems. This was followed by an assessment of the Focusing of inspection resources on key corrosion and
feasibility and requirements for the application of RBI. The final part materials degradation issues
of the study comprised two RBI pilot studies centring on known areas
of concern on the specific plants. The key results from this study were
as follows: The report also includes recommendations for implementation of RBI,
including support required and a breakdown of likely resources
A feasibility of applying (risk based inspection) RBI to the requirements.
A review of existing approaches to integrity management,
and any modification required to accommodate the RBI
approach were identified
Potential benefits of applying RBI to its facilities identified,
including improvements in equipment reliability and cost
reductions from optimisation of inspection planning and
r. Investigation of Double Block and Bleed Valve Vibration at
a Gas Processing Facility
Customer: Onshore Operator, Kazakhstan
Savings: Management of the risk of failures reduce the
occurrence of failures and the associated costs of
plant shutdown and remedial work
During the commissioning and early operational life of a large gas
processing facility, failures were experienced of a significant number
of small bore connections across the plant. This was determined to
be due to the poor design of these connections. Replacing all these
fittings would have been extremely costly, and a programme of
bracing of the large double block and bleed valves was therefore
undertaken. However, it was not known how effective this bracing
was in reducing the dynamic stresses to acceptable levels.
Methodology & Results:
GL undertook a study across the processing plant to
characterise the vibration of the small bore connections with large
mass double block and bleed valves. Dynamic stress measurements
were taken on a selection of connections, including a range of
different designs and bracing arrangements. This knowledge was
used to develop a screening method which could be used by Client
staff to assess all the connections on the plant to implement a
prioritised replacement plan.
Management of the risk of failure of these connections reduced the
occurrence of failures, and the associated costs of plant shutdown
and remedial work.
s. Long Term Monitoring of Pipework Vibration at Gas
Date: 2003 to 2008
Customer: UK Onshore Operator
Savings: Detailed understanding of the risk of pipework
vibration problems across operating range of
Earlier work programmes had carried out an initial assessment of
small bore connections at compressor stations, from which a large
programme of replacement and removal had been instigated.
However, some pipework vibration problems were known to occur at
operating conditions that were experienced only occasionally and had
not been assessed.
Methodology & Results:
GL developed a data acquisition and analysis system that would per-
form long term monitoring of a large number of sensors over ex-
tended periods. To date this has been installed on nine of the
twenty-six UK compressor stations for a period of at least three
months in each case, and has provided a comprehensive assessment
of the pipework vibration over the full station operating range. For
example, at several stations, pipework vibration problems were
identified which were a result of the interaction of the gas flow from
adjacent units, phenomena that would not have been picked up by
carrying out measurements on each unit separately. This equipment
has also been used to investigate vibration problems following specific
incidents on compressor stations and on seal and lubrication oil
Detailed understanding of the occurrence of pipework vibration
problems across the operating range of the plant ensures that full
consideration is given to the causes, directing any remedial action and
confirming safe operating ranges.
t. Assessment of risk of pipework failure due to vibration dur-
ing offshore plant uprating
Customer: UK Offshore Operator
Savings: Eliminated need for major changes to main
pipework, and allowed uprating to be achieved
within available timescales
Upgrade of two offshore compressor trains was planned to increase
gas flow rates. A preliminary study by the Client suggested that the
risk of vibration related failure of the main pipework was already
unacceptable and would be increased by uprating. The available
outage period was insufficient for significant design changes to the
pipework to be implemented.
Methodology & Results:
GL undertook a study to assess the dynamic stresses
experienced by the main pipework and small bore connections during
operation of the compressor units in their original configuration.
Assessment of the dynamic behaviour was carried out over a range of
operating conditions on both compressor trains. Knowledge gained
of the relationship between vibration and gas flow was subsequently
used to predict the likely behaviour of the pipework at the current
maximum and uprated conditions.
The study concluded that there was no need for major changes to
the main pipework prior to the uprating, allowing effort to be
concentrated on issues related to small bore connections.
The findings of this work eliminated the need for major changes to
the main pipework, achieving significant cost savings for the project
and allowing the uprating to be achieved within the available
u. Vibration screening at an onshore gas terminal
Date: 2005 to 2008
Customer: UK Operator
Savings: Demonstrated management of risk of vibration
related failure of pipework to regulatory bodies
To manage the risk of vibration related pipework fatigue failures a
structured vibration screening and assessment methodology was
required by the Client, to identify problem areas and define
Methodology & Results:
A phased approach was employed by GL to identify potential problem
areas on the main pipework and small bore connections. The initial
site survey consisted of a walk-round visual review of the site
processes and pipework, basic vibration measurements, and
assessment of the likelihood of failure of any connections. This
exercise identified key problem areas for immediate remedial action
and further investigation, allowing effort to be focused on the highest
risk areas in subsequent stages.
Recommendations included identification of pipework support design
and maintenance issues, changes to the design of small bore
connections that were identified to be at risk of failure, and
identification of areas of the plant to be assessed in greater detail to
develop an understanding of any problems identified and to develop
solutions. This subsequent detailed assessment work has included
installation of monitoring equipment to assess the behaviour of the
plant over its full operating range.
This methodology is now being deployed for the Client’s offshore
This project successfully demonstrated to the UK Health and Safety
Executive that the issue is being adequately managed across the
Asset Management Services
Plant Integrity Management Services
Industrial Services GmbH
Pipeline Integrity Management Services
Oil and Gas
Production Optimisation (Includes RAM
and Gas Processing) Steinhöft 9
20459 Hamburg, Germany
Dynamic and Steady State Simulation
Phone +49 40 36149-7700
Rotating Equipment Performance & Fax +49 40 36149-1781
Condition Monitoring including firstname.lastname@example.org
Gas Quality and Interchangeability www.gl-group.com/glis
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Issue no.001 15.05.2008