Pressure testing of spiral heat exchanger for gasket leak

[Tundra11]

Hi All,

Recently, our plant had an issue with a spiral heat exchanger that was inspected during our turnaround.

Turns out that we had only pressure tested one side (Hot side) as it was at a higher pressure compared to the Cold side.

So when it was commissioned, the heat exchanger started leaking from the bottom cover gasket.

My question is: Do we have to pressure test both the hot side and the cold side to check for gasket leaks?

My image of how a spiral heat exchanger works is that both hot and cold side will be in contact with the gaskets of the top and end covers. So why do we have to pressure test both hot & cold side?

Hope the more experienced guys here can help to enlighten a young learning engineer here.

Thanks!

 

[SnTMan]

Tundra11, seems you've discovered the answer to your own question

Seriously, if perchance your vessel is designed / constructed to Sec VIII, Div. 1, see UG-19, UG-99(e) on combination units. Testing of both chambers is required.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Ehzin]

Tundra,

Look into the construction of your particular spiral exchanger. Typically, the gasket seal on each side of the exchange only seals one of the two streams from external leakage; i.e. hot and cold side each have a seal. Testing only one side wouldn't expose the other side gasket to pressure unless you had failure of the boundary of the two streams.

The drawings of your exchanger should explain this point if your construction is similar to what I've seen.

Thanks,
Ehzin

 

[Ehzin]

Tundra,

As an additional note, at least for the spiral exchanger construction I'm familiar with, you can actually perform a hydro of one side with the cover off on the other. It requires very important consideration to prevent the spiral from extruding out but it can be done. There are many manufacturers out there but a good video that helped me understand at least the construction I needed to be familiar is below.

https://www.youtube.com/watch?v=6bCG82dOOew

Thanks,
Ehzin

 

[Tundra11]

Hi Ehzin,

A big thank you for the advice! I have checked the drawings and yes, indeed the top and bottom covers only seal one flow of either the hot or the cold side.

I really missed that small detail out. Now I understand the need to pressure test both sides.

Many thanks once again!

Regards,
Tundra