Rewelding of Existing Weld Joints 2

[napster385]

Hi Everyone,

When an API 650 tank is dismantled and relocated to a new location, can it be welded on its existing weld joints? Or is it required to cutoff the Heat Affected Zones (approx 2in) on each sides/edges of the plate before rewelding? The API 653 only states that "the existing weld joints shall meet the requirements of the as-built standard."

Appreciate any advise. Thanks.

 

[SectionIX]

Take a look at following from API 653:

10.3.3 Shells

10.3.3.1 Tank shell plates may be dismantled using one of the following methods or a combination thereof.

a) Any shell ring may be dismantled by cutting out existing weld seams and the heat affected zone (HAZ) of the weld.
For the purpose of this method, the minimum HAZ to be removed will be 1/2 of the weld metal width or 1/4 in.,
whichever is less, on both sides of the weld seam.

b) Any shell ring 1/2-in. thick or thinner may be dismantled by cutting through the weld without removing the HAZ.

c) Shell rings may be dismantled by cutting vertical and/or horizontal cuts through the shell a minimum of 6 in. away
from existing welds, except where cuts cross existing welds.


By the way, two inches for HAZ removal is excessive. What is the thickness, material?

 

[napster385]

Thank you very much for your valuable response.

The material we are using is ASTM A36 plate 10mm thick. Do you also have reference for ASME VIII Div.1 pressure vessel? What is the requirement for ASME VIII Div.1 for the same conditions?

 

[SectionIX]

Hi Napster,

API 650 and ASME Section VIII construction requirements and service conditions are like comparing an apple to an telephone. I recommend you consult an NBIC Inspector if you have a specific application in mind as he/she will require more information (age, current thickness, heat treatment, product, location, seismic, local jurisdiction code requirements, inspection history, etc.)

To put things in perspective, the words "dismantle" and "reconstruction" are not present in ASME Section VIII, Div. 1.