Schedule 40 vs 40S Pipe: Differences, Cost & Applications

What's the Difference?

Schedule 40 and Schedule 40S are both nominal pipe sizes with the same outer diameter (OD), but they differ in material and applications:

Feature	Schedule 40 (Carbon Steel)	Schedule 40S (Stainless Steel)
Material	Carbon steel (mild steel)	Stainless steel (typically 304 or 316)
Wall Thickness	Standard wall thickness for Schedule 40	Same OD, equivalent wall thickness to Sch 40
Corrosion Resistance	Poor; requires coating or maintenance	Excellent; natural oxide layer protects steel
Cost	Lower (typically 30-50% cheaper)	Higher (3-5x more expensive)
Temperature Range	-20°F to 450°F typical	-320°F to 1500°F+ (depending on grade)
Common Applications	General plumbing, HVAC, water lines, gas	Food processing, chemicals, marine, pharmaceuticals

When to Use Schedule 40

Budget-conscious projects: Lower material and installation costs
Low-corrosion environments: Dry indoor locations, protected from moisture
Standard plumbing/HVAC: Residential and commercial water/heating systems
Temporary or short-term use: When durability over decades isn't critical
Painted or coated applications: Where protective coatings will be applied

When to Use Schedule 40S (Stainless)

Corrosive environments: Coastal areas, chemical exposure, acidic/alkaline fluids
Food & beverage: Dairy, brewing, food processing industries
Pharmaceutical/Medical: Sterile or biocompatible applications
High-temperature applications: Steam, hot oil, industrial processes
Appearance matters: Visible piping that needs to look clean/maintained
Long-term durability: When pipe replacement costs exceed material savings

Cost Considerations

Schedule 40 is significantly cheaper, but stainless steel's long lifespan and lack of maintenance often justify the upfront cost:

Schedule 40 material: ~$5-15 per foot (varies by size/supplier)
Schedule 40S material: ~$15-60+ per foot (varies by size/supplier)
Labor: Same for both (installation cost doesn't differ much)
Total cost of ownership: Include replacement, painting, maintenance, and downtime costs over 20-30 years

Note: Always get current quotes from your supplier. Prices vary based on material availability, supplier, and order volume.

Availability & Lead Times

Schedule 40 (carbon) is widely stocked and has short lead times at most suppliers. Schedule 40S (stainless) may have longer lead times depending on material grade (304 vs 316) and supplier inventory.

Need Specific Dimensions?

Use our pipe lookup tool to find exact outer diameter, inner diameter, and wall thickness for any pipe size and schedule.