ASTM A105N Blind Flange | Carbon Steel ASME B16.5 Flange
What is ASTM A105N Blind Flange?
ASTM A105N Blind Flanges are forged carbon steel flanges designed for pressure piping systems requiring reliable sealing, pressure containment and pipeline isolation. Manufactured according to ASME B16.5 dimensional standards, ASTM A105N blind flanges are widely used in oil & gas, petrochemical, refinery, power generation and industrial process piping systems.
The “N” designation in ASTM A105N indicates the material has been supplied in normalized heat-treated condition, providing improved toughness, refined grain structure and better mechanical consistency compared with standard ASTM A105 forged flanges.
ASTM A105N blind flanges are commonly available in Raised Face (RF), Ring Type Joint (RTJ) and Flat Face (FF) configurations for different sealing and pressure applications.
ASTM A105N Blind Flange Specification
| Specification | Details |
|---|---|
| Material Standard | ASTM A105 / ASTM A105N |
| Product Type | Blind Flange |
| Dimension Standard | ASME B16.5 |
| Pressure Rating | Class 150 – 2500 |
| Material Type | Forged Carbon Steel |
| Manufacturing Method | Forged & CNC Machined |
| Facing Types | RF / RTJ / FF |
| Heat Treatment | Normalized |
| Size Range | 1/2” – 24” |
Large diameter flanges can also be supplied according to ASME B16.47.
Chemical Composition of ASTM A105N Blind Flanges
ASTM A105N chemical composition is controlled to provide good weldability, machinability and pressure performance.
| Element | Composition (%) |
|---|---|
| Carbon (C) | ≤ 0.35 |
| Manganese (Mn) | 0.60 – 1.05 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.040 |
| Silicon (Si) | 0.10 – 0.35 |
| Copper (Cu) | ≤ 0.40 |
| Nickel (Ni) | ≤ 0.40 |
| Chromium (Cr) | ≤ 0.30 |
| Molybdenum (Mo) | ≤ 0.12 |
| Vanadium (V) | ≤ 0.08 |
Mechanical Properties of ASTM A105N
ASTM A105N forged carbon steel blind flanges provide reliable mechanical performance for industrial pressure piping systems.
| Property | Requirement |
|---|---|
| Tensile Strength | 485 MPa Minimum |
| Yield Strength | 250 MPa Minimum |
| Elongation | ≥ 22% |
| Reduction of Area | ≥ 30% |
| Hardness | ≤ 187 HBW Typical |
The normalization process helps achieve more uniform mechanical properties and improved toughness.
What Does the “N” Mean in ASTM A105N?
The “N” in ASTM A105N indicates the flange has been supplied in normalized heat-treated condition.
Benefits of normalizing include:
- improved toughness
- refined microstructure
- enhanced weldability
- stable machining performance
Normalized ASTM A105N blind flanges are commonly specified for refinery and petrochemical applications.
ASTM A105N Blind Flange Pressure Rating
Pressure-temperature ratings for ASTM A105N blind flanges shall comply with ASME B16.5 requirements.
| ASME Class | Pressure Application |
|---|---|
| Class 150 | Low Pressure |
| Class 300 | Medium Pressure |
| Class 600 | High Pressure |
| Class 900 | Severe Service |
| Class 1500 | Very High Pressure |
| Class 2500 | Critical Pressure Service |
Actual pressure ratings depend on:
- operating temperature
- gasket type
- flange dimensions
- bolting material
Flange Facing Types of ASTM A105N Blind Flanges
Raised Face (RF)
Raised Face blind flanges are the most commonly used flange type for industrial piping systems.
Ring Type Joint (RTJ)
RTJ blind flanges are designed for high-pressure and high-temperature sealing applications.
Flat Face (FF)
Flat Face blind flanges are typically used for low-pressure piping systems and cast iron flange connections.
Selection of flange facing type depends on:
- operating pressure
- service temperature
- gasket design
- piping code requirements
ASTM A105N Blind Flange Dimensions
ASTM A105N blind flanges are manufactured according to ASME B16.5.
Available Sizes
- 1/2” to 24”
Available Pressure Classes
- Class 150
- Class 300
- Class 600
- Class 900
- Class 1500
- Class 2500
Facing Options
- RF
- RTJ
- FF
Custom dimensions are available upon request.
Manufacturing Process of ASTM A105N Blind Flanges
The manufacturing process typically includes:
- raw material cutting
- hot forging
- heat treatment
- CNC machining
- drilling
- facing machining
- marking
- dimensional inspection
- Packing
Strict quality control ensures dimensional accuracy and material integrity.
Surface Treatment and Coating
ASTM A105N blind flanges can be supplied with:
- black painting
- anti-rust oil
- zinc coating
- galvanizing
- FBE coating
- customer specified coating
Protective coatings help prevent corrosion during transportation and storage.
ASTM A105N Flange Marking
Typical flange marking includes:
- ASTM material grade
- flange size
- pressure class
- heat number
- ASME standard
- manufacturer logo
Full traceability can be supplied according to project requirements.
Is ASTM A105N Blind Flange NACE Compliant?
ASTM A105N blind flanges can be manufactured for sour service applications according to:
- NACE MR0175
- ISO 15156
- NACE MR0103
Additional sour service requirements may include:
- hardness testing
- HIC testing
- PMI inspection
- low sulfur chemistry control
Maximum hardness is typically controlled for H₂S environments.
Inspection and Testing
ASTM A105N blind flanges can be supplied with:
- PMI Testing
- Ultrasonic Testing (UT)
- Hardness Testing
- Dimensional Inspection
- Hydrostatic Testing
- EN 10204 3.1 Certification
Third-party inspection is available upon request.
Applications of ASTM A105N Blind Flanges
ASTM A105N blind flanges are widely used in:
- oil & gas pipelines
- petrochemical plants
- refinery process piping
- power generation systems
- water treatment plants
- industrial pressure piping systems
Their reliable sealing performance makes them suitable for high-pressure industrial applications.
Frequently Asked Questions
What is ASTM A105N material?
ASTM A105N is normalized forged carbon steel used for flanges and piping components in pressure systems.
Is ASTM A105N suitable for high-temperature service?
Yes. ASTM A105N is suitable for ambient and moderate elevated-temperature applications.
What is the difference between RF and RTJ blind flange?
RF flanges use raised face sealing surfaces, while RTJ flanges use metallic ring gaskets for high-pressure sealing applications.
Is ASTM A105N flange NACE compliant?
Yes. ASTM A105N blind flanges can be manufactured according to NACE MR0175 / ISO 15156 requirements.
Why Choose Our ASTM A105N Blind Flanges?
We provide:
- full material traceability
- precision CNC machining
- strict quality inspection
- fast delivery
- project customization
- third-party inspection support
- worldwide export service
Our ASTM A105N carbon steel blind flanges are manufactured according to international piping standards for reliable industrial performance.
How to order our Blind Flange?
Blind Flange 1 inch, 150P, RF. Material grade is A105 , B16.5 . QTY: 2 Each.
Blind Flange 2-1/2 inch, 150B, RF. Material grade is A105 , B16.5
Blind Flange 4 inch, 150B, RF. Material grade is A105 , B16.5
Blind Flange 16 inch, 150P, RF. Material grade is A105 , B16.5
ASTM A105N blind flanges provide a reliable and cost-effective solution for pressure piping system isolation.
With normalized heat treatment, compliance with ASME standards, and strict quality control, A105N blind flanges ensure safe and long-term performance in demanding industrial applications.
ASTM A105N Blind Flange ANSI B16.5
