1. What are the advantages of U-shaped titanium tubes compared to straight tubes? What operating conditions are they suitable for?
A: The characteristics of U-tube heat exchangers are that each tube can expand and contract freely without expansion joints, and can withstand large temperature stress differences (the temperature difference between the tube side and the shell side can reach over 100℃). Simultaneously, the tube bundle can be removed from the shell for shell-side cleaning, making it suitable for applications where the shell-side medium is prone to fouling. The disadvantage is that it is impossible to mechanically clean the fouling inside the tubes; therefore, the tube side medium should be clean or have a low fouling tendency. Typical applications: tube side is corrosive high-temperature materials (such as hot brine, dilute acid), and shell side is cooling water or steam.
2. Can titanium U-tubes be used at high temperatures? What is the extreme temperature limit?
A: Titanium alloys absorb oxygen at high temperatures, forming an embrittlement layer. Therefore, the actual operating temperature is limited by the medium and pressure. Gr12 is recommended for long-term operation at ≤300℃ (water or neutral media), with short-term limits up to 350℃. For Cr2 industrial pure titanium, a temperature ≤250℃ is recommended. At higher temperatures, the oxidation weight gain and decreased mechanical properties of titanium need to be considered; zirconium or nickel-based alloys are recommended.
3. Will titanium pipes rust or corrode? How long can they be used in seawater?
A: Titanium hardly corrodes in seawater, wet chlorine gas, and chloride solutions, with an annual corrosion rate typically <0.005mm. In flowing seawater, titanium pipes can last for more than 20 years; in static seawater, there is virtually no pitting or crevice corrosion. However, it should be noted that titanium corrodes rapidly in anhydrous strong oxidants (such as fuming nitric acid), high-temperature concentrated sulfuric acid (>10%, >120℃), hydrofluoric acid, and fluoride-containing media; their use should be avoided.
4. How to ensure the quality of the U-shaped bend? How much is the wall thickness reduced at the bend?
A: We use cold-bending or hot-bending processes. The bending radius is typically ≥2 times the outer diameter of the pipe (minimum 1.5 times). The thinning rate of the outer diameter sidewall after bending is controlled to ≤15% (according to ASTM B338 requirements), and no cracks or wrinkles appear. Each U-tube undergoes a ball-passing test (ball diameter 85%~90% of the inner diameter of the tube) and a hydrostatic test (test pressure 1.5 times the design pressure) before leaving the factory. For thin-walled tubes or small bending radii, filling bending or CNC tube-bending machines can be used to ensure accuracy.
5. What are the difficulties in welding titanium U-tubes to tube sheets? How to ensure sealing?
A: Titanium has high chemical reactivity and is easily contaminated by air, moisture, and grease during welding, leading to weld embrittlement or cracking. We take the following measures: Thorough pre-welding cleaning of pipe ends and tube sheet orifices (degreasing, pickling); Use of argon arc welding, with argon gas protection throughout the welding area (front + back shielding); Strict control of interpass temperature, employing a combined expansion and sealing welding process when necessary; Post-weld, 100% penetrant testing and helium leak testing are conducted (leakage rate ≤1×10⁻⁷ Pa·m³/s).
6. How to determine the required titanium U-tube specifications? Can you provide non-standard customization?
A: Users need to provide the following parameters: Heat exchanger tube material (Gr1/Gr2/Gr12, etc.), outer diameter × wall thickness (commonly: 12~50mm × 0.5~2.5mm); Straight tube length (L), U-bend radius (R), and end protrusion; Tube bundle arrangement (e.g., triangular arrangement, square arrangement); Design temperature, pressure, and medium composition (to determine suitability for titanium); Standards: National Standard GB/T3625, GB/T3624, or American Standard ASTM B338/B861, or classification society certification (CCS, ABS, etc.).
We can provide fully custom non-standard products, including reducing pipes, unequal length U-tubes, coils, etc.
7. Why is the price of titanium U-tubes much higher than that of stainless steel pipes? Are there any cost reduction solutions?
A: The price of titanium raw materials is approximately 5 to 8 times that of 304 stainless steel, and processing is more difficult (requiring special molds, protective welding, and low-speed cold bending). However, the total lifecycle cost must be considered: under corrosive conditions, stainless steel pipes may perforate and leak within 1-2 years, while titanium pipes can last 15-20 years, reducing replacement, downtime, and maintenance costs. If the budget is limited, consider:
Using Gr2 instead of Gr12 (if the medium is not highly corrosive);
Reducing the pipe wall thickness (strength needs to be recalculated);
Using a titanium pipe only on the pipe side, and a carbon steel or composite plate on the shell side.
8. What is the typical delivery time? What is the minimum order quantity?
A: Standard specifications (e.g., Φ19×1.2mm, Gr2, R=50mm) are in ample stock and can be shipped within 7-10 days. Special materials or non-standard bends (e.g., Gr12, large diameter, thin wall, small bending radius) take approximately 25-35 days. Minimum order quantity: Trial orders can be as low as 20 pieces (for prototypes or repairs), bulk orders are usually ≥200 pieces or calculated by weight.
Contact information:
Tel: +86-0917- 3664600
WhatsApp: +8618791798690
