Duct connectors can be round conical, rectangular, or square, fabricated as reducers or in
some cases the transition piece from rectangular or square to round ducts. Flanged
connectors are furnished with steel back up rings or plates, and where the outside
exposure demands it, steel may be hot dipped galvanized or fabricated from stainless
steel. Since there are no standard duct flanges, they are usually drilled to specific
drawings. In some cases, the mating flanges cannot be properly measured, or the existing
holes follow no particular pattern, we furnish the assemblies with both the rubber and
retaining flanges undrilled for drilling in the field.
Rather than flanged ends, we often supply slip on designs that are clamped or banded.
Depending on the specified movements, the body of the expansion joint may have an arch or
arches similar to piping expansion joints or they may be straight or ballooned.
Mercer Rubber joints do not get up to high enough temperatures for applications in boiler
breaching, but they are used in a temperature range as high as 400° F and commonly
located in the hot high pressure duct work in waste water and sewage treatment plants.
They are used throughout the chemical industry, and we have supplied diameters as large as
145" for wind tunnels at both military and civilian research centers.
If you need an unusual duct connector, send the inquiry on to us. It is most likely we can
build to your exact specifications and provide just what is needed.
Picture 1 A rectangular heavy duty flexible duct connector installed in the top
horizontal discharge of a boiler forced draft blower. Pressure 12psi.
Picture 2 Concentric reducers installed in the suction and discharge air
connections of a positive displacement high pressure blower, reduce stress to the flanges
and facilitate hook-ups.
Picture 3 Round duct connectors installed in the duct work of a sewage treatment
plant allow for major hot duct expansion.