Ammonia Condenser - Full Length liner installation

[sahsanb]

We have been facing repeated tube leakages issues with our ammonia condensers having carbon steel tubes. Exchanger shell side has Ammonia at 130oC and 17 kg/cm2g while tube side has cooling water at 34oC and 4.2 kg/cm2g. Tube OD is 19.05 mm and ID is 14.83 mm. We suspect due to poor cooling water quality, tubes fouling and subsequent corrosion is the cause of tube leakages. We have engaged a vendor for providing us a solution to salvage the exchanger before it gets beyond repair. They have proposed installation of SS 316L full length liners of 0.7 mm thickness on the 11.7 meter long horizontal shell & tube type heat exchanger.

Vendor has claimed in addition to salvaging the non-leaking tubes, full length liners will also reclaim the leaking tubes. Considering your experience please share:

What is the extent of leakage in terms of through & through flaw size that full length liner can bear
What is the likelihood that full length liner will fail under differential pressure of shell and tube side pressure when installed on a leaking tube.
Considering tube thickness of 2.11 CS metallurgy and liner thickness of 0.7 mm how much heat transfer capability will be reduced in terms of approx %age / tube
Any other areas we must look into prior to installing the lines on our equipment

Regards,

 

[EdStainless]

This approach has been used in hundreds of heat exchangers.
You do this to extend life so that you have time to have the correct heat exchanger (all stainless, or putting sleeves into a brand new CS unit) built.
The first question should be is 316 good enough to handle your water?
When I have seen this done the liners have no detectable leak in about 95% of the tubes with known holes.
So if you have 100 tubes that are plugged with leaks you can get 95 of them back into service.
This largely depends on the condition of the ID of the tubes. The rougher they are the harder it is to seal.
The heat transfer loss is only a couple of percent, so putting 10 tubes back into service is usually enough to offset it.
Honestly, your fouling is costing you more heat transfer than the liners will.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

We had installed full length liners in our large steam condenser tubes but only in the air removal section where OD wastage can be a problem.

If done correctly it becomes a tube within a tube using hydraulic expansion. The interface between the existing tube and thin wall sleeve is leak tight because of metal to metal contact from deformation in surrounding tube material with no wastage. A full length sleeve will extend the time until retubing. The sleeve is not a permanent solution.

 

[georgeverghese]

What is the TEMA configuration of these condensors?

 

[EdStainless]

I know of an application in fin-fan coolers where buying the units in full stainless is expensive and has a long lead time. Instead they buy new units in CS and have them lined before they ever are installed. They are getting over 5 years out of these installations. Straight CS was lasting 18 months.

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P.E. Metallurgy, Plymouth Tube

 

[mrfailure]

Have you removed and analyzed one of the leaking tubes? You should confirm that your assumption is right before taking corrective actions. In particular, you should confirm leakage is coming from the water rather than the ammonia side.