SIST EN ISO 16784-1:2008

SLOVENSKI STANDARD
01-julij-2008
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Corrosion of metals and alloys - Corrosion and fouling in industrial cooling water systems
- Part 1: Guidelines for conducting pilot-scale evaluation of corrosion and fouling control
additives for open recirculating cooling water systems (ISO 16784-1:2006)
Corrosion des métaux et alliages - Corrosion et entartrage des circuits de
refroidissement a eau industriels - Partie 1: Lignes directrices pour l'évaluation pilote des
additifs anticorrosion et antitartre pour circuits de refroidissement a eau a recirculation
ouverts (ISO 16784-1:2006)
Ta slovenski standard je istoveten z: EN ISO 16784-1:2008
ICS:
77.060 Korozija kovin Corrosion of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16784-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2008
ICS 77.060
English Version
Corrosion of metals and alloys - Corrosion and fouling in
industrial cooling water systems - Part 1: Guidelines for
conducting pilot-scale evaluation of corrosion and fouling control
additives for open recirculating cooling water systems (ISO
16784-1:2006)
Corrosion des métaux et alliages - Corrosion et entartrage Korrosion von Metallen und Legierungen - Korrosion und
des circuits de refroidissement à eau industriels - Partie 1: Fouling in industriellen Kühlwassersystemen - Teil 1:
Lignes directrices pour l'évaluation pilote des additifs Leitfaden für die Bewertung von Zusatzstoffen gegen
anticorrosion et antitartre pour circuits de refroidissement à Korrosion und Fouling in offenen
eau à recirculation ouverts (ISO 16784-1:2006) Kühlwasserrezirkulationssystemen (ISO 16784-1:2006)
This European Standard was approved by CEN on 21 March 2008.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16784-1:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
The text of ISO 16784-1:2006 has been prepared by Technical Committee ISO/TC 156 “Corrosion of metals
and alloys” of the International Organization for Standardization (ISO) and has been taken over as EN ISO
16784-1:2008 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of
which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by October 2008, and conflicting national standards shall be withdrawn at
the latest by October 2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 16784-1:2006 has been approved by CEN as a EN ISO 16784-1:2008 without any
modification.
INTERNATIONAL ISO
STANDARD 16784-1
First edition
2006-03-01
Corrosion of metals and alloys —
Corrosion and fouling in industrial
cooling water systems —
Part 1:
Guidelines for conducting pilot-scale
evaluation of corrosion and fouling
control additives for open recirculating
cooling water systems
Corrosion des métaux et alliages — Corrosion et entartrage des circuits
de refroidissement à eau industriels —
Partie 1: Lignes directrices pour l'évaluation pilote des additifs
anticorrosion et antitartre pour circuits de refroidissement à eau à
recirculation ouverts
Reference number
ISO 16784-1:2006(E)
©
ISO 2006
ISO 16784-1:2006(E)
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ii © ISO 2006 – All rights reserved

ISO 16784-1:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms. 2
4 Types of testing . 2
4.1 Laboratory and off-site testing. 2
4.2 On-site testing. 2
4.3 On-line testing. 2
5 Test unit design parameters. 3
5.1 General. 3
5.2 Construction materials. 3
6 Operating parameters. 5
6.1 General. 5
6.2 Surface temperature. 5
6.3 Water velocity. 5
6.4 Residence time. 5
7 Water quality . 5
7.1 General. 5
7.2 Natural versus synthetic water supplies. 6
7.3 Fresh water. 6
7.4 Seawater and brackish water . 6
7.5 Recycle/reuse water . 6
7.6 Dual and combined make-up systems .6
8 Contamination. 7
8.1 General. 7
8.2 Process leaks. 7
8.3 Biological matter. 7
8.4 Airborne solids and gases. 7
9 Parameters to be evaluated in pilot test units . 7
9.1 Corrosion. 7
9.2 Fouling . 9
9.3 Practical problems in operating systems — Multiple combinations of problems. 10
9.4 Water treatment additives. 10
10 Design of pilot-scale performance testing facilities . 11
10.1 Objectives. 11
10.2 The importance of simulating specific application environments . 11
10.3 Compromises in pilot-scale performance testing . 11
11 Pilot-scale facility operations . 13
11.1 Documentation of design. 13
11.2 Repeatability of results and comparison with field performance. 13
11.3 Record-keeping and reports. 13
Bibliography . 14

ISO 16784-1:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16784-1 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
ISO 16784 consists of the following parts, under the general title Corrosion of metals and alloys — Corrosion
and fouling in industrial cooling water systems:
⎯ Part 1: Guidelines for conducting pilot-scale evaluation of corrosion and fouling control additives for open
recirculating cooling water systems
⎯ Part 2: Evaluation of the performance of cooling water treatment programmes using a pilot-scale test rig
iv © ISO 2006 – All rights reserved

