IEC 62765-1:2015

IEC 62765-1 ®
Edition 1.0 2015-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear powers plants – Instrumentation and control important to safety –
Management of ageing of sensors and transmitters –
Part 1: Pressure transmitters
Centrales nucléaires de puissance – Instrumentation et contrôle-commande
importants pour la sûreté – Gestion du vieillissement des capteurs et des
transmetteurs –
Partie 1: Transmetteurs de pression

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IEC 62765-1 ®
Edition 1.0 2015-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear powers plants – Instrumentation and control important to safety –

Management of ageing of sensors and transmitters –

Part 1: Pressure transmitters
Centrales nucléaires de puissance – Instrumentation et contrôle-commande

importants pour la sûreté – Gestion du vieillissement des capteurs et des

transmetteurs –
Partie 1: Transmetteurs de pression

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.20 ISBN 978-2-8322-2629-2

– 2 – IEC 62765-1:2015 © IEC 2015
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Abbreviations . 12
5 Background . 12
5.1 General . 12
5.2 Type of transmitter and interface. 12
5.2.1 Type of transmitters . 12
5.2.2 Interface between sensing part and process . 13
5.3 Reasons for transmitter ageing management . 13
5.4 Environmental stressors . 14
5.4.1 General . 14
5.4.2 Radiation . 14
5.4.3 Temperature . 15
5.4.4 Humidity . 15
5.4.5 Pressure transients . 15
5.4.6 Vibration . 15
5.4.7 Corrosive chemical reaction . 15
5.5 Sensing line problems to be considered with transmitter ageing . 16
5.6 Techniques for detecting pressure transmitter ageing . 16
6 Ageing management of transmitters . 17
6.1 General . 17
6.2 Methodology of ageing management . 17
6.3 Identification of ageing by performance verification test . 18
6.4 Test and inspection interval . 18
6.5 Test location . 19
6.6 Calibration of measurement and test equipment . 19
6.7 Test and inspection results . 19
6.8 Validation of test methods . 19
6.9 Classification of condition monitoring system and its software . 19
6.10 Replacement of transmitter or its parts . 19
7 Acceptable means for transmitter testing . 20
8 Relationship between initial qualification and transmitter ageing management . 20
Annex A (informative)  Calibration for type tests or periodic tests . 21
A.1 General . 21
A.2 Configuration for calibration of transmitters . 21
A.3 Uncertainty and TDF between M&TE and EUT . 21
A.4 Criteria for calibration tolerance . 22
A.4.1 As-found value and as-left value . 22
A.4.2 Allowable conditions for adjustment in calibration . 22
A.5 Calibration with adjustment . 22
Annex B (informative) Performance verification tests . 23
B.1 Test – Verification of performance . 23

B.2 Acceptable limits for test . 23
B.2.1 Linearity and accuracy . 23
B.2.2 Response time . 24
B.3 Alternative method with on-line calibration . 24
B.4 Remedial actions for inoperable transmitters . 25
B.5 Written procedure for calibration . 25
Bibliography . 27

Figure 1 – Conceptual methodology of ageing management . 18
Figure A.1 – Process and transmitter configuration for calibration . 21

Table 1 – Examples of ageing effects that can cause performance degradation in PTs . 14
Table 2 – Examples of environmental stressors with potential to damage transmitters . 16
Table B.1 – Consideration for verification of performance (see IEC 62385:2007,
Clauses 5 and 6) . 23
Table B.2 – Uncertainty of elements for Pressure transmitters (see IEC 61888:2002,
5.3.1) . 24
Table B.3 – Comparison between traditional and on-line tests of response time . 24
Table B.4 – Required actions followed by as-found value during calibration test as an
example . 25

– 4 – IEC 62765-1:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR POWERS PLANTS –
INSTRUMENTATION AND CONTROL
IMPORTANT TO SAFETY – MANAGEMENT
OF AGEING OF SENSORS AND TRANSMITTERS –

