AMENDMENTS TO THE IMSBC CODE AND SUPPLEMENTS

Transcription

1 E SUB-COMMITTEE ON CARRIAGE OF CARGOES AND CONTAINERS 4th session Agenda item 5 CCC 4/5/6 6 July 2017 Original: ENGLISH AMENDMENTS TO THE IMSBC CODE AND SUPPLEMENTS Review of the test methods given in the IMSBC Code for classifying materials which evolve flammable gas when wet Submitted by the United Kingdom SUMMARY Executive summary: This document reviews the criteria for classifying cargoes that evolve flammable gas when wet MHB (WF) as required in provision of the International Maritime Solid Bulk Cargoes (IMSBC) Code Strategic direction: 5.2 High-level action: Output: Action to be taken: Paragraph 11 Related documents: Resolutions MSC.268(85) and MSC.393(95) Introduction 1 This document brings to the attention of the Sub-Committee some limitations with the testing requirements given in the IMSBC Code for classifying bulk materials which emit flammable gas when wet MHB(WF). Background 2 In January 2017, a general cargo ship called at a UK port and loaded a solid bulk cargo which was unassessed and did not have a schedule within the IMSBC Code. The vessel, while at anchor after loading, experienced an explosion on board. The explosion was caused by a build-up of hydrogen gas in the cargo hold. At the time of the incident the shipper had not approached any competent authority to seek approval for shipping. As such, the cargo had not undergone any of the testing required for assessing carriage requirements.

2 Page 2 3 Immediately after the incident, the UK Administration prevented further loading of this product, and instructed the shipper to comply with requirements within the IMSBC Code. 4 The first test results stated there was 'no observable gas', indicating that the cargo did NOT meet the criteria for MHB(WF). The tests had been conducted in line with the United Nations Manual of Tests and Criteria, part III, , as required by provision of the IMSBC Code. However, the test results clearly contradicted the hazards, as evidenced by the recent incident. Discussion 5 Given the contradiction between the test results and the facts established after the incident, further consideration to the parameters of the tests required by provision of the IMSBC Code is needed. For ease of reference an extract from the United Nations Manual of Tests and Criteria, part III, is given in the annex. 6 Areas of concern include:.1 the mass of the sample required for testing compared against the mass of a solid bulk consignment. The tests call for <2 mm diameter of testing substance. Comparing this to the size of the cargo (in this instance >3,500 tonnes), it is difficult to consider this size testing sample can be representative of the cargo as shipped. Highly heterogeneous cargoes especially risk being misrepresented by using a testing substance of only <2 mm diameter;.2 the saturation requirements of the test; the UN test is open to interpretation on the matter of saturation, and at least two of the requirements are quite conservative in this area, especially when considered against the conditions the cargo might experience within an enclosed cargo hold; and.3 the lack of requirements for testing multiple samples; although the UN test stipulates the test to be performed three times, there is currently no requirement for testing more than one sample, which is at odds with the IMSBC Code sampling procedures, such as those given in section As a result of the above concerns, further tests were sought from an independent testing house. This laboratory sampled the cargo, applied the UN specified test, and found a rate of H2 generation of 0.43 l kg-1 h-1. The same testing house then re-tested the samples using a testing method developed in-house. The secondary test found a rate of H2 generation of 0.77 l kg-1 h-1. The principal reason given for the higher rate found using the in-house testing method was that "the UN test used a much lower liquid-to-solid ratio than the [in-house] NLS tests (ratios of 1.5 and 6 respectively)." Parties interested in reading any of the test reports mentioned in this paper should contact IMSBC@mcga.gov.uk 8 It is worth noting that materials which emit flammable gas when in contact with water MHB(WT), and materials which evolve toxic gas when in contact with water MHB(WF), are classified using the same test given in the United Nations Manual of Tests and Criteria, part III, The points raised in paragraph 6, therefore, apply equally to establishing classification of MHB(WF) and MHB(WT).

3 Page 3 Conclusion 9 There appears to be a disparity between the UN test requirements for classifying MHB(WF) & MHB(WT) and the application of these tests when applied to heterogeneous solid bulk cargoes. Proposal 10 The provisions and of the IMSBC Code could be revised to require the MHB tests to use a larger sample, i.e. 1 kg, and to request that the test substance be fully saturated during the course of the test. Additionally, these sections could include a requirement for replicate tests to be performed, i.e. three replicates. These changes would go some way to reducing the issues raised within this document. Actions requested of the Sub-Committee 11 The Sub-Committee is invited to consider the revision to the testing criteria for MHB(WF) and MHB(WT) given in the IMSBC Code and take action as appropriate. ***