ISO 16784-1:2006(E)
Introduction
Environmental requirements, water shortages, and business pressures have forced industrial plants and
power stations to operate with longer production runs, reduced maintenance outages, fewer operating
personnel, and increased stress on cooling water systems. Similarly, commercial refrigeration (heating,
ventilating, and air conditioning [HVAC]) systems have experienced increased heat loads and requirements
for a long-term, continuous, cooling water supply to computer facilities, large retail establishments, campuses,
and office complexes.
Under these increasingly severe conditions, cooling water chemical treatment programmes are expected to
maintain optimum operating efficiency and, at the same time, protect the economic life of the equipment by
inhibiting corrosion, mineral scaling, microbiological fouling, and miscellaneous deposition on heat-transfer
surfaces.
Cooling system design and operating characteristics vary widely, within individual plants, from site to site, and
worldwide. Thus, selection and optimization of water treatment programmes must be a site-specific process.
In most systems, optimized cooling water chemical treatment is the key to successful long-term operations.
The subject of this part of ISO 16784 is, therefore, the establishment of criteria for the pilot-scale evaluation of
the performance of cooling water additives under field-specific operating conditions.
This part of ISO 16784 is intended for use by cooling system owners/operators, water treatment companies
and others who must evaluate the performance of cooling water additives under field-specific operating
conditions.
[4]
This part of ISO 16784 was developed on the basis of NACE RP0300 .

INTERNATIONAL STANDARD ISO 16784-1:2006(E)

Corrosion of metals and alloys — Corrosion and fouling
in industrial cooling water systems —
Part 1:
Guidelines for conducting pilot-scale evaluation of corrosion
and fouling control additives for open recirculating cooling
water systems
1 Scope
This part of ISO 16784 applies to corrosion and fouling in industrial cooling water systems.
This part of ISO 16784 covers the criteria that must be defined and implemented in a pilot-scale testing
programme to select water treatment programmes for use in specific recirculating cooling water systems.
This part of ISO 16784 covers only open recirculating cooling water systems. Closed cooling systems and
once-through cooling water systems are specifically excluded.
This part of ISO 16784 applies only to systems incorporating shell-and-tube heat exchangers with standard
uncoated smooth tubes and cooling water on the tube side. Heat exchangers with shell-side water, plate and
frame and/or spiral heat exchangers, and other heat exchange devices are specifically excluded. However,
when the test conditions are properly set up to model the surface temperature and shear stress in more
complex heat-transfer devices, the test results may predict what may occur in an operating heat exchanger of
that design.
The test criteria established in this part of ISO 16784 are not intended to govern the type of bench and
pilot-scale testing normally carried out by water treatment companies as part of their proprietary
product-development programmes. However, water treatment companies may choose to use the criteria in
this part of ISO 16784 as guidelines in the development of their own product-development test procedures.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 8044:1999, Corrosion of metals and alloys — Basic terms and definitions
ISO 16784-2, Corrosion of metals and alloys — Corrosion and fouling in industrial cooling water systems —
Part 2: Evaluation of the performance of cooling water treatment programmes using a pilot-scale test rig
ISO 16784-1:2006(E)
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms and definitions given in ISO 8044:1999 and the following
abbreviations and symbols apply.
ASTM: ASTM International
BOD: Biological oxygen demand
COD: Chemical oxygen demand
HVAC: Heating, ventilating, and air conditioning
LPR: Linear polarization resistance
MIC: Microbiologically influenced corrosion
NACE: NACE International
PVC: Polyvinyl chloride
s/V ratio: Surface-to-volume ratio
UNS: Unified Numbering System
4 Types of testing
4.1 Laboratory and off-site testing
4.1.1 Laboratory testing, or testing at alternative off-site locations, may in some cases be necessary for
selecting cooling water chemical treatment programmes. This type of testing could be used for new
construction start-up programmes, when operating systems are not available, or for evaluating alternative
treatment programmes. In such cases, the evaluation should include site-specific design criteria and
environmental regulations that affect the cooling water system. Site-specific water supplies should be used
whenever possible. All criteria in this part of ISO 16784 relating to water compositions, test unit configuration,
heat exchanger design, and operating conditions should be followed insofar as possible.
4.1.2 No laboratory or off-site testing programme can completely duplicate plant conditions. Site-specific
factors, such as process leaks, microbiological growth, corrosion products, airborne contamination, etc., may
affect the operation of cooling water systems and the performance of chemical treatment programmes in ways
that override the results of laboratory or off-site testing programmes.
4.2 On-site testing
4.2.1 Whenever possible, water treatment programmes should be evaluated on site, using plant water
supplies and actual design and operating conditions, particularly those that cannot be duplicated in the
laboratory. Criteria for these effects are discussed in 9.1.2.
4.2.2 Specific attention shall be given to site-specific rules and environmental regulations that may affect
the types of chemical products that can be used, the allowable amount and composition of blowdown water,
and air quality regulations affecting cooling tower discharge.
4.3 On-line testing
Whenever possible, all off-site, laboratory, and on-site pilot-scale testing should be validated by monitoring
actual performance results on-line. Pilot units can be adapted for on-line work by using a sidestream from the
plant circulating cooling water as feedwater, bypassing the pilot unit cooling tower. Such on-line testing serves
to validate the off-line/laboratory tests. Cooling systems may be evaluated on-line; however, the data collected
will be the result of the combination of any existing treatment and all additional chemicals that were added for
the evaluation period. On-line testing in this way can be useful for optimizing the treatment programme to
2 © ISO 2006 – All rights reserved

