Issues regarding level gauges in vertical steam boilers
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This post was last edited by A If Foolish A on 2019-4-8 at 14:55. The water level in vertical steam boilers fluctuates greatly; the gauge shows that the water level keeps rising and falling, and occasionally it even goes beyond the range of the sight glass. This leads to frequent high or low water level alarms in the boiler. Currently, the length of the sight glass attached to the water level gauges with readings below 440 is 190 mm; if a larger range of water level display were available, it would be possible to avoid alarms by adjusting the length of the water level electrodes. Now, the gauge supplier has proposed a solution: to connect the two existing 190mm sight glasses together, thereby making the total length of the sight glasses 380mm. The display range **has been increased**. But now there is another problem: there is a blind spot of about 30 mm at the junction of the two viewports, as the outside of the glass panel is surrounded by a steel frame. The question I would like to ask is whether using such a level gauge in boilers with a pressure below 1.25 MPa will affect the boiler’s acceptance The regulations only require that the water level gauge have clear indicators for the highest, lowest safe water levels and the normal water level. If the normal water level as well as the alarms for high and low water levels are all set in blind areas, would that still meet the requirements of the regulations?
It is best to ensure that the lowest water level is 100 mm above the highest fire boundary; this distance is usually indicated on the general layout plan.
That’s for sure; I’m just struggling with the issue of this water level gauge right now.
Personally, I think making such a big change will only draw the attention of the inspectors. Everyone in this industry deals with electrode grinding; there are plenty of people who tamper with the level gauges, and everyone turns a blind eye to it. For this design flaw, it would be better to weld a liquid level stabilizer inside if possible.
Well, that makes sense. Thank you so much!
Referring to clause 6.3.2(4) of TSG G0001-2012, it is clear that such actions by the water level gauge supplier do not comply with the specification requirements.
This post was last edited by A If foolish A on 2019-4-8 at 16:37. According to clause 4 of 6.3.2, a level gauge with blind spots like this should not meet the requirements; however, if two such level gauges are used together, it should satisfy the specifications. Two water level gauges can continuously indicate the water level.
I have a question: is the water supply to your pump continuous? If you make such modifications... it seems there’s no rule stating that it’s not allowed, but will it pass the annual inspection? That can’t be reliable!