Most rigid chimney liner sections are made of nonmagnetic, series 304 or series 316 stainless steel. Unlike the flexible stainless steel liner, rigid pipe comes in sections and is usually round in shape and one to four feet long and five to ten inches or more in diameter. The most common wall thickness is 24-guage (0.024 in.) or 22-guage (0.029 in.) stainless steel.
The seam running down the length of each liner sections is factory sealed. Individual liner sections are joined together with the crimped, male end facing down. Stainless steel pop rivets and stainless steel screws secure the joints.
Pop rivets are recommended by most manufacturers since screws may work themselves loose from the expansion and contraction of the liner. Usually rigid relining jobs are supported at the bottom of the chimney or at the thimble area.
Stainless steel tee sections are used at the thimble and clean out areas. Rigid stainless steel liners can expand several inches during heating. To accommodate for this expansion the liner moves up and down in a sleeve at the top of the chimney.
A storm collar over the rigid pipe prevents moisture from entering the chimney along the outside of the liner. The area around the rigid liner at the top of the chimney, the area in between the rigid liner and the flue, is sealed with a stainless steel top plate. This top plate serves 2 purposes. first it seals of the flue area and prevents water or any other foreign substance to enter in the chimney. Second, the top plate combined with a support clamp maintain the liner position in the chimney
The use of rain caps are recommended for use on chimneys with stainless steel liners. It can be very important to have the most efficient venting possible.
A smooth walled rigid liner offers the most efficient venting due to the decreased turbulence. You can shape it to take full advantage of every cubic inch and offer maximum draft. It can be shaped into rectangular, square or oval.