ISO 16784-1:2006(E)
meet specific plant requirements. For example, small quantities of a treatment chemical may be added just
ahead of the test heat exchanger to measure the effects of increasing additive dosage, or the possible
synergistic effects of a new chemical added to the existing treatment programme.
5 Test unit design parameters
5.1 General
Careful evaluation of the mechanical design and operation of each cooling water system is a necessary
prerequisite for designing a pilot-scale water treatment product-evaluation programme. It may not be practical
to simulate a specific critical plant heat load or water flow pattern exactly. Contamination in a pilot cooling
tower may not develop in the same way as in the plant systems; compromises may therefore be necessary. In
all such cases, plant design and operations must be followed as closely as possible, and deviations must be
noted in the test reports.
5.2 Construction materials
5.2.1 Cooling towers
5.2.1.1 Small cooling tower basins may be made of uncoated, plastic-coated, galvanized low-carbon
steel, or stainless steel. Large tower basins are usually concrete. Splash fill may be wood, ceramic, or plastic.
It is not important that the pilot cooling tower duplicates the design of the plant towers. However, if the plant
system contains galvanized steel, galvanized steel should be included as a non-heat-transfer test material in
the pilot system.
5.2.2 Special requirements for film fill
5.2.2.1 If the plant cooling towers contain film fill, a section of this fill (if available) should be used in the
pilot tower. Film fill consists of closely packed layers of lightweight plastic material, normally PVC, arranged in
a honeycomb-like structure. This maximizes the surface area over which water must flow, and thereby
improves evaporation efficiency. However, the increased surface area also encourages deposit formation in
the fill.
5.2.2.2 Deposits may consist of mineral scales formed by evaporation of water, corrosion products and
silt carried into the tower, and microbiological deposits. Biofilms tend to act as a “glue” that encourages other
deposits to adhere to the fill. Because the space between adjacent layers of fill is often quite small, deposited
material may “bridge” the fill and block water flow. This is a serious problem, because film fill cannot be
cleaned chemically unless water can flow through all parts of the fill.
5.2.2.3 Mechanical cleaning, including water lancing, often damages the lightweight fill material. In
addition, the weight of a significant deposit in the film fill can mechanically damage it. Hence, one performance
requirement of any cooling water chemical treatment programme intended for use in a film-fill cooling tower
shall be to prevent bridging of the fill.
5.2.2.4 The condition of film fill in an operating cooling tower can be monitored by using a “fill test box.”
This is simply a section of fill, roughly a 0,6 m (2 ft) cube, enclosed in a supporting box open at the top and
bottom. The box is exposed to the “rain” falling below the fill in the cooling tower, in an accessible location. A
slippery feeling on the fill surfaces, or appearance of a visible deposit layer, indicates fouling conditions in the
fill.
5.2.2.5 A fill test box is a very useful qualitative monitoring tool in an operating cooling tower, but
because of space and size limitations, it may not be practical in a pilot cooling tower. In such cases, it is best
to design the pilot cooling tower so that the actual tower fill can be accessed conveniently for visual and
physical inspection.
ISO 16784-1:2006(E)
5.2.3 Non-heat-transfer metal surfaces
5.2.3.1 Circulating water lines may be carbon steel, copper, brass, fiberglass, polyethylene or
cement-lined. Unless process-side conditions dictate otherwise, heat exchanger shells are usually made of
carbon steel.
5.2.3.2 All corrosion-prone metals that are present in the operating system should be included as
non-heat-transfer test coupons in the pilot study. This is important for two reasons: localized corrosion of
piping systems can lead to unexpected failures; and corrosion product deposits can accumulate on
heat-transfer surfaces, leading to losses in efficiency and opportunities for underdeposit corrosion. Water
treatment chemicals can only provide corrosion protection when the chemicals can reach the metal surfaces.
Unprotected metal areas beneath deposits thus become potential sites for underdeposit corrosion.
5.2.4 Heat exchangers
5.1.4.1 Heat exchanger design is generally focused on process-side requirements and on the actual
process involved (liquid cooling, gas cooling, or condensing). Process heat exchangers are designed to
control the temperature of a process fluid under the most severe expected conditions, that is, the warmest
cooling water and the maximum production rate.
1)
5.2.4.2 Heat exchangers are designed with a built-in fouling factor that allows the unit to produce the
desired process temperature control with some loss of efficiency due to either water- or process-side fouling of
the tubes. For these reasons, process heat exchangers are often oversized. To achieve the desired
process-side outlet temperature control, operators throttle the water flow in response to ambient conditions,
production demands, and the degree of fouling in the heat exchanger. Reducing the water flow rate through
the tubes increases the surface temperature and provides more opportunity for suspended solids to settle on
the tube surfaces and for mineral scale deposits to form. Both of these effects lead to losses in heat-transfer
efficiency and increased opportunities for corrosion of the tubes. See also 9.3.1.
5.2.4.3 One very important function of the chemical water treatment programme is to minimize corrosion
and deposit formation of all kinds on heat exchanger surfaces. In designing a pilot-scale testing programme,
one critical set of parameters involves the configuration of the heat-transfer section. Heat-transfer tubes may
2)
be made of carbon steel, copper, copper alloys, or UNS S30400 and S31600 (types 304 and 316 stainless
steels). If required in petrochemical plants or other locations with severe process-side conditions, heat-transfer
tubes may include a wide variety of other alloys and a few nonmetallic materials.
5.2.4.4 Care should be taken in the selection of the heat exchanger to be modelled. The most
appropriate heat exchanger is the one with a combination of the highest surface temperature and the lowest
velocity, within reason. Some judgment may be required in the selection process.
5.2.4.5 Petrochemical plants sometimes include vertically oriented shell-and-tube heat exchangers.
Because of process requirements, water is often on the shell side in such exchangers. Shell-side water
creates particularly severe corrosion and fouling problems that cannot be satisfactorily simulated in the type of
pilot-scale equipment covered by this part of ISO 16784. This is especially true of vertical shell-side water heat
exchangers.
NOTE As stated in the fourth paragraph of the Scope, shell-side heat exchangers are specifically excluded from this
part of ISO 16784.
1) Fouling factor or fouling thermal resistance refers to the measured resistance to heat transfer caused by a deposit on
a heat-transfer surface. Fouling factor is also used in heat-exchanger design to increase the heat-exchanger surface area
to compensate for the thermal inefficiency expected to occur due to a deposit on the heat-transfer surface. The term
fouling factor is commonly used for both. However fouling thermal efficiency may be substituted for the measured fouling
factor.
2) Metals and Alloys in the Unified Numbering System (latest revision), a joint publication of the American Society for
Testing and Materials (ASTM) and the Society of Automotive Engineers Inc. (SAE), 400 Commonwealth Dr., Warrendale,
PA 15096.
4 © ISO 2006 – All rights reserved

