API Riveted Tank -- Repair of Horizontal and Vertical Seams

[JeffLester]

I'm reviewing the repair plan for an API riveted tank. The plan calls for the replacement of various shell sections including some intersections of horizontal and vertical seams. The shell is 3/8" CS. I've reviewed 653 and have some preliminary issues with how this replacement would be done. Any thoughts on this would be greatly appreciated.

 

[JoeTank]

Why don't you share your issues and maybe you will get some good responses.

Joe Tank

 

[JeffLester]

Joe -- My apologies, I am not trying to be cryptic. I'm having difficulty envisioning a repair plate that doesn't have at least half of the perimeter fillet-welded to form a lap joint. Wouldn't this then be considered a lap-welded repair patch plate? If so, I'm inclined to apply the criteria detailed in Section 9.3. See sketch link for simplistic view of replacement shell section. Regards, Jeff

http://files.engineering.com/getfil...785-548e2314d94d&file=jeff_20090130165140.jpg

 

[JoeTank]

First of all, API-653 reaaly doesn't cover much about riveted tanks, so you have to use engineering judgement about most things. For what you are trying to do, yes, I suspect you will have at least on third or more of it as a lap patch. I had similar problem and used a repaire plate that was twice as thick as required. This allowed me to work out a detail that butt-welded around entire perimeter.

Joe Tank

 

[chicopee]

Find out when the tank was constructed from the nameplate or stamping because you'll need that ASME code of that year to repair this tank; also get a copy of an older NBIC of that same era and the Manufacturer's Data Sheet from the National Board of boilers and Pressure Vessels as there is a lot of info on repairing that tank. I got a 1972 copy and there is ample info on repairing riveted tanks.
I personally think that you should forgo the expensive repair for a new or second tank.

 

[chicopee]

I screwed up, this is an API tank not ASME.

 

[TankDude]

Jeff,
One common method is to use a butt-welded insert for the vertical seams and simply lap-weld the horizontal. I have used this detail and it has worked nicely. I utilized the basic rules for lap-welded tanks as discussed in the old Process Equipment Design text.
Another detail that I have used successfully is a butt-welded insert accounting for the thickness of both the lower and upper courses. This can amount to a fairly thick plate, and it requires a welder with a higher skill level, however if done properly it is a good detail. The basic idea is to "split the difference" of the thickened plate taking care to follow typical rules from API-650 for thickened insert plates.
As Joe mentions there are no hard and fast rules in 653 for this type of repair and good judgement must be used. I hope this helps.

 

[MJCronin]

Jeff..

Be careful when weld repairing old tanks...of mysterious metallurgy. How old are these tanks anyway ?

In December 2008, there was a catastropic failure of a large rivetted tank that the federal govenment is currently investigating. The tank was one of three that was recently repaired (by an unknown technique)

http://www.csb.gov/news_releases/docs/CSBNewsReleaseAlliedTerminals12.8.08.pdf

http://www.csb.gov/index.cfm?folder=current_investigations&page=info&INV_ID=85

I agree with the comments above....time for a new tank..!!!

Let us know about your final decision

Regards


-MJC

 

[API123]

What is driving the replacement of the shell sections?

What product are you storing and tank size?

As previously mentioned, some of the older codes published by API and NBIC are some areas to investigate. Might even look into 12C, a lot of good information there as well.

Prior to any welded repair(s) take place, you may want to get some testing done on the existing material to determine the mechanical properties!!!

Hard to know exactly what you are going through right now, but you should try to replace it if possible if there are major repairs.

If there is no way possible to replace, send some more details and be very cautious of striking an arc on the shell until you can get some additional information.

Hope that helps you.

 

[chicopee]

Are there still firms out there that will do riveted work?

 

[IFRs]

Sure - I know of two on the East Coast. Where is your tank located?