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Alloy 59 (NiCr23Mo16Al) with a lot of chromium, molybdenum and nickel possesses excellent resistance not only to reducing but also oxidizing chemicals. Both the Nickel alloy 59 and the superaustenitic steel alloy 31 have already been used as shell materials for tank vehicles or tank containers. Use of these alloys allows the transport of a signifi-cantly more wider variety of chemicals and, especially, waste mixtures than the use of common aus-tenitic steels. Another advantage is the extension of test intervals of for 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 issued by the Federal Institute for Materials Research and Testing (BAM). Com-patibility evaluations of selected metallic material groups as well as polymeric gasket and lining materials under the influence of approximately 7000 dangerous goods and water-polluting sub-stances are published in the BAM-List. Alloy 59 belongs 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 performed a comprehensive corrosion test programme with welded specimens of the nickel alloy 59 and the superaustenitic steels alloy 926 and alloy 31 in the period 2002 - 2010. Especially In particular alloy 59 and alloy 31 were exposed to a large number of corrosive sub-stances such as various mixtures of both nitric acid/sulphuric acid and nitric acid/phosphoric acid at 55 °C. Other corrosive test substances were different organic and inorganic halogenides, peroxyace-tic acid and molten substances. In the case of molten chemicals such as monochloroacetic acid the test temperature was increased to more than 100 °C. The test results presented in this paper are al-ready included in the 10th edition of the BAM-List and, therefore, available to the customer.
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 undertaken by the BAM - Federal Institute for Materials Research and Testing. Compatibility evaluations of selected metallic materials as well as of polymeric gasket and lining materials under the influence of approximately 7000 dangerous goods have been published in the BAM-List since 1989.
The duplex Steel 1.4362 (2304, UNS S32304) was originally developed as substitute for the austenitic grades 1.4404 (316L, UNS S31603) and 1.4571 (316Ti, UNS S31635). Due to its characteristic profile this Steel was qualified for applications requiring high strength values at concomitant adequate corrosion resistance. Because of its lower content of the alloy elements nickel and molybdenum this duplex Steel is a cost-efficient alternative to the molybdenum containing austenite. Only a limited number of corrosion test results of 1.4362 under the influence of dangerous goods published in the BAM-List were available. Therefore test specimens of this Steel were exposed to selected corrosive substances.
Due to the reduced alloy content a reduced corrosion resistance of the duplex Steel 1.4362 in acidic substances, such as formic acid, acetic acid and sulfuric acid, in comparison to the austenitic CrNiMosteels was observed. Tests in the alkaline medium showed a sufficient resistance.
Comparison of the corrosion resistance to dangerous goods of austenitic CrNiMo and duplex steels
(2014)
The “BAM-List - Requirements for Tanks for the Transport of Dangerous Goods” is the basis in Germany for substance-related prototype approvals for tank Containers in Germany. Compatibility evaluations of selected metallic materials and polymeric materials under the influence of approximately 7200 dangerous goods have been published in the BAM-List since 1989. The austenitic CrNi- and CrNiMo-steels - UNS S30403, UNS S31600, UNSS31603 and UNS S31635 - are the materials mostly used worldwide for transport tanks. The duplex Steel UNS S31803 has been put on the BAMList due to the great interest of tank producers and transport Companies. Using UNS S31803 instead of 316L, the weight of the tanks can be reduced, and the list of transportable goods can be extended. The objective of these investigations was to compare the corrosion resistance of duplex Steel UNS S31803 and austenitic Steel UNS S31603. Therefore, test specimens of both steels were exposed to selected corrosive substances, such as formic acid, acetic acid, phosphoric acid, sulfuric acid, nitrating acid, monochloroacetic acid and trichloroacetone at 55 °C (30 °C, 70 °C). The test results have shown that the duplex Steel UNSS31803 is a good alternative to austenitic CrNiMo-steel UNS S31603 for tanks carrying corrosive dangerous goods.