Minimum metal width between holes in a support plate
Minimum metal width between holes in a support plate
(OP)
I'm changing a PTFE support plate in a packed distillation column for a SS316 plate.
This plate must have the maximum possible open area to minimize capacity limitations before flooding in the column, so i must drill the maximum possible number of holes (I know that there are special designed support plates to maximize the area, but im truth i need only a small improvement over the actual suport plate).
How can i calculate the minimum metal width between the holes of a plate with holes drilled in a triangular pattern (exactly like this one http://www.comtelasms.com.br/wp-content/uploads/20...) ?
1mm spacing between holes seems good enough for the plate not bending, given the small support beams spacing right bellow this plate. I've done some estimations based on cross-sectional sizing of wires supporting pontual loads, but i don't think it is the right aproach.
Data:
Column diameter: 300 mm
Plate diameter: 280 mm (16 mm calculated at max. thermal expansion)
Plate thicknes: 1,5 mm
Hole diameter: 15 mm
Temperatura range: 10-110°C
Total Load: 89 kg of packing (1,5 m of 1" ceramic random packing over a 70686 mm² area)
Support beamns width: 15 mm
Support beams spacing: 25 mm
316 tensile strenght: 485 Mpa
Thank you all in advance for your time.
This plate must have the maximum possible open area to minimize capacity limitations before flooding in the column, so i must drill the maximum possible number of holes (I know that there are special designed support plates to maximize the area, but im truth i need only a small improvement over the actual suport plate).
How can i calculate the minimum metal width between the holes of a plate with holes drilled in a triangular pattern (exactly like this one http://www.comtelasms.com.br/wp-content/uploads/20...) ?
1mm spacing between holes seems good enough for the plate not bending, given the small support beams spacing right bellow this plate. I've done some estimations based on cross-sectional sizing of wires supporting pontual loads, but i don't think it is the right aproach.
Data:
Column diameter: 300 mm
Plate diameter: 280 mm (16 mm calculated at max. thermal expansion)
Plate thicknes: 1,5 mm
Hole diameter: 15 mm
Temperatura range: 10-110°C
Total Load: 89 kg of packing (1,5 m of 1" ceramic random packing over a 70686 mm² area)
Support beamns width: 15 mm
Support beams spacing: 25 mm
316 tensile strenght: 485 Mpa
Thank you all in advance for your time.





RE: Minimum metal width between holes in a support plate
elastic properties of perforated metal
RE: Minimum metal width between holes in a support plate
At a minimum, the edges of the holes will be distorted by the mechanical stress associated with cutting the holes mechanically.
You can make thinner webs, and non-circular holes with more open area, by getting the plate fabricated by laser or waterjet cutting.
Mike Halloran
Pembroke Pines, FL, USA
RE: Minimum metal width between holes in a support plate
You are right. Talked with maintenance team. It would be very hard to drill with less than 3 mm spacing without bending the plate, so it will be laser cutted.
2 mm spacing x 2 mm thickness was advised based on experience to be very safe values, and it's good enough for my intended performance increment. But i wish to understand how this kind of calculation could be done.
RE: Minimum metal width between holes in a support plate
If so, I'd be wondering if the details of the edges of the holes might be reducing the flow coefficient more than the increased area will help.
http://image.slidesharecdn.com/2012pereviewhyd-141...
http://www.tasonline.co.za/toolbox/pipe/velorif.ht...
RE: Minimum metal width between holes in a support plate
Yes, there are fluids flowing thru the holes quickly.
But the holes are suposed to be well rounded. Thus, the thickness of the plate will be reduced from 3 mm (PTFE plate) to 1,5-2 mm (SS316 plate), wich helps reduce the head loss through the orifice (i'm not taking this "bonus" capacity due to thickness reduction in consideration, though).