Part 1: Pressure transmitters
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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International Standard IEC 62765-1 has been prepared by subcommittee 45A:
Instrumentation, control and electrical systems of nuclear facilities, of IEC technical
committee 45: Nuclear instrumentation.
The text of this standard is based on the following documents:
FDIS Report on voting
45A/1001/FDIS 45A/1015/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC 62765-1:2015 © IEC 2015
INTRODUCTION
a) Technical background, main issues and organisation of the standard
With the majority of NPPs over 20 years old, the management of ageing of transmitters
(pressure, level, flow) is currently a relevant topic, especially for those plants that have
extended their operating licenses or are considering this option. This standard is intended
to be used by operators of NPPs (utilities), systems evaluators, and by licensors.
b) Situation of the current standard in the structure of the IEC SC 45A standard series
IEC 62765 is the third level IEC SC 45A document comprising several parts to tackle the
specific issue of management of ageing of sensors and transmitters in nuclear power
plants (NPPs) for I&C systems important to safety. Part 1 of IEC 62675 is dedicated to
pressure transmitters.
IEC 62342 is the second level standard of SC 45A covering the domain of the
management of ageing of nuclear instrumentation systems used in NPPs to perform
functions important to safety. IEC 62342 is the introduction to a series of standards to be
developed by IEC SC 45A covering the management of ageing of specific I&C systems or
components such as electrical cabling systems (IEC 62465), and sensors and transmitters
(IEC 62765).
IEC 62765 is to be read in association with IEC 62342 and IEC/TR 62096, which is the
appropriate IEC SC 45A Technical Report that provides guidance on the decision for
modernisation when management of ageing techniques are no longer successful.
For more details on the structure of the IEC SC 45A standard series, see item d) of this
introduction.
c) Recommendations and limitations regarding the application of this standard
It is important to note that this standard establishes no additional functional requirements
for safety systems. Ageing mechanisms have to be prevented and thus detected by
performance measurements. Aspects for which special recommendations and limitations
are provided in this standard are:
– criteria for evaluation of ageing of pressure transmitters in NPPs;
– steps to be followed to establish pressure transmitter testing requirements for an
ageing management program for NPP instrumentation systems; and
– relationship between on-going qualification analysis and ageing management program
with regards to pressure transmitters.
It is recognised that testing and monitoring techniques used to evaluate the ageing
condition of NPPs transmitters are continuing to develop at a rapid pace and that it is not
possible for a standard such as this to include references to all modern technologies and
techniques.
This standard identifies minimum requirements aimed at ensuring that any potential
impacts on NPP safety due to ageing of pressure transmitters of NPP can be identified
and that suitable actions are undertaken to demonstrate that the safety of the plant will not
be impaired.
To ensure that this standard will continue to be relevant in future years, the emphasis has
been placed on issues of principle, rather than specific technologies.
d) Description of the structure of the IEC SC 45A standard series and relationships
with other IEC documents and other bodies documents (IAEA, ISO)
The top-level document of the IEC SC 45A standard series is IEC 61513. It provides
general requirements for I&C systems and equipment that are used to perform functions
important to safety in NPPs. IEC 61513 structures the IEC SC 45A standard series.
IEC 61513 refers directly to other IEC SC 45A standards for general topics related to
categorization of functions and classification of systems, qualification, separation of
systems, defence against common cause failure, software aspects of computer-based
systems, hardware aspects of computer-based systems, and control room design. The
standards referenced directly at this second level should be considered together with
IEC 61513 as a consistent document set.

At a third level, IEC SC 45A standards not directly referenced by IEC 61513 are standards
related to specific equipment, technical methods, or specific activities. Usually these
documents, which make reference to second-level documents for general topics, can be
used on their own.
A fourth level extending the IEC SC 45A standard series, corresponds to the Technical
Reports which are not normative.
IEC 61513 has adopted a presentation format similar to the basic safety publication
IEC 61508 with an overall safety life-cycle framework and a system life-cycle framework.
Regarding nuclear safety, it provides the interpretation of the general requirements of
IEC 61508-1, IEC 61508-2 and IEC 61508-4, for the nuclear application sector. In this
framework IEC 60880 and IEC 62138 correspond to IEC 61508-3 for the nuclear
application sector. IEC 61513 refers to ISO as well as to IAEA GS-R-3 and IAEA GS-G-3.1
and IAEA GS-G-3.5 for topics related to quality assurance (QA).
The IEC SC 45A standards series consistently implements and details the principles and
basic safety aspects provided in the IAEA code on the safety of NPPs and in the IAEA
safety series, in particular the Requirements SSR-2/1, establishing safety requirements
related to the design of Nuclear Power Plants, and the Safety Guide NS-G-1.3 dealing with
instrumentation and control systems important to safety in Nuclear Power Plants. The
terminology and definitions used by IEC SC 45A standards are consistent with those used
by the IAEA.
NOTE It is assumed that for the design of I&C systems in NPPs that implement conventional safety functions
(e.g. to address worker safety, asset protection, chemical hazards, process energy hazards) international or
national standards would be applied, that are based on the requirements of a standard such as IEC 61508.

