Alloy 31 and 59 as Tank Material for Transport of Highly Corrosive Dangerous Goods

Alloy 31 (X1NiCrMoCu32‑28‑7) is an iron-nickel-chromium-molybdenum alloy with nitrogen addition which fills the gap between the existing stainless steels and the nickel alloys. Alloy 59 (NiCr23Mo16Al) with a high chromium, molybdenum and nickel possesses excellent resistance not only to reducing but also to oxidizing chemicals.
The superaustenitic steel alloy 31 and the nickel alloy 59 were already used as shell materials for tank vehicles or tank container. The use of these alloys allows the transport of quite more chemicals and especially waste mixtures than the use of the common austenitic steels. Another advantage is the extension of the test intervals 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 the Federal Institute for Materials Re­search and Testing (BAM). 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. Alloy 31 and Alloy 59 belong to the group of metallic materials in the BAM-List.
Due to the large number of dangerous goods in the BAM-List BAM, IKS Dresden and ThyssenKrupp VDM continued the corrosion test programme with welded specimens of these higher-alloyed materials.
Various mixtures both of nitric acid/sulfuric acid and of nitric acid/phosphoric acid were included into 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 the test temperature is increased to more than 100 °C. The test results, presented in this paper, will be included in the next edition of the BAM-List and therefore available for the costumer.