API 653 tank shell repair

[ird192]

I have a client that has a above ground storage tank , a chemical spill damaged a area of the shell 10" wide 18' vert. the shell plate is three different thickness . My interpretation of Section 9 allows for removal of the damaged shell plate and 1 continuous insert plate to be welded back while meeting vert. spacing requirements in API 653 . The plate would cover 2 horizontal welds which si acceptable per this code . I dont see any issue with installing 1 continuous plates as long as it meeting the design requirements of API 650 , verus installing 3 spearte insert plates, comments are welcom , B hart API 653 / PE Thanks

 

[HTURKAK]

As far as i understand, your plan is to cut and remove the damaged shell plate and use three insert plates . Pls read again 9.2 REMOVAL AND REPLACEMENT OF SHELL PLATE MATERIAL
(.....9.2.2.2 Where one or more entire shell plates or full height segments of shell plates are to be removed and replaced, the
minimum spacing requirements specified in Figure 9-1 for vertical weld joints shall be maintained. It is acceptable to remove and replace entire shell plates or full height segments of shell plates by cutting and rewelding along the existing horizontal
weld joints....)

The width of the insert plates shall be choosen to provide minimum spacing requirements specified in Figure 9-1 for vertical
joints.

Pls read also 9.3 SHELL REPAIRS USING LAP-WELDED PATCH PLATES the requirements 9.3.1.1 thru 9.3.1.10.

In order to get better responds, provide more info.( thickness of shell plates, remaining thickness, size and service...)

 

[ird192]

My proposal is to install 1 continuous vertical insert plate over the three shell plates versus installing 3 separate plates which will require more welding , I do not see any prohibition to that route, meeting the vertical spacing requirements and sizing the plate thickness to meet API 650653 requirements. I'm only looking for comments on the concept of 1 plate versus the three plate option. the Lap plate option para. (9.3.4.6)
requires a inspection of the orginal damaged shell plate at future intervals, and could result in another repair . I dont care which way they go just think the 1 insert plate option is acceptable per API 653

 

[HTURKAK]

If the repair will be ( 9.3 SHELL REPAIRS USING LAP-WELDED PATCH PLATES ) 9.3.1.7 The maximum vertical and horizontal dimension of
the repair plate is 48 in. and 72 in., respectively.


API 653 and 650 are standards. If the repair area 10" wide 18' vert, you are expected to follow ( 9.2 REMOVAL AND REPLACEMENT OF SHELL PLATE MATERIAL ).

If you want a meaningful respond, provide more info. ( the shell course thicknesses, a sketch showing the vertical and horizontal joints of the shell w.r.t. repair area, dimensions of the tank, service, ..etc)

There is a forum ( Storage tank engineering ). You may post this thread there to see the comments of others..

 

[bimr]

You probably would get more responses if you posted this in the Storage Tank Engineering forum.

 

[pbc825]

I'm a tank engineer, and I do a few tank repair projects each year. I would consider a full-length (18') plate to be field-installed only if the existing plates are outside-stacked. I don't think this is common, but should be field confirmed. If they're centre or inside stacked, then the maximum lap-plate length should be in-line with the existing horizontal joints for another horizontal field joint.

One other think to consider, is 9.3.1.7 and the limitation of 6' as noted above. The horizontal welds are not critical (therefore, the quality and inspection requirements are typically relaxed), and the time/cost of two additional horizontal welds will be minimal in the project scope.

PC

 

[HTURKAK]

The original thread was ,


and this is defined at 9.2 REMOVAL AND REPLACEMENT OF SHELL PLATE MATERIAL .

API 650 and 653 are standards and do not allow full vertical joints to be aligned.

and in API 653

However ,I have seen full aligned single vertical joint tanks in eastern countries.