ISO 16784-1:2006(E)
5.2.4.6 Many plant heat exchangers include multi-tube and multi-pass designs. Such designs are difficult to
simulate in a pilot-scale unit. This part of ISO 16784 refers to single-tube, single-pass designs with parameters
selected to simulate the conditions under study in the plant exchanger.
6 Operating parameters
6.1 General
For any given heat exchanger design, the kinetics of fouling and corrosion are controlled by four parameters:
surface temperature, water velocity, residence time, and water quality. Because it is not possible, in a small
pilot-scale unit, to duplicate all of the characteristics of an operating heat exchanger, compromises must be
made in controlling each of these parameters.
6.2 Surface temperature
6.2.1 The surface temperature of the heat-transfer surface controls the rate of temperature-driven corrosion
and fouling reactions. The surface temperature, in turn, is a function of the heat flux, metallurgy, water flow,
and the degree of water- and process-side fouling of the tubes.
6.2.2 During testing of water treatment programmes under the most severe conditions that can realistically
exist in a specific plant, the surface temperature of the heated tube sections in the pilot unit should match the
highest surface temperature in the operating heat exchanger. This temperature can be estimated from
measured water- and process-side flows and temperatures, and the design data for the heat exchanger.
6.3 Water velocity
6.3.1 Water velocity through the heat exchanger tubes determines the rate of transfer of dissolved and
suspended matter between the bulk cooling water and the water film in contact with the tube wall. These
materials can include scaling i
...