Replacing Surface Condenser Tubes

Why are you stating a 25 day outage to replace 2000 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.

As Syd says, you need a good survey. Eddy current the tubes. You need to know how many need to be replaced not just the leakers. Then you need to do an economics comparison of replacing condenser verse replacing bad tubes. Before you do either you need to know why they are failing and correct that issue before putting in another sacrificial condenser.

In addition to the above, what is the condenser tube material? Are the leaks in roll joints or in the tube material? If you replace only half the tubes and have no idea as to their condition or faiure mechanism, you could be in trouble.

The tube Material is DIN St35.8 (Equivalent to ASTM A179 i.e Carbon Steel)and the tube sheet material is DIN 17155. The plant is relocated and the condenser was a part of the old plant.The leak is from the tube part (not from the joints.The tubes OD is 25 mm and thickness is 2.2 mm. There are actually 15 baffles.The trend of the leaky tubes is on the lower half portion. There is no leaky tube in the upper half portion.The old plant record shows that the same exchanger has been replaced one time in the past. I just wanted to know which will be the better approach:
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 ?

Still you need to know the extent and cause of your tube failures. No one can tell you the "right" answer. But you can gather the data and decide based on your plants situation.

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.

If you are already past the plugging limit, then you will have to retube to some extent.

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

Check the water side of the condensor tubes: If the water side is getting plugged (mussels, biologics, mud, algea, etc) then the corrosion will be greater in the tubes with the stopped flow.

Through tube leaks are not as common as joint leaks and leaks at the tubesheet.

I have dug out the inspection reports (of the previous owner) of the condenser and found that:

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.

If you can't replace or plug, it appears your only option comes down to sleeving. As Ash mentioned, that cuts down on heat transfer.

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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franklin55, it is possible to only replace what you might call the bundle of your condensers. It is often possible to gain performance in the process. See, for expample,
Regards,

Mike

Mid Februrary is 3 months away. I doubt that any condenser manufacturer could produce a replacement tube module much faster than they could produce an entire condenser. I have replaced several (although none as small as this one) and can't see one being fabricated in the limited time available.

rmw

Given sufficient applications of cash, many things become possible

Can anyone provide estimated time required for replacing approx. 1000 tubes keeping in view the construction of this condenser (25 mm O.D and 7 meter tube length with 15 baffles)

Country of work being done? Local regulations on field work?

-TJ Orlowski

Water box type (bolted cover or do you have to cut it off)??? Access (tube pull area)??? Elevation (is this thing in a building, basement, etc?)??? Best guess of condition of the support plates??? (they will have to possibly be aligned and each hole ball burred to clean out.

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

Check the videos at the site below to get an idea how things can work. These videos are in real time. There are faster pullers on the market. You should be able to rent all the tooling required for the job. As posted above the logistics are the key. A changing out a thousand tubes is no problem if the access is open.

There is no access problem. The one side of the condenser is faced towards an open area.

Most of the condensers that I was ever involved with retubes for were numbered in the tens of thousands of tubes and that was per waterbox, and most were 2-4 waterboxes per condenser. We retubed some auxiliary cooling water Hx's that were around 1000 tubes, ~20-30 ft long and those ranged in the 100-150,000 USD range, but that was 4-6 years ago (and the tubing was 90-10 CuNi).

rmw

Thanks rmw for valuable information.Can you advise please whether you had used some special tube puller or had done it manually?