docs: def baffle_thickness(Dshell, L_unsupported, service='C'):
      r'''Determines the thickness of baffles and support plates in TEMA HX
      [1]_. Applies to latitudinal baffles along the diameter of the HX, but
      not longitudinal baffles parallel to the tubes.
  
      Parameters
      ----------
      Dshell : float
          Shell inner diameter, [m]
      L_unsupported : float
          Distance between tube supports, [m]
      service : str
          Service type, C, R or B, [-]
  
      Returns
      -------
      t : float
          Baffle or support plate thickness, [m]
  
      Notes
      -----
      No checks are implemented to ensure the given shell size is TEMA compatible.
      The baffles do not need to be strongas the pressure is almost the same on 
      both of their sides. `L_unsupported` is a design choice; the more baffles
      in a given length, the higher the pressure drop.
  
      Examples
      --------
      >>> baffle_thickness(Dshell=.3, L_unsupported=50, service='R')
      0.0095
  
      References
      ----------
      .. [1] Standards of the Tubular Exchanger Manufacturers Association,
         Ninth edition, 2007, TEMA, New York.
      '''
      if Dshell < 0.381:
          j = 0
      elif 0.381 <= Dshell < 0.737:
          j = 1
      elif 0.737 <= Dshell < 0.991:
          j = 2
      elif 0.991 <= Dshell  < 1.524:
          j = 3
      else:
          j = 4
  
      if service == 'R':
          if L_unsupported <= 0.61:
              i = 0
          elif 0.61 < L_unsupported <= 0.914:
              i = 1
          elif 0.914 < L_unsupported <= 1.219:
              i = 2
          elif 1.219 < L_unsupported <= 1.524:
              i = 3
          else:
              i = 4
          t = _TEMA_baffles_refinery[j][i]
  
      elif service == 'C' or service == 'B':
          if L_unsupported <= 0.305:
              i = 0
          elif 0.305 < L_unsupported <= 0.610:
              i = 1
          elif 0.61 < L_unsupported <= 0.914:
              i = 2
          elif 0.914 < L_unsupported <= 1.219:
              i = 3
          elif 1.219 < L_unsupported <= 1.524:
              i = 4
          else:
              i = 5
          t = _TEMA_baffles_other[j][i]
      return t