All diameters of SDR 13 S pipe have pressure bearing capacity that is ___________________.

The pressure bearing capacity of all diameters of SDR 13 S pipe being the same is due to the way the Standard Dimension Ratio (SDR) is defined. SDR is a method of rating the thickness of the pipe wall in relation to its diameter. Specifically, SDR is calculated as the ratio of the pipe's outside diameter to its wall thickness.

For SDR 13 S, this standardized rating indicates that all variations in diameter maintain a consistent wall thickness relative to the outer diameter, resulting in equal pressure ratings across all sizes. This uniformity provides significant advantages in engineering and installation, as it simplifies calculations and ensures that the integrity and performance of the system remain consistent, regardless of the diameter chosen for a specific application.

In contrast, options implying that the pressure capacity is unequal or varies (such as graduated or standard) do not reflect the inherent design characteristics of SDR 13 S pipe, thereby reinforcing the notion that the pressure capacity is indeed the same across all diameters.