Nominal Pipe Sizes & Schedules vs. PVC DWV Pipe
Comparing 2 standards across 14 specifications. 14 key differences identified.
Nominal Pipe Size (NPS) and Schedule designations under ASME B36.10M standardize the outer diameter, wall thickness, and pressure capabilities of forged steel, wrought iron, and stainless pipe. For NPS 1/8 to NPS 12, the nominal number represents approximate inside diameter, while maintaining a standardized fixed outer diameter across Schedule 40 (Standard) and Schedule 80 (Extra Strong) walls.
Schedule 40 PVC DWV (Drain-Waste-Vent) pipe governed by ASTM D2665 is the standard rigid white thermoplastic pipe for residential and commercial gravity sanitary drainage, waste discharge, and sewer venting. Engineered with smooth non-porous bore walls to prevent clogs, it joins via chemical solvent cement welding.
Specification Comparison Table
14 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standard
|
ASME B36.10M / ASTM A53 / ASTM A106 | — |
|
Metric Equivalent
|
DN (Diamètre Nominal) in millimeters (e.g., NPS 1/2 = DN 15) | — |
|
NPS 1/2" Dimensions
|
OD: 0.840" (21.3 mm) | Sch 40 Wall: 0.109" (2.77 mm) | Sch 80 Wall: 0.147" (3.73 mm) | — |
|
NPS 3/4" Dimensions
|
OD: 1.050" (26.7 mm) | Sch 40 Wall: 0.113" (2.87 mm) | Sch 80 Wall: 0.154" (3.91 mm) | — |
|
NPS 1" Dimensions
|
OD: 1.315" (33.4 mm) | Sch 40 Wall: 0.133" (3.38 mm) | Sch 80 Wall: 0.179" (4.55 mm) | — |
|
NPS 2" Dimensions
|
OD: 2.375" (60.3 mm) | Sch 40 Wall: 0.154" (3.91 mm) | Sch 80 Wall: 0.218" (5.54 mm) | — |
|
Schedule Transition Boundary
|
For NPS ≥ 14, Nominal Pipe Size equals the exact Outer Diameter in inches | — |
|
Governing Standards
|
— | ASTM D2665 / ASTM D1785 / CSA B181.2 / NSF-dwv |
|
1-1/2" DWV Dimensions
|
— | OD: 1.900" (48.3 mm) | Min Wall: 0.145" (3.68 mm) | Sinks, tubs, showers |
|
2" DWV Dimensions
|
— | OD: 2.375" (60.3 mm) | Min Wall: 0.154" (3.91 mm) | Washing machines, floor drains |
|
3" DWV Dimensions
|
— | OD: 3.500" (88.9 mm) | Min Wall: 0.216" (5.49 mm) | Water closets (toilets), soil stacks |
|
4" DWV Dimensions
|
— | OD: 4.500" (114.3 mm) | Min Wall: 0.237" (6.02 mm) | Main building sewer drain |
|
Primary Joining Method
|
— | Purple primer + solvent cement (chemical molecular fusion weld) |
|
Maximum Operating Temperature
|
— | 140°F (60°C) continuous service |