Crush strength of a heated polymer pipe
Crush strength of a heated polymer pipe
(OP)
I'm looking to calculate the force required to crush various polymer-type pipes through the use of intumescent materials in fire collars. The force contact patch would be around 20mm in length on the outside of the pipe, with the force crushing the pipe from all directions circumferentially on the outside. I cant seem to figure out an accurate formula(s) to use to calculate the strength of the pipe and how the pipe strength would be affected as it softens due to the heat in a fire.
Any help or ideas would be greatly appreciated on this topic. Thanks!
Any help or ideas would be greatly appreciated on this topic. Thanks!






RE: Crush strength of a heated polymer pipe
Mike Halloran
Pembroke Pines, FL, USA
RE: Crush strength of a heated polymer pipe
RE: Crush strength of a heated polymer pipe
I think you need to conduct a physical experiment to see if a burning collar will cause _any_ deformation of the specific pipes you intend to use, using an actual fire, and a pretty good mockup of the actual roof you intend to use.
Mike Halloran
Pembroke Pines, FL, USA
RE: Crush strength of a heated polymer pipe
H
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
RE: Crush strength of a heated polymer pipe
Thanks again!
RE: Crush strength of a heated polymer pipe
Mike Halloran
Pembroke Pines, FL, USA
RE: Crush strength of a heated polymer pipe
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Crush strength of a heated polymer pipe
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
RE: Crush strength of a heated polymer pipe
RE: Crush strength of a heated polymer pipe
What is your ultimate goal in this ? Are you trying to make sure the firewall stays sealed so no flame can penetrate ? Even if the pipe melts completely.
I have a sneaking suspicion that in a fire, the firewall coating will not expand enough to seal a hole if the pipe melts completely, especially if the pipe is bigger than 25 to 35 mm .
B.E.
You are judged not by what you know, but by what you can do.
RE: Crush strength of a heated polymer pipe
RE: Crush strength of a heated polymer pipe
Here is a draft copy of our local (California USA ) specifications for your perusal. They cover a lot of the things you are working on.
B.E.
You are judged not by what you know, but by what you can do.
RE: Crush strength of a heated polymer pipe
I am more looking for actual calculations/equations which might give a required expansion pressure to crush the pipe for different materials.
RE: Crush strength of a heated polymer pipe
I am afraid Mike Halloran already answered that for you I think you need to conduct a physical experiment to see if a burning collar will cause _any_ deformation of the specific pipes you intend to use, using an actual fire, and a pretty good mockup of the actual roof you intend to use.
I know he said roof when you are actually dealing with firewalls, but the principle is the same, I think you are going to have to assemble empirical data by make and model number of product.
B.E.
You are judged not by what you know, but by what you can do.
RE: Crush strength of a heated polymer pipe
RE: Crush strength of a heated polymer pipe
For reference, the mufflers look rather like oval automobile mufflers, except for being much larger, and made of FRP instead of steel. The pipes are 8" OD or so. I'm guessing the muffler bodies' elliptical shells have major dimensions of ~24" and minor dimensions of ~12", and are ~6 feet long. The walls are about 1/2" thick. The resin used is nominally a thermoset, but it behaves more like a thermoplastic when it gets hot. At some point it does burn and char, but the shells clearly didn't get quite that hot. By the time I got there to inspect them, they had cooled to ambient temperature and were quite rigid and strong, just misshapen.
Mike Halloran
Pembroke Pines, FL, USA