Replacing Surface Condenser Tubes
Replacing Surface Condenser Tubes
(OP)
We have a surface condenser for a steam turbine being in operation for the last 07 years. Now its tubes have started leaking. The No. of leaky tubes have exceeded the maximum number that are allowed to be blinded. We have now two options with us:
1. Replacing the whole equipment with a new one (costly option)
2. Replacing half of the tubes in Annual maintenance shutdown this year and the remaining half number in the next turn around.
the total number of tubes is 4000. there are 8 baffles in the condenser and 8 m is the tube length. The shutdown duration is around 25 days.
Can anyone advise: which option is the better one..keeping in view the replacement cost and the time required for replacement in both the cases.
1. Replacing the whole equipment with a new one (costly option)
2. Replacing half of the tubes in Annual maintenance shutdown this year and the remaining half number in the next turn around.
the total number of tubes is 4000. there are 8 baffles in the condenser and 8 m is the tube length. The shutdown duration is around 25 days.
Can anyone advise: which option is the better one..keeping in view the replacement cost and the time required for replacement in both the cases.





RE: Replacing Surface Condenser Tubes
Why are the tubes failing?
Have you done s survey of the tubes to see how many are bad. If you have a good survey this will dictate your approach.
RE: Replacing Surface Condenser Tubes
RE: Replacing Surface Condenser Tubes
RE: Replacing Surface Condenser Tubes
1. Re-tubing
2. Sleeving
3. Replacement
Time Schedule and cost both should be taken into account.
Are any parties available for providing services of sleeving ?
RE: Replacing Surface Condenser Tubes
As for sleeving, it cuts down on heat transfer and usually saves no money over the other two options unless very few tubes need to be sleeved. It is a better option compared to plugging but not for extensive damage.
RE: Replacing Surface Condenser Tubes
If your leakers are limited to the lower half of the tube field, then you could scrape by by just retubing the lower half and leaving the upper half to later.
But then, you'd be faced with retubing the top half some day and you won't know how fast that day may approach without some type of EC testing to determine what the condition of the remaining tubes is.
A large portion of the cost of the retube is the mobilization of the retubing crew, the removal of the water boxes, connecting piping etc. If you retube half at a time, you will duplicate all those costs. The incremental costs of the second half of the tubes based on the cost of the tubing and the labor to r/r the second half may be much less than paying the mobilization and tear down labor twice.
Where is the air cooling zone of this condenser? You may be getting attack in the tubes located in the air off take zone due to oxygen in the air attacking the carbon steel tubes. Check your air removal equipment.
Hope some of these thoughts help.
rmw
RE: Replacing Surface Condenser Tubes
Through tube leaks are not as common as joint leaks and leaks at the tubesheet.
RE: Replacing Surface Condenser Tubes
1. This condenser has been in service for nearly 24 years.
2. Out of 4000 tubes 95 have been blinded till now.
3. Destructive inspection of one of non-leaking tube was carried out a few years back (at the old location) showed internal pits, while the outside surface of the tube was not too much corroded. It means that the corrosion is on inside of the tbe not outside.
4. The wall thickness of the inspected tubes (one from lower half and one from upper half) was measured as 1.42 mm (lower half) and 1.81 mm ( upper half) (2.2 mm is the thickness of the new tube)
5.Further inspection report show that:
- no baffle cutting damage
- Little attack on the outside wall surface
- Corrosion pitting damage on the inner wall surface
yestrday I have received some quotations for the new condenser from different manufacturers with the delivery time of 4-5 months. As we have to shutdown the plant in mid february 2011, the option of replacing the whole equipment cannot be considered now because of time limitations.
Therefore I request to suggest any measures that can be taken for the repair of the leaking tubes.
I am sorry for not providing the detailed information in my initial post.
RE: Replacing Surface Condenser Tubes
You might want to go back to the manufacturers and ask about costs to move the time frame forward -- could they get you new tubes to support your February outage.
Patricia Lougheed
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RE: Replacing Surface Condenser Tubes
Regards,
Mike
RE: Replacing Surface Condenser Tubes
rmw
RE: Replacing Surface Condenser Tubes
RE: Replacing Surface Condenser Tubes
RE: Replacing Surface Condenser Tubes
-TJ Orlowski
RE: Replacing Surface Condenser Tubes
Obstructions (has someone run some piping or conduit right in front of the condenser where you need to be pulling and insereting tubing)???
Lots of stuff needs to be known before hazarding a guess.
rmw
RE: Replacing Surface Condenser Tubes
http://www.condenserandboilertools.com/index.html
RE: Replacing Surface Condenser Tubes
RE: Replacing Surface Condenser Tubes
rmw
RE: Replacing Surface Condenser Tubes
RE: Replacing Surface Condenser Tubes
Might be able to find the contractor info if interested.
Regards,
Mike
RE: Replacing Surface Condenser Tubes
I've used all of the above tools and procedures along with the method posted SnTManon heavier wall tubes. If as you state time is very important you will want to use any tools available.
You have to remember that retubing, the installation of the new tubes can far exceed the removal time.
One other question is what type of plugs were used for plugging the leakers?
RE: Replacing Surface Condenser Tubes
RE: Replacing Surface Condenser Tubes
http://www.tubeplug.com/index.html
RE: Replacing Surface Condenser Tubes
Here is another site to root around on. They used to have a fantastic video of a tube puller/chopper.
http://www.retubeco.com/
They certainly have some great photos, but most of what I saw was way bigger than what you have (same range as what I alluded to in an earlier post.)
I'll leave it to you to root around and glean what you can use from the site. Lots of good stuff there.
rmw