def req_thickness(t_min, t_corr, f_tol):
    """Return the required wall thickness [m] based on the mechanical allowances - 
    extrapolated from PD8010-2 Equation (4).

    :param float t_min: Minimum wall thickness [m]
    :param float t_corr: Corrosion allowance [m]
    :param float f_tol: Fabrication tolerance [-]
    """
    try:
        return (t_min + t_corr) / (1 - f_tol)
    except ZeroDivisionError:
        raise ZeroDivisionError(
            "Divide by zero. Check fabrication tolerance.")