def req_thickness(t_min, t_corr, f_tol):
    """
    Number [m], Number [m], Number [-] -> Number [m]

    Returns the required wall thickness based on the following mechanical
    allowances:
    - Corrosion allowance
    - Fabrication tolerance

    Exrapolated from Equation (4)
    """
    try:
        return (t_min + t_corr) / (1 - f_tol)
    except ZeroDivisionError:
        raise ZeroDivisionError('Divide by zero. Check fabrication tolerance.')
