TÜV works for safety
TÜV Rheinland Group is
currently taking care of more than 5,000 steam boiler systems from manufacturing
and operation to providing expert reports in cases of damage insofar as this is
necessary. The public authorities recognized the need for statutory monitoring
of these systems in the middle of the 19th century after a number of serious
accidents had occurred. Today, steam boiler systems are among the safest
commercially used systems. Not least thanks to the TÜV experts
| Pressure Equipment and Materials Technology |
Design, Calculation, Measurement
| Preliminary Inspection and
Calculation |
Components for steam boilers, pressure vessels and pipe
installations must be subjected to a preliminary test prior to manufacture. This
tests whether or not the components can withstand the envisaged operating
conditions. To do so, calculations taken from national and international
regulations are used or, in complicated cases, numerical calculating methods
(Finite Element Method).Pressure vessels can also be calculated online on the
Internet by the "click-and-calc" application.
The TÜV Rheinland Group has always been a reliable partner in the field of
preliminary inspection of:
- pressurised components, which fall under the scope of national and
internationalregulations (Ordinance on Pressure Vessels, on Steam Boilers,
Directive on Pressure Devices,ASME Code, British Standards etc.) or which have
to be inspected inaccordance with special company specifications.
- Structures falling under the VawS (flat-bottom tanks, DIN
tanks,pressure-less or pressurised rectangular tanks ...)
- Tanks for transporting hazardous substances (GGVS, GGVE, RID ...)
As a rule, the preliminary test is done on the basis of manufacturing
documents, e.g. drawings, parts lists, welding diagrams and calculations. Using
the most modern tools (e.g. Finite Element calculations) we are however also in
a position to give you advice on dimensioning at the planning stage if you have
problems concerning the strength of structural components.
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| Stress Analysis and Vibration
Technology |
Using modern measuring methods and processes we identify
the actual operating loads and stresses. These are of help to the design
engineer. In cases of damage they provide answers to questions concerning the
causes and the true stresses as regards size, passage of time and frequency
spectrum.
Why measurement analyses?
Both the design engineer and the operating engineer are often faced with the
question of what in the plant has an effect on component parts, machinery and
installations. With the aid of measurements we can answer these questions.
Stress analysis
Measuring and evaluation
of loads and stresses during operation - realistically. We diagnose, analyse and
advise as experts. Our speciality: high-temperatures strain measuring technology
up to 600°C.
Measuring of stresses during real operation - even when
things get "hot"
There are many good reasons for measuring mechanical
stresses during real operation:
- Checking of the calculations,
- Examination of the real processes in the plant,
- Proof for third parties (e.g. authorities or customer),
- Inspections in a case of damage with unclear cause.
For the
measuring examinations we use strain gauges and various sensors for pressure,
temperature, paths etc.
The use of high-temperature strain gauges - when things get "hot"- i.e. for
temperatures up to 600°C, is no problem for us as we were the ones who developed
this technology.
We use modern, efficient multi-channel measuring technology and evaluation
software to carry out the measurements and analyses.
We advise and help you to optimise structures or installations
Vibration technology and shock
protection
Vibrations may cause operational problems or cause damage.
We measure and evaluate vibrations and shocks and help, if necessary, with
remedial measures.
Why should vibrations be taken seriously
?
Vibrations have an effect on the strength of structural components:
increasedmaterial stresses, reduced service life or damage.
Vibrations in
plant and machinery are often disturbing, e.g. in production plants.
Vibrations also have an effect on people.
The measuring technology and
the software permit a wide range of analyses in the time andfrequency areas as
well as calculations of vibrations.
We also carry out:
- Field balancing of machines
- Expert opinions in cases of damage
- Training of personnel
- vibration course
We are actively engaged in shock
protection
Specialists from TÜV Rheinland Group measure and assess:
- Effects on humans in accordance with DIN 4150-2
- Effects on construction plant in accordance
with DIN 4150-3 We
are a recognised vibration measuring body in accordance with BImSch
§26.Forecasting vibrations is one of our main fields of activity.We also advise
you in your search for suitable remedial measures.We also carry out for you
training courses for plant environmental officers.
Special tasks and intelligent solutions
We
deal with special questions on structure-borne noise and on flow-excited
vibrations. Moreover, we have completed the design and testing of an
anti-vibration damper with the aid of an hydraulic exciter. You only have to
contact us. Creep strain measurements
The
stress-to-rupture behaviour concerns component structures >450°C and results
in a finite life span. Special sensors are used to measure the actual creep. In
conjunction with structure replica technology it is possible to take advantage
of the residual life considerably longer.
