A105 Blind Flange – Complete Guide by Fortis Forge
Introduction
When it comes to pipeline sealing and pressure containment, nothing matches the reliability of an A105 blind flange. Designed for closing off pipe ends, manholes, or vessel openings, A105 blind flanges are a staple in oil, gas, petrochemical, and industrial applications.
At Fortis Forge, we manufacture high-precision A105 blind flanges from premium carbon steel, ensuring they meet ANSI, ASME, ASTM, and other global standards for high performance in demanding environments.
1. What is an A105 Blind Flange?
An A105 blind flange is a solid disk-shaped fitting with no opening in the center, used to seal the end of a piping system. It’s made from ASTM A105 carbon steel, a material known for its high tensile strength, toughness, and ability to withstand high pressures and temperatures.
Key Functions:
Permanently or temporarily block the end of a pipe
Allow easy access for maintenance and inspection
Withstand internal system pressure without deformation
2. Material Specification – ASTM A105 Carbon Steel
The ASTM A105 standard covers forged carbon steel piping components suitable for ambient and high-temperature service.
Chemical Composition:
Carbon (C): 0.35% max
Manganese (Mn): 0.6–1.05%
Phosphorus (P): 0.035% max
Sulfur (S): 0.040% max
Silicon (Si): 0.10–0.35%
Mechanical Properties:
Tensile Strength: 485 MPa (min)
Yield Strength: 250 MPa (min)
Elongation: 22% min
3. Types of A105 Blind Flanges
3.1 Flat Face Blind Flange (FF)
Ideal for low-pressure applications
Provides even contact between flange faces
3.2 Raised Face Blind Flange (RF)
Common in high-pressure systems
The raised surface allows better sealing with gaskets
3.3 Ring Type Joint Blind Flange (RTJ)
Designed for high-pressure and high-temperature service
Uses a metal ring gasket for sealing
3.4 Custom Machined Blind Flange
Designed for specialized applications and unique pipe sizes
4. Manufacturing Process at Fortis Forge
Material Selection – ASTM-certified A105 carbon steel billets
Forging – Hot forging for grain refinement and strength
Machining – CNC turning, drilling (if required), and surface finishing
Heat Treatment – Normalizing or tempering to achieve mechanical properties
Inspection & Testing – Dimensional check, pressure test, and NDT (Non-Destructive Testing)
5. Standards & Compliance
Our A105 blind flanges comply with:
ASME B16.5 – Flanges and flanged fittings (½” to 24” sizes)
ASTM A105 – Forged carbon steel standard
MSS-SP-44 – Steel pipe line flanges
API 6A / 6B – Oilfield flange standards
6. Advantages of A105 Blind Flanges
High Strength: Handles extreme pressures and temperatures
Corrosion Resistance: Coated or galvanized options available
Versatile Use: Suitable for oil, gas, chemical, and power plants
Maintenance Friendly: Easy removal for cleaning or modifications
Cost-Effective: Long service life with minimal maintenance
7. Applications
Oil & Gas Pipelines – Sealing unused pipeline sections
Petrochemical Plants – Closing process lines during shutdowns
Power Generation – High-pressure steam lines
Marine & Offshore – Corrosion-resistant sealing in harsh environments
Water Treatment Facilities – End-point sealing for large water lines
8. Pressure Ratings
A105 blind flanges are available in various pressure classes:
Class 150
Class 300
Class 600
Class 900
Class 1500
Class 2500
9. Installation Tips
Ensure correct pressure rating for the system
Use suitable gaskets (spiral wound, ring joint, etc.)
Torque bolts evenly in a star pattern to prevent warping
Avoid over-tightening, which may damage gasket or flange face
10. Maintenance Guidelines
Inspect for corrosion, pitting, or cracks annually
Replace gaskets when reassembling
Ensure bolt tension is within specifications
Store unused flanges in dry, covered conditions
11. Why Choose Fortis Forge for A105 Blind Flanges?
Premium ASTM A105 Steel – Sourced from trusted mills
Precision CNC Machining – Ensures perfect fit and sealing
Wide Range of Sizes & Pressure Ratings – Ready stock for quick supply
Customization – Machining to client-specific requirements
Global Shipping – Reliable logistics for timely delivery
12. Frequently Asked Questions (FAQs)
Q1: Can A105 blind flanges be used in high-temperature systems?
Yes, ASTM A105 material is suitable for temperatures up to 425°C.
Q2: Do blind flanges require gaskets?
Yes, gaskets ensure leak-proof sealing between flange faces.
Q3: How are A105 blind flanges different from caps?
Flanges are bolted for easy removal; caps are welded permanently.
Q4: Can they be reused?
Yes, if the flange face and structure are intact after inspection.
Conclusion
The A105 blind flange is a vital component for sealing pipelines, ensuring safe maintenance, and preventing leaks in high-pressure and high-temperature environments. With Fortis Forge’s expertise in forging, machining, and quality control, you get reliable, standards-compliant blind flanges that deliver long-lasting performance.
Whether for oil and gas, power generation, petrochemicals, or water treatment, Fortis Forge has the right A105 blind flange for your needs.