ReplyThe problem may be the contact cement you are using to hold the gasket in place. It could be incompatible with the gasket material, or it could also be allowing the gasket to slip. What kind of material are the gaskets made of?
Regular Guest
Second time i have changed out these gaskets on the evaporator bundle of the chiller and for some reason a small section blows out after i nitrogen test it, and charge it. I know the torque specs are 55 lbs, i glew the gaskets with some contact glue onto the baffle so they stay in place. Everything looks great i then nitro check it with 125 lbs soap the **** out of it. Pull vaccum then weigh in my charge. Units running great i leave then at some point a small section blows out. Any suggestions would help, we all know losing 140lbs of r-22 we get ur butt fired in a hurry.
Professional Member
The problem may be the contact cement you are using to hold the gasket in place. It could be incompatible with the gasket material, or it could also be allowing the gasket to slip. What kind of material are the gaskets made of?
Don't pick the fly crap out of the pepper.
Professional Member
Before replacing too many more gaskets on this puppy, I would advise taking a good straught edge and verify that the end sheet is flat across..The gasket can tolerate a few thousanths of an inch bowing, but more than that and the gaskets "Will" continue to blow out. I have seen up to almost 1/8" bowing out in the middle of this design evaporator bundle.(Acme) Whilst' thee is at it, also check the End plate(s) for flatness across all the wiggly surfaces. If you have an addittional plate between the head and the tube sheet, it should also be true, but it will conform as long as the tube sheet and the head are true. Lay the nickel never-sieze to the studs and follow the torque sequence to the letter. Be "VERY" careful not to get any of the never-sieze on or even near the gasket areas. Only use the never-sieze after the head is in position.
Let us know how bad the tube sheets "are" deformed and then we will go from there.
Ain't "None" of us as smart as "All" of us..
Professional Member
Way back when the same gaskets were a problem in the LCHA series. If you know your York nomenclature you know I'm talking way back. A couple of things the factory came up with then was convex washers put over the studs, also they specified a torque pattern and stated it was to be done in TWO steps. I don't know the exact specs, but for example if the final torque value was 55 ftlbs. then the first one was done at 35 and the second at 55.
Professional Member
Absolutely correcto amigo..Originally Posted by KnewYork
The washers, called "Belleville Washers" were...and are available thru Mcmaster Carr in stainless or regular steel and are great in assuring adequate force even with the varying temperatures and the shrinkage/expansion that affects the fastener. About $15-20 for 50 of them is also great insurance for a very small price.
But I still think the OP has a deformed tube sheet.........
Ain't "None" of us as smart as "All" of us..
Professional Member
had to deal with this several times... had some that were so bad I had to replace the barrell. I was also told to make sure the gaskets are clean and "DRY" when installing them. One other thing I had happen..... If your working on a multi-system unit and still have pressure in one side, be very careful when evacuating the system your working on....... I had the gaskets blow out during this proccess...big uh-oh!
Professional Member
I was wondering what your final outcome was. I have a similar reoccurring problem. Any input would be appreciated.
Regular Guest
I tighten the bolts to 95 lbs to torque and said a prayer it's worked last 2 times for me.
Professional Member
Did u use a York gasket and what did u use for your adhesive?
Professional Member
I've used a 3M spray adhesive, but only enough to hold the gasket in place, yes the York gasket. Make sure the adhesive is completely dry before installing head, anything slippery will cause the gasket to shift...
Regular Guest
just finished a ycwz the other day. would look at the tube sheet and as well as the baffle plate sound like it may be warped.
we use an anerobic gasket selant the stuff cures in a vacuum
aslo will fill small gaps up to .25mm
i torque all the bolt in the spec patteren and use four step just tight 33% of torque 66% and 100% watching to be sure gaskets seat eaqually.
Professional Member
Revisting this topic, I'd think that you should adhesive should be used sparing so the gasket isn't forced into compliance.
The seal is a function of elasticity of materials of parts as well as the gasket. So, for OEM spec torque to have just the right seals, the gasket must have the same properties. OEM vs aftermarket head gasket is a big topic in engine repairs. Seal won't last if the mating surfaces aren't true. This video isn't for refrigeration equipment, but its the same process. www.youtube.com/watch?v=yaX9feg0C5E
If you find the end plate isn't perfectly flat, NAPA auto parts with machine shop service maybe able to resurface it. This is something to keep in mind depending on cost or lead time of replacement parts. The gasket is supposed to compensate for inevitable thermal expansion and limits of machining accuracy. Not to make up for damage on surfaces or warping.
I think you've got to do more than two passes. I'd hand seat in sequence, hand snug, then torque 3 times for total of five times. Take 2-3 times the time here and replenish the refrigerant once with a good hope of having a proper seal. Or, you can rush it and do it in 1/3 the time now and replenish total loss of charge 2-3 times.
Check with factory if reusing bolts are permissible. Just as car engines have a huge rework cost, total loss of refrigerant has a huge cost.
Posting Permissions