Which schedule listed below would have the thickest wall?

The schedule number in piping systems indicates the wall thickness in relation to the pipe's diameter, with higher numbers signifying thicker walls. Schedule 120 has the highest wall thickness, making it the ideal choice when considering strength and pressure requirements. This thicker wall design helps manage a greater amount of internal pressure, making it suitable for applications that necessitate higher durability and resistance to deformation under load.

In contexts where pressure and strength are significant factors, understanding the implications of wall thickness can be vital for selecting the appropriate pipe for specific applications. Hence, utilizing pipes with higher schedule numbers ensures greater structural integrity and extends the pipe's lifespan in demanding conditions.