In the ancient days we had to use ridged stainless steel pipe and very heavy-duty flex pipe to line a chimney. The liner would frequently get caught up in bends in the chimney system and cause us much grief. We install liners to make chimneys safe, and as mechanical code requires when installing to the exhaust ports of woodstoves and oil-fuel furnaces. Now we have light-weight stainless steel flex material that lines the entire run of the chimney and is much easier to install. One word of caution though: care needs to be taken when sweeping these liners. A chimney sweep can damage one of these liners if done improperly with the wrong equipment. The photo below is of a flexible stainless steel liner kit.
Have a good day!
Owner- Rooftop Chimney