Tall chimney liner
Tall chimney liner
(OP)
We are contemplating GRP for a loose liner in an industrial chimney 8 ft dia 270 ft high 60 degree Centigrade. Made up as 30 ft lengths, joined by flanges. Anyone know if there is any published data on such a project.How can we establish the buckling load for the lowest length .We guess it might be 0.5 inches thick from high quality laminate.Thanks in anticipation of any comments. David Whitlock.





RE: Tall chimney liner
Compare with the pro-rata weight of the complete structure + allowance for other forces that may induce sway, such as high wind.
RE: Tall chimney liner
RE: Tall chimney liner
We are in the process of reviewing a series of large diameter GRP chimney liners. Never seen one joined by flanges, usually a field fiberglass joint. In terms of buckling and liner design in general, guidance can be obtained from ASTM D-5364. You need to establish the laminate make up before concluding anything about buckling capacity.
RE: Tall chimney liner
rd78(structural) your own findings would be very very usefulland anything you might say will help formulate our plans. I am not a Chimney designer and find difficulty in comprehending an 85 mtr freestanding steel stack, even if the base is 3.6 mtr dia. The top sways 0.8 mtrs.. The flue gas can be contained by a good quality vinyl ester resin but the client wants 15 yrs life. The chimney builder believes his competitors are offering for a lined wind shield,and this gives me confidence to continue down this road.
Please keep your ideas coming , positive or negative.
Thanks in advance . David Whitlock.
RE: Tall chimney liner
We are an end user, and have many stacks that are made of only FRP. Overall we have had good success with these. However, we have two stacks where the liner has completely delaminated from the structural layers. It started with blisters that reached as large as 2 feet by 4 feet.
The root cause investigation determined that the laminate was not properly cured prior to installation (using DSC of retained cut outs, and cutouts from the stack after service of 2 years) and that the liner was not properly prepped prior to application of the structural layers. The liner showed little if no signs of chemical attack after 4 years of service(ie High Barcols, no attack of the glass examined via SEM).
I would recommend eliminating the exotherms, especially between the corrosion and structural layers (applicable for hand layup throughout only). If you cannot eliminate the exotherm, then great care should be taken to prep the surface at each exotherm. Our company requires the surface to be ground after exotherms if more than 3 hours have elapsed or the surface is no longer tacky. I would also recommend post curing the resin as high of a temperature as you have the capacity, up to the Tg of the resin.
RE: Tall chimney liner
Why not go with a thin skin with an exoskeleton bonded to the outer surface. Scaffolding pipe for example at 500mm centres around the circumference. Scaf pipe has male female ends to guide and lock sections into place. U brackets aligned vertically on the steel outer skin to correspond with the scaf pipe skeleton.
Go for a flange joint and bond with epoxy resin. Caulk it to ensure a seal.
Simple to make, simple to install. Strong flexible and light.
RE: Tall chimney liner
You are right to worry about the mismatch between the metallic and FRP thermal expansion. The idea of the all FRP chimney can work if you have the real estate to support it with a framework or guy wires. Wind oscillation can be a problem, moreso than with steel.
If you go with the internal liner, you support it at a convenient elevation, perhaps leaving the bottom half in tension and the upper section in compression. You'll need lateral supports periodically to ensure the liner doesn't become misaligned with respect the the chimney in a wind event.
Regards,
Rick D.