Shell Limpet Length Calculation
We have kept all the dimension in mm / meter as per usual practice. [all dimensions in mm, final length requirement in meter]
1. Shell OD (Do) 'mm' = Shell ID (Di) 'mm' + 2x Vessel Thickness (tv) 'mm'
2. Continuous Limpet Coil Size = LMC (NB)* x (t) 'mm'
*Limpet Pipe size are normally mentioned in NB or NPS size.
Please find Limpet Pipe Outer Diameter (do) 'mm' and NB size LMC(NB) co-relation @ Product Range on https://www.kronosmetalcraft.com/continuous-limpet-coil
(t) is the thickness of the limpet coil.
3. Number of Turns required on the shell (#T) = Limpet Jacket Height (HL) 'mm' / Pitch (P) 'mm'
4. Generally 5/10mm Clearance (CL) is kept between the Shell OD (Do) and the Limpet Coil Jacket ID (DLi)
DLi 'mm' = Do 'mm' + CL 'mm'
5. First calculate the Outer Diameter of the Limpet Coil Jacket (DLo)
DLo 'mm' = DLi 'mm' + do 'mm'
6. Limpet Coil Length required in one turn (L1) will be calculated as,
L1 'meter/Turn' = DLo 'mm' x 𝛑 / 1000
7. Total Limpet Coil Length (L) is calculated then as,
L 'meter' = L1 'meter/Turn' x #T
Example
Data:
Shell ID (Di) = 2500mm
Vessel Thickness (tv) = 12mm
Limpet Coil Size LMC 80 x 3 mm
Shell Height = 3000mm
Limpet Height (LH) = 2500mm
PItch (P) = 125mm
Clearance (CL) = 5mm
Calculation:
1. Shell OD (Do) = 2500 + 2x12 = 2524mm
2. Limpet Coil NB Size = 80 Limpet Pipe OD (do) = 88.9mm Limpet Coil Thickness t = 3mm
3. Number ot Turns (#T) = 2500/125 = 20
4. Limpet Coil Jacket ID (DLi) = 2524 + 5 = 2529mm
5. Outer Diameter of the Limpet Coil Jacket (DLo) = 2529 + 88.9 = 2617.9mm
6. Limpet Coil Length required in one turn (L1) = 2617.9 x 𝛑 / 1000 = 8.224meter
7. Total Limpet Coil Length (L) = 8.224 x 20 = 164.488meter ~ 165meter