ASTM A312 253MA / UNS S30815 / EN 1.4835 Stainless Steel Seamless Pipe Pickling
ASTM A312 253MA / UNS S30815 / EN 1.4835 Stainless Steel Seamless Pipe
253MA is a heat-resistant austenitic stainless steel alloy. It contains chromium, nickel, and nitrogen as its main alloying elements. This alloy offers excellent oxidation resistance at high temperatures up to 1150°C, making it suitable for use in high-temperature applications such as furnace components, heat exchangers, and exhaust systems. They are commonly used in industries such as chemical processing, power generation, and oil and gas exploration. It is designed to fill the gap between standard 304/316 stainless steels and more expensive high-alloy steels and nickel-based alloys.
Equivalent Grades of ASTM A312 253MA Stainless Steel Seamless Pipe Pickling
| Grade | UNS | WERKSTOFF NR. | EN | SS |
| 253MA(UNS S30815) | S30815 | 1.4835 | X9CrNiSiNCe21-11-2 | 2368 |
Chemical Composition of Stainless Steel Seamless Pipe Pickling
| Grade |
C max |
Si max |
Mn max |
P max |
S max |
Cr | Ni | Mo | N |
| UNS S30815 | 0.05~0.10 | 1.4~2.0 | 0.80 | 0.030 | 0.030 | 20.0-22.0 | 10.0-12.0 | / | 0.14-0.20 |
Physical properties of ASTM A312 253MA Stainless Steel Seamless Pipe Pickling
| Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat | Electrical Resistivity (nW.m) | |||
| 0-100°C | 0-600°C | 0-1000°C | at 20°C | at 1000°C | 0-100°C (J/kg.K) | |||
| 7800 | 200 | 17 | 18.5 | 19.5 | 15 | 29 | 500 | 850 |
Mechanical Properties of ASTM A312 253MA Stainless Steel Seamless Pipe Pickling
| Tensile Str (MPa) min | Yield Str 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
| Rockwell B (HR B) max | Brinell (HB) max | |||
| 600 | 310 | 40 | 95 | 217 |
- Process:
Pickling involves immersing the stainless steel pipe in a bath of mixed acids, typically Hydrofluoric (HF) and Nitric (HNO₃) acids.
- Purpose:
- Removes Scale: During hot-forming (e.g., extrusion or annealing heat treatment), a heavy, dark oxide layer (scale) forms on the pipe's surface.
- Removes Contamination: It dissolves embedded iron particles ("free iron") from tools or handling that can compromise the passive layer and lead to rust staining.
- Restores Passive Layer: The process dissolves a thin layer of the base metal, which then instantly reacts with oxygen in the air to form a new, continuous, and protective chromium oxide passive layer on the surface.
- Result: A clean, uniform, matte silver-gray surface that is fully corrosion-resistant and ready for service. A pickled surface is a critical quality indicator for high-performance stainless steel.
Apllications
Chemical
Pharmaceutical & Bio-Medical
Petrochemical & Refinery
Environmental
Food Processing
Chemical Fertilizer
Sewage Disposal
Desalination
Waste Incineration etc.
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