Bladder surge vessel- Freezing concern
Bladder surge vessel- Freezing concern
(OP)
For a water pipeline, The designer has proposed bladder surge vessels (5000 and 40000 liter each) for water hammer mitigation. He has also proposed a "standby" vessel. The vessels are outdoor with ambient temp of -10C while the water temp is specified 15C.
In my opinion, the water inside the connection piping and valves (from vessels to the main line)will ultimately become equal to the amb. temp. and so I am concern about freezing. Knowing that water freezing point is not changing with pressure and that there should not be a flow circulation in a surge vessel system, I am going to question the design.
Tips are needed here:
1- Am I thinking right?
2- Any experience with bladder type vessels especially with a large volume?
3- I am concern about the performance of the butyl rubber bladder under cold or freezing weather. any idea?
4- And finally, is there any need to have a "standby" surge vessel?
In my opinion, the water inside the connection piping and valves (from vessels to the main line)will ultimately become equal to the amb. temp. and so I am concern about freezing. Knowing that water freezing point is not changing with pressure and that there should not be a flow circulation in a surge vessel system, I am going to question the design.
Tips are needed here:
1- Am I thinking right?
2- Any experience with bladder type vessels especially with a large volume?
3- I am concern about the performance of the butyl rubber bladder under cold or freezing weather. any idea?
4- And finally, is there any need to have a "standby" surge vessel?





RE: Bladder surge vessel- Freezing concern
The 15 deg water might be circulated around/near or incontact the vessel, rather than through.
The freezing vessle problem could also potentially be avoided by operational procedures, safety instrumentation, and a temperature alarm for water reaching 2C or so where an alarm would sound and/or an automatic discharge valve would open, for one example.
I would expect to see an operating procedure that required the surge vessel to be drained within some reasonable time, definately before another surge was expected, or I would expect to see a vessel with a volume large enough to accept all surges that could happen within the time needed to drain it.
You wouldn't normally need a standby surge vessel, unless there is a high likelyhood of the first vessel being out of service, due to maintenance, due to freezing(?), or some other condition present when another surge is experienced, or if two surges might be expected, before the first could be drained off within a reasonable amount of time.
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RE: Bladder surge vessel- Freezing concern
Since I haven't seen any mention about this in the design and also there's no operating procedure (that I'm aware); I am going to check this and raise the issue.
The concern regarding the performance of the rubber bladder under cold temperature (0 to -10C) is still open for discussion. Any experience with bladder surge vessels?
RE: Bladder surge vessel- Freezing concern
I guess the surge vessel is installed on a T-piece. If so, the (nitrogen) charging pressure will press out the water when the system is stopped. The bladder will then fill the entire vessel.
The only reason for a stand-by vessel is a failure of the bladder in the first vessel. Make sure that the vessels you get have a bladder which can be exchanged. There are bladder vessels available which must be changed completely when the bladder fails.
RE: Bladder surge vessel- Freezing concern
Just a point: bladders are air-filled not nitrogen. Any preference?
RE: Bladder surge vessel- Freezing concern
RE: Bladder surge vessel- Freezing concern
They do not freeze, very reliable, require little maintenance, do not need spares and do not take up much additional space.
RE: Bladder surge vessel- Freezing concern
Offshore Engineering&Design