Alloy 20 Flanges
- UNS N08020 sulfuric acid resistant
- Niobium stabilized composition
- Excellent resistance to mixed acids
- Superior chloride pitting resistance
- 70+ years proven in chemical industry
Superior Corrosion-Resistant Alloy 20 Flanges for Aggressive Chemical Environments
MicroTech Stainless Steel Co. manufactures premium quality Alloy 20 Flanges (UNS N08020), a nickel-iron-chromium austenitic alloy specifically designed to provide exceptional corrosion resistance in sulfuric acid environments and other aggressive chemical processing applications. This specialized alloy offers superior performance where standard stainless steels fail.
Alloy 20 Flanges are widely recognized as the "sulfuric acid alloy" due to their outstanding resistance to sulfuric acid corrosion across a broad range of concentrations and temperatures. The addition of copper (3-4%) and molybdenum (2-3%) provides excellent resistance to general corrosion, pitting, and crevice corrosion in chloride-bearing environments.
Our Alloy 20 Flanges are manufactured to the highest quality standards including ASME B16.5, ASME B16.47, and ASTM B462 specifications. They are extensively used in chemical processing, pharmaceutical manufacturing, plastics production, food processing, and pollution control equipment where resistance to sulfuric acid and chloride stress corrosion cracking is critical.
We supply Alloy 20 Flanges in various configurations including Weld Neck, Slip-On, Blind, Socket Weld, Lap Joint, and Threaded Flanges in sizes ranging from 1/2" to 24" with pressure ratings from 150# to 2500#, complete with full material traceability and test certifications.
Outstanding resistance to sulfuric acid (Hâ‚‚SOâ‚„) at various concentrations and temperatures
Excellent resistance to chloride stress corrosion cracking
Superior resistance to pitting and crevice corrosion in chloride environments
Good resistance to phosphoric acid and nitric acid
Stabilized with niobium to prevent intergranular corrosion
Excellent fabricability and weldability without post-weld heat treatment
Cost-effective alternative to more expensive nickel-based alloys
Good mechanical properties at elevated temperatures
Resistant to general corrosion in mixed acid environments
100% PMI tested for chemical composition verification
Alloy 20 Flanges are specified for critical corrosion-resistant applications worldwide
Acid concentration, dilution plants, storage tanks, transfer systems
Reactors, heat exchangers, agitators, mixing vessels
Process vessels, piping systems, synthesis reactors
Refinery equipment, catalytic reforming, alkylation units
Polymerization reactors, monomer processing, extrusion equipment
Acidic food handling, pickling operations, vegetable processing
Scrubbers, stack gas cleaning, wastewater treatment
Rayon manufacturing, fiber spinning, chemical recovery systems
Alloy 20 exhibits exceptional resistance to sulfuric acid over a wide range of concentrations (20-100%) and temperatures up to approximately 60°C (140°F). It is particularly effective in dilute sulfuric acid solutions where conventional stainless steels experience rapid corrosion. The alloy's performance in H₂SO₄ makes it the preferred choice for acid handling equipment in chemical plants, fertilizer production, and ore processing facilities.
The high nickel content combined with copper and molybdenum additions provides outstanding resistance to chloride-induced stress corrosion cracking, a common failure mode in standard austenitic stainless steels. This makes Alloy 20 ideal for processes involving chlorides, such as pickle liquors, organic chloride contaminated streams, and seawater-cooled systems in chemical plants.
Alloy 20 demonstrates good resistance to phosphoric acid in concentrations up to 50% at temperatures up to 80°C (176°F). This property makes it suitable for fertilizer production, phosphate ore processing, and agricultural chemical manufacturing where phosphoric acid exposure is common.
The alloy performs well in mixed acid environments containing sulfuric acid with nitric acid, making it valuable in chemical synthesis operations, nitration processes, and spent acid recovery systems. Its stability in such corrosive conditions extends equipment life and reduces maintenance costs.
While Alloy 20 offers excellent corrosion resistance in many environments, it is not recommended for service in hydrochloric acid, reducing acids, or strongly oxidizing chloride solutions. For such applications, higher nickel alloys like Hastealloy C-276 or Alloy 625 should be considered.