What is the function of the lay line that runs the length of a flexible hose?

• A. To show if the line was twisted during installation.
• B. To indicate the hose diameter is correct.
• C. To identify the hose manufacturer.
• D. To show the hose color code.

Answer: (A)

A lay line on a flexible hose serves as a visual reference to detect twisting or rotation of the hose during installation or service. By running along the length of the hose, the line lets a technician quickly see if the hose has been torqued or twisted as it’s routed and secured. If the lay line appears twisted or misaligned relative to the hose’s fittings, it indicates that the hose has experienced twisting, which can create abnormal stresses and shorten service life, prompting reorientation or adjustment. This marking isn’t about hose diameter, manufacturer, or color code; those characteristics are identified by other markings, while the lay line’s purpose is specifically to reveal twisting.