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Due to the high damping mechanical properties of fiberboard materials, corrugated fiberboard boxes are widely used as transport packagings of dangerous goods. Since there is risk of vertical impact within the distribution system, drop tests are performed as design type tests to assess a package’s ability to withstand damage. In this context, however, little is known regarding the transient mechanical response of a filled fiberboard box. The reason is that the nature of the packaging material presents challenges in identifying the deformation mechanisms experimentally. The aim of this work is to provide a framework for predicting the damage resistance of complete, filled corrugated fiberboard boxes which are ready for transportation. Therein, drop test finite-element simulations are used and validated by experimental results. These numerical calculation models are a valuable tool for virtual product development and contribute to the optimization of the design cycle.
For dangerous goods packagings, drop testing onto an essential unyielding target can be used to assess the mechanical resistance to impact loads. Adopted regulations like ADR/RID require that the impact surface provided shall be integral with a mass at least 50 times than that of the heaviest package to be tested. The problem is that many manufacturers do not possess impact targets that satisfy the required 50 times mass ratio for regulative drop tests during series production. The objective of this work is to verify existing and define improved criteria for impact target structures based on systematic investigations. Previous evidence highlights the relevance of other parameters in addition to the mass ratio. Therefore, in this research, a variation of drop test parameters was carried out experimentally. Furthermore, numerical vibration analysis was applied to investigate the deformability of the impact surface. The results conclude that the mass ratio of 1:50 cannot be defined as a decisive criterion. In order to determine the influence of further drop test parameters, the research findings were used to validate a parametric model which assesses impact target deflection. An approximation quality of over 90 % was achieved. As a result, new evaluation criteria are proposed. Firstly, a method for identifying critical impact target designs is provided. Secondly, a new comprehensive formula compares the approximated maximum deflection of a real impact target to the respective theoretical threshold derived from a worst-case assumption. In practice, this leads to great advantages in the evaluation of already installed impact targets for dangerous goods packagings.
The flow properties of powdery or granular filling substances for dangerous goods packagings are safety-relevant parameters. To specify the flow behavior, the angle of repose is measured in the recognized test centers for dangerous goods packagings in Germany. Previous investigations performed on non-hazardous substances revealed that some of the methods currently used have disadvantages in application. Additionally, for occupational health and safety reasons, it was generally viewed critically to carry out measurements of the angle of repose for dangerous goods at all. Instead, the dimensionless Hausner ratio to describe the flow behavior was proposed.
In this work, the investigations were extended to real hazardous substances to concretize the assessment. Five exemplary hazardous substances were tested for their angle of repose using the methods commonly applied in the test centers. The Hausner ratio was also determined. In addition, the influence of a different climatic preconditioning on the angle of repose measurement was examined using three selected non-hazardous bulk materials.
The results show that the measurement of the angle of repose is not fundamentally excluded for dangerous goods. However, for reasons of applicability, repeatability and occupational health and safety, only the ISO method can be applied for dangerous filling substances. This method provides conservative results regarding a safety-related evaluation of flow properties for the transport of dangerous goods.
In principle, both the ISO method and the determination of the Hausner ratio can be used for dangerous goods. It is also essential especially with finely powdered filling goods, to carry out controlled preconditioning.
The mechanical and geometrical properties of impact targets greatly influence the outcome of a drop test. The International Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) as well as ISO 2248 describe the characteristics of impact targets for drop tests of dangerous goods packagings.
According to these regulations, the impact target’s surface needs to be unyielding, under testing conditions non-deformable, flat, and integral with a mass at least 50 times that of the heaviest packaging to be tested. The problem is that many production facilities, especially manufacturers of corrugated fibreboard boxes, do not have their own testing device with the required 50 times mass ratio of the impact target for a regulation compliant drop test during series production. Furthermore, at UN level it is considered necessary to revise these requirements.
In the present paper, the impact target requirements are examined in detail and compared with those in other technical areas (e.g., impact target for container for the transport of radioactive materials). A research method is being developed to investigate the dependency between the mass ratio of the packaging and the target as well as the damage resistance of a drop tested package in relation to specific design characteristics. The results are of high relevance for industry purposes and intended to ensure a uniform level of safety assessment for the mechanical testing of dangerous goods packagings.
To ensure safety when transporting dangerous goods, it is important to specify the flow properties of the respective solid filling substance of the packagings. For this purpose, the angle of repose is currently used for the UN approvals in Germany. Measurements were carried out on 12 powdery or granular substances applying the angle of repose measuring methods customary in the test centres. The results of the methods differ significantly from each other. In addition, some of the techniques cannot be applied for very cohesive or coarse-grained materials. The results for the angle of repose show a strong scatter for some constellations (coefficient of variation more than 20 %). Safety during transport of dangerous goods cannot be guaranteed with this currently practiced system of measuring the angle of repose. As a consequence, an alternative parameter to characterize the flow properties of bulk materials should be used in the recognized test centers for dangerous goods packagings, such as the Hausner ratio. This approach leads to more precise test results for the substances examined (maximum coefficient of variation 2.8 %). It also has advantages in terms of applicability and occupational safety.
