Double-wall spiral ductwork must move air efficiently while helping control the noise generated by fans, equipment, and airflow. To accomplish both goals, HVAC manufacturers commonly use a solid outer shell, insulation, and a perforated metal inner liner.
That inner liner begins as the perforated spiral coil bought from the perforator. The coil is fed into a spiral-forming machine, where it is formed and joined using a spiral lock-seam process. This creates a durable interior surface that supports the insulation while allowing sound energy to reach the acoustical material behind it.
For manufacturers producing double-wall ductwork, purchasing coil in a consistent 5.394-inch width can simplify this process and help keep production moving.
Why Spiral Ductwork Uses a Perforated Inner Wall
Noise created by fans and moving air can travel through ductwork and into occupied spaces. In a double-wall spiral duct, insulation is installed between the solid outer shell and the perforated inner wall to help absorb that noise.
The holes give sound a path into the insulation instead of allowing it to continue down the duct. A solid inner wall would block that path. The metal liner also covers the insulation and helps protect it from erosion caused by air moving through the system.
This combination makes perforated spiral coil useful in HVAC systems installed in offices, schools, hospitals, entertainment venues, and other environments where air distribution and noise control both matter.
For round ductwork, the inner wall is formed from 5.394" slit coil using a spiral lock-seam process. Accurate's stocked coil has 3/32" holes on 3/16-inch staggered centers—the common perforation configuration used for this application.
Stocked Specifications for HVAC Production
Accurate keeps 5.394" perforated coil on hand in two gauges:
- 22 gauge
- 24 gauge
Both options are produced from pre-galvanized steel conforming to ASTM A653 Type B and carry a G60 galvanized coating. Other coating weights are available upon request.
For HVAC products that require another format, Accurate can also perforate coils up to 60 inches wide.
Why Stocked Coil Matters to HVAC Manufacturers
Material availability can directly affect a duct manufacturer's production schedule. Waiting to source, slit, and perforate steel adds steps before spiral forming can begin.
Accurate keeps 5.394-inch perforated coils in stock and ready to ship when customers need them. HVAC manufacturers can order off-the-shelf instead of waiting for a new perforating run, helping keep spiral duct production moving.
Source Perforated Spiral Coil From Accurate
Accurate Perforating has supplied perforated components to the HVAC industry for more than 20 years. Our high-speed perforating equipment supports recurring coil requirements, plus custom widths, gauges, patterns, and coating weights.
If you manufacture spiral ductwork, silencers, or other HVAC components, talk with Accurate about your material specifications, required volume, and production schedule. Request a quote for 5.394-inch perforated spiral coil today.