1. What is ASTM A671 CF65 Class 72 Pipe?
Answer:
ASTM A671 CF65 Class 72 is a high-strength electric-fusion-welded (EFW) carbon steel pipe designed for cryogenic service down to -65°F (-54°C) and moderate elevated temperatures.
Standard: ASTM A671 (EFW pipes for pressure vessels)
Grade: CF65 indicates carbon steel with enhanced low-temperature toughness
Class 72: Specifies minimum yield strength of 72 ksi (500 MPa)
Key Feature: Superior impact resistance at cryogenic temps compared to standard carbon steels
2. What are the Critical Material Specifications?
Answer:
Chemical Composition:
C ≤ 0.30%, Mn ≤ 1.35%
Strict control of S/P (≤0.025% each) for crack resistance
Mechanical Properties:
Tensile strength: 85-110 ksi (586-758 MPa)
Charpy V-notch: Minimum 20 ft-lb (27 J) at -65°F
Heat Treatment: Typically supplied in normalized condition
3. How Does It Compare to Similar Grades?
| Parameter | CF65 Class 72 | CF65 Class 70 | CC65 Class 72 |
|---|---|---|---|
| Yield Strength | 72 ksi | 70 ksi | 72 ksi |
| Impact Test Temp | -65°F | -65°F | -65°F |
| Typical Use | High-pressure cryogenic | General cryogenic | Structural cryogenic |
4. What are the Standard Dimensions & Tolerances?
Answer:
Diameter Range: 16" to 144" OD (common for LNG pipelines)
Wall Thickness: 0.375" to 2.5" (9.5-63.5 mm)
Tolerances per ASTM A671:
OD: ±0.5% (for ≤24") / ±1% (>24")
Wall: +20%/-10%
Length: +0/-1/8" for random lengths
5. Where is This Grade Typically Used?
Answer:
Primary Applications:
LNG infrastructure (storage tanks, loading arms)
Ethylene plants (-150°F process piping)
CO₂ transport systems (CCUS projects)
Design Standards:
ASME B31.3 Process Piping
EN 13480 (European equivalent)
