E
SUB-COMMITTEE ON SHIP DESIGN AND
EQUIPMENT
56th session
Agenda item 13
DE 56/13/5
11 November 2011
Original: ENGLISH
CONSIDERATION OF IACS UNIFIED INTERPRETATIONS AND AMENDMENTS
TO THE ESP CODE
Application of SOLAS Regulation II-1/3-2 Performance Standard for Protective
Coatings(PSPC) for dedicated seawater ballast tanks in all types of ships
and double-side skin spaces of bulk carriers, as adopted by
resolution MSC.215(82) – IACS UI SC 223
Submitted by the International Association of Classification Societies (IACS)
SUMMARY
Executive summary:
This document provides at annexes the latest changes to IACS
Unified Interpretation UI SC 223, relating to the application of
SOLAS regulation II-1/3-2 Performance standard for protective
coatings (PSPC) for dedicated seawater ballast tanks in all types of
ships and double-side skin spaces of bulk carriers, as adopted by
resolution MSC.215(82)
Strategic direction:
1.1
High-level action:
1.1.2
Planned output:
1.1.2.2
Action to be taken:
Paragraph 26
Related documents:
DE 52/17; MSC 88/26 (paragraph 7.3); MSC.1/Circ.1378 and
MSC.1/Circ.1381
Introduction
1
MSC 88 approved MSC.1/Circ.1378 on Unified interpretations of the Performance
standard for protective coatings for dedicated seawater ballast tanks in all types of ships and
double-side skin spaces of bulk carriers (resolution MSC.215(82)) (see paragraph 7.3 of
MSC 88/26). This MSC circular had been developed by the DE Sub-Committee and was
based on IACS UI SC 223.
2
Initially, Corr.1 of IACS UI SC 223 was submitted at the annex to document
DE 52/17. IACS subsequently submitted document DE 53/17/2 proposing a revision to
this UI to take account of the comments at DE 52 regarding the term "assistant inspectors".
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3
Since IACS UI SC 223 was submitted at the annex to document DE 52/17, in light of
technical developments and innovations in coating technology, IACS has produced two sets
of substantive revisions to this unified interpretation, as explained below.
Revision 1 of IACS UI SC 223
4
Revision 1 of UI SC 223 was developed to address questions that had been raised
by the industry on the meaning of the term "equivalency" for non-zinc containing or not
silicate based shop primers as defined by the IMO PSPC Table, Section 2.3.
5
Table 1, section 2 under paragraph 2.3 of the IMO PSPC specifically defines "Zinc
containing Inhibitor Free Zinc Silicate based shop primers" to be used or equivalent.
Inherently, according to section 8 of the IMO PSPC, acceptance of "equivalency" or not,
determines whether or not coatings shall be considered "alternative systems" which have to
meet the acceptance criteria in right columns of tables in appendix 1 and appendix 2 to the
annex 1 to the IMO PSPC.
6
In this regard, it was noted that the definition of "equivalents" given in SOLAS
regulation I/5, i.e. "at least as effective as that required by the present regulations". IACS
Members agreed that, while a shop primer may pass the pre-qualification test, a zinc-silicate
shop primer is more durable than an epoxy-iron based shop primer.
7
After extensive discussion among its Members, IACS agreed to apply the
equivalency acceptance criteria given in the prequalification test alternative system in
appendix 1 and appendix 2 to the annex 1 to MSC.215(82), Column B for such non-zinc
containing or not silicate based shop primers.
8
The changes to the section of the UI entitled "PSPC 4 Table 1: 2 PSP (Primary
Surface Preparation)" – shown as additions – are shown at annex 1 to this document.
9
The Sub-Committee is invited to note that IACS Members have been
uniformly implementing Rev.1 of UI SC 223 on ships contracted for construction on or
after 1 July 2011, unless otherwise instructed by the Administration on whose behalf they are
authorized to act as a recognized organization.
