Industrial-grade ductwork built to last. 90 GSM zinc-coated galvanized steel, up to 20% stronger than longitudinal pipe. Available in 3″–48″ diameters — ready to ship from Memphis.
At SIDCO Spiral Duct Inc, we manufacture galvanized spiral duct in Memphis, TN — supplying contractors, HVAC installers, and industrial facilities across the country. Our duct is fabricated from high-quality zinc-coated galvanized steel using precision spiral-lock seam technology.
The helical spiral seam is inherently stronger than a straight longitudinal seam — our pipes are up to 20% stronger than smooth-wall pipe of the same gauge. That means less reinforcement, fewer hangers, and faster installation on every job.
We stock standard sizes from 4″ through 16″ for immediate same-day shipment. Larger diameters up to 48″ are fabricated within 1–2 business days. We also manufacture custom lengths, gauges, and diameters to your exact specifications.
Precision-formed seam minimizes air leakage and maximizes structural integrity.
Heavy zinc coating resists corrosion in humid and industrial environments.
Low-friction inner surface delivers maximum airflow with minimal pressure drop.
Tell us your specs — we manufacture any size or gauge to your drawings.
Standard specification for residential and light commercial systems up to 15″ diameter. Ideal for supply air, return air, and exhaust.
Heavier gauge for larger commercial and industrial installations. Greater wall thickness handles higher static pressure ratings.
G90 galvanized coating (90 grams/m² total both sides) provides superior corrosion resistance for long service life.
Available in both 5-foot and 10-foot lengths to minimize scrap and simplify layout. Custom lengths available on request.
Office buildings, hotels, and retail centers rely on galvanized spiral duct for its strength, clean appearance, and reliable long-term performance in exposed ceiling installations.
Welding booths, manufacturing plants, and spray booth stacking demand the rigidity and corrosion resistance of galvanized spiral. Handles high-velocity airflows without resonance.
The smooth interior bore of spiral duct keeps particulate-laden air flowing efficiently. Widely specified for woodworking shops, paper trim lines, and material handling systems.
Long building lifecycles demand durable ductwork. Galvanized spiral holds up through decades of HVAC operation and is easy to clean to meet indoor air quality standards.
Kitchen exhaust and makeup air systems for commercial kitchens benefit from galvanized steel's heat resistance and the hygienic, smooth surface that resists grease buildup.
Galvanized spiral duct meets the cleanroom standards required for pharmaceutical manufacturing, providing reliable, leak-free airflow distribution in controlled environments.
We are not a distributor reselling someone else's product. We fabricate our duct in-house at our Memphis, TN facility — which means tighter quality control, faster lead times, and prices that reflect real manufacturing costs, not distributor markups.
The helical lock seam used in spiral duct fabrication is structurally superior to straight longitudinal seams. Our pipes test up to 20% stronger than smooth-wall equivalents at the same gauge — meaning more hanger spacing, less bracing, and faster installs.
Every section of duct we manufacture is coated to G90 standard (90 grams per square meter total, both sides). This is the galvanization level specified for HVAC systems expected to perform for 20+ years in commercial environments.
Need an odd diameter? Non-standard gauge? A specific length not in the table? We manufacture to customer specs. Contact our team with your drawings or dimensions and we'll quote you the same day.
We manufacture all the fittings that go with your duct — elbows, reducers, saddle taps, start collars, end caps, couplings, offsets, and volume dampers — so every component is compatible and built to the same quality standard.
Most stock sizes ship the same day. We regularly fulfill large orders across the Southeast and beyond, including recent shipments of 48″ diameter spiral duct to customers in Pennsylvania. We'll coordinate LTL and full truckload freight to your jobsite.
Correct duct sizing is the foundation of an efficient HVAC system. Under-sized duct creates excessive velocity and noise; over-sized duct wastes material and space. This guide walks through velocity-based and static pressure-based sizing methods, and explains when each approach applies — from small residential supplies to large commercial mains.
Read More →Stainless steel duct costs 3–5× more than galvanized. Is it worth it? The answer depends on your environment. We break down the corrosion resistance, temperature ratings, and application categories where each material makes sense — and why galvanized G90 is the right spec for the vast majority of commercial HVAC installations.
Read More →Rectangular duct has been losing ground to spiral for 20 years — and for good reason. Round spiral duct installs faster, leaks less, handles sound better, and looks cleaner in exposed ceiling applications. We explain the mechanical and economic advantages that are making spiral the default specification for new commercial construction.
Read More →Improper duct support is one of the most cited deficiencies in HVAC inspections. SMACNA publishes maximum hanger spacing tables based on duct diameter and gauge — but understanding why those numbers exist helps you make smart decisions in the field. This post covers the load mechanics and shows you what to look for when specifying supports for spiral duct up to 48″.
Read More →Studies show that a poorly sealed duct system can lose 20–30% of conditioned air before it reaches the occupied space. That energy goes straight into your utility bill. We explain how spiral duct's tight lock seam compares to rectangular duct's transverse and longitudinal seams, and the sealing methods that bring duct leakage to near zero.
Read More →Galvanized steel is built for longevity — but like any building system, it performs better with periodic attention. This guide covers inspection intervals, what early corrosion looks like versus normal patina, how to address condensation risks in humid climates, and when it makes sense to reline versus replace a section of aging duct.
Read More →Get a personalized quote for galvanized spiral duct — any size, any gauge, custom lengths available. Fast turnaround from our Memphis facility.
Protected with 90 GSM Zinc coating. Strong Spiral Pipes are available in 4-inch to 22-inch diameter in 5 & 10 foot lengths. It is considerably stronger than longitudinal pipe of the equivalent gauge.
Our Spiral pipe are up to 20% stronger than smooth pipe systems of the same gauges. Pipes are commonly used in dust collection, industrial ventilation, spray booth stacking, welding booths, paper trim, pharmaceutical clean rooms, etc.
| Diameter (d) | Gauge | Lenght | Type | Price | Price (per feet) |
|---|---|---|---|---|---|
3″ | 26 | 10′ | Single Wall | $66.00 | $6.60 |
4″ | 26 | 10′ | Single Wall | $43.00 | $4.30 |
5″ | 26 | 10′ | Single Wall | $55.00 | $5.50 |
6″ | 26 | 10′ | Single Wall | $49.00 | $4.90 |
7″ | 26 | 10′ | Single Wall | $58.00 | $5.80 |
8″ | 26 | 10′ | Single Wall | $63.00 | $6.30 |
9″ | 26 | 10′ | Single Wall | $76.00 | $7.60 |
10″ | 26 | 10′ | Single Wall | $79.00 | $7.90 |
12″ | 26 | 10′ | Single Wall | $92.00 | $9.20 |
14″ | 26 | 10′ | Single Wall | $107.00 | $10.70 |
16″ | 24 | 10′ | Single Wall | $133.00 | $13.30 |
18″ | 24 | 10′ | Single Wall | $149.00 | $14.90 |
20″ | 24 | 10′ | Single Wall | $176.00 | $17.60 |
22″ | 24 | 10′ | Single Wall | $198.00 | $11.98 |
24″ | 24 | 10′ | Single Wall | $198.00 | $19.80 |
26″ | 24 | 10′ | Single Wall | $238.00 | $23.80 |