repair misalignment of shell courses

[mechglitch]

What is the procedure to correct misalignment of two courses in a vessel? Can the weld be cut open and redone, or does material on both sides of the circumferential weld need to be removed? The misalignment occurs where a 40 mm thick course butts to a 35 mm course. Where is this type of repair addressed in the codes?

 

[vesselfab]

The code does not generally address how repairs are made.

It says alignment mus be like this.

we line up the surface of the courses that is called out on the drawings....I.D. or O.D.

then we make transition with the weld seam. If the length of transition is longer than the with of the seam, the portion of thinner can that will be covered by weld transition, is subject to NDE as prescribed by code.


All this of course is subject to my understanding of your mis-alignment problem

 

[metengr]

Repairs to nonconformances are not addressed by the Code for obvious reasons. It is up to the manufacturer to rectify the nonconformance to the satisfaction of the AI and to the customer (if required by contract or the QA Manual).

 

[mechglitch]

Say the upper course was incorrectly positioned relative to the lower course.

What would be an acceptable procedure to make this right? The original misalignment was accepted by the purchaser, but the purchaser now wishes to have it corrected.

For example, let's say an entire horizontal weld was deemed defective. What is the correct procedure to replace that sheet or course?

Should the vessel be cut back several inches on either side of the weld? How far apart would these new horizontal welds need to be? (Or is there a way to just 'redo' the weld by gouging out ane rewelding?)

 

[metengr]

For example, let's say an entire horizontal weld was deemed defective. What is the correct procedure to replace that sheet or course?

If it was me, I would simply remove the defective weld by grinding, arc gouging or machining, re-position as necesary and re-weld.

 

[unclesyd]

if you takeout the weld make sure your centerline and face to face dimensions are within the stated tolerance.

 

[mechglitch]

Sounds like anything can be done. Two horizontal welds spaced 1 or 2 inches apart are not too close together? Please reference the codes so I know what inspectors look for as far as a well constructed vessel. What NDE, preheat, or PWHT would be required by the codes for such a repair of 40 mm plate.