Do SCH40 Pressure Fitting and SCH40 DWV have the same thickness?
Great question! No, Schedule 40 Pressure fittings and Schedule 40 DWV fittings generally do not have the same wall thickness, even though both are labeled "Schedule 40."
Here’s why:
- Schedule 40 Pressure Fittings (used for pressurized water, air, or other fluids) are made to handle internal pressure and therefore have thicker walls designed and tested to withstand those pressures safely.
- Schedule 40 DWV Fittings (Drain, Waste, and Vent) are intended for non-pressurized gravity flow systems like sewer or vent pipes. Because they don’t need to hold internal pressure, their walls are typically thinner than pressure fittings, even though they share the "Schedule 40" label.
Summary:
| Aspect | SCH40 Pressure Fittings | SCH40 DWV Fittings |
|---|---|---|
| Purpose | Pressurized plumbing systems | Gravity drainage, waste, and vent |
| Wall Thickness | Thicker to handle pressure | Thinner, designed for non-pressure |
| Standards/Certifications | ASTM D2466 (PVC Pressure) | ASTM D2665 (PVC DWV) |
| Pressure Rating | Rated for pressure (psi varies) | Not rated for pressure |
Important:
They often look very similar and can even fit together dimensionally in some cases, but DWV fittings should never be used for pressure applications because they lack the necessary wall thickness and certification.
Wall Thickness Comparison: SCH40 Pressure vs. SCH40 DWV PVC Fittings
| Nominal Size | SCH40 Pressure Wall Thickness (in) | SCH40 DWV Wall Thickness (in) | Notes |
|---|---|---|---|
| 1/2 inch | ~0.109 | ~0.065 | DWV is much thinner |
| 3/4 inch | ~0.113 | ~0.083 | DWV thinner but closer |
| 1 inch | ~0.133 | ~0.090 | Noticeably thinner DWV |
| 2 inch | ~0.154 | ~0.113 | Pressure fittings thicker |
| 3 inch | ~0.216 | ~0.125 | DWV wall significantly thinner |
| 4 inch | ~0.237 | ~0.140 | Similar pattern continues |
Note: These numbers are approximate and vary slightly by manufacturer but illustrate the general trend.
Why the Difference
- SCH40 Pressure fittings are designed to hold internal pressure safely, so they have thicker walls.
- SCH40 DWV fittings are for gravity-driven systems with no internal pressure, so thinner walls are enough and reduce material costs.
How to Identify SCH40 Pressure vs. DWV Fittings
- Markings/Labels:
- Pressure fittings usually have ASTM D2466 printed on them.
- DWV fittings usually have ASTM D2665 printed.
- Look also for NSF and pressure rating stamps on pressure fittings.
- Wall Thickness & Weight:
- Pressure fittings feel heavier and thicker when handled.
- Intended Use Stamped on Fitting:
- DWV fittings may be labeled explicitly for "Drain, Waste & Vent."
- Color Differences:
- Both are typically white, but sometimes DWV pipes/fittings are marked or sold separately.
Summary
- Don’t substitute DWV fittings in pressurized systems — they lack the required wall thickness and certification.
- Pressure fittings can physically fit DWV pipe and vice versa, but always verify specs before using.
Quick Reference Guide: SCH40 Pressure vs. DWV PVC Fittings
| Feature | SCH40 Pressure PVC Fittings | SCH40 DWV PVC Fittings |
|---|---|---|
| ASTM Standard | ASTM D2466 | ASTM D2665 |
| Typical Wall Thickness | Thicker — designed for pressurized systems | Thinner — designed for gravity flow systems |
| Pressure Rating | Rated for internal pressure (up to 450 psi for smaller sizes) | Not pressure rated |
| Typical Applications | Water supply, irrigation, compressed air | Drain, waste, vent plumbing |
| Markings | ASTM D2466, NSF, pressure ratings | ASTM D2665, DWV labeling |
| Color | Usually white | Usually white |
| Joint Type | Solvent weld socket | Solvent weld hub/socket |
Example Manufacturer Datasheets and Specs:
- Charlotte Pipe — Leading manufacturer, publishes detailed specs on their website:
- SCH40 Pressure fittings: Charlotte Pipe Schedule 40 PVC Pressure Fittings PDF
- SCH40 DWV fittings: Charlotte Pipe DWV fittings PDF
- LASCO Fittings — Another top brand with spec sheets available online.
- JM Eagle — Offers technical specs for PVC DWV and pressure pipe/fittings.
- 247Garden/ERA - Visit 247Garden.com
Example Datasheet Key Info to Look For:
- Wall thickness (inches or mm) by nominal pipe size
- Pressure rating (psi) for pressure fittings
- Material compliance (PVC Type 1, Cell Classification 12454)
- Standards compliance (ASTM D2466 for pressure, ASTM D2665 for DWV)
- Dimensions (hub diameter, socket depth)
247Garden Quick Reference Chart: SCH40 Pressure vs. DWV PVC Fittings
| Nominal Size | SCH40 Pressure Wall Thickness* | SCH40 DWV Wall Thickness* | ASTM Standard (Pressure) | ASTM Standard (DWV) | Pressure Rating (PSI)** |
|---|---|---|---|---|---|
| 1/2 in. | 0.109 in | 0.065 in | ASTM D2466 | ASTM D2665 | ~600 PSI |
| 3/4 in. | 0.113 in | 0.083 in | ASTM D2466 | ASTM D2665 | ~480 PSI |
| 1 in. | 0.133 in | 0.090 in | ASTM D2466 | ASTM D2665 | ~450 PSI |
| 1-1/2 in. | 0.145 in | 0.110 in | ASTM D2466 | ASTM D2665 | ~330 PSI |
| 2 in. | 0.154 in | 0.113 in | ASTM D2466 | ASTM D2665 | ~280 PSI |
| 3 in. | 0.216 in | 0.125 in | ASTM D2466 | ASTM D2665 | ~260 PSI |
| 4 in. | 0.237 in | 0.140 in | ASTM D2466 | ASTM D2665 | ~220 PSI |
*Wall thicknesses are approximate and vary slightly by manufacturer.
**Pressure ratings are for SCH40 PVC pipe (not fittings) at 73°F. Ratings decrease at higher temperatures.
Key Differences at a Glance:
- Pressure Fittings (ASTM D2466):
- Thicker walls.
- Designed to handle water pressure.
- NSF-certified for potable water.
- Heavier-duty and more expensive.
- DWV Fittings (ASTM D2665):
- Thinner walls.
- Only used for gravity-fed drain/waste/vent systems.
- Lighter, less expensive.
- Never use for pressurized systems.
How to Use This Chart:
Keep this chart near your workbench or project planning area to quickly:
- Match fittings to pipe size and system type.
- Avoid using DWV in pressure systems.
- Double-check ASTM standards printed on fittings.