Revision 2 of IACS UI SC 223
10
Inter alia, Revision 2 of UI SC 223 takes account of:
.1
IMO's action in response to DE 53/17/2 relating to "assistant to coating
inspectors". The text of section 4 under the heading "PSPC 6 – Coating
Inspection Requirements" in UI SC 223 was made consistent with the text
in MSC.1/Circ.1378; and
.2
MSC.1/Circ.1381 following consideration of the revised NACE standard
SP0508-2010 concerning judging equivalency of methods for the
measurement of levels of soluble salts.
Noting that these elements of Revision 2 of UI SC 223 merely bring the IACS UI in line with
MSC.1/Circ.1378 and MSC.1/Circ.1381, these changes are not reproduced in the annexes to
this document.
11
Revision 2 of IACS UI SC 223 also addresses the issue of Dry Film Thickness
(DFT). Annex 1 of the PSPC (resolution MSC.215(82)) provides a test procedure for coating
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qualification. In this procedure the requirements for the DFT are given as a minimum value.
During the laboratory testing of the coatings, very high values are easily achieved to avoid
having measurements below the minimum value. The question was therefore raised as to
whether, during testing, a maximum value for the average DFT should be specified.
12
A possible consequence of a type approval based on test reports where a coating
has been tested with very high DFT values is that the coating might fail if tested closer to the
nominal dry film thickness. Acceptance of testing on lower values than the IMO
requirements was discussed, but it was concluded that the "90/10" rule should be followed.
13
The changes to the section of the UI entitled "PSPC 4 Table 1: 1 Design of coating
system – Method A: Laboratory Test" – shown as additions – are shown at annex 2 to this
document.
14
Revision 2 of IACS UI SC 223 also addresses the issue of "alternative systems".
IACS Members agreed that it would be beneficial to develop a clearer and easier
interpretation of the definition of "alternative systems" (section 8 of the PSPC) in order to
facilitate global and consistent implementation of this phrase.
15
According to section 8 of the PSPC, "normal" coating systems, i.e. not "alternative"
systems, are epoxy-based systems applied according to table 1 of this Standard. This
means alternative systems are:
.1
epoxy-based systems not applied according to table 1 of this Standard; or
.2
non epoxy-based systems applied according to table 1 of this Standard; or
.3
non epoxy-based systems not applied according to table 1 of this Standard.
16
Having discussed the issue, IACS Members agreed that if section 3.4 of Appendix 1
and 2 of PSPC (see below) was referred to, the definition of "alternative systems" would be
more comprehensible.
"3.4
Alternative systems not necessarily epoxy-based and/or not necessarily
applied according to table 1 of this Standard shall satisfy the criteria for alternative
systems as indicated in the table above."
17
In the event a coating system is defined as an "alternative system", it was agreed
the coating system should satisfy the criteria for alternative systems described in the table of
Appendix 1 and 2 through a pre-qualification test. The "alternative system" should be type
approved according to the same process as for "normal" coating systems, including taking
account of the results of the pre-qualification test.
18
For example, a one-coat solvent-free epoxy coating system is classified as an
'alternative system' because the coating system is an epoxy-based system, but it is not
applied according to table 1 of the PSPC. The coating system would be type approved if it
passes the pre-qualification test satisfying the criteria for 'alternative systems'.
19
IACS Members were aware that solvent-borne epoxy paints are commonly used
coating systems for water ballast tanks. These systems require a two-coat application system
at least. Considering solid volume and rheological properties, solvent-borne paint is
necessarily applied by at least two coats to build sufficient dry film thickness, in order
to achieve the target useful life recommended in PSPC, whereas one coat is enough for
solvent-free paint to achieve the thickness due to its high solid volume and rheological
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superiority, i.e. sag resistance. IACS examined a body of evidence showing that application of
one coat solvent-free epoxy paint system presents no problems from a technical perspective.
This evidence is provided in Annex 2c of the Technical Background for UI SC223 Revision 2,
which can be found at: http://www.iacs.org.uk/document/public/Publications/TBs/UITB.pdf
20
IACS subsequently concluded that the one coat solvent-free epoxy paint system
could be a good alternative to the current multi-coat solvent-borne epoxy paint system.
