Desuperheater

[Paul V.]

I'm working on a thermotron F62 chamber. A leak developed
at the very end of the desuperheater. It is a custom made
water cooled heat exchanger. The end of the heat exchanger
is capped with a 3"cap, the leak is a hair line crack in the cap. To remove the cap I would have to remove the desuperheater (big job). Here's my question, Could I braze
the crank closed? Will it last?

[rimek]

The question is- Is this crack an indicator of general integrity of the heat-x? Do you know why it cracked? Is this a water side leak from freezing? What pressures and temps will this repair experience? If it is a low pressure water side leak, you may be able to get away with an epoxy patch, while drawing a vacuum on the water side to get penetration. How long is the crack, and what is separation?

[Paul V.]

The crack is a hair line crack about 1/2 inch. Its on the hot gas side of the heat exchanger. 250psi. Water not an issue here. The crack may have occured from vibration, the clamp holding the discharge line to the chassis was removed. Don't know when or why probably many years ago. The chamber is over 25 years old. I brazed over the crack and it's holding now. Manufacturer said it should be ok but I am not comfortable with this repair. What do you think. Will it hold?

[rimek]

What refrigerant is this? Did you do N2 sweep? Dynaflow or 45% alloy? By brazing, you have annealed or hardened the copper in the area of the crack, that may become more brittle. I'm picturing that there is an outlet tube coming out near or in the middle of this endcap? Do you think that you can secure the heat-x and tubing to keep stress? Is this heat-x buried in insulation normally or will you be able to see it always?
questions, questions...