Protection of pressure vessels in hot, sunny

[maxh]

Dear all

I have to provide some pressure vessels, containing unheated water at up to 20 BarG, for use in Saudi Arabia on a pumping station.

The vessels are located outdoors and our client has suggested that we need to protect the vessels against the sun.

Has anyone experience of these type of environement and what is the usual practice, my experience is in the UK where we don't have much sun (I know what to do about rain !!).

Is this really a problem, can't I get away with a suitable UV resistant paint ?

Thanks for any help
Max

 

[Ashereng]

When your client says protection against the sun, does he mean protect against the heat or UV or ... what?

I have seen pictures of oil storage tanks in Saudi (you can actually google earth it), and it seems like they are just metal tanks painted white, much like anywhere else.

Is there anything specific about your cold water tank?

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[JStephen]

If the tanks contain pressurized water, they don't need any protection against the sun unless they are intended to stay at some particular temperature. If they are, your customer needs to specify that temperature, or specify what other insulation requirements, etc., are desired.

I'm assuming you've designed the tanks so that thermal expansion is not an issue.

 

[deanc]

Paint will chalk,plastic will oxidize and become brittle within 8-12 months,glass fogs,and gauges become unreadable.

So---do you have any attachments or controls? The surface temprature of the vessel may get hot enough to literally fry an egg on.

At least you don't need to worry about rust. The only thing that does not need protection from the sun is the sand.

 

[maxh]

To answer and clarify some of the points.

Re: Instruments and attachments
We are supposed to provide level and pressure gauges and spring loaded pressure relief valves. There will be some instrumentation cabling - I guess we can shade this from direct sunlight by careful design.

Re: Duty
The tanks are to be provided for surge protection on the pumping station discharge lines, so they wil just sit there half full of water, half full of air, and remain at ambient temperature.

Our client has no specific requirements for protection other than the wonderful standard "Vendor proposal" so I guess we only need to be responsible in what we propose.

 

[unclesyd]

You might want to look a this or a similar material for the tank insulation. I've seen several tank installations in my area that have used this type product.

Look under "Breaking News" for some applications.

http://www.eaglecoatings.net/

 

[SJones]

What 'ambient' temperature and what design temperature are you working to? Operating in a similar part of the world, 'sun protection' here consists of a good (and qualified) 3 layer paint system with a PU topcoat.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[maxh]

Steve,
We haven't been specified a site temperature, not a helpful client, so I guess we are left with the possibility that if we leave the tank exposed we might get a surface temperature of anything up to 150-200 Deg F (egg frying temperatures).

I would think the air temperatures will quite happily get to over 100 F.

Max

 

[chicopee]

It appears to me that your client may be requiring protection from the sun so that the tank,piping and appurtenances do not get too hot for servicing purposes.
As much as the tank and content may get hot during the day time, at night that same system and content will cool down probably just as much since night time temperatures will drop significantly and you would experience a significant radiation cooling. I would look at the same paint system used on propane bulk storage tanks if your client agrees to a paint system. Also if it is convenient look at similar installations in the region.

 

[stanier]

You could bury the tanks?

Geoffrey D Stone FIMechE C.Eng;FIEust CP Eng

http://www.waterhammer.bigblog.com.au

 

[davefitz]

Not familiar with this specific problem, except that :

a) if the tank is left isolated with no significant influent or effluent, then the thermal expansion of the liquid can lead to tank failure unless an adequately sized relief valve is provided. This means determining max rate of heat absorption and max rate of d(rho)/dT for liquid water. An inlet check valve may effectively cause tank isolation during periods of no flow.

b) unless there is an inlet check valve , then swelling of teh water can lead to backflow to the upstream system, and there may be some cases where that is not permitted.

c) To avoid having to drain teh tank in order to maintain a leaking relief valev, you may want to mount 2 relief valves downstream of a 3-way block valve.

 

[SJones]

If it helps, we work to a black bulb temperature of 82 deg C. We can get ambient temperatures up to 60 deg C

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[vesselguy]

maxh,

I see lot of good answers to your question, but it appears everyone is just making assumption on what the question is. Simple answer to your question is, when in doubt, ask your client in writing to get a clear specification on what he wants. Your client will be very mad if you assume and not be able to meet what he had in mind. Remember what Benny Hill says about "assume"?

 

[maxh]

Thanks guys
Yes I do remember Benny Hill.
Your help is appreciated.
Max