1. Applicable Standards and Design Basis
Our Carbon Steel Air Vent Heads are designed, manufactured, and tested in strict compliance with:

• ISO 15364: Ships and marine technology — Pressure/vacuum valves and air pipe heads, defining type-testing and performance requirements.

• SOLAS Chapter II-2: Mandatory fitting of corrosion-resistant flame screens at all tank vent outlets.

• IACS UR F1/F2: Unified requirements covering air pipe head strength, automatic closing function, and fire resistance considerations.

• Classification Society Rules: ABS, DNV, Lloyd’s Register, BV, CCS, NK, KR, RINA, and other IACS members’ specific type approval criteria.

• ASME B16.5 / EN 1092-1 / JIS B2220 / GB/T 2501: Flange standards as required by the vessel’s piping specification.

2. Material Selection and Corrosion Protection

• Body & Weatherhood: Fabricated or cast from marine-grade carbon steel. Components are formed and fully welded for strength, then protected by hot-dip galvanizing to ISO 1461 (providing a sacrificial zinc coating) or a high-build, two-component marine epoxy coating system. The weatherhood is designed for robust drainage and deflection of solid water.

• Float & Closing Mechanism: Non-collapsible, solid stainless steel (AISI 316L) or heavy-duty polypropylene float, providing reliable buoyancy and corrosion-free operation. The float guide, stem, and sealing disc assembly are manufactured from stainless steel to ensure jam-free, maintenance-free movement.

• Sealing Seat: Replaceable EPDM (standard for seawater, freshwater, and ballast), NBR (for oil and fuel tanks), or FKM (for chemical cargoes and elevated temperatures). The seat ring provides a bubble-tight, watertight seal when the float is activated.

• Flame Screen: Stainless steel (AISI 316L) woven wire mesh, compliant with SOLAS, securely clamped inside the vent outlet. Easily removable for periodic inspection and cleaning.

• Mounting Flange: Integrally welded or cast carbon steel flange, drilled to customer-specified standards (DIN PN10/PN16, JIS 5K/10K/16K, ANSI Class 150/300, GB/T 2501). Flange facing is smooth, raised-face, or RTJ as required.

3. Key Technical Features and Performance Benefits

• High Mechanical Strength: Carbon steel construction withstands the highest impact loads, heavy seas, and physical abuse encountered on exposed decks. It provides a significant margin of safety for vent pipes subject to bending moments or vessel flexing.

• Superior Fire Resistance: With an appropriate fire-resistant coating or inherent melting point, carbon steel vent heads can be integrated into fire-safe cargo systems, providing an added layer of protection for flammable and combustible tank contents.

• Automatic Positive Shut-Off: The buoyancy-driven float rises instantly upon water ingress, pressing the sealing disc firmly against the seat to prevent tank flooding. When the water recedes, the float drops back freely, instantly restoring full-bore ventilation.

• Full Flow Capacity: The internal cross-sectional area is designed to meet or exceed the required air flow rate per ISO 15364 and class rules, preventing over- or under-pressure that could damage tank structures during high-flow cargo operations.

• Corrosion Protection Systems: The combination of hot-dip galvanizing (metallurgical bond) or specialized marine epoxy coatings provides exceptional long-term resistance to salt spray, UV exposure, and mechanical abrasion. Touch-up kits are available for on-site maintenance if coatings are damaged.

• Low Maintenance: The simple, robust float-and-seat mechanism, combined with stainless steel internal parts and heavy-duty corrosion protection, ensures years of trouble-free operation. The removable cover allows quick visual inspection without dismantling the pipe.

4. Typical Marine Applications
Carbon Steel Air Vent Heads are specified where strength, impact resistance, and durability are paramount:

• Cargo oil and ballast tanks on crude oil and product tankers

• Chemical and product carrier deepwell pump vents

• Offshore supply vessels and platform deck vents

• Fuel oil and diesel oil storage tank vents on large vessels

• Bilge, sludge, and sewage holding tank vents in heavy weather areas

• Void spaces and cofferdam ventilation on ice-class and Arctic vessels

• General applications where high mechanical strength and extended service life are required

5. Quality Assurance, Testing, and Certification

• Type Testing: Every design is type-tested to ISO 15364 for automatic closing under simulated flooding conditions, air flow capacity, and pressure drop. Fire-resistant variants undergo additional fire testing where required by class.

• Production Testing: Each unit is subjected to dimensional inspection, float function verification, and seat leakage test (at 1.1 times rated pressure where applicable) before delivery.

• Material Traceability: Full EN 10204 Type 3.1 material certificates are supplied for the carbon steel body, float, sealing seat, flame screen, and coating system. Permanent markings include manufacturer’s name, size (DN), pressure rating (PN/Class), material grade, heat number, and standard designation.

• Class Approvals: Our Carbon Steel Air Vent Heads can be delivered with type approval certificates from all major IACS classification societies, ensuring immediate acceptance during newbuilding and repair surveys.