What does the weld symbol represented by two vertical parallel lines signify?

The weld symbol represented by two vertical parallel lines signifies a square weld. This symbol is used in piping and structural applications to indicate that the edges of the materials being joined will be welded together in a square-shaped joint, typically along the edges of plates or similar materials. The square weld is advantageous because it provides a strong join with a relatively simple welding technique. This type of weld is commonly employed in fabricating components where the material edges are aligned at a right angle, ensuring good strength and structural integrity. Understanding the symbols used for different types of welds is crucial for correctly interpreting engineering drawings, ensuring proper fabrication and adherence to industry standards.