HTS is responsible for flange fastening and related flange repair at key parts of the 1 million tons/year ethylene plant of Baolai Chemical. The fastening parts include ethylene-cold zone, compression zone, hot zone, quench zone, cracking zone, ethylene low-temperature tank, key flanges of low-temperature loading dock, key flanges of 20-40pp unit, key flanges of LDPE unit and key flanges of cracking steam hydrogenation unit.