Construction Steel Pipe With Flange

Construction Steel Pipe with Flange is a specialized structural and fluid-handling component consisting of a carbon, stainless, or galvanized steel tube with circular steel rims (flanges) permanently welded to one or both ends. These flanges are precision-drilled with standardized bolt holes (according to ASME B16.5, EN 1092-1, or DIN standards) to allow for secure, bolt-and-nut mechanical joining between pipe sections, valves, or equipment.

Unlike permanent welded joints, flanged pipes provide high structural rigidity while allowing for rapid assembly and non-destructive disassembly, making them indispensable for high-pressure water mains, HVAC systems in high-rise buildings, and heavy-duty structural supports in bridge or port construction.

Ensure a Perfect Fit – Request a Custom Quote for Flange Pipes Tailored to Your Specific PCD and Standards (ASME, EN, DIN, or AS/NZS).

Flanged Joint Pipe Specification Table

Connection Method of Flange Pipe

Flange pipes utilize a mechanical "sandwich" connection method that does not require on-site welding:

Alignment: Two flanged pipe ends are brought together, ensuring the bolt holes are perfectly aligned.

Sealing (Gasket): A gasket (made of rubber, EPDM, PTFE, or spiral wound metal) is placed between the two flange faces to create a leak-proof seal.

Bolting: High-strength bolts are passed through the holes and tightened with nuts in a star pattern to ensure even pressure distribution.

Disassembly: The connection can be broken simply by removing the bolts, allowing for maintenance or reconfiguration of the construction layout.

Materials of Flange Pipe

Pipe Substrate:

Carbon Steel: ASTM A106 Gr. B, ASTM A53 Gr. B, Q235B, Q355B (most common for structural use).

Stainless Steel: SS304/304L, SS316/316L (for corrosive environments).

Galvanized Steel: Pre-galvanized or Hot-dip galvanized for rust prevention.

Flange Material:

Forged Steel: ASTM A105 (Standard for carbon steel pressure systems).

Stainless Steel: ASTM A182 F304/F316.

Plate Steel: Carbon steel plate for low-pressure structural applications.

Applications

High-Rise Building Infrastructure: Firefighting sprinkler systems, chilled water lines for HVAC, and vertical drainage stacks.

Structural Support & Piling: Used as structural columns or temporary supports in bridge and subway construction where sections must be bolted together.

Municipal Water Systems: Large diameter water transmission lines and sewage treatment facilities.

Temporary Construction Piping: Water and air supply lines at large-scale construction sites that need to be moved or reused.

Industrial Cooling: Piping networks for factories and power plants.

Features

Ease of Maintenance: Allows for the removal of specific pipe sections for cleaning or inspection without cutting the pipe.

High Structural Rigidity: The flange acts as a reinforced collar, providing extra strength at the joint against bending and vibration.

No On-Site Welding: Ideal for "hot-work prohibited" zones or sites where skilled welders are unavailable, significantly speeding up installation.

Excellent Leak Prevention: When combined with the correct gasket and torque, flanged connections are highly reliable for high-pressure fluid conveyance.

Corrosion Resistance: Most construction flange pipes are hot-dip galvanized (HDG), offering superior protection against soil and atmospheric moisture.

GNEE Flanged Joint Pipe Factory

GNEE Flanged Joint Pipe Test equipments

GNEE Flanged Joint Pipe certificate

FAQ

Can flange pipes be used underground?

Yes, flange pipes can be used underground, but they require specific precautions:

Corrosion Protection: Because bolts and nuts are highly susceptible to soil corrosion, the joint must be protected using petrolatum tape (Denso tape), epoxy coatings, or heavy-duty heat-shrink sleeves.

Maintenance Access: They are most commonly used in valve pits or manholes where the joint remains accessible for inspection and tightening.

Soil Stability: Unlike welded or flexible joints, flange joints are rigid. They are best suited for stable ground, as significant soil settlement can put extreme stress on the bolts and lead to leaks.

How is the weld quality between the pipe and the flange?

We utilize double-sided full-penetration welding to ensure the joint strength exceeds the pipe body. Upon request, we provide Non-Destructive Testing (NDT) such as Magnetic Particle Inspection (MPI) or Ultrasonic Testing (UT), along with Welding Procedure Specifications (WPS).

How do you protect the pipe and flange from corrosion?

We offer multiple protection methods:

Hot-Dip Galvanizing (HDG): Per ASTM A123, providing a zinc layer of 85μm+ for 30-50 years of service life.

Epoxy/FBE Coating: Ideal for water and sewage transmission.

Mechanical Protection: All flange faces are coated with anti-rust oil and fitted with plastic end caps to prevent surface damage during transit.

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