ASTM A105 / ASME SA105 Specification for Carbon Steel Forgings
A105 Overview
ASTM A105 defines the requirements for carbon steel forgings used in pressure piping systems operating at ambient and elevated temperatures.
ASME SA105 is the ASME Section II adopted equivalent material specification widely used in boiler and pressure vessel applications.
ASTM A105 / SA105 is one of the most widely applied carbon steel forging materials in global piping engineering due to its balance of strength, ductility, machinability, and cost efficiency.
It is commonly used in:
- Flanges
- Forged fittings
- Valve components
- Pressure-containing forged parts
Engineering Definition and Purpose
ASTM A105 is designed for forged carbon steel components used in pressure systems.
The key engineering purpose of this material is to ensure:
- Structural integrity under internal pressure
- Reliable performance under thermal cycling
- Consistent mechanical properties across forged components
- Compatibility with ASME piping design codes
Forged materials such as A105 provide continuous grain flow, which significantly improves mechanical reliability compared to cast materials.
Applicable Standards
ASTM A105 components are typically manufactured and used in accordance with:
- ASME B16.5
- ASME B16.47
- ASME B16.11
- ASTM A961
- NACE MR0175
- ISO 15156
Material Classification
ASTM A105 is classified as:
- Carbon Steel Forging Material
- Pressure Piping Components
- Ambient and Elevated Temperature Service
Manufacturing Processes
- Open die forging
- Closed die forging
- Ring rolling
- Machined forgings
Chemical Composition (Typical Limits)
| Element | Maximum Content |
|---|---|
| Carbon (C) | 0.35% |
| Manganese (Mn) | 0.60 – 1.05% |
| Silicon (Si) | 0.15 – 0.35% |
| Phosphorus (P) | 0.035% max |
| Sulfur (S) | 0.040% max |
| Copper (Cu) | 0.40% max |
| Chromium (Cr) | 0.30% max |
| Nickel (Ni) | 0.40% max |
| Molybdenum (Mo) | 0.12% max |
The composition is controlled to ensure:
- Weldability
- Mechanical strength
- Ductility
- Pressure resistance
Mechanical Properties
\sigma_u \ge 485,\text{MPa},\quad \sigma_y \ge 250,\text{MPa}
Minimum Mechanical Requirements:
- Tensile Strength: ≥ 485 MPa
- Yield Strength: ≥ 250 MPa
- Elongation: ≥ 30%
These properties make ASTM A105 suitable for medium to high-pressure piping systems.
Heat Treatment Requirements
Heat treatment is not mandatory for all ASTM A105 forgings, but may be required depending on:
- Pressure class
- Component thickness
- Low-temperature service
- Project specifications
Available Heat Treatments:
- Normalizing
- Normalizing + Tempering
- Quenching + Tempering
- Annealing (special applications)
Engineering Purpose:
- Grain refinement
- Improved toughness
- Stress relief
- Uniform mechanical properties
ASTM A105 vs A105N
| Grade | Description | Application |
|---|---|---|
| A105 | As-forged condition | General piping systems |
| A105N | Normalized condition | Higher toughness / offshore / low temperature |
A105N is preferred in critical service applications requiring improved impact toughness.
Pressure Ratings
ASTM A105 components are commonly used in ASME pressure classes:
- Class 150
- Class 300
- Class 600
- Class 900
- Class 1500
- Class 2500
Actual pressure capability depends on temperature and ASME design calculations.
Product Forms
ASTM A105 is widely used in the following forged components:
Flanges
-
-
A105 Weld Neck Flanges (WNRF)
- ASTM A105 Weld neck flanges B16.5 Nace MR 0175
-
Slip-On Flanges (SOFF)
-
A105 Blind Flanges (BLRF)
-
Socket Weld Flanges (SWRF)
-
Threaded Flanges (THRF)
-
Forged Fittings
- Elbows
- Tees
- Couplings
- Caps
- Unions
Special Forgings
- Rings
- Blocks
- Custom machined components
Applications
Oil & Gas Industry
- Pipeline systems
- Offshore platforms
- Refinery piping systems
Petrochemical Industry
- Process piping
- High-pressure reactor systems
Power Generation
- Steam pipelines
- Boiler systems
Industrial Systems
- Compressors
- Pumps
- Pressure vessels
Sour Service / NACE Compliance
NACE MR0175
ISO 15156
ASTM A105 can be used in sour service when:
- Hardness limits are controlled
- Heat treatment is properly applied
- Environmental restrictions are met
Inspection & Testing
ASTM A105 products can be supplied with:
- Chemical composition analysis
- Tensile testing
- Hardness testing
- Ultrasonic testing (UT)
- Magnetic particle testing (MT)
- Dimensional inspection
- Third-party inspection (SGS / BV / DNV / TUV / ABS)
Packaging
- Export seaworthy wooden cases
- Anti-corrosion oil protection
- Plastic wrapping
- Beveled end protection
- Standard ASTM marking
Specification Summary
| Item | Value |
|---|---|
| Standard | ASTM A105 / ASME SA105 |
| Material Type | Carbon Steel Forging |
| Size Range | 1/8″ – 60″+ |
| Pressure Range | Class 150 – 2500 |
| Standards | ASME B16.5 / B16.47 / B16.11 |
| Certification | EN 10204 3.1 / 3.2 |
| Service | Pressure piping systems |