Stainless heat exhanger

James,

I work for a company which manufactures Very large industrial Washing machines, the whole machine is contructed of stainless and for the pipework for the steam heating coils in the wash and rinse tanks we use 316 as this works well with steam at up to 4 bar @ 100 degrees C on the inside which we all know can be abrasive and on the outside of the coil we have water with a heavy concentration of either Acid or Alkaline Detergent to aid the washing. The coils are fully welded also. The material puts up well with the conditions it finds itself under.

Mart> I'm looking for ideas and guidance on building a heat exchanger. This

In message , James writes

Would a spear point 'U' tube be of any use? A couple of model engineering suppliers sell these. Typically a pair of close spaced parallel tubes, say 3/8" diameter, 3/8" apart welded together at one end to form a spear point 'U' tube up to about 24" long.

Thats the sort of thing I was thinking about - I thought I might be able to fashion a tube heat exchanger out of some say 3/8" tubes about a foot or two long - insert this with end plates into a larger tube - put end-caps on the larger tube and that would provide a decent heat exchanger - the only problem with that is mounting fixings along the length of the tube for the cold water.

Alternatively I was thinking of winding some copper tube around a stainless one (after filling with sand or salt) and then crudly soldering the two together to help the heat connectivity. I think I'd get an okay result but I'm not sure. The good thing about this is that its easy and simple.

Any other ideas?

welding a various points along the length to

larger tube and weld the end in position to the end

transfer from the inside tube to the external

The other thing I remember seeing done was that the larger main tube was filled with an aggitator. Something like a screw or series of paddles to make sure the fluid inside made as much contact with the wall surface as possible.

This is where i'm stumped though - I don't know what to use to make something like this in a backyard workshop :(

Your right though - wall thickness is very important.

Hi James --

From time to time in my work I have to make a small SS tube-in-tube cooler, and this is how I do it. (Remember this is just a hand sketch and I would recommend only using it for small tubing, that is where the outer tubing is

3/8-inch OD or smaller. I have seen them made with 3/4-in OD tubing but not coiled by hand.

Using this method and swagelok or similar tube fittings, you don't need to weld anything. Let me know if this gives you any ideas or not.

Fred

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Hello all.

I've been lurking here for a while and am a regular contributor to the uk.rec.engines.stationary NG. I notice I am not alone and have seen several of the Usual Suspects monikers lying around unattended ;o))

To the matter at hand - if somewhat tardy - my daughter is a licensee and having been in her cellar I know that all the lines that cool and deliver the beer etc are stainless. I suggest, James, you might find exactly what you are looking for in a scrapyard that deals in pub and catering scrap. All ready made, too!

regards,

Kim Siddorn.