Inspection of finned convection tubes 1

[kevlar49]

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.

 

[metengr]

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.

 

[strider6]

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

 

[kevlar49]

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.

 

[EdStainless]

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

 

[kevlar49]

I am looking for ID damage. Fins are welded.

 

[metengr]

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.

 

[ash9144]

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

 

[EdStainless]

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

 

[kevlar49]

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?

 

[dcasto]

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.

 

[0707]

Intelligent pigs can be the way to inspect convection heater finned tubes

Go to

http://www.questtrutec.com/Default.aspx?tabid=60

http://216.90.67.19/Portals/0/Brochures/QTT Fired Heater Services.pdf

Good luck

Luis Marques

 

[dcasto]

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