ASTM A358 TP304H / 1.4948 Stainless Steel Welded Pipe EFW Pipe for Corrosive Environment
ASTM A358 TP304H / 1.4948 Stainless Steel EFW Pipe Double Welded Pipe
ASTM A358 TP304H EFW pipe is an electric-fusion-welded, high-carbon (0.04–0.10%) stainless steel pipe. Manufactured from plate, it is solution-annealed for enhanced creep-rupture strength above 550°C. Specified under Class 1 for 100% radiography, it is designed for high-temperature, pressure-retaining services like boiler headers and refinery transfer lines. Choose ASTM A358 over ASTM A312 for welded pipe because A358 is exclusively designed for large-diameter, heavy-wall fabrication from formed plates using double-sided submerged arc welding (SAW). It enforces strict radiographic examination classes (e.g., Class 1 = mandatory 100% RT) critical for verifying weld integrity under high-temperature creep conditions.
Equivalent Grade of ASTM A358 Grade 304H Stainless Steel Welded Pipe EFW Pipe
| Grade | UNS No | Old British | Euronorm | ||
| BS | En | No | Name | ||
| 304H | S30409 | 304S51 | - | 1.4948 | X6CrNi18-11 |
| These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted. | |||||
Chemical Composition % of ASTM A358 Grade 304H Stainless Steel Welded Pipe EFW Pipe
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | |
| 304H | min. | 0.04 | - | - | -0.04 | - | 18.0 | - | 8.0 | - |
| max. | 0.10 | 2.0 | 0.75 | 0.030 | 20.0 | 10.5 | ||||
Mechanical Properties of ASTM A358 Grade 304H Stainless Steel Welded Pipe EFW Pipe
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
| Rockwell B (HR B) max | Brinell (HB) max | ||||
| 304H | 515 | 205 | 40 | 92 | 201 |
| Note: 304H also has a requirement for a grain size of ASTM No 7 or coarser. | |||||
ASTM A358 offers different classes based on non-destructive testing requirements. For high-temperature, critical service, Class 1 is usually mandatory:
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Class 1: Fully radiographed (100% RT) along the entire weld length.
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Class 2: Spot radiographically examined.
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Class 3: Not radiographically examined (hydrostatic test only).
For high-temperature/pressure boilers, Class 1 is strictly recommended.
Applications
Because of the robust welding method and high corrosion resistance, this pipe is used in demanding environments:
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Chemical Processing: Handling acids, sulfates, and chlorides.
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Petrochemical Refineries: High-temperature hydrocarbon service.
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Food Processing: Where cleanliness and corrosion resistance are vital.
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Water Treatment: Desalination plants and wastewater treatment (resists chloride corrosion).
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Power Generation: Flue gas desulfurization (FGD) systems.
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