– 8 – IEC 62765-1:2015 © IEC 2015
NUCLEAR POWERS PLANTS –
INSTRUMENTATION AND CONTROL
IMPORTANT TO SAFETY – MANAGEMENT
OF AGEING OF SENSORS AND TRANSMITTERS –

Part 1: Pressure transmitters
1 Scope
This part of IEC 62765 provides strategies, technical requirements, and recommended
practices for the management of ageing to ensure that ageing of pressure transmitters
important to safety in nuclear power plants (NPPs) can be identified and that suitable
remedial actions are undertaken as necessary to demonstrate that the safety of the plant will
not be impaired. This standard is aligned with the IEC 62342 standards, which provides
guidance on ageing management for I&C systems important to safety in NPPs. This standard,
IEC 62765-1, is the first part for pressure transmitters in the IEC 62765 sensor and transmitter
series for pressure, temperature, neutron and other sensors.
This standard deals with analogue electronic pressure transmitters, which have an electrical
signal output that is a function of pressure applied on the sensing part, and which are
included in I&C systems important to safety in accordance with IAEA terminology.
Any software used for data acquisition, data qualification, or data analysis for transmitter
testing or condition monitoring system for pressure transmitter is classified according to
IEC 62138 depending on its functionality as specified in IEC 61226. The qualification of the
software for the digital data processing is beyond the scope of this standard.
Additional condition monitoring system for ageing management of the pressure transmitters is
classified according to IEC 61226 with respect to its functionality. If classified, the software
installed in the monitoring system complies with IEC 62138 for its B or C categorised function.
Regarding environmental qualification, the requirements of IEC 60780 apply. For assessing
the performance of transmitters in the safety system instrument channel, the IEC 62385
methods, IEC 61888 requirements and IEC 60671 surveillance testing requirements apply.
Pressure measurements may be used for the measurement of other parameters that can be
related to pressure, e.g., level or flow. Interfaces which include sensing lines, condensing
pots, and primary (e.g., flow) elements between process and transmitters are within the scope
of this standard.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60671, Nuclear power plants – Instrumentation and control systems important to safety –
Surveillance testing
IEC 60780, Nuclear power plants – Electrical equipment of the safety system – Qualification

IEC 61226, Nuclear power plants – Instrumentation and control important to safety –
Classification of instrumentation and control functions
IEC 62138, Nuclear power plants – Instrumentation and control important for safety –
Software aspects for computer-based systems performing category B or C functions
IEC 62342, Nuclear power plants – Instrumentation and control systems important to safety –
Management of ageing
IEC 62385:2007, Nuclear power plants – Instrumentation and control important to safety –
Methods for assessing the performance of safety system instrument channels
IEC 62465:2010, Nuclear power plants – Instrumentation and control important to safety –
Management of ageing of electrical cabling systems
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
accuracy of measurement
closeness of the agreement between the result of a measurement and the conventionally true
value of the measurand
Note 1 to entry: The parameter may be, for example, a standard deviation (or a given multiple of it), or the half-
width of an interval having a stated level of confidence.
3.2
ageing assessment
evaluation of appropriate information for determining the effects of ageing on the current and
future ability of systems, structures, and components to function within acceptance criteria in
all operating conditions (e.g., in normal conditions and after design basis events)
[SOURCE: IEC 62465:2010, 3.2]
3.3
ageing management
engineering, operations and maintenance actions to control within acceptable limits ageing
degradation of structures, systems or components.
[SOURCE: IAEA Safety Glossary, 2007 edition]
3.4
allowable value
a limiting value that the trip setpoint may have when tested periodically, beyond which
appropriate action shall be taken
[SOURCE: IEC 61888:2002, 3.1]
3.5
analytical limit
limit of a measured or calculated variable established by the safety analysis to ensure that a
safety limit is not exceeded. The margin between the analytical limit (of the setpoint) and the
safety limit allows to take into account:
– the response time of the instrument channel,
– the range of transients due to the considered accident.

