Plate & Frame Heat Exchanger - leaks (pin holes)
Plate & Frame Heat Exchanger - leaks (pin holes)
(OP)
Anyone ever experienced pin holes in the exact same location on different plates in a plate & frame heat exhanger? The supplier tried to tell us it was due to a chemical used in our process, but the holes were in the same spot on multiple plates - 141 out of 258 stainless steel plates.
This clearly looks like a mfg defect with the stamping to us???
This clearly looks like a mfg defect with the stamping to us???





RE: Plate & Frame Heat Exchanger - leaks (pin holes)
I may be that your service is aggressive enough to attack in crevices and that their design places the tightest crevices in the same place on each plate.
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Plymouth Tube
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
TTFN
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RE: Plate & Frame Heat Exchanger - leaks (pin holes)
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
Give a basic description of the HX, two pass, four pass, more than that pass, simplex, duplex (two services in one frame) type? If it is mechanical and not corrosion, we need to know a lot more about the physical characteristics of the plate. What is the size of the heater, length and width of the plates.
Is there any significant temperature cycling?
Did you get any spare plates (or have any plates from the original plate pack that were pulled out for performance reasons) that you can look at to examine the area in question prior to being in service?
Sorry, but for me if it were chemical attack the chemical wouldn't be selective enough to pick this special point on each plate and ignore all the other crevices and corners and bends and twists and turns and even dead zones like gasket trays unless you had a phase change at the offending point. Right now I am going with mechanical defect or thinning due to rubbing at contact points. But then again, the jury hasn't come back in yet either until we hear from you more about his heater.
rmw
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
I have seen pinhole leaks in a plate and frame exchanger occur in the same location. In this case 'same location' meant within the same localized area on different plates. I don't know if that is what you mean by exact same location. This was definitely process related. I also have seen multiple gasket failures through a pack at what I would say is the "exact same location" and again this was definitely process related.
However, if you are dealing with the pinhole occuring quite precisely at the exact same location I would side with rmw.
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
The mfg is saying it is corrosion but as rmw says I can't see how it would be so selective as to fail multiple plates in the same location. Here is some data on the plates:
Material = 316SS (not 316L)
Thickness = .6mm
Plate size - 18" wide x 36" tall
Gasket Material = EPDM
Total Plates = 260 (at least 140 had pin-holes)
Using 30% PG (I am told with a corrosion inhibitor)
This is a 2-pass chiller
The exhanger is used for chilling rather than heating. The unit does see 185DEG F for approximately 20 minutes once per week.
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RE: Plate & Frame Heat Exchanger - leaks (pin holes)
I'm not a metallurgist and there are some really good ones that lurk this site, but if this was my plate I'd be sending it out to some metallurgical lab to see if it is what it is said to be.
I would expect chemical attack of the plate to be as EdStainless' signature used to say 'relentless' and to exhibit itself much more wide spread than these locations.
One of the pictures looked more like cavitation than corrosion. I am trying to get my mind around how that could happen at that particular location.
rmw
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
There does appear to be some sort of consistent mechanical damage. However, you need to look at as-delivered plates versus your failed ones. Are there damage indications on new plates?
Who assembles the plates into the exchanger, you or the supplier? If you, then you need to dismantle a new assembly and see if there's some sort of precursor damage or other feature that you can correlate to the corrosion.
TTFN
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RE: Plate & Frame Heat Exchanger - leaks (pin holes)
Is the damage at points of contact between plates or at gaskets?
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Plymouth Tube
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
Check the gaskets and thier curing compounds as well as the type of glue used by the manufacturer.
Good Luck
RE: Plate & Frame Heat Exchanger - leaks (pin holes)
I think EdStainless's question bears further investigation. If there is a phase change within the exchanger at a certain point of differential pressure it could explain the area around the pin holes in the first photo.
rmw