Residual life of structural components exposed to creep
rupture
The stress-to-rupture behaviour of structural components
starts at temperatures over 450°C. Operation in excess of the calculated life -
as a rule 200,000 operating hours - is possible. This however requires
observation of the component with respect to damage to it and to its elongation
development - reaching the critical tertiary creeping area.
Structure
replica examinations are carried out and creep strain sensors installed on the
structural component for determining residual. Readings and assessments are
carried out at given intervals of time.
In many cases it was possible to
considerably extend the service life.
Creep behaviour
After the relatively short
primary creep phase, secondary creep begins. Secondary creep is characterised by
increasing linear elongation. The tertiary creep is critical, as the strains
grow exponentially.
Seen under a microscope, damage begins to occur in the
structure. This can be detected with the aid of structure replica technology and
classified in particular categories of damage.
Pipe bends in power stations are particularly affected by creeping, e.g.
due to ovalness.
Application of creep strain technology
We
use capacitive sensors. They are mounted onto the structural component at
particular points. The sensors are protected against outside influences. Before
use they are tested in the laboratory for long-term stability and adapted to
suit the respective material. Potential probe measuring technology
The
detection of a fault in a component structure (e.g. a crack) does not always
signify the "end of the road". The potential probe measuring technology for
fault monitoring is a good method for increasing safety when continuing to use a
faulty component.
Monitoring of faults for growth
Does the
detection of a defect, a fault or an incipient crack mean the "end of the road"
for a structural component? In many cases, continued operation is technically
justifiable, even when the fault is inaccessible, such as on the inside of a
pipe for example.
Safe continued operation
Using the
potential probe method, the structural component is constantly monitored in
operation to see if the fault continues to expand. The potential method offers a
number of practical advantages and makes a significant contribution to plant
safety.
Since 1997 there have been concrete examples of use at home and
abroad, in particular in powerstations.
Applications
- Monitoring of faults in respect of crack growth
- Monitoring of faults on the inside
- Monitoring of faults on the outside
- High resolution of the growth in the fault
- Quantitative determination of the growth
Advantages
- Continued operation of faulty structural components (pipe or tank)
- Continuous monitoring in operation- Cost benefits
- In nuclear power stations: reduction in radiation exposure
Long-term measurement of
pipelines
Subsidence in mining areas as well as tunnelling or civil
engineering work put additional stresses on pipelines. Strain measuring
technology and regular readings mean immediate recording of these additional
stresses.
Basic monitoring of pipelines
Using simple
means but a systematic procedure, we monitor pipelines in power stations. This
allows faults to be detected early - as a preventive measure - and damage to be
avoided.
Our additional range of services:
- Creep strain measuring technology: utilisation of the residual life (e.g.
pipe bends)
- Potential probe measuring technology: continued operation of structural
components with cracks
- Long-term monitoring of pipelines
Fracture mechanics
Fracture
mechanics are used to assess whether or not a structural component with a crack
in it can still be used.
What to do when cracks are discovered in the structural
component
Ignorance often causes an exaggerated reaction: continued
operation seems possible only with a new component. This means high costs for
procurement, repairs and loss in production. We offer you an alternative. A
fracture mechanical assessment of the crack.
The effect of the crack - reduction of cross-section, peak stresses - is
considered in the fracture mechanical calculation. The result of the calculation
is the assessment of the crack.
It may be possible to continue operating the
structural component with its incipient crack if there are sufficient safety
reserves, to operate it for a limited period of time or subject to certain
restrictions such as monitoring of the crack using the potential method.
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This field of work includes for example investigations of
the residual life of power station components subjected to heavy stresses and
simulation of the dynamic behaviour of installations.
Residual life
Examinations of the residual life of
components subjected to stress in operation: a number of power station
components are either exposed to a high temperature or to cyclic pressure and
thermal loading, especially when starting up and shutting down. Both of these
influencing factors limit the service life. The assessment of the residual life
of components subjected to stress in operation is important for the safety and
availability of the power station.
Simulation of the dynamic behaviour of a power
station block
Examination of a technical installation using a model is
one of the standard methods employed by the design engineer. Instead of a real
physical model however, an imaginary mathematical model can also be used to
examine the behaviour of an installation to be planned or one already in
operation. This is a good alternative especially when tests on a real
installation are too expensive or too risky. Situations can be played out on a
model which could never be brought about intentionally on a real installation.
We have carried out these types of tests in the past for numerous plant
operators at home and abroad.
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