Southwark Metal SP58-24GA_18X16 Spiral Pipe Reducer

Product Description

The SOUTHWARK METAL SP58-24GA_18X16 is a tapered spiral pipe reducer fabricated from hot dip galvanized steel at 24 gauge material thickness. It transitions round spiral ductwork from an 18-inch diameter down to a 16-inch diameter in a single fitting. The tapered profile maintains smooth airflow through the transition, reducing turbulence and pressure drop at the connection point. HVAC sheet metal mechanics install this fitting in low-pressure supply and return air distribution systems where a step-down in duct diameter is required. Construction meets ACCA and SMACNA standards for commercial and residential duct fabrication.

This reducer is suited for residential and light commercial HVAC duct systems using spiral round pipe. Typical applications include main trunk-to-branch transitions, air handler supply plenums, and rooftop unit distribution runs where duct diameter decreases as airflow is distributed to successive zones or outlets. The galvanized steel construction holds up in both conditioned and unconditioned spaces such as attics, mechanical rooms, and crawlspaces.

Key Features

• Tapered design provides smooth diameter transition from 18 inches to 16 inches
• Hot dip galvanized steel resists corrosion in humid and unconditioned installation environments
• 24 gauge material thickness meets SMACNA and ACCA fabrication standards for spiral duct fittings
• Compatible with standard spiral round duct pipe systems
• Tapered geometry minimizes static pressure loss through the transition

Compatibility

Designed as an OEM-style replacement and new-installation fitting for residential and light commercial spiral round duct systems with an 18-inch to 16-inch diameter transition, built to ACCA and SMACNA applicable standards.

Installation Notes

Installation is performed by licensed HVAC technicians or qualified sheet metal mechanics. Shut down and lock out the air handling unit before cutting into or connecting ductwork. Secure the fitting to adjoining spiral pipe sections using sheet metal screws and seal all joints with UL-listed duct sealant or foil tape per SMACNA installation guidelines. Do not compress or over-crimp the fitting ends during installation, as deformation will affect the sealing surface.

Technical Specifications

• Larger End Diameter: 18 inches
• Smaller End Diameter: 16 inches
• Material: Hot Dip Galvanized Steel
• Material Thickness: 24 Gauge
• Type: Tapered
• Applicable Standards: ACCA, SMACNA

Standard Information

• Brand: SOUTHWARK METAL
• Manufacturer Part Number: SP58-24GA_18X16