1. Design Standards and Hydraulic Principles
Stainless Steel Suction Bellmouths are designed and fabricated in accordance with relevant hydraulic and marine standards:

• Hydraulic Institute (HI) Standards: Inlet configuration, recommended minimum submergence, and vortex prevention design.

• Classification Society Rules (Marine): ABS, DNV, LR, BV, CCS, and others for bilge, ballast, fire pump, and cargo pump suctions, including strainer and anti-vortex requirements.

• Flange Standards: Outlet flanges are machined to any international standard—ASME B16.5 (Class 150/300), EN 1092-1 (PN10/PN16), JIS B2220 (5K/10K), or GB/T 2501—for direct bolt-up to existing stainless or dissimilar metal piping (with appropriate isolation).

• Material Standards: Raw materials comply with ASTM A240/A312, EN 10028/10216, or equivalent for stainless steel plate, pipe, and fittings.

2. Material Grades and Surface Finish
We offer stainless steel bellmouths in the following grades to suit every service:

• AISI 316L (1.4404): The standard choice for marine and industrial applications. The molybdenum content provides excellent resistance to pitting and crevice corrosion in chloride-rich environments, including seawater up to moderate temperatures. Suitable for ballast, bilge, fire main, and freshwater systems.

• AISI 304L (1.4307): For less aggressive environments such as potable water, clean process water, and indoor industrial applications. More economical while still providing excellent corrosion resistance.

• Duplex Stainless Steel (UNS S32205 / 1.4462): Superior strength (approximately twice the yield strength of 316L) and enhanced chloride stress corrosion cracking resistance. Ideal for high-pressure suctions, deep tank applications, and warm seawater systems on offshore platforms and FPSOs.

• Super Duplex / 6Mo Grades (UNS S32750 / 1.4410): For extreme chemical environments, sour gas exposure, and aggressive cargo tank suctions on chemical and product tankers.
  All surfaces are supplied in the pickled and passivated condition to remove weld discoloration and optimize the natural passive chromium-oxide layer. Electropolishing is available for hygienic and ultra-clean services.

3. Design Configurations and Key Features

• Bellmouth Profile: Precision-formed from stainless steel plate with a smooth, elliptical or radiused flare (inlet diameter typically 1.5–2.0 times the nominal pipe size). The seamless internal surface minimizes entrance turbulence, reduces the loss coefficient, and prevents flow separation and cavitation.

• Anti-Vortex Device: A stainless steel cross-vane or flat plate is fully welded inside or above the bellmouth inlet to disrupt rotational flow at low liquid levels, preventing air entrainment and vortex formation.

• Integral Strainer / Guard: A removable or welded stainless steel perforated plate, bar grating, or heavy-gauge wire mesh protects the pump and downstream equipment from debris, marine growth, ice, or solids. The large open area keeps approach velocity low, minimizing pressure drop and clogging.

• Mounting Feet / Stand: Heavy-duty stainless steel legs or a ring stand are welded to the bellmouth body to maintain precise clearance from the tank floor, preventing sediment aspiration while providing stable support.

• Flanged Outlet: The stainless steel flange is fully welded to the bellmouth neck and faced flat or raised-face, with bolt holes drilled to the required standard.

• Optional Lifting Lugs: For large, heavy bellmouths, stainless steel lifting lugs are incorporated for safe handling during installation.

4. Key Technical Benefits

• Absolute Corrosion Immunity: Stainless steel cannot rust, delaminate, or suffer from under-film corrosion. It remains structurally and functionally intact for the life of the vessel or installation, even in the most aggressive environments.

• Hygienic and Cleanable: The smooth, non-porous surface is easily cleaned and does not support bacterial growth. It is the required material for potable water, pharmaceutical, food, and beverage suction lines.

• Zero Coating Maintenance: No painting, galvanizing, or cathodic protection is needed. The passive layer is self-repairing in the presence of oxygen, meaning scratches and minor damage naturally re-passivate.

• High Strength-to-Weight Ratio: Duplex grades allow thinner wall thicknesses for the same pressure rating, reducing weight and facilitating installation in confined spaces.

• Full Penetration Welds: All structural and pressure-retaining welds are fully penetrated, ground smooth internally to avoid crevices and ensure uninterrupted flow and cleanability.

• Pump Protection and Performance: Smooth inflow, vortex prevention, and debris screening ensure the pump operates at its best efficiency point with minimal risk of cavitation, impeller damage, or blockage.

5. Typical Applications

• Marine:

• Seawater cooling pump suctions (main engine, auxiliary, AC condensers)

• Fire pump and foam pump sea chest inlets

• Ballast and bilge pump suctions

• Cargo pump suctions on chemical, product, and LNG carriers

• Fresh water generator and potable water tank suctions

• Industrial:

• Chemical plant process pump suctions handling corrosive or high-purity fluids

• Pharmaceutical and food processing tank outlets

• Desalination plant seawater intake and brine pump suctions

• Water and Wastewater:

• Potable water reservoir and clear well outlets

• High-purity water systems for electronics and power generation

• Fire Protection:

• Suction inlets for fire pumps drawing from tanks, reservoirs, or seawater