The BRUGG Pipesystems BIOFLEX is a 316L Stainless Steel Corrugated pipe which acts as an internal heat exchanger. BIOFLEX pipe is vastly superior in its rate of heat transfer, and it also installs faster than any other pipe. One of the reasons for the superior heat transfer is the pipe’s helical corrugation, which increases the heat transfer surface by 40% over smooth bore pipe. BIOFLEX pipe comes “endless” resulting in seamless, continuous runs inside the digester.