– 10 – IEC 62765-1:2015 © IEC 2015
[SOURCE: IEC 61888:2002, 3.2]
3.6
calibration
set of operations that establish, under specified conditions, the relationship between values of
quantities indicated by a measuring instrument or a measuring system, or values represented
by a material measure or a reference material, and the corresponding values realised by
standards
3.7
commissioning test
test of a device or equipment, carried out on the site, to prove the correctness of installation
and operation
3.8
condition monitoring
continuous or periodic tests, inspections, measurement or trending of the performance or
physical characteristics of structures, systems and components to indicate current or future
performance and the potential for failure
[SOURCE: IAEA Safety Glossary, 2007 Edition]
3.9
drift
variation in transmitters or instrument channel output that may occur between calibrations that
cannot be related to changes in the process variable or environmental conditions
[SOURCE: IEC 62385:2007, 3.7]
3.10
environmental stress
factor influencing at least one ageing mechanism of the system which is not caused by the
change of its physical state
Note 1 to entry: In this standard, to apply this definition pressure transmitters are considered as systems.
[SOURCE: IEC 62465:2010, 3.9, modified]
3.11
impulse line
sensing line
piping or tubing connecting the process to the sensor; impulse lines/sensing lines are usually
used to connect pressure, level, and flow transmitters to the process
Note 1 to entry: They vary in length from a few metres to a few hundred metres. Sensing lines may also include
isolation and root valves and other piping hardware along their length.
[SOURCE: IEC 62385:2007, 3.8]
3.12
pressure transmitter
PT
pressure, level, and flow transmitters that are based on the principle of pressure or differential
pressure measurement, and are collectively referred in this standard as pressure transmitters,
pressure sensors, PT, or just transmitters
[SOURCE: IEC 62385:2007, 3.14]

3.13
qualified life
period for which a structure, system or component has been demonstrated, through testing,
analysis or experience, to be capable of functioning within acceptance criteria during specific
operating conditions while retaining the ability to perform its safety functions in a design basis
accident or earthquake
[SOURCE: IAEA Safety Glossary, 2007 edition]
3.14
response time
period of time necessary for a component to achieve a specified output state from the time
that it receives a signal requiring it to assume that output state
[SOURCE: IAEA Safety Glossary, 2007]
3.15
routine test
conformity test made on each individual item during or after manufacture
3.16
test interval
elapsed time between the initiation of identical tests on the same sensor and signal
processing device, logic assembly or final actuation device
[SOURCE: IEC 60671:2007, 3.13]
3.17
turn down factor
TDF
URL (Upper Range Limit) divided by the calibrated span of the device, which is a ratio, i.e.
dimensionless quality
[SOURCE: ISA67.04.02]
3.18
type test
conformity test made on one or more items representative of the production
3.19
verification
process of ensuring that an equipment fulfils the specified conditions
Note 1 to entry: The IEC 61513 verification definition which applies to activities differs and reads “confirmation by
examination and by provision of objective evidence that the results of an activity meet the objectives and
requirements defined for this activity”. This verification definition applies not to activities but to equipment.
3.20
system validation
confirmation by examination and provision of other evidence that a system fulfils in its entirety
the requirement specification as intended (functionality, response time, fault tolerance,
robustness)
Note 1 to entry: In this standard, to apply this definition pressure transmitters are considered as systems.
[SOURCE: IEC 61513:2011, 3.59]

