Xingang refers to a area. Do you mean the port, dock or other places. Anyway, you can get to XIngang Salu and take the regular bus at the end of the road to Yangliuqing. The bus pass Tianjin Railway Station. By taxu, it will be more than 200 rmb (200 is the fairly cost from Nankai District to Tanggu, Xingang is much further).