Titanium alloy casing

TC4 (Ti-6Al-4V) titanium alloy

TC4 (Ti-6Al-4V) is a widely used titanium alloy material in the petroleum industry, with excellent strength, toughness, and corrosion resistance. It is commonly used in petroleum extraction equipment such as drill pipes, casings, and wellhead equipment.

TC4 Titanium alloys are widely used in subsea equipment such as wellhead components and manifolds due to their high strength and corrosion resistance. In a marine environment, corrosion from seawater and salt is one of the main problems encountered with equipment, so the use of corrosion-resistant materials is critical to the long-term use and performance of the equipment. Titanium alloys are excellent in this regard and have become one of the commonly used materials for subsea equipment.

Specification of casing

The specifications and dimensions of TC4 titanium alloy casing are usually customized according to specific requirements. Here are some common parameters for reference:

Outer diameter range: 2 3/8 inches – 20 inches

Wall thickness range: 0.190 inches – 0.562 inches

Length range: customized according to customer requirements, generally not more than 13 meters

Grade: according to API specifications, generally J55, N80, P110 grade

In addition, the mechanical performance indicators of TC4 titanium alloy casing also need to meet API specifications, such as tensile strength, yield strength, elongation, etc. At the same time, the surface of the casing also needs to be treated specially to ensure its good corrosion resistance.

Titanium alloy grades

Here are some common titanium alloy grades:

Ti-6Al-4V (TC4): This is a common titanium alloy grade that has good strength, toughness, and corrosion resistance. In the petroleum industry, TC4 is often used for drill pipes, casings, and wellhead equipment.

Ti-3Al-2.5V (TA18): This is a titanium alloy grade that has excellent strength, weldability, and corrosion resistance. In the petroleum industry, TA3 is often used for manifolds and wellhead equipment.

Ti-6Al-2Sn-4Zr-2Mo (Ti-6242): This is a high-strength, high-temperature titanium alloy that has good corrosion resistance and fatigue life. In the petroleum industry, Ti-6242 is often used for casings and drill pipes.

It is important to note that different application scenarios require different material properties, so the specific use of which titanium alloy grade to choose depends on the specific situation.

Normal oil casing is prone to deformation, fracture, surface damage, and other failure phenomena under specific service conditions. However, titanium alloy oil casing exhibits excellent resistance to hydrogen sulfide stress corrosion, pitting corrosion, and general corrosion. It is insensitive to hydrogen-induced cracking and demonstrates outstanding resistance to H2S/CO2 corrosion under high-temperature and high-pressure conditions. Its corrosion resistance and stress cracking resistance are superior to 22Cr duplex stainless steel, nickel-based alloys (such as Alloy 028, Alloy 825, and Alloy G3), etc. Therefore, it can greatly mitigate the occurrence of failure phenomena, thereby achieving prolonged service life and reduced maintenance costs. Additionally, the specific gravity of seamless titanium alloy pipes is only 54% of that of nickel alloy pipes, which means that pipes of the same specifications weigh only 54% of their nickel alloy counterparts. This significantly reduces the friction and resistance during the installation of the oil casing.