– 12 – IEC 62765-1:2015 © IEC 2015
4 Abbreviations
AFV As-found Value
ALV As-left Value
AV1 Allowable Value
AV2 Analytical Value
DBE Design Basis Event
EUT Equipment Under Test
FT Flow Transmitter
LT Level Transmitter
M&TE Measurement and Test Equipment
NPP Nuclear Power Plant
PT Pressure Transmitter
QA Quality Assurance
TDF Turn Down Factor
URL Upper Range Limit
V&V Verification and Validation
5 Background
5.1 General
Transmitters in NPPs can suffer degradation due to ageing. For example, transmitters can
drift and degrade due to ageing and malfunction during plant operation or in accident and
post-accident conditions. Therefore, it is necessary to monitor, test or calibrate, and inspect
transmitters to assess ageing mechanisms predicted at the design stage, to help identify
unanticipated behaviour or degradation that might occur in service, and to identify needed
corrective actions.
5.2 Type of transmitter and interface
5.2.1 Type of transmitters
The ways that pressure transmitter ages depend to some extent on how pressure is converted
to a physical displacement, the type of sensor used to measure this displacement, and the
type of electronics that they use.
Electro-mechanical type pressure sensors are generally used for process – i.e. pressure, level
or flow – measurement within the safety system of NPPs. Pressure transmitters use elastic
sensing parts and direct display indicator or transmitting line to signal processing
instrumentation. The commonly used parts for the sensing element are a diaphragm, bellows
or Bourdon tube.
The displacement of the diaphragm, bellows, or Bourdon tube is typically measured by:
a) a variable resistance strain gauge,
b) a variable capacitance metal plate,
c) a variable inductance created by changing air gap permeance,
d) a differential transformer with moving core,
e) a wired potentiometer with sliding contact, or
f) a piezo-electric sensor.
A sealed pressure sensing part has a fluid medium isolated from process fluid. This type of
sensor provides a degree of damping of the pressure variation and may eliminate rapid
fluctuations
5.2.2 Interface between sensing part and process
5.2.2.1 Sensing line for pressure transmitters
Sensing lines (instrumentation line or impulse line) are tubes that connect the process to be
measured to the sensing part of pressure transmitters. Sensing line may contain liquid or gas.
5.2.2.2 Primary elements for flow measurement
Where pressure transmitters are used for measurement of flow, a primary element
(mechanical devices) that creates the differential pressure that is related to flow is needed.
The primary element may be an orifice plate, a venturi tube, a pipe elbow, or a flow nozzle.
The differential pressure transmitter with a primary element is defined as flow transmitters
(FT).
5.2.2.3 Reference leg for level measurement
Where pressure transmitters are used for measurement of level, a reference leg with
condensation pot that creates the head pressure as a reference level of full tank is needed.
The differential pressure between reference leg tap (high-pressure side) and tank tap (low-
pressure side) is inversely proportional to the level of tank. The differential pressure
transmitter with a reference leg is defined as level transmitters (LT).
5.3 Reasons for transmitter ageing management
Ageing of pressure transmitters can cause measurement errors, erratic signals, spikes, noise,
degradation of response time, and other anomalies that may affect plant operation or safety.
Ageing can also invalidate the environmental qualification of pressure transmitters that are
required to operate in harsh environments during accident conditions. Such effects may affect
individual transmitters or result in common cause failure of transmitters. There are also
problems such as loss of fill fluid due to ageing, which can occur in pressure transmitters
leading to performance degradation. In transmitters, transfer agent such as oil may be used.
Any leakage of oil can lead to calibration change, response time increases, and loss of
linearity. In other transmitters where oil is used for lubrication and other purposes, leakage of
oil is not as detrimental to transmitter performance. Both calibration changes and response
time degradation due to oil loss can be identified using the online-monitoring techniques
mentioned in this standard. Examples of ageing effects that can cause calibration failure, slow
response time or total failure of PTs are summarised in Table 1 (this information is also
provided in Table B.1 of IEC 62342:2007 and the related research report Sensor Performance
and Reliability listed in the bibliograhy).

