a method for securing a component to a tank includes forming the tank having a wall of multiple layers of polymer material with an opening in the wall , outer layers of polymer , and an inner layer of polymer having an inner surface whose color is dark relative to a natural color of the outer layers . the component is formed with a mounting surface of polymer . the tube wall opening is used to install the component in the tank such that the mounting surface contacts the inner surface . energy is transmitted onto an area of a surface of the tank wall where the mounting surface contacts the inner surface . the transmitted energy is use to produce a weld between the mounting surface and the tank wall .