ASTM A105N Weld Neck Flange | WNRF ASME B16.5
ASTM A105N weld neck flanges are normalized forged carbon steel flanges used in pressure piping systems for ambient and elevated-temperature service. A105N is commonly specified for weld neck raised face (WNRF) flanges where controlled heat treatment, consistent mechanical properties and reliable pressure-piping performance are required.
We manufacture and supply ASTM A105/ ASME SA-105 normalized carbon steel flanges to ASME B16.5, including weld neck, blind, slip-on, socket-weld and threaded types with EN 10204 3.1 certification and project-specific inspection.
ASTM A105N WNRF Quick Specification
| Item | Specification |
|---|---|
| Material Standard | ASTM A105/A105M / ASME SA-105 |
| Common Designation | A105N |
| Condition | Normalized |
| Flange Type | Weld Neck Raised Face / WNRF |
| Dimensional Standard | ASME B16.5 |
| Size | NPS 1/2–24 |
| Pressure Class | 150 / 300 / 400 / 600 / 900 / 1500 |
| Class 2500 | NPS 1/2–12 |
| Facing | RF / FF / RTJ as applicable |
| Manufacturing | Forged |
| Certification | EN 10204 3.1 / 3.2 when specified |
What Is ASTM A105N?
ASTM A105N is not a separate ASTM material grade.
The base material specification is ASTM A105/A105M, which covers forged carbon steel piping components such as flanges, fittings, valves and similar pressure-system parts.
The suffix “N” is commonly used in purchasing documents and industry practice to indicate that A105 material has been supplied in the:
Normalized condition
Normalization refines and homogenizes the microstructure after forging and can provide more consistent mechanical properties and toughness compared with uncontrolled as-forged conditions.
Therefore:
A105N = ASTM A105 material + normalized heat-treatment condition
The chemical composition remains ASTM A105.
ASTM A105 vs A105N
A105N is the A105 material with Normalized.
| Item | ASTM A105 | ASTM A105N |
|---|---|---|
| Material Specification | ASTM A105 | ASTM A105 |
| Separate ASTM Grade? | Base material | No |
| “N” Meaning | — | Normalized |
| Chemistry | ASTM A105 | Same ASTM A105 chemistry |
| Heat Treatment | As permitted or required by specification | Normalized |
| Mechanical Requirements | ASTM A105 | ASTM A105 |
| Main Difference | Supply condition | Controlled normalized condition |
A105N does not have a different chemical composition from A105.
The main distinction is its documented normalized heat-treatment condition.
ASTM A105 Chemical Composition
| Element | Requirement |
|---|---|
| Carbon, C | 0.35% max |
| Manganese, Mn | 0.60–1.05% |
| Phosphorus, P | 0.035% max |
| Sulfur, S | 0.040% max |
| Silicon, Si | 0.10–0.35% |
| Copper, Cu | 0.40% max |
| Nickel, Ni | 0.40% max |
| Chromium, Cr | 0.30% max |
| Molybdenum, Mo | 0.12% max |
| Vanadium, V | 0.08% max |
The combined limits for residual alloying elements must also comply with the applicable ASTM A105 edition.
Actual heat chemistry is reported on the Material Test Certificate.
ASTM A105 Mechanical Properties
Typical ASTM A105 minimum mechanical requirements include:
| Property | ASTM A105 |
|---|---|
| Tensile Strength, min. | 485 MPa / 70 ksi |
| Yield Strength, min. | 250 MPa / 36 ksi |
| Elongation, min. | 22% |
| Reduction of Area, min. | 30% |
| Hardness, max. | 197 HBW |
Older A105 references may show 187 HB, so the exact ordered ASTM edition should always be checked when a project specifies a hardness limit.
The room-temperature mechanical properties should not be used directly as piping allowable stresses. Pressure-temperature design must follow the applicable ASME code and flange rating tables.
Heat Treatment Requirements
Heat treatment is not mandatory for every ASTM A105 flange.
ASTM A105 requires heat treatment for certain components, including:
- Flanges above Class 300
- Special-design flanges whose design conditions exceed Class 300 Group 1.1 ratings
- Special-design flanges where design pressure or temperature is not known
- Certain larger and higher-rated forged piping components
Permitted heat treatments include:
- Annealing
- Normalizing
- Normalizing and tempering
- Quenching and tempering
When a customer orders A105N, the flange is specifically supplied in the normalized condition even where normalization may not otherwise be mandatory.
ASTM A105N Weld Neck Raised Face Flange
A WNRF flange combines a weld neck hub with a raised-face sealing surface.
The flange is butt-welded directly to the pipe.