Since the flow properties are safety-relevant, both in terms of mechanical safety and safety against the release of dangerous substances, the testing practice in the recognized test labs should be improved and standardized.
The leaks of dangerous goods from actually intact bags detected in the years 2018 to 2020 tend to be at an almost constant high level. These releases of powdery or granular dangerous goods represent violations of the sift-proofness required in the dangerous goods regulations. This article first analyzes the causes.
The components of the bags that are affected by leaks are micro-perforations, joins and closures, in particular internal sleeve valves. A distinction must be made between bags closed in conformity with or contrary to the manufacturer's instructions. The particle release is determined by a number of influencing factors of the filling substance, the packaging and other boundary conditions.
Therefore, a comprehensive test concept is developed in this work, which takes all these factors into account. The application of this test concept facilitates the planning of the test setup and the experiments. On this basis, the complex mechanisms involved in the release of solid substances can be systematically investigated in the test laboratory.
To prevent releases of powdery or granular substances from intact bags, it is necessary that the user has access to the closing instructions and the relevant properties of the test substance used for the design type approval. Further experimental investigations are needed to assess whether filling substances change their properties during transport and whether this enables them to escape.
Gemäß den internationalen Gefahrgutvorschriften müssen Säcke und flexible Großpackmittel (Flexible Intermediate Bulk Container - FIBC) für feste Gefahrgüter staubdicht sein.
In der Praxis der stichpunktartigen Kontrollen von Gefahrguttransporten durch die Autobahnpolizei Münster werden jedoch immer wieder Austritte von pulverförmigen oder körnigen Gefahrgütern aus eigentlich intakten Säcken und FIBC detektiert.
Es wird ein Überblick über die im Jahr 2019 festgestellten Gefahrgutaustritte aus diesen Arten von Gefahrgutverpackungen gegeben. Darauf aufbauend wird eine systematische Einordnung hinsichtlich betroffener Bauarten und eine Diskussion möglicher Lösungsansätze vorgenommen.
The Dangerous Goods Regulations currently do not include limit leakage rates orsensitivity requirements for industrial leak testing procedures that are equivalent tothe bubble test, which is the prescribed test method for design type testing ofdangerous goods packagings. During series production of such packagings, variousmethods are used, which often do not meet the requirements of the bubble test withregard to important criteria.Sensitivity, flow direction, pressure level and automatability are particularly importantfactors when selecting a suitable industrial leak testing method.The following methods are in principle both suitable and equally effective as thebubble test: pressure rise test (vacuum chamber), ultrasonic bubble leak detectionand gas detection methods (pressure technique by accumulation and vacuumchamber technique).To ensure a uniform test level during design type testing and production line leaktesting and therefore a comparable safety level as required by the Dangerous GoodsRegulations, it is necessary to include a more precise specification in these regula-tions. This requires, on the one hand, information about the sensitivity of the bubbletest and, on the other hand, the inclusion of a list of suitable, equally effective indus-trial test methods with their specific boundary conditions.
This work focuses on the question if the bubble test prescribed in the Dangerous Goods Regulations has sufficient sensitivity to detect leakage rates, which could result in the formation of explosive atmospheres during transport. The sensitivity of the bubble test is not directly comparable with other leak testing methods because of its different flow conditions. Therefore, a normalized minimum detectable leakage rate under Helium test conditions is calculated for the bubble test. This sensitivity of the bubble test under reference conditions is compared with limit leakage rates for a worst‐case transport scenario. The sensitivity of the bubble test is not sufficient to prove the limit leakage rates for 6‐L packagings. The formation of explosive vapour‐air‐mixtures cannot be excluded. Therefore, more sensitive leak testing methods should be considered for smaller packaging design types.
Sift-proofness is a requirement for different types of dangerous goods packagings for solid substances according to the international Dangerous Goods Regulations. In these regulations, a sift-proof packaging is defined as a packaging that is completely impermeable to dry contents. This means indirectly that absolutely no mass transport of solid substances is allowed. Moreover, this requirement applies both to the original filling substance and to fine solid material generated during transport. Further specifications, test conditions or tolerable limit values are not given. This is in contrast to physical principles and the usual practice in other fields of technology in which sift-proofness is relevant. This paper shows the necessary steps for how the requirements for sift-proofness of dangerous goods packagings can be defined more precisely. Physical basics of the term ‘sift-proofness’ are explained. A qualitative as well as a quantitative approach is possible. In any case, it is essential to carry out appropriate vibration tests to assess the siftproofness. There is a need for systematical investigations of the sift-proofness of dangerous goods packagings.