What is the pressure rating for ASTM A269?
Why Pressure Rating Matters for ASTM A269 Tubing?
ASTM A269 is a widely used specification for seamless and welded austenitic stainless steel tubes, mainly for general corrosion-resistant applications in industrial systems. While the standard itself does not specify fixed pressure ratings, the pressure capacity of ASTM A269 tubing depends on key factors such as:
Outside diameter (OD)
Wall thickness (WT)
Material grade (e.g., TP304, TP316, TP316L)
Temperature
Tube construction (seamless or welded)
How Is ASTM A269 Tube Pressure Rating Calculated?
Calculations are based on the ASME B31.3 Process Piping Code and use the following formula:
Where:
P = Working pressure (psi)
S = Allowable stress (psi) at design temperature
t = Wall thickness (inches)
D = Outside diameter (inches)
📌 Welded tubes may have a weld factor applied (typically 0.85 if not full-penetration).
ASTM A269 Pressure Rating Chart
Material: TP304 / TP304L
Design Temperature: 100°F (38°C)
Allowable stress (S): 20,000 psi
| Tube Size (OD x Wall) | Wall (in) | Working Pressure (psi) | Burst Pressure (approx.) |
|---|---|---|---|
| 1/4" x 0.035" | 0.035 | ~7,600 | ~22,800 |
| 1/4" x 0.049" | 0.049 | ~10,400 | ~31,200 |
| 3/8" x 0.035" | 0.035 | ~5,200 | ~15,600 |
| 3/8" x 0.065" | 0.065 | ~9,000 | ~27,000 |
| 1/2" x 0.035" | 0.035 | ~3,700 | ~11,100 |
| 1/2" x 0.065" | 0.065 | ~6,600 | ~19,800 |
| 3/4" x 0.049" | 0.049 | ~2,700 | ~8,100 |
| 3/4" x 0.083" | 0.083 | ~4,500 | ~13,500 |
| 1" x 0.065" | 0.065 | ~2,300 | ~6,900 |
| 1" x 0.109" | 0.109 | ~3,800 | ~11,400 |
Temperature Derating Factors for Austenitic Stainless Steel
To adjust pressure ratings at elevated temperatures, apply the following temperature correction factors:
| Temperature (°F) | Correction Factor |
|---|---|
| 100°F (38°C) | 1.00 |
| 200°F (93°C) | 0.96 |
| 400°F (204°C) | 0.85 |
| 600°F (316°C) | 0.76 |
| 800°F (427°C) | 0.69 |
Example:
A 1/2" × 0.049" 316L tube has a base rating of 4,000 psi at 100°F.
At 600°F:
4,000 × 0.76 = 3,040 psi
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