Key characteristics include:
- Long tapered hub
- Gradual stress transition between pipe and flange
- Full-penetration butt-weld connection
- Good performance under pressure and temperature cycling
- Suitable for critical process piping
- Compatible with common gasket systems
The flange bore is normally selected to match the pipe inside diameter or schedule specified in the purchase order.
Typical applications include:
- Oil and gas piping
- Refineries
- Petrochemical plants
- Power generation
- Steam and process systems
- Industrial pressure piping
- Pump and compressor connections
ASME B16.5 Sizes & Pressure Classes
Current ASME B16.5 dimensions and ratings must be applied according to flange size and pressure class.
| Pressure Class | Standard Size Range |
|---|---|
| Class 150 | NPS 1/2–24 |
| Class 300 | NPS 1/2–24 |
| Class 400 | NPS 1/2–24 |
| Class 600 | NPS 1/2–24 |
| Class 900 | NPS 1/2–24 |
| Class 1500 | NPS 1/2–24 |
| Class 2500 | NPS 1/2–12 |
Therefore, Class 2500 should not be described as available to NPS 24 under ASME B16.5.
For large-diameter flanges above NPS 24, ASME B16.47 may be applicable depending on the project design.
NACE MR0175 / ISO 15156 A105N Flanges
A105N flanges may be supplied for NACE MR0175 / ISO 15156 sour-service applications when required by the project.
A105N Flange should be with a Brinell hardness not exceed than 187 according to NACE MR0175
Sour-service qualification can involve:
- Material condition
- Hardness
- Heat treatment
- Welding and fabrication
- H₂S partial pressure
- Environmental conditions
- Applicable ISO 15156 requirements
- Project-specific supplementary requirements.
Inspection & Certification
ASTM A105N flanges can be supplied with:
- EN 10204 Type 3.1 MTC
- EN 10204 Type 3.2 certification when specified
- Heat chemical analysis
- Mechanical test results
- Hardness testing
- Normalizing heat-treatment records
- Dimensional inspection
- Visual inspection
- PMI when specified
- UT when specified
- MT when specified
- Third-party inspection
- NACE / ISO 15156 documentation when applicable
Full traceability can be maintained through the heat number, flange size, pressure class and material marking.
Complete Carbon Steel Piping System
ASTM A105N flanges are commonly used as part of a complete carbon-steel pressure piping system.
| Component | Typical Related Material |
|---|---|
| Flange | ASTM A105 / A105N |
| Seamless Pipe | ASTM A106 Grade B |
| Butt-Weld Fitting | ASTM A234 WPB |
| Stud Bolt | ASTM A193 B7 |
| Nut | ASTM A194 2H |
| Low-Temperature Flange | ASTM A350 LF2 |
ASTM A105 vs ASTM A350 LF2
A105 and A350 LF2 are both widely used forged carbon-steel piping materials, but their service focus differs.
| Item | ASTM A105 | ASTM A350 LF2 |
|---|---|---|
| Main Service | Ambient / elevated temperature | Low-temperature service |
| Product | Flanges / forged components | Flanges / forged components |
| Notch Toughness | Not the primary standard basis | Required by A350 |
| Impact Testing | Project-dependent | Core requirement |
| Typical Selection | General pressure piping | Low-temperature piping |
A350 LF2 should be considered when low-temperature notch toughness is required rather than treating A105 and LF2 as interchangeable grades.
Frequently Asked Questions
What does N mean in ASTM A105N?
N means normalized. A105N generally refers to ASTM A105 forged carbon steel supplied in the normalized heat-treated condition.
Is ASTM A105N a separate grade?
No. A105N is not a separate ASTM grade. The material specification remains ASTM A105; “N” identifies the normalized condition.
What is the difference between A105 and A105N?
The chemistry and minimum ASTM material requirements are the same. A105N has specifically undergone normalization, while A105 does not automatically imply one particular heat-treatment condition.
Is ASTM A105N NACE MR0175 compliant?
It can be supplied for NACE MR0175 / ISO 15156 service when all applicable material, hardness and service-environment requirements are satisfied. Normalization alone does not establish NACE compliance.
What is the maximum hardness of ASTM A105?
Recent ASTM A105 editions specify a maximum hardness of 197 HBW. Older references may show 187 HB, so the specified edition and project requirements should be verified.
ASTM A105N Weld Neck Flange Manufacturer
We manufacture and supply ASTM A105 / ASME SA-105 normalized carbon steel weld neck flanges for oil and gas, petrochemical, power and industrial piping systems.
Available products include:
WNRF, blind, slip-on, socket-weld and threaded flanges with RF, FF or RTJ facing as applicable.
For quotation, please specify:
Material + Heat Treatment + Flange Type + NPS + Pressure Class + Facing + Standard + Quantity + Inspection Requirements
Example:
ASTM A105N, WNRF, NPS 8, Class 600, RF, ASME B16.5
