Specialty Fittings

Plugs & Caps, Couplings, Offsets, Ball Joints & Register Saddles

Plugs & Caps
Pipe Plug (P-1) fits into pipe
Fitting Cap (P-1-F) fits over fitting

Specialty Fittings Plugs Caps

To order, specify “D” dimension and P-1 or P-1-F. Also available with bird screen.

Pipe Coupling (C-1) fits into pipe
Fitting Coupling (C-1-F) fits over fitting

Specialty Fittings Couplings

To order, specify “D” dimension and C-1 or C-1-F


Specialty Fittings Offset

List dimensions in order of D, X, Y.

Register Saddle

Specialty Fittings Register Saddle

List dimensions in order of A, B, P.
L is available in any length.

Ball Joint

Specialty Fittings Ball Joint

Table 17-1 Ball Joint Dimensions
D A B C Wgt. Lbs.
3″ 5 3/8 4 3/4 23° 1
4″ 7 1/2 6 1/2 23° 1.75
5″ 9 7 7/8 27° 2.5
6″ 7 1/2 8 7/8 27° 3
7″ 10 3/8 7 7/8 22° 4
8″ 13 11 27° 7
9″ 14 5/8 12 27° 8
10″ 14 5/8 11 1/4 22° 9
12″ 16 1/2 12 1/4 20° 10


Spun steel galvanized ball joints provide flexibility in ducts that serve moving equipment such as cutter heads. The duct can swing through an arc while maintaining exhaust flow. Available in 3” through 12” diameter.

Round Duct Fittings from Spiral Manufacturing

In addition to spiral round duct, Spiral Mfg. manufactures specialty fittings for a wide variety of applications. We provide plugs and caps, couplings, offsets, ball joints, and register saddles built to meet your specifications. To order round duct fittings that meet your requirements, refer to the images and instructions above. To order ball joints with the correct specifications, refer to table 17-1.

You can trust Spiral Manufacturing to meet all of your spiral pipe needs. Founded in 1962, we have been manufacturing round duct and round duct fittings of the highest quality for six decades. Thanks to our diverse range of capabilities, we are able to offer a vast array of products in many different sizes and materials.

Contact Spiral Mfg. Today

If you need a specialty fitting for your HVAC application or dust collection system, contact Spiral Mfg. today. As a leading provider of spiral round duct and round duct fittings, we can provide you with the perfect solution for your project. Call 763-755-7677, email info@spiralmfg.com, or fill out our online contact form here. We look forward to working with you.