Stainless Steel 904L Explained
Stainless Steel 904L is a super-austenitic, low-carbon stainless steel alloyed with very high nickel, molybdenum, and copper content to provide exceptional resistance to highly aggressive chemical environments. It exhibits outstanding protection against sulfuric, phosphoric, and nitric acids, along with excellent resistance to chloride stress corrosion cracking, pitting, and crevice corrosion.
Widely used in chemical processing plants, acid handling equipment, offshore oil and gas platforms, marine piping systems, heat exchangers, and pollution control units, SS 904L delivers unmatched durability, weldability, and long-term reliability in extreme corrosive service conditions.
904L STAINLESS STEEL SHEETS AND PLATES EQUIVALENT GRADES
| STANDARD |
|---|
| SS 904L |
SPECIFICATION OF STAINLESS STEEL 904L SHEETS AND PLATES
| Standard | ASTM A240 / ASME SA240 |
|---|---|
| Dimension Standard | JIS, AISI, ASTM, GB, DIN, EN, etc |
| Width | 1000mm, 1219mm, 1500mm, 1800mm, 2000mm, 2500mm, 3000mm, 3500mm, etc |
| Length | 2000mm, 2440mm, 3000mm, 5800mm, 6000mm, etc |
| Thickness | 0.3 mm to 120 mm |
| Form | Coils, Foils, Rolls, Plain Sheet, Shim Sheet, Perforated Sheet, Chequered Plate, Strip, Flats, Blank (Circle), Ring (Flange) etc. |
| Surface Finishing | Hot rolled plate (HR), Cold rolled sheet (CR), 2B, 2D, BA, NO.1, NO.4, NO.8, 8K, mirror, Chequered, embossed, hair line, sand blast, Brush, etching, SATIN (Met with Plastic Coated) etc. |
CHEMICAL COMPOSITION OF STAINLESS STEEL 904L SHEETS AND PLATES
| C% | Cr% | Cu% | Mn% | Mo% | Ni% | P% | S% | Si% |
|---|---|---|---|---|---|---|---|---|
| 0.02 max | 19.0-23.0 | 1.0-2.0 | 2.0 max | 4.0-5.0 | 23.0-28.0 | 0.045 max | 0.035 max | 1.0 max |
MECHANICAL PROPERTIES OF STAINLESS STEEL 904L SHEETS AND PLATES
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (Rockwell B) | Hardness (Brinell) |
|---|---|---|---|---|---|
| 904L | 490 min | 220 min | 36 min | 70-90 typical | 150 |
💡 Practical Difference in Use
Use Stainless Steel 904L when: extremely high resistance to strong acids, chlorides, and aggressive chemical environments is required along with excellent durability and weldability. → Example: chemical processing equipment, sulfuric acid plants, offshore piping systems, and heat exchangers in corrosive service.
Applications of Stainless Steel 904L Sheets and Plates
Stainless Steel 904L is a high-alloy austenitic stainless steel with elevated nickel, chromium, molybdenum, and copper content, designed for severe corrosive environments where standard grades fail.
- Chemical Processing Equipment: Exceptional resistance to sulfuric, phosphoric, and organic acids.
- Offshore & Marine Systems: Excellent protection against chloride-induced pitting and crevice corrosion.
- High-Purity Processing Plants: Ideal for pharmaceutical and specialty chemical production.
When to Choose Stainless Steel 904L?
Stainless Steel 904L is selected where extreme corrosion resistance, long service life, and reliability under aggressive chemical exposure are critical.
Choose SS 904L when:
- Service involves strong acids such as sulfuric and phosphoric acid
- High resistance to pitting, crevice corrosion, and SCC is required
- Operating conditions include high chlorides and humidity
- Long-term corrosion reliability is more important than cost
- Used in offshore, fertilizer, and chemical processing industries
- Superior weld integrity and fabrication quality are essential
Industries That Use Stainless Steel 904L Sheets and Plates
Stainless Steel 904L sheets and plates are widely used in the most aggressive environments where exceptional corrosion resistance and long-term operational safety are required.
Primary application due to outstanding acid resistance.
Uses
Acid reactors, heat exchangers, and storage tanks.
Why SS 904L?
Exceptional resistance to sulfuric and phosphoric acid.
Used in highly corrosive marine and offshore environments.
Uses
Offshore piping, seawater systems, and platform structures.
Why SS 904L?
Superior resistance to chloride attack and pitting.
Critical for high-purity production environments.
Uses
Process vessels, reactors, and sterile transfer systems.
Why SS 904L?
Non-contaminating surface with excellent corrosion resistance.
Used in highly corrosive cooling and process systems.
Uses
Heat exchangers, condenser plates, and brine handling systems.
Why SS 904L?
Outstanding resistance to saline and acidic water.
Used in flue gas treatment and scrubber systems.
Uses
FGD units, scrubbers, and duct linings.
Why SS 904L?
Resists acidic condensates and aggressive exhaust gases.
Used where strong acidic media is processed.
Uses
Vinegar plants, acid cleaning systems, processing vessels.
Why SS 904L?
Excellent corrosion resistance for acidic food environments.
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