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Inspection of finned convection tubes

Inspection of finned convection tubes

Inspection of finned convection tubes

(OP)
I am trying to measure corrosion in finned convection section tubes.  Does anyone have a good inspection tool for this?  Someone suggested laser profilometry, but I have no experience with it.  Is it an effective technique?  If so, what do I need to specify for good results?  If not, why?

Thanks.

RE: Inspection of finned convection tubes

kevlar49;

Not enough information to help you. Are the finned tubes accessible from the OD, or ID surface? Are they installed in a vessel? What is the fin material and tube material? What type of corrosion damage do you suspect?

Maybe, all you need is just a good visual inspection, on a periodic basis.

RE: Inspection of finned convection tubes

kevlar

The first thing when you have to decide the inspection method is to have a look of the item, at least is necessary a skecth or drawings, and also to know the materials.

Strider6

http://www.corrosionist.com

RE: Inspection of finned convection tubes

(OP)
Sorry, was in a hurry to write this message.  The tubes are carbon steel with carbon steel fins.  OD of the top most and the bottomost tubes is accessible, but that is it. I suspect sulfidation damage caused by stratification of flow in this furnace. I need to be able to inspect the 12 o'clock position of the tubes because of the high concentration of H2S vapors in that phase.

RE: Inspection of finned convection tubes

Are you looking for OD damage or ID damage?
Are they welded fins? Wrapped?
Any leaks?

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: Inspection of finned convection tubes

(OP)
I am looking for ID damage.  Fins are welded.

RE: Inspection of finned convection tubes

If you can access the tube ID surface, remote field eddy current testing should do it. We have used this method to inspect carbon steel, membrane welded boiler tubes.

RE: Inspection of finned convection tubes

If you can't easily access ID, Xray could be another option.  Xray service tubes, Xray a new tube and compare.

RE: Inspection of finned convection tubes

The ID laser scan systems will find pitting and wastage, but they only work if the tubes are clean.

http://asnt.org/publications/materialseval/solution/apr99solution/apr99sol.htm
for some good info.

If you are looking for cracks or metallurgical damage then one of the ET methods would be best.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: Inspection of finned convection tubes

(OP)
Sorry, guess I forgot to mention the tube size: 6 " NPS.  Would 90 degree contact RT shots be appropriate.  

Would smart pig with magnetic flux leakage be a good quick way to inspect?

RE: Inspection of finned convection tubes

Typically the the convection section of the heater, the tubes have parallel welded fins with sharp 3R 180's and very close spacing, so inspecting them will be a challange.  My recommendation is to inspect what you as adviced above, then crunch some numbers and get into a turnaround replacement program.  The downtime, cost to inspect, sometimes isn't worth it.  Flat out replecement after 5 years of harsh service maybe be cheaper.  I've even had a proceedure that called for only visual inspections and operator monitoring and let the tube leak and then do a replacement.

RE: Inspection of finned convection tubes

0707,Is Quest Truetech also the true tech gamma scanning company that was in LaPorte, TX?

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