SS Pipe Size & Schedule Chart – Dimensions for 304/316 Pipes
SS Pipe Size & Schedule Chart – Dimensions for 304/316 Pipes
When choosing stainless steel pipes for your industrial, commercial, or plumbing needs, understanding the correct size and schedule is essential. This guide offers a detailed overview of SS 304 and SS 316 pipe dimensions, wall thickness, and schedule classifications to help you make informed decisions.
What Are Stainless Steel Pipes?
Stainless steel (SS) pipes are made from an alloy of iron with at least 10.5% chromium, which provides excellent corrosion resistance. SS 304 and SS 316 are the two most widely used stainless steels for piping applications. These pipes are used in construction, food processing, marine, chemical industries, and even residential plumbing.
Understanding Pipe Size Standards
Pipe sizes are typically measured using Nominal Pipe Size (NPS) in inches and Nominal Bore (NB) in millimeters. The outside diameter (OD) remains fixed for a given NPS, while the wall thickness varies based on the schedule number, affecting the internal diameter (ID). This system ensures that fittings and pipes can be easily matched.
Common Stainless Steel Pipe Grades
- SS 304: An austenitic stainless steel with good corrosion resistance, ideal for indoor and mild environments.
- SS 316: Contains molybdenum for enhanced corrosion resistance, especially in saline or chemical-heavy environments like marine industries.
What Is a Pipe Schedule?
Pipe schedule refers to the wall thickness of a pipe. Common schedules used in stainless steel pipes include:
- Schedule 5S: Ultra-thin wall, used in low-pressure environments.
- Schedule 10S: Light-duty use, cost-efficient and widely available.
- Schedule 40S: Medium wall thickness, ideal for pressure pipelines and general use.
- Schedule 80S: Heavy-duty, thicker wall for high-pressure applications.
- Schedule 160: Very high-pressure services, often used in industrial and chemical plants.
SS Pipe Size & Schedule Chart (in mm and inches)
The following chart shows typical outer diameters (OD), wall thicknesses, and nominal sizes for common pipe schedules:
| NB (mm) | NPS (inch) | OD (mm) | Schedule | Wall Thickness (mm) |
|---|---|---|---|---|
| 15 | 1/2" | 21.3 | 10S | 1.65 |
| 20 | 3/4" | 26.7 | 10S | 1.65 |
| 25 | 1" | 33.4 | 10S | 1.65 |
| 32 | 1 1/4" | 42.2 | 10S | 1.65 |
| 40 | 1 1/2" | 48.3 | 10S | 1.65 |
| 50 | 2" | 60.3 | 10S | 1.65 |
| 65 | 2 1/2" | 73.0 | 10S | 2.11 |
| 80 | 3" | 88.9 | 10S | 2.11 |
| 100 | 4" | 114.3 | 10S | 2.11 |
| 150 | 6" | 168.3 | 10S | 2.77 |
SS 304 vs SS 316 – Which One to Choose?
Choosing between SS 304 and SS 316 depends on your use case:
- For general purpose or indoor plumbing: SS 304 is sufficient and more economical.
- For marine, food, or chemical exposure: SS 316 is recommended for its better resistance to corrosion and pitting.
How to Read a Pipe Chart
When you read a pipe chart, remember:
- The OD remains constant for each NPS size
- The ID varies based on the wall thickness/schedule
- Use this chart to calculate volume, pressure handling, or to match with fittings
Applications of SS Pipes
SS pipes are used in:
- Water pipelines in residential/commercial plumbing
- Food-grade processing units and clean rooms
- Oil and gas transmission lines
- Chemical transport pipelines
- Marine and coastal installations
- Fire sprinkler and HVAC systems
Buying Tips
- Check for ISI/ASTM markings and mill certificates
- Match thickness to pressure requirement
- Buy from reputed suppliers with traceability
- Compare SS 304 vs 316 prices to optimize budget
Related Resources
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