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Gas turbine materials
Condition assessment, Failure analyses, Inspections and quality control, Refurbishment, Reverse engineering, Laboratory facilities
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Gas turbine materials
The materials used in the hot gas path of gas turbines represent
the cutting edge in material technology for high-temperature
materials under high mechanical and thermal loads. Superalloys are
frequently used, and they are protected by advanced coating
systems, including Thermal Barrier Coatings. Still, there is a
neverending search for turbines with higher efficiency. In many
cases this is related to higher firing temperatures, those again
are more demanding from the material.
It is no surprise that these materials are costly an have
limited life. For that reason, many questions arise among operators
on material condition. In general, the idea is to reduce life cycle
cost while maintaining asset reliability. This often means that
decisions need to be made whether components can be refurbished or
have to be replaced. KEMA has dealt with the support of customers
having these questions many times and can offer you the following
services in this field:- Failure analysis
- Condition assessment
- Refurbishment consultancy
- Reversed engineering and design review
- Inspections and quality control
- Facilities / Laboratories
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Condition assessment
Looking at the ex-service components during a hot gas inspection
or a major overhaul, everyone can see the striking difference in
colour and shape between the original components and the ex-service
components. Only the experts can provide you with the knowledge
which colour difference is relevant and which cracks do jeopardise
the components integrity.
KEMA can provide these experts. Moreover, sophisticated
NDT-techniques are available in-house and on site to determine the
remaining life of the coating as well as the depth and size of
cracks. Broad experience with both remaining life assessment
evaluations and with the standard degradation due to operating
service provide a sound basis to estimate the effect of defects
found and assess the reparability.
Detailed reporting of the relevant observations of ex-service
components provide a knowledge base for the user. He wants to get
to grips on the life consumption of the key components. The
knowledge base proves to be extremely useful during quality control
of refurbishment procedures.
Assessments can be carried out both using NDT-techniques as well
as using metallographic techniques.
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Failure analyses
KEMA Power Generation & Sustainables has experience with
failure analysis carried out on a wide range of gas turbines from
different manufacturers. Failure analysis has been carried out on
all hot gas path components as well as compressors, inlet ducts and
boilers. Sound knowledge of the effect of different types of
service on the condition of the turbine and of the complicated
material principles related to superalloys as well as specialised
preparation techniques of metallograph samples are available in
house. Because of the combination of hands-on experience with gas
turbines and the in-house availability of a wide selection of
experts in areas ranging from operational issues to crack growth
estimations, both relatively simple and complicated analysis can be
carried out within days. Each failure analysis is concluded by
providing a solution that will solve the problem or may initiate a
proposal for a more detailed evaluation.
As an independent consultancy company, KEMA is an acknowledged
party both in and out court in arbitration between owners and
suppliers.
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Refurbishment
Gas turbine hot gas path components have finite life. Therefore,
operators recurrently find themselves facing component replacement.
Decisions have to be made on whether these components are to be
replaced by new components (original or reverse engineered) or
whether the condition of the component can be restored by a repair
or refurbishment procedure.
KEMA provides operators objective independent advice on the
classification of parts to assure that components are not
unnecessarily scrapped or repaired beyond allowable material
degradation constraints. Acting as the customers technical
representative KEMA can provide services starting with quantitative
condition determination, as well as writing a request for tender,
bid evaluation and discuss and monitor repair activities at the
original equipment manufacturer (OEM) or third party repair
companies. Not only non-confirmalities are detected and recorded,
we will also advice our client of the effect of the
non-confirmality on the technical integrity and/or expected
lifetime of the component.
Our inspectors are familiar with repair shops all over the
world, both from OEM’s as well as specialised third party
companies. Technical back up by a wide range of in-depth experts on
matters as temperature and stress distributions in components,
welding aspects and coating application problems is only a
telephone call away.
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Inspections and quality control
The availability and reliability of your installations is of
major importance to you and to your customers. Reducing costs and
staying in control become increasingly important in our dynamic
industrial climate. You need peace of mind. You need to have your
plant inspected by reliable, experienced people, to be able to show
you have done your utmost to prevent failure.
KEMA has over thirty years of experience. Our inspectors, with
their detailed, wide-ranging expertise, can anticipate your needs
and give you the best picture of the quality and operation of your
plant at the lowest cost. These inspections, completely impartial,
make sure you meet your contractual requirements. Although many
contractors and manufacturers of installations work to ISO 9000
quality standards, that may not guarantee the work meets your
quality demands as a whole, but KEMA’s inspections will.
KEMA normally uses a well-considered, approved plan of action,
but our inspectors will base their recommendations upon your
approach and your plans, giving you an individual custom-made
service. Inspections can be made during the manufacture of new
components and during maintenance stops at operating installations.
Besides registering defects, our inspectors will suggest solutions,
giving you access to all KEMA’s testing and calculation facilities
and any other expertise you might require, for example the control
of corrosion and our knowledge of metal, composites, ceramics
plastic and rubber. We can carry out non-destructive tests (Eddy
Current and TOFD) corrosion and damage research and Fitness to
Purpose Evaluation, give advice on Life Time Management and
periodic extension, lengthening the fixed legal inspection
interval. KEMA also handles Due Diligence research when the value
of the asset is to be estimated, for example, when it is to be sold
or taken over.
Using KEMA Power Generation & Sustainables’ inspectors
means:- Reduced risk of plant failure and loss of operation
- Reduced maintenance costs
- Better specifications for and planning of maintenance and
inspection;
- Clear, relevant and concise reports, arriving quickly
- Inspection reports reduce unnecessary discussion with
manufacturers and regulatory authorities
- Inspection teams are available for new plant or modified
installations, at the design stage or following damage or
repair
You will have access to a wide field of expertise – technical
engineers, assembly co-ordinators, technical commissioning experts,
planners, project and site managers.
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Reverse engineering
Due to the high costs associated with purchasing new components,
many repair shops are offering reverse engineering for gas turbine
components. The price difference is often significant but, what
about the risks? No one can rule out all accidents at an affordable
price but one can use the expert’s knowledge to look over the
shoulder and to ask the relevant questions. Just copying the
components and getting round all patent claims does not necessarily
mean that the new components will stand the job! Will you e.g. be
able to repair the components after a certain service period?
Assistance of an independent expert to pinpoint the relevant
bottlenecks will enable you to manage the costs and timetable the
reverse engineering project.
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Facilities
If you are looking for an independent laboratory to provide you with services related to the state of your (gas turbine) materials, KEMA can offer you a wide range of testing services in our own facilities.
Modelling tools- ANSYS: finite element calculations for stress, strain, creep and fatigue
- FLOTRAN: computational fluid dynamics modelling and heat transfer
- MathCAD: sophisticated pre- and postprocessing calculations.
Metallographic laboratories- DICOM®; a specialised preparation technique optimised for gas turbine materials
- Optical light microscopy and scanning electron microscopy including image processing and analysis techniques.
For more information please contact us.
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