Round Single Wall Duct

Monroe Metal fabricates round spiral duct according to ASHRAE and SMACNA specifications and is manufactured from galvanized steel meeting ASTM A-527. We currently operate four spiral pipe machines that have the capability of running 3” to 84” diameter in maximum 20’ lengths. We can provide this maximum length or cut your duct to length to save you time in the field. We can produce from 13 gauge to 26 gauge spiral and are the only manufacturer capable of running 16 gauge stainless steel spiral.

We offer you several options:

Monroe Standard Spiral:
• High pressure application
• Exterior 4-ply lockseam provides increased strength and maintains roundness while interior remains smooth for non-turbulent airflow
• No welds or riveted seams to distort material or mar appearances
• Machine-made precision guarantees uniformity and reliable performance

Monroe “V-Rib” Spiral:
• Low pressure application
• Light gauge material with five reinforcing ribs for extra rigidity
• Same machine-made quality and characteristics as standard spiral
• Available in 20’ lengths or cut to length
• Lighter weight means easier handling and less labor cost to you
• Monroe V-Rib can also be used in your medium pressure jobs

Longitudinal Welded Seam and Hammerlock Seam Duct is available upon request.

We offer fabrication in a wide range of materials, including Paint Grip, Stainless Steel, Aluminum, Aluminized Steel, Black Iron and P.V.S. (poly-vinyl-sulfide). Our complete line of matched fittings can assure you that Monroe Metal is truly your One Stop Fabricator.

Products & Accessories

Accessory Fittings

To complete your job, we also offer a complete line of accessory fittings. These can be factory installed or shipped loose for field installation.

• Access Doors
• Angle Rings
• Insulation Stops
• Grille/Register Taps to fit double wall duct
• Rectangular to Oval
• Saddle Taps

Saddle taps can be lined or unlined and fabricated to fit major or minor axls.

No other manufacturer can offer such a complete line of accessories!

Duct Construction Standards
Single Wall Round Spiral- High Pressure, 1985 SMACNA
Pipe:       Major Width  Gauge Fittings:Major Width Gauge
 3" - 14"26 3" - 14"24
 15" - 26"24 15" - 26"22
 27" - 36"22 27" - 50"20
 38" - 50"20 52" - 60"18 
52" - 84"1862" - 84"16

Single Wall Round Spiral Duct- Low Pressure, 1985 SMACNA
Pipe:       Major Width  Gauge Fittings:Major Width Gauge
 3" - 26"26 3" - 14"26
 27" - 36"24 15" - 26"24
 38" - 50"22 27" - 36"22
 52" - 60"20 38" - 50"20
62" - 84"1852" - 60"18
    62" - 84"16

Single Wall Longitudinal Seam Welded Duct - 1985 SMACNA
Pipe:  Major Width  Gauge                                     
 3" - 14"26  
 15" - 26"24 
 27" - 50"22 
 52" - 50"20 
52" - 60"18
 62" - 84"18   

* Special materials and gauges available upon request
* Spiral pipe in 1" increments to 30"; 2" increments above 30"
* Spiral duct constructed with a 4-ply spiral lockseam made of galvanized metal meeting ASTM A-527
* Pipe is available in 20' lengths maximum or cut to length
** High pressure fittings are continuously welded with seams painted to prevent corrosion
*** Low pressure fittings are spot welded and sealed