304 stainless steel pipe pressure rating

Here is a technical and procurement-friendly guide to the pressure rating of 304 stainless steel pipe, considering factors such as wall thickness, diameter, and temperature:

304 stainless steel pipe pressure rating

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📌 304 Stainless Steel Pipe Pressure Rating Guide

The pressure rating of 304 stainless steel pipes depends on:

Pipe size (nominal diameter)

Wall thickness (schedule)

Operating temperature

Manufacturing standard (e.g., ASTM A312)

🧮 Pressure Rating Formula (Basic Concept)

For a rough estimate, the ASME B31.3 or B31.1 formula for allowable pressure is often used:

P = (2 × S × t) / (D – t)
Where:

P = Internal pressure (MPa)

S = Allowable stress (temperature-dependent)

t = Wall thickness (mm)

D = Outside diameter (mm)

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🔍 Example Pressure Ratings for 304 Stainless Steel Pipe (ASTM A312, SCH 40)

Nominal Pipe Size	Outside Diameter (mm)	Wall Thickness (mm)	Max Pressure @ 100°F (38°C) (psi / MPa)
1/2"	21.34	2.77	3,150 psi / 21.7 MPa
1"	33.40	3.38	2,370 psi / 16.3 MPa
2"	60.33	3.91	1,250 psi / 8.6 MPa
4"	114.30	6.02	1,070 psi / 7.4 MPa
6"	168.28	7.11	910 psi / 6.3 MPa

✅ Material Standard: ASTM A312 TP304
✅ Design Code: ASME B31.1 or B31.3
⚠️ Note: Pressure drops as temperature increases. For example, allowable stress for TP304 drops by ~30% at 400°F (204°C).

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📉 Effect of Temperature on Allowable Pressure

Temperature (°F)	Allowable Stress (psi)
100	20,000
400	18,000
600	16,700
800	15,000

(Based on ASME SA-312/TP304 limits)

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🛠️ Key Considerations for Buyers

Specify pipe schedule (e.g., SCH 40, SCH 80) when requesting quotes.

Confirm temperature and pressure requirements in the service environment.

Use certified test reports (MTCs) to validate material grade and compliance.