Sealed Rectangular Tubing - Stress from temp. increase
Sealed Rectangular Tubing - Stress from temp. increase
(OP)
Hello,
We're designing a structural system that will have HSS 8x4x5/16 members approximately 8ft. long spanning in between two S12x31.8 beams. The tubes are water-tight welded to the edge of the structural steel; we need these tubes to be water-tight because the structure will be partially submerged and is made from galvanized steel.
A pictorial representation:
I======I
Our client is requiring that all aspects of our system meet the requirements of a 150* temperature differential (-40F cold night to 110F hot day).
Using a simple ideal gas law calc, we found an internal gauge pressure of 5.3 psi. I'd like to calculate the stress on the beam from this but I can only find spherical and rectangular stress equations for pressure vessels.
Is there a quick way of checking to make sure our sealed tubes won't blow up/ crack welds? One of our more conservative engineers is concerned that we will need to add a venting system to the structure.
Thanks,
Brandon
We're designing a structural system that will have HSS 8x4x5/16 members approximately 8ft. long spanning in between two S12x31.8 beams. The tubes are water-tight welded to the edge of the structural steel; we need these tubes to be water-tight because the structure will be partially submerged and is made from galvanized steel.
A pictorial representation:
I======I
Our client is requiring that all aspects of our system meet the requirements of a 150* temperature differential (-40F cold night to 110F hot day).
Using a simple ideal gas law calc, we found an internal gauge pressure of 5.3 psi. I'd like to calculate the stress on the beam from this but I can only find spherical and rectangular stress equations for pressure vessels.
Is there a quick way of checking to make sure our sealed tubes won't blow up/ crack welds? One of our more conservative engineers is concerned that we will need to add a venting system to the structure.
Thanks,
Brandon





RE: Sealed Rectangular Tubing - Stress from temp. increase
I assume your refering to the air in the HSS section? so why not multiply the pressure inside the HSS to get a point load on the beam and stress the beam in the weak axis or have I missed something.
Also what about the physical expansion and contraction of the HSS they will impose loads possibly on the beams, assuming the beams are restrained.
desertfox
RE: Sealed Rectangular Tubing - Stress from temp. increase
Your galvanizer may require vent holes for galvanizing, though- check with them and see. Normally handrail pipes and things like that have to be vented.
RE: Sealed Rectangular Tubing - Stress from temp. increase
We've got a unique situation and we're working with our galvanizer to figure out the best way to both vent the tubes but make sure they are ultimately sealed water-tight.
RE: Sealed Rectangular Tubing - Stress from temp. increase
To vent for galvanizing and be water tight after, I would suggest several NPT pipe bosses be welded on the structure
To be capped after galvanizing is complete. I realise of course that you may already have thought of that.
B.E.