ASTM A358 EFW Stainless Steel Pipe Explained: Classes, Specifications & Manufacturing Process
ASTM A358 EFW Stainless Steel Pipe is an electric fusion welded austenitic chromium-nickel alloy steel pipe designed for high-temperature, high-pressure, and corrosive environments. These pipes are widely used in petrochemical, chemical processing, oil & gas, pharmaceutical, and power generation industries where weld integrity and corrosion resistance are critical.
Metalsin Tech supplies ASTM A358 EFW stainless Steel Pipes in sizes ranging from Φ8mm to Φ3600mm, with wall thicknesses from 0.2mm to 120mm.
What Is ASTM A358 EFW Stainless Steel Pipe?
ASTM A358 covers electric-fusion-welded (EFW) austenitic chromium-nickel alloy steel pipes manufactured from stainless Steel Plates conforming to ASTM A240 specifications.
The EFW welding process produces a uniform weld seam and consistent pipe wall thickness, making these pipes suitable for severe service conditions involving:
- High temperature
- High pressure
- Corrosive media
- Critical industrial piping systems
ASTM A358 stainless steel pipes are commonly used in:
- Petrochemical plants
- Oil & gas processing
- Chemical facilities
- Pharmaceutical systems
- Power generation projects
What Material Grades Are Available for ASTM A358 Pipes?
ASTM A358 EFW pipes can be manufactured using a wide range of stainless steel and nickel alloy grades.
Common Austenitic Stainless Steel Grades
- 201 (S20100)
- 304 (S30400)
- 304L (S30403)
- 304H (S30409)
- 304N (S30451)
- 304LN (S30453)
- 309S (S30908)
- 310S (S31008)
- 316 (S31600)
- 316L (S31603)
- 316H (S31609)
- 316N (S31651)
- 316LN (S31653)
- 317 (S31700)
- 317L (S31703)
- 321 (S32100)
- 347 (S34700)
- 347H (S34709)
- 348 (S34800)
High Alloy & Nickel Alloy Grades
- N08020
- N08367
- Alloy 800 (N08800)
- Alloy 800H (N08810)
- N08904
- N08926
- S31254
These material grades are selected according to corrosion resistance, operating temperature, pressure conditions, and application requirements.
What Are the ASTM A358 Pipe Classes?
ASTM A358 EFW stainless steel pipes are classified into five classes based on welding method and radiographic examination requirements.
ASTM A358 Class 1
- Double welded
- Filler metal used in all passes
- Completely radiographed
Class 1 pipes are among the most widely used ASTM A358 pipes for critical industrial applications.
ASTM A358 Class 2
- Double welded
- Filler metal used in all passes
- No radiographic examination required
ASTM A358 Class 3
- Single welded
- Filler metal used in all passes
- Completely radiographed
ASTM A358 Class 4
- Same as Class 3
- The weld pass exposed to the inside pipe surface may be made without filler metal
ASTM A358 Class 5
- Double welded
- Filler metal used in all passes
- Spot radiographed
How Are ASTM A358 EFW Stainless Steel Pipes Manufactured?
The manufacturing process of ASTM A358 EFW stainless steel pipes includes several critical stages to ensure weld quality, dimensional accuracy, and corrosion resistance.
Plate Cutting and Rolling
The stainless steel plate is cut to the required dimensions and rolled into a cylindrical shape. The plate edges are then machined or ground to prepare for welding.
Fusion Welding Process
An electric current is used to fuse the plate edges without applying external pressure.
Depending on the pipe class, the pipe may be manufactured using:
- Single welding
- Double welding
The weld joints shall be full penetration butt joints using fusion welding processes.
Welding procedures and operators shall comply with ASME Boiler and Pressure Vessel Code Section IX requirements.
Except for Class 4 conditions, welds are produced using filler metal in all passes.
Solution Annealing Heat Treatment
Most ASTM A358 EFW pipes are solution annealed at temperatures between:
- 1900–1950°F
- 1040–1065°C
After heat treatment, the pipes are rapidly cooled in water.
Testing and Inspection
ASTM A358 pipes undergo multiple inspection procedures, including:
- Radiographic inspection of weld seams
- Chemical composition analysis
- Visual inspection
- Dimensional examination
- Transverse tension test
- Guided-bend weld test
- Hydrostatic test
Surface Finishing and Marking
After welding and heat treatment, the pipes may undergo:
- Pickling
- Passivation
These processes help improve corrosion resistance and surface cleanliness.
Each pipe is marked for traceability, and certified mill test reports are provided. Bar coding in different colors may also be available upon request.
What Is the Difference Between Single Welded and Double Welded ASTM A358 Pipes?
According to ASTM A358, EFW stainless steel pipes may be supplied in either single welded or double welded condition.
| Feature | Single Welded Pipe | Double Welded Pipe |
|---|---|---|
| Welding Side | One side | Both sides |
| Filler Metal | Typically used | Used in all passes |
| Radiographic Inspection | Full radiography required | Depends on class |
| Pipe Strength | Suitable for thinner wall pipes | Higher weld integrity |
| Typical Applications | Limited access conditions | High-pressure and high-temperature service |
Single welded pipes are generally suitable for thinner-wall applications or situations with limited access during fabrication.
Double welded pipes provide greater strength and complete weld penetration, making them preferred for severe service environments.
Among all classes, ASTM A358 Class 1 double welded pipes with complete radiographic inspection are the most commonly used.
Where Are ASTM A358 EFW Stainless Steel Pipes Used?
ASTM A358 EFW stainless steel pipes are widely used in industries requiring corrosion resistance and reliable performance under severe operating conditions.
Petrochemical Industry
Used for high-temperature and corrosive process piping systems.
Oil & Gas Industry
Applied in refinery piping and critical fluid transportation systems.
Chemical Processing Plants
Suitable for aggressive chemical environments requiring corrosion-resistant materials.
Pharmaceutical Industry
Used in piping systems requiring cleanliness and stainless steel durability.
Power Generation Facilities
Applied in high-pressure and high-temperature piping systems.
Why Choose ASTM A358 EFW Stainless Steel Pipes?
ASTM A358 EFW stainless steel pipes offer several advantages for industrial piping applications:
- Excellent corrosion resistance
- Reliable weld integrity
- Suitability for high-temperature service
- Availability in large diameters
- Multiple material grade options
- Strict inspection and testing procedures
These characteristics make ASTM A358 EFW pipes suitable for critical industrial environments where safety, durability, and performance are essential.
FAQ About ASTM A358 EFW Stainless Steel Pipes
What does EFW mean in ASTM A358 pipe?
EFW stands for Electric Fusion Welded, a welding process that uses electric energy to fuse stainless steel plate edges together.
What is the difference between ASTM A358 Class 1 and Class 2?
Class 1 pipes are completely radiographed, while Class 2 pipes do not require radiographic examination.
Are ASTM A358 pipes suitable for high-temperature service?
Yes. ASTM A358 pipes are designed for severe service applications involving high temperatures and high pressure.
What materials are commonly used for ASTM A358 pipes?
Common materials include 304L, 316L, 310S, 321, 347H, Alloy 800H, and S31254.
Why are double welded ASTM A358 pipes preferred?
Double welded pipes provide improved weld penetration, higher weld integrity, and better performance in critical applications.