  We analyse the properties of the X-ray emission from Seyfert 2 NGC 7172 which
are based on the 32 ks observational data from NuSTAR in 2014. This source
showed a constant Compton-thin obscuration $N_{H}\approx 8\cdot 10^{22}
cm^{-2}$, which is similar to that observed by XMM-Newton, Suzaku, ASCA and
BeppoSAX over past 30 years. We revealed the presence of a moderate reflection
component with <R>~0.44 and a narrow FeK{\alpha} line with $67^{+13}_{-14}$ eV.
The applied numerical models of torus confirmed the Compton-thin type of the
Seyfert nucleus and allowed us to obtain an estimate of the torus opening angle
${\Theta}_{t}\sim59\deg$ and inclination ${\Theta}_{i}\sim61\deg$. Using the
observation data of previous observation, we demonstrate also the long-term
variability of intrinsic luminosity $L_{intr}$(2-10 keV) almost by order and EW
$FeK_{\alpha}$ by factor $\sim4$ on a timescale of $\sim12$ years, that
coincides to the distance of $d\sim$3.7 pc between central source and
reprocessing medium. Such changes of intrinsic luminosity without changes in
$N_{H}$ value indicate the variability of a central source. In the same time
the spectral analysis results with the presence of the lag between variability
of intrinsic luminosity $L_{intr}$(2-10 keV) and EW $FeK_{\alpha}$, as well as
a behaviour of intensity $I_{FeK_{\alpha}}$ of the line are in agreement with
the scenario, where observed $FeK_{\alpha}$ line is generated in a distant
gas-dust torus.
