Many times, with corrugated metal pipe, there are sites that will require the pipe to curve around a corner or angle around a building. It is simple to provide a 90 degree or 45 degree turn, but what do you do when the turn isn’t so easy and it needs to be refined to a more precise curve?
These curves usually go around cul-de-sacs, around buildings, or special parking lot designs, and one way to make these curves is to “kink” the pipe at the joints. In other words, adding a deflection at the joint will allow for an angle and with multiple joints deflected it will create a curve. There is a limit for how far the pipe can be deflected which is outlined more in depth by ASTM A760 or AASHTO Construction Section 26. The specification mentions that in a soil-tight connection, the maximum opening should not exceed 1 inch. While that does not sound like much, when combined with multiple joints, especially with smaller pipe lengths, most curves can be achieved.
There is a small caveat when adding a kink to the joint and that is the band type that needs to be used. Due to the two pipes within the joint essentially being misaligned to achieve a deflection, the band needs to be able to flex along with the deflection. Preferably a flat band or a hugger band would be used, because of the flat section of the band that is directly over the joint and allows it to flex with the deflection.
So, if a project ever requires complex bends and turns and there is space available to create a curve to make it more aesthetically pleasing and hydraulically efficient, consider the use of joint deflections in corrugated metal pipes!