Understanding Ductwork Fabrication Industry Standards

November 6, 2015

It is crucial that all industrial ductwork fabrication fully meet all industry standards. That is because process ductwork needs to be able to carry huge amounts of very hot and often dusty air from one place to another. This air may reach temperatures as high as 900 – 1000 degrees Fahrenheit (482 – 515 degrees Celsius). Industry standards are critical because they help ensure that this air is conveyed safely to its destination. STI Group is committed to following all standards in duct fabrication and helping others understand them as well.

What Do Duct Designers Need to Know?

STI Group or any industrial fabrication company doing ductwork must have a complete understanding of how the metals being used will be affected by the heat traveling through the ducts, as well as, the potential hazards of excessive amounts of dust in the duct system, and general principles of structural design. The heat in the system causes the piping to grow, which presents a special challenge for the implementation of proper support mechanisms and the design of branches. Even more of a challenge is the large amount of dust that the system must be able to carry. Designers must consider the load of dust carried inside, which can reach as much as 25 percent of the pipe’s cross section if the pipe is horizontal.

The combination of heat from inside and moisture from the environment around the piping can result in corrosion. Because of this, designers need to use materials that can keep the ducts from corroding. Environmental forces such as wind and earthquakes also play a major role in the requirements of process ductwork. In rare situations, designers may even need to consider the possibility of heavy snow piling up on top of the duct, although the duct’s extreme heat usually causes all snow to melt.

Proper Structural Support is Essential

Well-placed structural supports are also necessary at the joints in order to prevent the branches from rotating or moving from side to side. These supports come in a variety of styles. Fixed supports are the simplest; they hinder any lateral motion of a branch. Link supports connect the duct frame to a foundation by means of a braced frame. For shorter frames, hinges must be present in the frame to account for the likelihood that the duct’s size will increase as it heats up. For longer frames, this is often not necessary. Similar to link supports, but slightly easier to design, are rod supports. These are generally more flexible than link supports. Certain process ductwork systems require supports that can move around. These are known as sliding supports and they are usually supported by a Teflon foundation that is somewhat far removed from the duct so that the sliding surface is not harmed by the heat. If heavy winds are likely to be a problem, duct designers may consider using guide supports, which keep the duct from moving side to side while still allowing it to grow vertically from the heat. STI Group considers the particularities of each situation carefully, and fabricates or provides a support method per client specifications and engineering methods that will lead to maximum strength and safety.

How Should ductwork Be Checked for Quality?

All types of piping must be checked thoroughly for adherence to the correct dimensions and other design specifications. ductwork must have the proper strength at all points along its path, and it must also have the requisite resistance to corrosion. Remember, these systems are meant to carry very hot air through all sorts of terrain. They must have the strength to resist the heat of the air inside as well as inclement weather and other pressures coming from outside. In addition, STI Group also checks each location where one duct joins up with another, since these are the most likely sources of weakness. Welding and fastening of ductwork sections are constant areas of great stress, engineered dwgs. are the best source of quality certified information pertaining to design requirements.

What Happens if Industrial Standards Are Not Followed?

Due to the extreme heat of the air carried by many process ductwork systems, the consequences of not following industry standards can be catastrophic. Poor welding or the failure to protect against corrosion can cause weak spots to build up in the ductwork over time. Eventually, the suction pressure from inside the piping can cause the duct to implode at these weak points, causing a disastrous situation and production downtime. For this reason, STI Group is always careful to fully comply with industry standards in ductwork fabrication. Our clients can rest assured that their fabricated ducts will be safe, durable, and effective.