When it comes to choosing between spiral lockseam pipe and straight-seam lockseam pipe for your metal duct work, you should consider several factors.
1. Straight-seam pipe is smoother and therefore avoids any buildup in crevices that is more likely to occur with spiral pipe.
2. Spiral pipe is more likely to leak air than straight-seam pipe is.
3. Spiral pipe can become unwound if connecting rings are put on the ends whereas a ring can be put on a straight-seam pipe with a van stone flange for a more secure fit. (A van stone flange is created when a mating flange ring is slipped over the pipe, when the end of the pipe is then flared out, and when the connection is sealed by connecting the rings.)
4. In certain applications like an oil mist, when the straight seam is installed with the seam toward the sky, the pipe is less likely to leak than spiral pipe.
5. In many applications, straight-seam looks better, e.g. several large retailers outfit their “big box” stores with painted straight seam lock seam pipe as downspouts.
Lockseam pipe can be fabricated through steel plate rolling and steel sheet rolling from 16 to 24 gauge, from 3 to 14 inch diameters, and in lengths up to 10 feet.
