1 The Sub-Committee on Carriage of Cargoes and Containers (CCC), at its
fifth session (10 to 14 September 2018), considered submissions from Australia,
Brazil, Canada, the United States, NACE International and IIMA relating to the
assessment of the Materials Hazardous only in Bulk (MHB) category "Corrosive
Solids", for which paragraph 9.2.3.7.3 of the IMSBC Code states that the UN C.1
testfootnote is an acceptable test.footnote The UN C.1 test, however, was developed for liquids
and solids that may become liquid during transportation and had never been validated
for solids. Industry experience was that the test resulted in anomalous and highly
variable results. A Global Industry Alliance (GIA) was formed under the auspices of
the International Council on Mining and Metals (ICMM) in order to improve the
assessment of solid bulk cargoes for the corrosive hazard.
2 After an international research programme across a range of commodities, the GIA
concluded that by defining and standardizing important parameters, potential sources
of variation can be removed and the degree of variability in test outcomes can be
reduced to acceptable levels. On the basis of this work, Australia, Brazil, Canada,
the United States, NACE International and IIMA proposed:
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.1 minor changes to section 9 of the IMSBC Code, specifically paragraph
9.2.3.7.3, to enhance the test method's applicability to the carriage of
solid bulk cargoes; and
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.2 the issuance of guidance that extends and details the MHB test method for
assessing solid bulk cargoes against the "corrosive solids: MHB (CR) hazard"
as described in paragraph 9.2.3.7.3 of the IMSBC Code. The guidance should
be utilized by test laboratories conducting the test in conjunction with the
MHB (CR) test description (paragraph 9.2.3.7.3 of the IMSBC Code).
3 CCC 5 agreed, in principle, that the modifications to paragraph 9.2.3.7.3 of the
IMSBC Code proposed by the submitters should be recommended for adoption in
amendment 06-21 to the IMSBC Code and that the proposed Interim guidance for
implementation of the test protocol should be approved by the Organization.
4 Notwithstanding the requirements that the sample contains at least 10% moisture by
mass and that aluminium test coupons are used in the test specified in paragraph
9.2.3.7.3 of the IMSBC Code, the Maritime Safety Committee, at its 100th session (3
to 7 December 2018), approved the Interim guidance for conducting the refined MHB
(CR) corrosivity test (MSC.1/Circ.1600).
5 The Maritime Safety Committee, at its 105th session (20 to 29 April 2022), approved
amendments to the Interim guidance, as prepared by CCC 7, resulting from the
amendments (06-21) to the IMSBC Code, adopted by resolution MSC.500(105). The
amended text of the Guidance is set out in the annex.
6 Member States are invited to bring the above information and the attached Guidance
to the attention of all stakeholders, requesting that appropriate action be taken
when carrying out the MHB (CR) test, taking into account the voluntary application
date of 1 January 2023 of amendments (06-21) to the IMSBC Code, pending their
envisaged entry into force on 1 December 2023.
7 This circular supersedes MSC.1/Circ.1600.