Heat exchanger rebuild

[collegebrewer]

we are about to take on the task of changing our heat exchanger's gaskets over the next couple of days. I have never taken one apart before and have heard horror stories about getting them back together. If anybody has any tips or pointers thats would be greatly appreciated.

Thanks

[kugeman]

Measure the width of the heat exchanger at several points around the body of the unit. It will make getting everything back together and properly tightened a lot easier.

And number the plates when you take the unit apart. It will save you headaches later.

[scott isham]

Find the diagram made for your specific heat exchanger that shows the correct plate order. Before you place the plates back in, stack them in the reverse order that they go in the frame on the floor, then double check on the order, then triple check. Then just place them in the frame and you should be good to go.

[Jephro]

Hutch & Scott give very good advice. While i have never done it myself, i did start at a brewery years ago and saw one go to the scrap yard, had been rebuilt and we just kept blowing gaskets. Not sure if it was just not glued properly, tightened too much or too little, plates out of order, warped...?

There is a good thread about this somewhere on here, try the search but i remember someone making a suggestion i really liked which involved taking a hacksaw and scribing a (shallow) diagonal line across the top of all of the plates so you are sure to get them back in order. It seems it would also allow you to see if you torqued it too much or too little.

Just remember if your going to clean the plates, and i would hope so, (i.e. caustic/acid soak) tape and/or sharpie ink may (and more than likely will) wash right down the drain and then your HX is FUBAR'd. Engraving on the flat edges could prevent proper gasket seal and/or give bugs a nice little hiding place.


oh yea, another one i remember, there is a pattern you should use when tightening and loosening the bolts (and i think it was not more than a 1/2 turn on each) to avoid warping the plates.

..ultimately i would contact the company that built the HX and ask them for detailed instructions for rebuild, i.e. how much torque on the bolts and the pattern if there is one. ..and have a backup plan to continue production in case it takes you longer or in case someone does eff it up.

Good Luck,
You're a braver man than i..

[Poc]

As above...

I don't envy anyone with this task on the horizon...

Anyway from my experience.:

• Find the instruction manual!
  
• Leave plenty of time between starting the task and when you next need to use the heat exchanger, if your planning to brew tomorrow don't start disassembling it today.
  
• Give it a thorough clean when it's apart.
  
• Make sure you have the right tools; spanners wrenches etc. it'll save a lot of time and aggravation.

[liammckenna]

Some advice:

1/Make a 'spacer' out of some 1x6 (or other size depending on your heat exchanger). Make it an exact fit. This spacer should just fit (with a little push) between the outside compression plates

2/ loosen the retaining bolts. Work on opposite bolts (ie top right bolt followed by bottom left, followed by top left, etc)

3/ Get yourself a big bucket of caustic and a brush (and safety glasses and gloves)

4/ when the plate pack is spread, working from one end, remove one plate at a time noting the plate orientation and gasket orientation. Scrub the plate, rinse and return to the plate pack in its original position.

5/ do this for each plate. When the plates are back in order, tight the plate pack the way you loosened it. Be careful that all gaskets/tabs are in order before tightening compression plates. Use your spacer to set the compression. Tighten opposite bolts as above.

Note: this above technique works on our heat exchanger (alfa-laval) because we can spread the plate pack and remove individual plates without completely removing the bolts.

Good luck

Pax.

[Sulfur]

Do you have spare gaskets in case some of the current ones need to be replaced?

[Roger Greene]

Torque Wrench

Male sure you have a torque wrench on hand. Over or under tightening can cause huge problems. Check with the manufacturer to get the right torque for the number of plates you have.


Good luck!

[lhall]

We spray-painted a diagonal line on two sides of the pack, helps when putting it back together to see if you have a plate in backwards. Definitely get the manual for the HX, and see the minimum distance you can compress the plates for the number of plates you have. With new gaskets you probably won't have to compress it quite as much as it was before you tore it down.

[TNbrewer]

+1

We are about to take on this task ourselves. I planned to order about 1/3 of the total number of gaskets in case we tear some when breaking it down (they are glued gaskets). If we can get it apart without tearing many, I planned on using the extras to replace gaskets starting at the front. Next time, we will replace the next 1/3 etc. or so. We have 64 total, so doing it all at once would be a little pricey. We aren't having any problems, so regasketing the whole thing may be overkill. I just wanted to pull it apart to double check CIP, make sure there is no scaling etc, since it has been a while.

Our manual does not specify torque, but instead specifies min/max distance between end plates. Water (pressure) test before putting into production.

Cheers,
Travis

[South County]

We spray-painted a diagonal line on two sides of the pack, helps when putting it back together to see if you have a plate in backwards. Definitely get the manual for the HX, and see the minimum distance you can compress the plates for the number of plates you have. With new gaskets you probably won't have to compress it quite as much as it was before you tore it down.

Agreed, mark you orientation! absolute must!

[liammckenna]

Excellent idea Mr. Hall. It will definitely be used in my future.

Orientation is everything.

Another comment, to echo Travis, compression distance is fundamentally important. Torque is helpful but can change for other reasons (dirty threads etc.). Measure everything start and finish even if you are replacing your gasket set. It will give you a good idea of where you are and where you came from moving forward.

I would hesitate to change out only a portion of gaskets. You may find that the recommended compression distance won't work (i.e. plate pack will leak and require over-compression which may affect your expected performance numbers).

Interesting thread (coming from someone who has had a few struggles with plate pack orientations in heat exchangers over the years.).

Pax.

Liam

[TNbrewer]

We've changed out only a few before, without issue. That having been said, we'll probably have catastrophic results...Our manual lists a min/max range. I kind of associate that max distance as "all new gaskets." At the minimum distance, you have plate to plate contact and the manual has some scary sentence or two discouraging that...

I've always heard the advice to number, etc. I would say that in the event that you didn't or it washed off in the caustic, in theory, if the plates haven't been damaged or warped, you should still be able to recover. Ours has pretty clear instructions on the order and orientation. At least on ours, and I think this is fairly common, the middle plates are just the same plate alternated north and south. It is the end plates that are different. The plates aren't specifically stamped for your unit, just pulled off a shelf and added in whatever number, size and configuration your application calls for. And of course all the gasketed sides should face the same way. Another point is that if you have glued gaskets, you have to make sure that ALL of the old glue is removed from the gasket seats before attempting to glue the new ones.

Now that I've thoroughly jinxed myself, I'll try to remember to post an update when we're done. Good thing I'm not superstitious...

[Jephro]

Spray paint, duh. I like that way better than cutting into the plates.

But, to echo my earlier comment, make sure the type of paint you use is not going to dissolve when your caustic brush hits it.

[HubCity]

I would suggest getting the plate diagram if at all possible from the manufacturer as getting the plates in the right order can mean the difference between a good working cooler and a boat anchor. We tore apart our old used one and found the plates were in the wrong order which lead to dead spots in HX that really didn't do much more than potentially trap particulate and breed bacteria.