However, it is considered that careful consideration needs to be given to the application of
one-coat solvent-free epoxy system once the paint is type approved, especially regarding the
uniformity of the dry film thickness achieved.
21
A new section of the UI entitled "PSPC 8 Alternative systems" – shown as additions
– are shown in annex 3 to this document.
22
Revision 2 of IACS UI SC 223 also addresses the issue of "Acceptance of other
methods for Secondary Surface Preparation". In particular, for the reasons outlined below,
IACS Members considered that it would be beneficial to review methods of surface
preparation other than dry grit blasting and/or power tooling during Secondary Surface
Preparation as defined by Section 3 of Table I under sections 3.2, 3.3 and 3.4 of the PSPC.
The provisions relating to Cleanliness and Roughness Profile Grades are defined by a
footnoted reference to ISO Standard 8501-1/2:1988, for which Sa2 and Sa 2.5 Grades could
be interpreted as a reference to dry grit blasting only. Also, section 3.3 of the same Table 1
refers to the power tooling standard "St3 or better or SA 2.5 where practicable", without any
definition of the term "better".
23
For reasons of the health and safety of those undertaking the work and the
protection of the environment, dry grit blasting during Secondary Surface Preparation in the
open air is no longer promoted and, in some parts of the world, is even illegal. For the same
reasons, it is known that some shipowners, builders and coating manufacturers voluntarily
prefer to adopt methods of secondary surface preparation other than dry grit blasting and/or
power tooling. IACS Members are aware that other methods (such as UHP Water Jetting)
may provide equal surface conditions as required by Table 1, Section 3. These methods are
also safer and have lesser impacts on health and the environment than dry grit blasting
during Secondary Surface Preparation.
24
The changes to the section of the UI entitled "PSPC 4 Table 1: 3 SSP (Secondary
Surface Preparation)" – shown as additions – are shown at annex 4 to this document.
25
The Sub-Committee is invited to note that IACS Members will uniformly implement
Rev.2 of UI SC 223 on ships contracted for construction on or after 1 July 2012, unless
otherwise instructed by the Administration on whose behalf they are authorized to act as a
Recognized Organization.
Action requested of the Sub-Committee
26
The Sub-Committee is invited to note the discussion above and the revisions
to IACS UI SC 223 provided at the annexes to this document and decide as appropriate
regarding MSC.1/Circ.1378.
***
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Annex 1, page 1
ANNEX 1
PSPC 4 TABLE 1: 2 PSP (PRIMARY SURFACE PREPARATION)
"2
PSP (Primary Surface Preparation)
2.1
Blasting and profile6, 7
Sa 21/2; with profiles between 30-75 μm
Blasting shall not be carried out when:
.1
the relative humidity is above 85%; or
.2
the surface temperature of steel is less than 3°C above the dew point.
Checking of the steel surface cleanliness and roughness profile shall be carried out at the
end of the surface preparation and before the application of the primer, in accordance with
the manufacturer's recommendations.
2.2
Water soluble salt limit equivalent to NaCl8
≤ 50 mg/m2 of sodium chloride.
2.3
Shop primer
Zinc containing inhibitor free zinc silicate based or equivalent.
coating system shall be confirmed by the coating manufacturer."
Compatibility with main
Interpretation of paragraph 2.2:
The conductivity of soluble salts is measured in accordance with ISO 8502-6 and
ISO 8502-9, and compared with the conductivity of 50 mg/m2 NaCl. If the measured
conductivity is less than or equal to, then it is acceptable. Minimum readings to be taken are
one (1) per plate in the case of manually applied shop primer. In cases where an automatic
process for application of shop primer is used, there should be means to demonstrate
compliance with PSPC through a Quality Control System, which should include a monthly
test.
Interpretation of paragraph 2.3:
Shop primers not containing zinc or not silicate based are considered to be "alternative
systems" and therefore equivalency is to be established in accordance with Section 8 of the
PSPC with test acceptance criteria for "alternative systems" given in section 3.1 (right
columns) of appendices 1 and 2 to Annex 1 of MSC.215(82).
