By Maya Gebeily BEIRUT (Reuters) – Victims of the 2020 Beirut port blast have filed a $250 million claim against U.S.-based firm TGS, their advocates told Reuters on Thursday, saying the company is “liable” for damages caused by ammonium nitrate that detonated in the Lebanese capital. The extremely explosive chemicals arrived at the Beirut port aboard the Moldovan-flagged Rhosus in 2013 and remained at the port until they blew up on Aug. 4, 2020, killing more than 215 and wounding thousands. The Rhosus had been sub-chartered in 2012 by seismic study firm Spectrum, which was acquired by geophys…