Ductwork fabrication involves the creation of ducts that distribute conditioned air throughout buildings. Properly fabricated ducts meet regulatory standards and ensure optimal airflow.
The key to improving ductwork fabrication is increasing flow. A well-organized shop can eliminate bottlenecks that stall production. To increase flow, look for what causes a pause: what are workers waiting on?
Design
Ductwork is a crucial part of a heating, ventilation and air conditioning system. It delivers comfortable temperatures, sanitary air quality and processing capabilities, as well as energy efficiency. It also provides the framework for systems to supply and remove air.
The duct system is designed to meet certain requirements, including pressure class, size and shape. For example, metal ducts must be built with a certain type of sheet metal to resist the pressure applied when blowing (positive) or sucking (negative) air through the system.
Using Revit MEP, stakeholders can create detailed and design intended models of the ductwork, which facilitates estimation, analysis, documentation, fabrication and project planning. Detailed ductwork models can help reduce construction delays, improve communication between disciplines and deliver higher quality designs.
Materials
The size and weight of the materials used in duct fabrication determine how much air pressure they can hold and whether they can be installed indoors or outdoors. Detailed CAD design considers custom fittings and optimizing airflow, and the fabricator then uses cutting tools such as shears and high-definition plasma equipment to precisely cut and shape sheet metal into duct sections.
Some ducts are made of stainless steel for increased durability and resistance to corrosion from chemicals. Aluminum is a lightweight material popular for outdoor ducting, and it also resists corrosion.
Some ducts are lined with ceramic or another substance to enhance heat or abrasion resistance, especially in harsh environments such as foundries or sand plants. Other ducts are composed of fabric, such as absorbent polyester, which is common in laboratory or school cafeteria ducting.
Cutting
Depending on its shape, ductwork can be made of different materials. For instance, process ductwork in cement plants and power plants needs to be heavy and durable to withstand high temperatures and pressures.
The process of cutting a sheet of metal into pieces for the ducts begins with a detailer creating drawings that show how the duct should be constructed. This information is then sent to a sheet metal fabrication shop where the ductwork is actually made.
The fabricators will use lock forming machines to bend the metal into the correct shapes for the ducts. A good way to check if the metal is being bent correctly is by sliding the edge of a ruler along the length of the duct. The marks the ruler makes should line up exactly with each of the one-inch measurements on the ducts.
Welding
The heating, ventilation and air conditioning (HVAC) system in a building requires precise fabrication to ensure proper distribution of heat and energy. This includes the ducts that carry the air from room to room, ensuring optimal efficiency and comfort.
Ductwork fabrication involves welding metals to form the desired duct shape and size. This process also involves adding beading to the edges of the ductwork, which helps to strengthen duct connections and prevent leaks.
Before beginning to weld, the sheet metal should be inspected for damage and defects. Protective clothing and a first aid kit should be on hand to deal with any potential injuries or accidents that may occur during the fabrication process. You should also have the following tools:
Assembly
The heavy metal ductwork that wraps around industrial facilities doesn’t just come off the shelf. It must be custom-fabricated to fit the process lines, HVAC, and other parts of a plant.
The fabrication process begins with an engineering drawing from a process engineer. The drawing is broken down into the components that can be fabricated with a combination of cutting, forming, and welding.
The cutting and forming process is usually automated using shears and high-definition plasma equipment, and a press brake or roller may be used to bend steel plate into the shapes required for a specific section of ducting. Layout tools and marking equipment are also employed to make precise measurements and mark positions on the pieces of metal. Safety gear is worn to protect against sharp edges and sparks.