Inconel Seamless Tube ASTM B163 Alloy 825 UNS NO8825 Oil Refineries Application

Overview

Incoloy 825 is highly resistant to corrosion. It has a high nickel content, sufficient to resist chloride ion stress corrosion cracking, and a very stable austenite structure. The levels of molybdenum and copper enable the alloy to resist reducing agents and acids. Chromium gives resistance to oxidising conditions, such as nitric acid solutions, nitrates and oxidising salts. The alloy is titanium stabilised to resist pitting and intergranular attack after fabrication, particularly welding, which includes heating in the critical sensitisation temperature range (650°C – 760°C). Alloy 825 offers exceptional resistance to corrosion by sulphuric and phosphoric acids and is often the most cost effective alloy in sulphuric acid service.

The characteristics of ASTM B163 Alloy 825 UNS NO8825

• Excellent resistance to reducing and oxidizing acids
• Good Mechanical Properties at both room and elevated temperatures up to approximately 1020° F
• Good resistance to stress-corrosion cracking
• Permission for pressure-vessel use at wall temperatures up to 800°F
• Satisfactory resistance to localized attack like pitting and crevice corrosion

Corrosion Resistance

Alloy 825 is a general purpose engineered nickel alloy with high resistance to corrosion by acids and alkali metals in oxidizing and reducing environments, and the nickel component gives the alloy effective resistance to stress corrosion cracking. Corrosion resistance is excellent in a variety of media such as sulfuric, phosphoric, nitric and organic acids, alkali metals such as sodium hydroxide corrosive, potassium hydroxide and hydrochloric acid corrosive solutions.

Alloy 825 is resistant to boiling sulfuric acid up to a concentration of 40% and to all concentrations of sulfuric acid up to a concentration of 60% at temperatures up to 80°C and corrosion up to 66°C. 825 has very good corrosion resistance to various concentrations of phosphoric acid.

It has good resistance to chloride-containing solutions, pitting in seawater, and stress corrosion. In addition, the intergranular corrosion also has good corrosion resistance.

The high overall performance of alloy 825 is demonstrated in nuclear combustion dissolvers with a wide variety of corrosive media, such as sulfuric acid, nitric acid and sodium hydroxide all handled in the same equipment.

Chemical Composition of ASTM B163 Alloy 825 UNS NO8825

Mechanical Strength of Astm B163 Alloy 825 UNS NO8825

Physical properties of ASTM B163 Alloy 825 UNS NO8825

Astm B163 Alloy 825 UNS NO8825

• Industrial furnaces
• Heat-treating equipment
• Chemical and petrochemical processing
• Super-heater and re-heaters in power plants
• Pressure vessels
• Heat exchanger
• Oil Refineries