Environmental Engineering Reference
In-Depth Information
Correct
Flat
Kinked
Wrinkled
Incorrect
figure 4.16 Correct and incorrect tubing bends
•
Stainless steel
is seamless and fully annealed and is also available
as a welded type, suitable for bending and flaring.
•
Special alloy
is made for carrying corrosive materials.
Like metal piping, metal tubing is made in both welded and seam-
less styles.
Welded
tubing begins as flat strips of metal that are then
rolled and formed into tubing. The seams are then welded.
Seamless
tubing is formed as a long, hot metal ingot and then shaped into a cylin-
drical shape. The cylinder is then extruded (passed through a die), pro-
ducing tubing in the larger sizes and wall thicknesses. If smaller tubing
(with thinner walls and closer tolerances) is desired, the extruded tub-
ing is reworked by drawing it through another die.
4.10.6 Typical Tubing applications
In a typical wastewater operation, tubing is used in unit processes
and machinery. Heavy-duty tubing is used for carrying gas, oxygen,
steam, and oil in many underground services, interior plumbing, and
heating and cooling systems throughout the plant site. Steel tubing is
used in high-pressure hydraulic systems. Stainless steel tubing is used
in many chemical systems. In addition, in many plants, aluminum tub-
ing is used as raceways or containers for electrical wires. Plastics have
become very important as nonmetallic tubing materials. The four most
common types of plastic tubing are Plexiglas
®
(acrylic), polycarbonate,
vinyl, and polyethylene (PE). For plant operations, plastic tubing usage
is most prevalent where it meets corrosion resistance demands and the
temperatures are within its working range (primarily in chemical pro-
cesses). Plastic tubing is connected either by fusing with solvent cement
or by heating. Reducing the plastic ends of the tubing to a soft, molten
state and then pressing them together produces a fused joint. In the
solvent cement method, the ends of the tubing are coated with a solvent
