Leakage of isolation fluid in Plan 53B
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This unit is equipped with a single-stage, double-suction, double-support pump, along with a series-connected bellows-type mechanical seal; it follows a 32+53B configuration. The mechanical seals at both the front and rear ends frequently experience leaks of the lubricant (white oil), either internally or externally. The pressure in the lubricant system drops rapidly, eventually reaching 0. The pump is operating very stably. Everyone, please analyze the reasons for this. I plan to have the manufacturer modify the seal design, changing the compensation mechanism from one based on the static ring to one based on the dynamic ring, thereby increasing the pressure on the medium-side seal.
Did the failure of your main seal, namely the PLAN32 seal, occur due to impurities or coking inside the bellows? Under normal conditions, the PLAN32 uses a clean medium at a moderate temperature; another possibility is that the pressure applied to the PLAN32 is insufficient, being lower than the pressure in the sealing chamber. At high-temperature operating conditions, stationary metal bellows are the preferred choice. The stationary metal bellows C-type structure is chosen because it enables the seal to overcome the situation where the positioning end face of the gland is not perpendicular to the axis line. In this structure, the bellows can deflect, ensuring good fit between the end faces of the non-compensating ring and the compensating ring. For the rotary metal bellows type B seal, every time the shaft rotates one full circle, in order to accommodate the tilt of the stationary ring, the bellows must bend in a different direction once. Of course, the rotation of the metal bellows can dislodge the coking and other impurities in the middle of the diaphragm.
No coking or impurities were found; the 32 injection should be normal. Thank you for your advice
You need to identify the causes of the failure of the main seal, such as coking and impurities mentioned earlier. The quality of the sealing cover material, such as whether there are bubbles in the graphite, etc
What is your medium? In a 53B system equipped with white oil, the temperature should not be too high. If the medium contains water, it is possible that the white oil and water will emulsify together, forming a barrier on the sealing surface that leads to a drop in pressure; in such cases, considering replacing the lubricant might be a good option
It’s probably not the diesel product; there’s also no leakage in the white oil cooler. Thank you for your advice
The manufacturer plans to adjust the compression amount and increase the width of the friction pair
What concerns me is that you mentioned the system pressure dropping to 0; perhaps the seal selection should be adjusted to achieve a balance, and it’s necessary to check how well the process parameters match the selected seals
If it’s only an internal leak, the value won’t drop to zero; there is also an external leak at the site, with over a dozen drops per minute. The parameters have been submitted to the manufacturer.