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5 Annex, page 1 ANNEX 1 EXTRACT FROM RECOMMENDATIONS ON THE TRANSPORT OF DANGEROUS GOODS MANUAL OF TESTS AND CRITERIA. SIXTH REVISED EDITION Division Substances which in contact with water emit flammable gases Purpose This section of the Manual presents the United Nations scheme for the classification of substances of Division 4.3 which in contact with water emit flammable gases (see section of the Model Regulations). The text should be used in conjunction with the classification principles given here in The test procedure is intended to determine whether the reaction of a substance with water leads to the development of a dangerous amount of gases which may be flammable The test procedures outlined here adequately assess the relative hazard of substance liable to emit flammable gases on contact with water (sometimes referred to as water reactive substances in the Model Regulations) so that an appropriate classification for transport can be made Scope New products offered for transport should be subjected to the classification procedures as set out in sub-sections and of the Model Regulations. The classification procedure should be undertaken before a new product is offered for transport Classification procedure for substances which in contact with water emit flammable gases The test method can be applied to solid and liquid substances. In case a pyrophoric substance is tested, the test should be executed under nitrogen atmosphere. The substance should be tested in its commercial form at ambient temperature (20⁰C) by bringing it into contact with water. If during any stage of the test the gas emitted ignites then no further testing is necessary and the substance should be assigned to Division 4.3. if spontaneous ignition of the emitted gas does not occur then the final stage of the test should be performed to determine the rate of emission of flammable gas. The recommendation test method, with possible results, is given here in Whether a substance is water-reactive substance of Division 4.3 and, if so, whether packing group I, II or III should be assigned is decided on the basis of the test results Test N.5: Test method for substances which in contact with water emit flammable gases 1 This annex is represented in English only. For French and Spanish version, please refer to:

6 Annex, page Introduction The ability of a substance to emit flammable gases on contact with water is tested by bringing it into contact with water under a variety of conditions Apparatus and materials No special laboratory apparatus is required Procedure The substance should be tested according to the procedures described below; if spontaneous ignition occurs at any stage then no further testing is necessary. If it is known that the substance does not react violently with water then proceed to A small quantity (approximately 2 mm diameter) of the test substance should be placed in a trough of distilled water at 20 ⁰C. it is noted: (b) Whether any gas is evolved; and If spontaneous ignition of the gas occurs A small quantity of the test substance (approximately 2 mm diameter) should be placed on the centre of a filter paper which is floated flat on the surface of distilled water at 20 ⁰C in a suitab keep the substance in one place, under which condition the likelihood of spontaneous ignition of any gas is greatest. It is noted: (b) Whether any gas is evolved; and If spontaneous ignition of the gas occurs The test substance should be made into a pile approximately 20 mm high and 30 mm diameter with a hollow in the top. A few drops of water are added to the hollow. It is noted whether: (b) Any gas is evolved; and If spontaneous ignition of the gas occurs For solids, the package should be inspected for any particles of less than 500 µm diameter. If that powder constitutes more than 1% (mass) of the total, or if the substance is friable, then the whole of the sample should be ground to powder before testing to allow for a reduction in particle size during handling and transport. Otherwise, as for liquids, the substance should be tested in its commercial state. This test should be performed three times at ambient temperature (20 ⁰C) and atmo enough of the substance (up to a maximum mass of 25 g) to produce between 100 ml and 250 ml of gas is weighted and placed in a conical flask. The tap of the dropping funnel is measured by any suitable means. The time taken for all the gas to be evolved is noted and where possible, intermediate readings are taken. The rate of evolution of gas is calculated over 7 hours at 1 hour intervals. If maximum time of 5 days. The five day test may be stopped if the rate of evolution becomes steady or continually decreases and sufficient data has been established to assign a packing group to the substance or to determine that the substance

7 Annex, page 3 should not be classified in Division 4.3. If the chemical identity of the gas is unknown, the gas should be tested for flammability Test criteria and method of assessing results A substance should be classified in Division 4.3 if: or Spontaneous ignition takes place in any step of the test procedure; (b) There is an evolution of a flammable gas at a rate greater than 1 litre per kilogram of the substance per hour Packing group I should be assigned to any substance which reacts vigorously with water at ambient temperatures and generally demonstrates a tendency for the gas produced to ignite spontaneously, or which reacts readily with water at ambient temperatures such that the rate of evolution of flammable gas is equal to or greater than 10 litres per kilogram of substance over any one minute period Packing group II should be assigned to any substance which reacts readily with water at ambient temperatures such that the maximum rate of evolution of flammable gas is equal to or greater than 20 litres per kilogram of substance per hour, and which does not meet the criteria for packing group I Packing group III should be assigned to any substance which reacts slowly with water at ambient temperatures such that the maximum rate of evolution of flammable gas is greater than 1 litre per kilogram of substance per hour, and which does not meet the criteria for packing groups I or II. Copyright United Nations, 2015.