Process duct work conveys large volumes of hot, dusty air from processing equipment to mills, baghouses to other process equipment. Process duct work may be round, or rectangular. Although round duct work costs more to fabricate than rectangular duct work, it requires fewer stiffeners and is favored in many applications over rectangular ductwork.
Structural process ductwork carries large volumes of high temperature, dusty air, between pieces of process equipment. The design of this ductwork requires an understanding of the interaction of heat softening of metals, potential effects of dust buildup in large ductwork, and structural design principles. there are two basic shapes for structural process ductwork, rectangular and round. Rectangular ductwork is covered be the ASCE "The Structural Design of Air & Gas Ducts for Process Power Stations and Industrial Applications".
Large, round process ductwork is usually fabricated from 1/4 in (6 mm) steel plate, with stiffening rings at 15 ft (5 m) to 25 ft (8 m) on center, regardless of diameter. These lengths allow for shipping by truck, and fabrication with most fabricator equipment.
There are several references for process duct work.
- ASCE - Structural Design of Air & Gas Ducts for Power Stations and Industrial Boiler Applications
- Roark & Young
- Tubular Steel Structures, Chapter, 2, 9 & 12
- US Steel Plate, Plate Structures, Volume I & II
- US Steel Plate, Steels for Elevated Service Temperatures 1974
- Lincoln Arc Welding, Blodgett, chapter 6
- Lincoln Arc Welding, Tubular Steel Structures
- Cold Formed Steel Structures
- ASHRE, for the design of pressure drop, elbows & fans
- API 360, contains references to minimize wind ovaling.
