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.