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ABSTRACT Resistance to oxidative degradation by nitric acid is one of the properties selected, together with the corresponding test method and tolerances, for the comparison of polyethylene grades of one design type in a European standard on suitability proof for alternative plastic resins used for packagings and intermediate bulk containers (IBCs) for the transport of dangerous goods. Comparison of resistance to oxidative degradation of polyethylene grades and comparison of the times to failure in stacking tests with 55 % (70 %) nitric acid at 40 °C and of the marginal drop heights determined in drop tests at - 18°C with pre-stored packagings made of these grades led to the same evaluation of the grades. Pre-storing the design types with 55 % nitric acid for 21 days at 40 °C caused an increase of the marginal drop heights of the design types in drop tests at -18 °C when compared with design types without pre-storage. Variations in a comparison of the design types produced of different polyethylene grades can be explained by applying additional examination methods such as Fourier transform infrared spectroscopy (FTIR). Measurement of tensile strength and breaking elongation is, in principle, suitable for a comparison of polyethylene grades regarding their resistance to oxidative degradation. INTRODUCTION The design type of packagings is defined by the construction, dimension, material and thickness in the United Nations (UN)-recommendations and international regulations for the transport of dangerous goods on road (ADR ), rail (RID ), container ships (IMDG-Code ) and aircraft (ICAO ). Design type tests - drop test, stacking test, hydraulic pressure test and leak-proofness test - must be performed for every design type and manufacturer. However, passing the minimum requirements of the design type tests is no criterion if the polyethylene grade of another production facility is a comparable grade for this design type. There is a problem in defining test methods which allow extrapolation of grade behavior to the behavior of packagings and IBCs, and it is necessary to determine the material parameters and tolerances which define an equal grade. The processing of polymers has an important influence on the structure and, thus, resultant properties. Therefore, the problem in determining the material parameters is that what is measured is not the quality of the grade but the quality of a mold of this grade, which depends on the manufacturing process. As a result, material parameters determined with test specimens or designs of a specified shape cannot be transferred to designs of a different shape. The plastics industry defined 30 years ago the standard liquids to be used as representative test substances in damaging polyethylene. Such damage is swelling, stress cracking, oxidative degradation and a combination of swelling and oxidative degradation. A standard liquid for the combination of environmental stress cracking and oxidative degradation is not defined. Proof of chemical compatibility by simulating of fill goods with standard liquids has been introduced in the international dangerous goods regulations ADR/RID.
Corrosion Resistance Of Alloy 31 And 59 In Highly Corrosive Dangerous Goods
Baessler, Ralph (BAM - Federal Institute for Materials Research and Testing) | Alves, Helena (ThyssenKrupp VDM GmbH) | Weltschev, Margit (BAM - Federal Institute for Materials Research and Testing) | Langer, Matthias (Institute for Corrosion Protection (IKS) Dresden)
ABSTRACT Alloy 31 (UNS N08031, X1NiCrMoCu32-28-7) is a superaustenitic iron-nickel-chromium-molybdenum alloy with nitrogen addition filling the gap between existing stainless steels and nickel alloys. Alloy 59 (UNS N06059, NiCr23Mo16Al) with a high chromium, molybdenum and nickel content possesses excellent resistance not only to reducing but also to oxidizing chemicals.Both are already in use as shell materials for tank vehicles or tank containers. They allow the transport of quite more chemicals and especially waste mixtures than when using common austenitic steels. Another advantage is the reduction of required inspections of the transport tanks.In Germany the “BAM-List - Requirements for Tanks for the Transport of Dangerous Goods” is the basis for substance-related prototype approvals for tank containers designed for the carriage of dangerous goods undertaken by BAM, the Federal Institute for Materials Research and Testing. Compatibility evaluations of selected metallic material groups as well as of polymeric gasket and lining materials under the influence of approximately 7000 dangerous goods and water-polluting substances are published in the BAM-List.Due to the large number of dangerous goods in the BAM-List the established corrosion test program with welded specimens of these higher-alloyed materials is being continued. Various acid mixtures were added to the exposures of the two materials at 55 °C. Other corrosive test substances are different organic an inorganic halogenides, peroxyacetic acid, and molten substances. In case of molten chemicals and due to other practical reasons the test temperature is increased to more than 100 °C. The test results, presented in this paper, are already included in the current edition of the BAM-List and therefore available to the costumer. INTRODUCTION The evaluation of corrosion resistance of metallic materials (i.e. carbon , austenitic CrNi-, CrNiMo-steels and aluminum) usually used for tank containers and transport tanks is performed following the criteria required in "BAM-List - Requirements for Tanks for the Transport of Dangerous Goods" . Such information about corrosion resistance is applicable for tank trucks and rail cars too.Unless otherwise specified, the compatibility evaluations apply for average operating temperatures up to 50 °C. They do not only contain the evaluation of corrosion caused by the dangerous good on the material but also potential dangerous effects of the material on the medium to be transported.According to the international dangerous goods regulations ADR/RID for road and rail transport in Europe and the IMDG-Code for international maritime carriage a compulsory internal inspection of the tank is required after a certain period. The test interval is generally five years for tank containers and six years for road tank vehicles. For rail tank cars test intervals of four and eight years are required by the dangerous goods regulations. For the time of the test intervals the corrosion resistance of the tank material must be provided considering the following criteria. Material/substance combinations for test intervals of five, six and eight years are considered suitable ifthe wall thickness reduction due to uniform corrosion does not exceed 0.1 mm/year and
- Transportation > Ground > Rail (1.00)
- Materials > Metals & Mining (1.00)
- Materials > Chemicals > Commodity Chemicals (1.00)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)