I have a boiler that needs 8 tubes replaced. A quick peak on the water side tells me there will be a bit of scale on the tubes. What are some common methods of removing a tube from the middle of a bundle when it's OD exceeds the tubesheet hole because of scale deposits, without damaging the tubesheet? Can you somehow collapse the tube? Tube size is 3". Do you create yourself a path to the manway by removing adjacent tubes?
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Removing tubes from a boiler
- Thread starter INBCPE
- Start date
Is it a firetube or watertube? Sounds like a firetube. If so there are several ways without cutting a path. I will tell you how if you answer the following questions.
Do you have someone experienced in this? If not you may damage the tubeholes or be unable to extract the tubes.
Are the tubes seal welded?
How old is the boiler? Is the rear tubesheet firechecked?
Have you ordered new tubes? Do you have tube expanding equipment? Beading tools? Ferrules? LP test kit?
You may wish to call a qualified boiler shop if you have no experience. It will save you money in the long run.
Do you have someone experienced in this? If not you may damage the tubeholes or be unable to extract the tubes.
Are the tubes seal welded?
How old is the boiler? Is the rear tubesheet firechecked?
Have you ordered new tubes? Do you have tube expanding equipment? Beading tools? Ferrules? LP test kit?
You may wish to call a qualified boiler shop if you have no experience. It will save you money in the long run.
- Thread starter
- #3
Answers:
Firetube boiler.
Yes.
No seal weld.
Oldest is 1962, youngest is 1988. What is firechecked?
No tubes have been ordered.
Equipment and boilermakers are available.
I'm curious as to how it's done - properly. I'm personally not doing it, but I want to hear or read exactly how it's done. If I can avoid removing a slew of tubes, I need to know how it's done.
Firetube boiler.
Yes.
No seal weld.
Oldest is 1962, youngest is 1988. What is firechecked?
No tubes have been ordered.
Equipment and boilermakers are available.
I'm curious as to how it's done - properly. I'm personally not doing it, but I want to hear or read exactly how it's done. If I can avoid removing a slew of tubes, I need to know how it's done.
Firechecks-would be on rear tubesheet. If you have a lot of scale it will insulate the tubesheet and allow it to overheat. Then you get cracks on the surface. They can go through the ligaments at the holes. This is why you need to dye check after you remove the tubes. May need welded repairs,may need a new tubesheet.
Remove tubes: from the front of the boiler.
1.If the scale is soft,cut the tube inside on the rear. Weld a U shaped piece inside the tube in the front. Collapse the roll joint and pull(comealong maybe).
2.If the scale is hard,follow above but pick a hole at the bottom of the replacement area. Cut the tube inside at both ends and remove the stubs. Enlarge the hole in front slightly by a,burr,sanding drum,or tube roll. Pull the tube thru the larger hole. Cut the rest and do the same thru that hole. Repair the hole by use of a copper ferrule before retubeing. You may have oversized holes from past work in an old boiler and need ferrules anyway to get proper wall crush from rolling. You can get them from a good tube supplier. Remember to clean and roll in,then reclean(emery cloth)
3.Cut a window in the front tubesheet and drop tubes to the hole. Replace it with a flush patch,new hole included.
There are a couple of other methods,but these have worked best for me.
Check the tubes you pull for thinning. It may be time to retube the entire boiler.
If you weld,need a R stamp. This is brief but should give you some ideas. A good boiler shop will know these methods.
There is always a way.
Remove tubes: from the front of the boiler.
1.If the scale is soft,cut the tube inside on the rear. Weld a U shaped piece inside the tube in the front. Collapse the roll joint and pull(comealong maybe).
2.If the scale is hard,follow above but pick a hole at the bottom of the replacement area. Cut the tube inside at both ends and remove the stubs. Enlarge the hole in front slightly by a,burr,sanding drum,or tube roll. Pull the tube thru the larger hole. Cut the rest and do the same thru that hole. Repair the hole by use of a copper ferrule before retubeing. You may have oversized holes from past work in an old boiler and need ferrules anyway to get proper wall crush from rolling. You can get them from a good tube supplier. Remember to clean and roll in,then reclean(emery cloth)
3.Cut a window in the front tubesheet and drop tubes to the hole. Replace it with a flush patch,new hole included.
There are a couple of other methods,but these have worked best for me.
Check the tubes you pull for thinning. It may be time to retube the entire boiler.
If you weld,need a R stamp. This is brief but should give you some ideas. A good boiler shop will know these methods.
There is always a way.
You remove tubes very carefully not to damage tubesheets. Some good tubes may have to be sacrifice to replace damage tubes. Flame cutting is the preferred means to remove tubes. When you install new tubes use four ball roller to flare tubes in the tubesheets--better than three ball roller-- Reason is a better sphere of influence exerted by the four ball roller.
Note that if leaking tubes were caused by low water condition, other tubes-not readily apparent- may have slightly sagged and may need to be replaced due to interference w/ new tubes and possible bridging of scale between tubes when restarting.
Note that if leaking tubes were caused by low water condition, other tubes-not readily apparent- may have slightly sagged and may need to be replaced due to interference w/ new tubes and possible bridging of scale between tubes when restarting.
One thing that I forgot about flame cutting tubes. You would do that inside of the tubes past the thicknesses of the tubesheets but take precautions that the tubes are properly restrained before cutting them out completely otherwise you could damage the tubesheets.
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