– 14 – IEC 62765-1:2015 © IEC 2015
Table 1 – Examples of ageing effects that
can cause performance degradation in PTs
Affected performance
Degradation Potential cause c
Steady Dynamic Total
a b
state state
1. Partial or total loss of fill fluid – Manufacturing flaws
– High pressure   
– Ageing (wear) of seals
2. Degradation of fill fluid – Viscosity changes due to

radiation and heat
3. Wear, friction, and sticking of – Pressure fluctuations and surges

mechanical linkages
– Corrosion and oxidation
4. Failure of seals, allowing – Embrittlement and cracking of
moisture into transmitter seals due to radiation and heat 
electronics
5. Leakage of process fluid into cell – Failure of seals
fluid, resulting in temperature
– Manufacturing flaws
  
changes in sensor, viscosity
– Rupture of sensing elements
changes in fill fluid, etc.
6. Deformation of sensing element, – Pressure cycling
resulting in changes in stiffness
 
– Over-pressurization
– Vibration
7. Changes in values of electronic – Heat, radiation, humidity
components
– Changes in power supply

voltages
– Maintenance
8. Changes in spring constants of – Mechanical fatigue
 
bellows and diaphragms
– Pressure cycling
9. Blockage of holes in ceramic – Normal aging
inserts in sensing modules or
– Manufacturing flaws 
crimped capillaries
– Mishandling
10. Drift of damping resistors – Thermal fatigue
– Radiation effects 
– Vibration
a
Steady-state performance: accuracy failure when calibrating.
b
Dynamic-state performance: slow response time.
c
Total failure.
5.4 Environmental stressors
5.4.1 General
Environmental stressors affect the components of the pressure transmitters, such as sensing
elements, electronic boards, insulators and mechanical parts – seals, fill fluid, springs, and
linkages. Those stressors with potential to damage transmitters are shown Table 2. Refer to
Table 1 of IEC 62465:2010 for other stressors of cabling system.
5.4.2 Radiation
Ionizing radiation plays a role in ageing. Materials such as organic fluids, elastomers, plastics
and electronics that are used in construction of some transmitters are especially susceptible
to radiation damage. Radiation can cause embrittlement and cracking of seals, especially in
the presence of heat; increase the viscosity of fill fluids; and affect the transmitter's
electronics, especially the integrated circuit components.

5.4.3 Temperature
Temperature is one of the dominant stressors in pressure transmitters. Temperature
predominantly affects the transmitter's electronics. Long-term exposure to high temperatures
is detrimental to the life of the transmitter. Temperature also increases the effect of humidity
because it increases the rate at which moisture diffuses through seals.
5.4.4 Humidity
Humidity affects the operation of a transmitter's electronics and can cause corrosion in other
parts of a transmitter. Moisture sources and sinks exist within the transmitter and are
therefore unavoidable. The humidity levels inside a nuclear power plant may be as high as
100 %, particularly in areas where there are water or steam leaks during normal plant
operation. Some moisture will leak into transmitters because the organic polymer seals used
in most transmitters cannot provide perfect sealing under long-term exposure to the
temperatures that exist around pressure transmitters. A significant degrading effect of
humidity is short circuits in the transmitter electronics. In addition, moisture weakens the
dielectric strength of insulators.
5.4.5 Pressure transients
Pressure transmitters are continuously exposed to small pressure fluctuations during normal
operation and large pressure surges during reactor trips and other events. Water hammer, for
example, is a well-known phenomenon in NPPs, which can degrade the performance of PT.
Other pressure-induced degradations occur during calibration and maintenance when
transmitters are inadvertently over-pressurised or cycled with pressures that are above or
below their normal range. Cyclic pressures accelerate wearing and loosening of parts in the
mechanical systems of transmitters.
5.4.6 Vibration
Vibration generated by nearby machinery during plant operation is transmitted to pressure
transmitters through the building structure. Normal vibration can produce mechanical fatigue
and loosen or disintegrate the transmitter components.
5.4.7 Corrosive chemical reaction
Chemicals or sludge in process fluids can cause blockages in sense lines, fouling or erosion
and corrosion of primary elements or sensing parts. Corrosion of sense element diaphragms
may dilute oil fills. Any of these effects may cause changes in calibration accuracy or time
response.
– 16 – IEC 62765-1:2015 © IEC 2015
Table 2 – Examples of environmental stressors
with potential to damage transmitters
Ageing stressor Affected component Con
...