Comparing pipe schedules: relative to Schedule 80 of the same nominal size, the wall thickness of Schedule 40 pipe is

Introduction / Context:
Pipe schedule numbers reflect wall thickness for a given nominal size. Higher schedule numbers mean thicker walls and higher pressure ratings (within material limits). Selecting the correct schedule ensures integrity while controlling cost and weight. This question probes the basic ordering between Sch 40 and Sch 80.

Given Data / Assumptions:

• Same NPS (nominal size) for both pipes.
• Standard carbon steel pipes per ASME/ANSI.
• Schedules compared under the usual definition (no special “XS/XXS” exceptions).

Concept / Approach:

Schedule number increases monotonically with wall thickness for a given NPS. Therefore, Schedule 80 is thicker than Schedule 40. The thicker wall reduces ID and increases weight per length, allowing higher pressure rating but increasing cost and hydraulic losses for the same volumetric flow rate.

Step-by-Step Solution:

Verification / Alternative check:

Dimension tables show, for example, NPS 2: Sch 40 wall ≈ 0.154 in; Sch 80 wall ≈ 0.218 in (thicker).

Why Other Options Are Wrong:

“More” and “same” contradict definitions; “either” is incorrect because schedule strictly defines wall for a given NPS; “twice” is not generally true.

Common Pitfalls:

Confusing schedule with series or with copper/metric tube standards; overlooking that OD remains constant while ID changes.

Final Answer:

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