CRA (Corrosion Resistant Alloy) Pipe

Depending on alloy contents, CRA pipe can be broken into follows:
• Stainless steel: 316L, 625 (Inconel), 825, 904L, etc.
• Chrome based alloy: 13 Cr, Duplex (22 Cr), Super Duplex (25 Cr), etc.
• Nickel based alloy : 36 Ni (Invar) for cryogenic application such as LNG (liquefied natural gas) transportation (-160oC)
• Titanium: Light weight (56% of steel), high strength (up to 200 ksi tensile), high corrosion resistance, low elastic modulus, and low thermal expansion, but high cost (~10 times of steel). Good for high fatigue areas such as riser touchdown region, stress joint, etc.
• Aluminum: Light weight (1/3 of steel), low elastic modulus (1/3 of steel), high corrosion resistance, but low strength (only up to 90 ksi tensile). Applications can include casing, air can, and risers.
Some key properties of each material are introduced in Table 7.2.1.

Depending on sour contents in the fluid, different chrome based alloy pipe should be selected as shown in Table 7.2.2.

Source:

Lee, Jaeyoung. 2007. Introduction to Offshore Pipelines and Risers.