Die Schweißverbindung im chemischen Apparatebau und ihr Korrosionsverhalten im Betrieb

Welded joints in the construction of chemical equipment and their corrosion behaviour in operation. This contribution surveys the possible kinds of corrosion damage to fully austenitic welded stainless steels in the presence of heat cracks. Such cracks can be avoided by the presence of ß-ferrite. However, under certain conditions of attack ß-ferrite can cause selective corrosion. That is especially so on decomposition of ß-ferrite. Intercrystalline susceptibility in the zone of thermal influence can be avoided by use of stabilized or low-carbon steels. The tendency to undergo granular disintegration increases with increasing nickel content. The resistance to pitting of stainless steels is reduced at places bearing tempering colour layers. Such layers should therefore be avoided in welding or they should be removed if they persist in formation.     

Verwendung von Kohlenstoff-Fasern im Apparatebau

Use of carbon fibres in equipment constuction . Carbon fibres are characterized by high tensile strengths, high modulus of elasticity, and good corrosion resistance. They are therefore especially suitable for reinforcement of components made of plastics (CFC). Carbon fibre reinforced parts made of resin-impregnated graphite withstand higher mechanical stress and offer greater reliability in operation. CFP materials is an economical alternative to high-alloyed steel for use in corrosive media. Apart from graphite CFC is one of the few materials of construction suitable for use up to temperatures of over 2000 °C. It has also been sucessfully used for highly corrosion-resistant equipment such as grids and piping.     

Chemischer Apparatebau im Aufbruch?

Chemical Apparatus Engineering at a Turning Point? The ACHEMA conference is the leading international exhibition on chemical‐apparatus engineering, closely connected with the epochal developments of chemical and process engineering. At the moment it is most timely to think about new opportunities of development. Large‐scale plant engineering and general plant construction has experienced considerable improvement over the past decades, and the effects of these changes are particularly perceptible in the economic sector of German apparatus engineering. Economic pressures have given an additional impetus to a considerable shrinking process. Chemical apparatus engineering will have to focus on two main pillars in the near future: highly qualified standard and innovative products. Especially the latter must be developed in close interaction with chemical engineering in order to put the hardware required for new technologies and process strategies on the market. This article names the important fields of current general technical progress, showing that the main thrust is directed toward an elevated level of product quality that can be achieved through apparatus engineering. Such superior product properties are one important means to achieve higher profitability.     

Wirtschaftlicher Einsatz von korrosionsbeständigen Werkstoffen im Apparatebau

Economic use of corrosion-resistant materials in plant construction . Particular attention must be paid to choice of materials, constructional design, and production processes in order to achieve optimum, favourably priced solutions in the planning and construction of equipment for chemical plant. In the choice of materials, special stainless steels and non-ferrous metals of recent development, should be given special attention, particularly with respect to cost-saving substitution of expensive quality materials. The use of clad steel sheet fulfills requirements for optimum design of components for many applications; however, the economic use of these composite materials must be compared with that of solid materials from case of case – due attention being given to the strength and working properties of the materials. The lining of equipment with high-quality corrosion-resistant materials is also an economic production method but its limited applicability should be borne in mind. Welding is a cost-relevant production method. Use of welding techniques with high fusion rates, which is feasible for some high quality materials, can lead to considerable cost savings. Economic production of curved plates from Superferrit Remanit 4575 is possible by welding together individual rounds.     

Biologisch abbaubare Kunststoffe: Testverfahren und Beurteilungskriterien

Biodegradable Polymers: Test Methods and Assessment Standards. Technological difficulties in plastics recycling as well as critical emission into the environment during waste incineration give rise to considerations of utilizing plastics in composting systems. While market supply of ‘biodegradable plastics’ is increasing there is a need for test methods and assessment standards for these substances. This paper presents the basis and discusses microbial procedures, analytical techniques and requirements for the tests to be developed.     

Beispiele zur Anwendung von Feinkornbaustählen im chemischen Apparatebau

Examples of the use of fine-grained structural steels in chemical plant construction . Apparatus and vessels made of high-tensile steels of types St E 36 and St E 47 have for many years been successfully employed in chemical plant construction. Special attention must still be paid to the properties of these materials in design and fabrication. This requires close collaboration between materials technologists, constructional engineers, and process engineers. Should special operating conditions have to be met with – e.g. pulsating stresses, stress corrosion, etc. – these must be taken into consideration in the materials selection and construction. The choice of material and the design greatly influence the construction requirements, and thus also the construction costs. As can be shown with examples, carefully designed and constructed apparatus and vessels have proven essential for long-term operation. Using already approved designing principles and manufacturing regulations, operationally reliable construction units for chemical plant can continue to be manufactured from St E 36 and St E 47 steels.