***
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Annex 2, page 1
ANNEX 2
PSPC 4 TABLE 1: 1 DESIGN OF COATING SYSTEM – METHOD A: LABORATORY TEST
1.3.5
For the coating pre-qualification test, the measured average dry film thickness (DFT)
on each prepared test panels shall not exceed a nominal DFT (NDFT) of 320 microns
plus 20% unless a paint manufacturer specifies a NDFT greater than 320 microns. In the
latter case, the average DFT shall not exceed the specified NDFT plus 20% and the coating
system shall be certified to the specified NDFT if the system passes the tests according to
Annex 1 of MSC.215(82). The measured DFT shall meet the "90/10" rule and the maximum
DFT shall be below the maximum DFT value specified by the manufacturer.
***
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Annex 3, page 1
ANNEX 3
PSPC 8 ALTERNATIVE SYSTEMS
"8.1
All Systems that are not an epoxy-based system applied according to table 1 of this
Standard are defined as an alternative system.
8.2
This Standard is based on recognized and commonly used coating systems. It is
not meant to exclude other, alternative, systems with proven equivalent performance, for
example non epoxy-based systems.
8.3
Acceptance of alternative systems will be subject to documented evidence that they
ensure a corrosion prevention performance at least equivalent to that indicated in this
Standard.
8.4
As a minimum, the documented evidence shall consist of satisfactory performance
corresponding to that of a coating system which conforms to the coating standard described
in section 4, a target useful life of 15 years in either actual field exposure for 5 years with final
coating condition not less than "GOOD" or laboratory testing. Laboratory test shall be
conducted in accordance with the test procedure given in annex 1 to this Standard."
Interpretation
The definition of alternative systems
1
Normal coating systems, i.e. not alternative systems is:
.1
2
epoxy-based system applied according to table 1 of PSPC
Alternative systems can be coating systems which are:
.1
epoxy-based systems, but not applied according to table 1 of PSPC;
.2
non epoxy-based systems applied according to table 1 of PSPC; or
.3
non epoxy-based systems, but not applied according to table 1 of PSPC.
The requirement of coating system approval for alternative systems
1
Type Approval Certificate shall be issued subject to satisfaction of the test
procedure given in annex 1 to this standard, evaluated according to the acceptance criteria
for alternative systems.
The inspection of application of alternative systems
1
The coatings are to be inspected according to the coating inspection requirement
in PSPC.
The application of alternative systems
1
The necessary conditions for application, especially for difference from conventional
epoxy coating system should be specified in the coating technical file as per section 3.4.
of MSC.215(82).
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Annex 3, page 2
2
It is recommended that the work for confirmation of the suitability of application
(workability, coating quality, worker's skill and so on) is demonstrated before the project
starts.
***
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Annex 4, page 1
ANNEX 4
PSPC 4 TABLE 1: 3 SSP (SECONDARY SURFACE PREPARATION)
"3.2
Sa 21/2 on damaged shop primers and welds
Sa 2 removing at least 70% of intact shop primer, which has not passed a prequalification
certified by test procedures in 1.3."
"3.3
Surface treatment after erection6
Butts St 3 or better or Sa 21/2 where practicable. Small damages up to 2% of total area:
St 3. Contiguous damages over 25 m2 or over 2% of the total area of the tank, Sa 21/2 shall
be applied.
Coating in overlap shall be feathered."
"3.4
In case of full or partial blasting 30-75 μm, otherwise as recommended by the
coating manufacturer."
Interpretation
Methods such as, but not limited to UHP Water Jetting may be considered for Secondary
Surface Preparation, where it can be demonstrated that the surface conditions specified by
PSPC Table 1, section 3 can be achieved before the application of the main coatings.
Usually, the fillet welding on tank boundary watertight bulkhead is left without coating on
block stage (because not yet be leakage tested), in which case it can be categorized as
erection joint ("butt") to be power tooled to St 3.
___________
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