Spiral Pipe and Fittings

Southwark's spiral ductwork provides efficient airflow help to increase system efficiency with easy installation in residences and light commercial applications.

ASHRAE Advanced Energy Design Guides recommend that circular duct be used whenever possible over rectangular duct to help reduce energy use. Without corners or longitudinal locks, there is less turbulence and friction of air flow, causing less noise, collecting less dust and other contaminants, and creating easier flow.

Spiral pipe has long shown lower leakage rates and less static-pressure loss than rectangular duct. Southwark’s spiral pipe features seams using SMACNA approved RL-1 locks – rectangular ductwork can lose up to 15% of its airflow due to longitudinal seams. Pipe joints come in 10 foot lengths, allowing for less joints to seal together with fewer opportunities for air leakage.

Spiral systems have lower losses in static pressure as they have less surface area than rectangular ductwork to move the same amount of air – minimizing heat or air loss through the wall of duct.  Southwark’s spiral pipe is fabricated for up to 10 inches of positive water gauge pressure for greater efficiency and flexibility with system pressure and velocity options. They can be installed with less duct hangers and supports, less insulation, less duct sealant than with other rectangular options.

Furnace Filter Bases

Southwark offers Furnace Filter Bases available for use in both up-flow gas furnaces and fan/coil units. Made from 22 Gauge galvanized steel, it makes changing the air filter stress-free, with no panels or doors to remove with extra tools. It presents a clean and professional installation in residences and light commercial applications.

At the base of a blower fan or at the base of a furnace, an air filter stands as the last chance for dust, dirt, mold spores, and other debris in the air to be caught before recirculating through the HVAC system. The longer a filter is installed and not replaced, the more dust and dirt is collected, making the filter less and less effective at stopping the flow of debris through to the equipment. Dirty filters reduce airflow across the furnace and can upset the balance of heating and cooling throughout the home, making an HVAC system both inefficient and ineffective. Having a filter base that is easy to access, making the filter panels easy to remove and replace, helps add value to the consumer by allowing them to take part in the maintenance of their home.

The filter base has a hinged door with a magnetic latch and handle for easy access to the filters. The base is available in 3”, 4”, and 6” heights; the tallest being able to accommodate 1”, 2” and 4” filters with removable rails to adapt to the installer’s and user’s preference. An outboard flange with mounting holes provides stability for installation and rounded corners to lessen incidents of damage or injury. The base is spot welded and riveted for strength, and is individually boxed for convenient warehousing and shipping.


Who is Southwark?


Southwark Metal Manufacturing Company has been manufacturing prefabricated sheet metal ducts and fittings for over 75 years. Their mission is to ensure the greatest value for their customers’ dollar, by providing the best products, service, and industry support every day.


With over 3,000 items in stock and the ability to produce custom fittings. They able to fill customers most exacting specifications at competitive prices. Working with you to ensure that your pipe and fittings comply with all industry standards, codes, and applications that arise in the changing, energy-efficient HVAC marketplace.


All Southwark Metal duct and fittings are constructed from prime galvanized steel. Their large steel inventory makes it possible for each of their 7 facilities across the United States to meet customer’s largest order requirements as well as allows each division to replenish stock seamlessly for constant product inventory.

Southwark's products are hand-crafted to reduce noise and friction and constructed to maximize efficiency by increasing airflow without leaks. The quality of their galvanized steel allows them to create fittings that are rust-resistant, durable, and consistent in quality.


Southwark Metal maintains a high level of efficiency to effectively meet customer’s needs in a timely manner. 

We are able to fill our customers most exacting specifications at competitive prices. We will work with you to ensure that your pipe and fittings comply with all industry standards, codes, and applications that arise in the changing, energy-efficient HVAC marketplace.

Shop More Southwark Products