On the corrosion issue of titanium tube heat exchangers
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Hello, sea friends. At the beginning of 2019, our company installed a heat exchanger with a surface area of 220㎡. The material used for the tube side is TA2, and the tube specifications are ø38*1.2*6000. This equipment is used in our company’s three-effect evaporation system, with wastewater flowing through the tube side and steam flowing through the shell side. Recently, internal leakage was detected. After opening the upper and lower end caps and conducting pressure tests, it was found that there was leakage at the pipe connections on the lower end cap’s tube sheet, while the upper tube sheet was in good condition. Please see the attached images. Could you tell me whether this is due to a quality issue with the equipment or some other cause? Thank you!
First, determine what is causing the internal leakage. If it is due to an issue with the material of the tubes, or if the heat exchange tubes are welded tubes and the leakage occurs at the welds of those tubes, then it is a quality issue with the equipment； Since titanium is being used, the material in question must be one that contains chloride ions or similar substances. If internal leakage occurs after the equipment has been in use for a certain period of time, then it is likely either due to a quality issue with the equipment or to corrosion caused by the material. If the material contains magnesium and calcium ions at certain temperatures, this can lead to corrosion of the titanium. The above are merely personal suggestions for reference only.
This post was last edited by wanlirn on 2021-7-15 at 15:58. There are seam pipes; bids for them are drastically lowered during tendering. Vertical heat exchangers suffer from scaling, and it’s difficult to determine whether it’s the pipe fittings or the pipes that are leaking
1. Is it the pipe fitting that is leaking or the pipe itself? 2. Generally, the design of heat exchangers used as evaporators is not standardized; the tube sheet is usually a composite sheet, which requires additional expansion jointing procedures ； 3. How is the baffle arrangement designed? Is the spacing between the baffle plates meeting the requirements? Is the thickness of the baffle up to requirement? Too large a spacing or too thin baffle plates can easily cause the heat exchange tubes to vibrate and wear out ； The wall thickness of the titanium tube itself isn’t that thick!
Judging from the appearance, the lower part is severely corroded while the upper part seems fine. It is recommended to pull out the pipe to check whether it is the pipe end or the pipe itself that is leaking. Personally, I think this is caused by corrosion of the material.
It seems to be a problem with equipment corrosion; check the fluoride and chlorine levels in the wastewater as well as the pH value
From the picture, I personally think material corrosion is the main cause.
In fact, there are many reasons for internal leakage in heat exchangers, and it’s very difficult to determine the exact cause based solely on your photos and the observed symptoms. A few suggestions can be offered for your reference. I. Reasons for the operation: Check the operation records to see if there were any instances of overpressure or overload operation, and whether leaks were caused by frequent start-stop cycles resulting in thermal stress. II. Is the location of the leakage representative, such as the impact of gas-liquid two-phase flow on the tube sheet? III. To determine whether it is due to material defects or manufacturing issues, it is necessary to ask the equipment manufacturer for records of the materials used and the manufacturing process. IV. Material corrosion: Is there a deviation between the properties of the material under operation and the data specified in the design?
Is the concentration of wastewater high at the bottom of your evaporator, and is the temperature there also high?