Stainless steel contains a minimum of 10.5% chromium which imparts it corrosion resistance by forming an oxide layer on the surface. The most common stainless steel is the austenitic type (300 series) which contains chromium and nickel as alloying elements. Other types include ferritic, martensitic and duplex stainless steels. Most stainless steels are considered to have good weldability characteristics. Most common processes used for welding stainless steel are TIG (GTAW) and MIG (GMAW). But, stick welding (SMAW) is also utilized.
Differences in Properties:
The properties of stainless steel differ from mild steel, and these differences need consideration when welding as below:
- Higher coefficient of expansion, 50% more for austenitic – this results in more distortion
- Lower coefficient of heat transfer – welding requires lower heat input as it is conducted away slowly
- Lower electrical conductivity – using the correct and consistent stick-out distance is more critical when using MIG/TIG, higher wire speed for the same current is required when MIG welding
Inspection, Surface Prep and Non-destructive Testing
Are you in the oil & gas industry? Are you involved in non-destructive testing, inspection, or surface preparation? How about maintenance of pipelines, heat exchangers, or pressure vessels? If you deal with these or similar operations, proper cleaning of surfaces might well be a process you regularly undertake.
Cleaning Delicate Equipment Safely
What is the best way to clean surfaces of such equipment? While there is no one best way for every circumstance, dry ice cleaning is a state-of-the-art method that can save time and money. It uses recycled CO2 in the form of solid dry ice particles as the cleaning media. Dry ice is soft and non-abrasive to most surfaces and can thus be used around delicate components, including electronics, that would be damaged by water or solvents. As the blasting equipment is portable it can be used in place, thus minimizing disassembly and other preparation time. Lastly, dry ice turns to a gas after contact with the surface being cleaned — cleanup time is rock bottom minimum, there is nothing to dispose of, contamination of moving parts is not an issue.