Stainless steel is defined as iron alloys with a minimum of 10.5% chromium. Other alloying elements are added to enhance their structure and properties, but fundamentally, stainless steel tubes are considered for selection as steels with corrosion resistant properties.

Selection Stainless Steel for Handling Sodium Hydroxide NaOH

Sodium Hydroxide (Caustic Soda) is a strong base. It is used in metal degreasing and cleaning processes in a wide range of industry applications.

Stainless steel types 304 and 316 can be considered resistant below 80 degC, up to the limit of solubility.

Both 304 and 316 stainless steel types are resistant to a wide range of concentration and temperature. Below 80 degC they can be considered resistant to any concentration of sodium hydroxide, up to the limit of solubility. There can be a risk ofstress corrosion cracking (SCC) attack at higher temperatures, which is common to both the 304 and 316 types.

Selection Stainless Steel for Handling Sulphuric Acid H2SO4 By yaang.com

Sulphuric acid is oxidising when concentrated but is reducing at low and 'intermediate' concentrations.

The response of most stainless steel types is that in general they are resistant at either low or high concentrations, but are attacked at intermediate concentrations. Commercially concentrated acid is around 96 wt % (sg = 1.84).

The improvement in corrosion resistance moving from stainless steel 304 /1.4301 to 316 / 1.4401 is due to the addition of molybdenum. Further additions of moybdenum and copper in the 1.4539 904L grade extend the corrosion resistance in these reducing acid conditions. The molybdenum in types 316 stainless steel and grade 1.4539 also helps improve resistance to chloride attack, when present as impurities in the acid.

Stainless Steel Types Info By yaang.com

One of the key advantages of stainless steel lies in the materials sheer versatility. The fact that the precise composition of stainless steel can be altered to create a metal which is perfectly suited to a particular task means that it’s basic properties – strength, malleability and resistance to staining and corrosion – can be brought to bear in a wide range of situations.