For over 50 years, Spunstrand® Inc. has furnished miles of underslab HVAC duct systems, above ground industrial and municipal duct systems and various special applications. Installations are in every state and foreign countries. All these years and miles of pipe have produced a multitude of reliable services available to engineers, contractors and architects.

These services include:

• Duct sizing and layout assistance
• Trenching and backfill considerations
• Full structural calculations for burial, pressure, vacuum, etc.
• A unique system for underslab in boot buried dampers
• Design for flex connections and expansion boots
• Field joint procedures and demonstrations
• On-site factory training
• Carbon vessel design, selection and sizing
• Absorbtion media selections
• Shop drawing reviews for factory manifolded considerations
• Quality control procedures
• Visual inspection criteria
• CSI format specs as word or pdf files

Underslab Capabilities and Variations

Spunstrand® Inc. has been manufacturing underslab HVAC ductwork for over forty years in both insulated and non-insulated forms. Insulated and non-insulated ductwork is available in but not limited to standard sizes 2″¯ through 120″¯. Custom sizes, larger and smaller, round or rectangular are also available. Rectangular or square duct systems are not usually designed and laid out for underground use except for vertical boot risers. Boot risers are typically sheet metal that can be made out of fiberglass if extremely high water table or corrosive soil conditions exist.

Insulation values are available in ICC listed and code approved standard insulation values of R-4, R-6, R-8, R-10 and R-12. Greater values required can be easily accommodated. Wall thickness may also be varied to attain greater depths of burial, or to provide better structure for pipe racks and other equipment used for conveyances through the duct system.

Spunstrand® Inc. does offer a complete line of pre-insulated or non-insulated fittings. If fittings other than standard or variations from standard are required, these can be handled upon request and normally at no additional cost. Pre-manifold sections or factory-attached fittings are also available.

Capabilities List

• Watertight joints
• Direct burial
• Special shapes and sizes
• Complete line of pre-insulated or heavier wall thickness non-insulated fittings
• Pre-drilled duct for solar bed aeration
• Greater insulating values
• Factory manifolding
• Custom lengths
• Alternate joint systems
• Custom fittings, round or rect.
• Deep burial engineering square to round
• Consulting
• FRP boots

Spunstrand® fiberglass reinforced plastic duct (FRP) is rated Class 1 and code approved for direct underground burial serving any commercial application which has the supply and/or return air system under the building slab. Typical applications include the following.

Underslab HVAC/Slab on Grade Construction

• Banks
• Carbon Monoxide Exhaust
• Churches
• High Rise Construction
• Libraries
• Hotels
• Housing Projects
• Hospitals (HVAC & Garage Exhaust)
• Restaurants
• Schools/Gymnasiums
• Supermarkets
• Swimming Pools (HVAC & Heat Recovery Systems)
• Theaters/Auditoriums

Spunstrand® Inc. duct for these applications is manufactured using the filament wound method, where continuous fiberglass strands are impregnated with resin and machine wound on a mandrel which has first received a foil scrim kraft surface liner. Winding continues until the desired wall thickness is reached and then the mandrel with the duct laminate is moved to a heated curing station where it is rotated until the resin is set. The approximate glass content of the filament wound duct is 70%.

The internal surface liner provides the Class 1 rating for this product, while the fiberglass fibers furnish strength, dimensional stability, and temperature resistance. The type of resin is chosen to provide chemical and electrical resistance, color, finish hardness and thermal properties.

Capabilities and Variations Spunstrand® Inc. has been manufacturing filament wound fiberglass reinforced plastic duct and piping for over forty years. Variations in resin, glass, liners, wall thickness, and their applications in corrosive air, HVAC, or fluids, are as diverse as the markets we serve. We have made just about every size and shape imaginable and even provided insulated industrial ductwork. We also have an FDA approved insulated duct for use in food manufacturing plants. The standard guide specification we use is centered around the National Bureau of Standards PS 15-69 and/or the new SMACNA Thermoset FRP Duct construction manual. We also manufacture to various ASTM specifications, ANSI, Military specs and many custom application specifications. We do more custom spec work and spec writing than most FRP manufacturers due to the diversity of product lines, personnel and years of FRP experience. Capabilities List

• Custom spec work
• Special shapes and sizes
• Polyester, vinylester, epoxy, phenolic duct and piping
• Custom wall thickness
• Factory manifolding
• Round sizes std. from 2″ to 120″
• All fittings; round and rectangular
• Carbon Scrubbers
• Technical drawings
• Custom liners (glass, synthetic, Teflon)
• Insulated duct
• Flanges, blast gates, dampers, (manual or motorized), access doors, etc.
• Zero Leak Isolation Dampers
• Complete line of fittings and accessories
• Color options
• Consulting (product or field)

Spunstrand® Inc. Fiberglass Reinforced Plastic Duct is custom manufactured for Industrial Corrosion Resistant Fume Exhaust applications. The resin system used is determined by the chemical, pressure and temperature exposures that the duct is subjected to. Typical applications include the following.

• Industrial FRP Ducting/Corrosive Fume Handling
• Wastewater Treatment Plants
• Petrochemical Plants
• Laboratory Exhaust
• Glass and Metal Foundries
• Clean Rooms
• Plating & Metal Finishing Facilities
• Micro-Electronic Plants
• Pulp and Paper Industry
• Aerospace Industry
• Automotive Industry
• Marine Exhaust Systems
• Food Processing Facilities

Spunstrand® Inc. duct for these applications is manufactured using the filament wound method, where continuous fiberglass strands are impregnated with resin and machine wound onto a mandrel, providing a stronger part than hand lay-up or centrifugally cast laminate. A corrosion barrier is first applied on the mandrel. For the standard 20 mil resin rich surface mat or synthetic veil corrosion barrier, the duct is filament wound prior to the gellation of the liner in order to ensure a complete bond. Liner type and thicknesses are available from 10 to 200 mils depending on specifications and customer requirements.