Some of the more complex alloys in low strength, can have mechanical properties equivalent to steels. The various types of aluminium alloy are identified and guidance is given on fabricating components without impairing corrosion and mechanical properties of the material or introducing imperfections into the weld.

• Material types
• Aluminium alloy types

The demand for weldable 13%Cr pipes with outside diameter such as 18", 20" and 24" has increased greatly. Considering such a requirement, Dalmine and NKK have developed a new production route for OD 20" pipes. Girth welded joints (GTAW) were produced. The mechanical properties of both base material and welded joints meet the target requirements.

Under a Coating of Molten NaCl-KCl-Na2SO4

Hot corrosion behavior of Ni-10mass%Cr alloys having several Mo content under a molten NaCl-KCl-Na2SO4 mixture in 75vol%O2-N2 atmosphere containing 0.1vol%HCl was examined by thermogravimetry, chemical analyses of scale formed on the alloys and electrochemical technique.

Corrosion damage in three types of concrete (C25, C45, and C55), resulting from HCl with various contents, was investigated by comparing the mechanical properties of different types of concrete and their corrosion damage.

Corrosion, or the oxidation of metal, can occurs by the presence of moisture in the air. A high Relative Humidity causes a thin layer of water vapour molecules to settle on the surface of the metal, thus supplying an electrolyte to the corrosion process.

SULFUR RECOVERY PLANTS
In sulfur plants,sulfur is recovered from hydrogen sulfide present in natural gas.There are several processes for this conversion,which is basically called the Claus process.

In 1940s, Du Pont developed a process to make ethylene glycol, or antifreeze, from hydroxyacetic (glycolic) acid. Over the next 30 years, the company developed other markets for glycolic acid, and in the mid-1970s, when more cost-effective methods of producing antifreeze had been discovered, the company opted to continue making the product for its growing list of new applications.

Zirconium is one of the few metals that resist attack by sulfuric acid at all concentrations to 70% and temperatures to boiling and above. These conditions are so corrosive to metals that most chemical processes are designed to circumvent them. In some cases, however, efficiency of operations and product yields dictate operating parameters that are in this envelope where sulfuric acid is extremely aggressive.

There are 3 main areas where sulfuric acid dewpoint temperature measurement can have major benefit:

• Process Control
• Thermal Efficiency
• Emissions Control

Zirconium and alloys of it, have found increased use in sulfuric acid service in media where many other engineering materials have fallen short.

Hydrogen embrittlement in boiler

Hydrogen embrittlement of mild steel boiler tubing occurs in high-pressure boilers (above 10 bars), when atomic hydrogen forms at the boiler tube surface as a result of corrosion.

Microbiologically induced corrosion of copper intrauterine devices “TCu380A” and “Nova T” by Enterobacter sp. in a synthetic intrauterine medium was investigated.

Potentially corrosive species produced by various types of bacteria include sulfuric acid, organic acids, enzymes and sulfur containing compounds. Given the right conditions, bacteria populations can undergo explosive growth, as can be illustrated in a simplistic growth model.

In the final repository, the canister must be protected against corrosion.  Above all oxygen and sulphide ions (S2-) of the substances, which are present in the groundwater, can cause corrosion of the canister. Oxygen can react with copper and form copper oxides. The sulphide ions form copper sulphide when they react with the copper.