Gas-liquid vibration in steam pipelines
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Our company uses low-pressure steam pipelines with a diameter of 250, and the pressure is around 6 kilograms. A tee fitting is connected about 4 meters from the end of the pipeline; this is also a 250-sized pipeline. Both ends of these pipelines are equipped with blind flanges, and at the blind flanges at the ends of the pipelines, DN32 pipelines have been connected to serve as drainage lines. In one of the lines with a DN250 blind flange, there is a slight leakage in the gasket – very minor, with just a few dozen drops of water per minute. Due to the damage of the steam trap in the water supply pipeline at the end of the short line, the manual valve at that end was closed, and no drainage was carried out for about 3 months; liquid water should have accumulated in that section of the pipeline. Today, team members manually opened the manual valve to drain the water, and a few minutes later the pipeline suddenly started vibrating, causing the seal at the 250-series blind flange at the end to be damaged. What is the reason for this? Gas-liquid resonance? I hope the experts here can give me some advice!
1. Describing it in words is less direct than drawing a simple schematic diagram. If it hasn’t been drained for 2 or 3 months, then the pipe will be filled with water; won’t there be any liquid-sloshing noise during use? 3. Normally, when it is not hydrophobic, the temperature of the pipeline may drop; after being made hydrophobic, hot steam exchanges heat intensely with the cold pipe walls, leading to
After the check valve is damaged, the manual valve should be opened slightly or the valve should be opened periodically to allow water to flow.
This phenomenon is likely water hammer, with condensate in the pipeline (branch).
The water hammer phenomenon occurred due to the failure to drain water for an extended period, which resulted in a large amount of condensed water accumulating at the end. When the drain was opened, the local temperature rose, and the mixture of steam and water caused water hammer. Because the blind tube was short, the effect of water hammer became apparent immediately; it is possible that there were quality issues with the welding at the blind end, which led to the aforementioned incident.
Don’t bother asking the experts either; this operation is too scary. Drain it slowly; the drainage speed is too fast.
With water hammer phenomena, especially when the system has not been in use for a long time and is being used again, the valve should be opened slowly – just a little at a time – to allow water to drain gradually. If there is a thermometer, monitor the temperature as water drains to see if it is rising. Once the pipes are fully heated, this situation hardly occurs anymore
It is necessary to drain water promptly; otherwise, it is very dangerous. During degassing, start by slowly releasing it from the front discharge port.
Water hammer is very dangerous; if the check valve is damaged, just replace it