Integrity of vessel with additional weld joints

[Inspectengr]

we have a pressure vessel having following specsifications:

0.03 kg/sq.cm & 140 degree Centrigrade
Shell = carbon stell ASTM A516 Gr. 55 thk. 13 mm
cladding= AISI 304L thk. 3 mm
Design Code =ASME Sect. VIII Div. 1

Due to the reduced thickness of shell cladding , vessel's shell courses was replaced with 16mm full strength SS 304L sheets........But due to time constraints vessel shell pieces was replaced without keeping in view of the original configuration of Shell courses...
So now at this time, the vessel is composed of many different small pieces instead of two shell courses and not a single circumferential joint is in line


Now the Question is on the Intergrity of this vessel due to increased no of welded joints in longitudnal & circumferential postions of shell. Please tell with reference to ASME Section VIII or any other international code the effects of additional weld joints on the vessel integrity.

How we can assure the reliabilty & Integrity of pressure vessel in such condition. Please elaborate the response.
For any other information please do not hesitate to write.
Regards

[mechcolor]

There is no issue as far as you have taken the recommended joint efficiencies mentioned in ASME Sec. VIII Div. 1 when assessing the shell plate thickness. I am referring to the joint efficiencies taken considering the level of inspection made on the welds (spot Radiography, full or none)
Moreover, an industrial practice of minimum distance between two weld joints (longitudinal or circumferential) is kept at 6 in. which I am sure must be adhered in this case of vessel.

[ben]

I agree with mechcolor.
Welds which have been 100% radiographed would be as good as the original steel plate keeping a reasonable distance between the welds while staggering the seams too so that HAZ must not overlap and the stress concentration remain in acceptable limits.

[mechengr]

@mechcolor

But what could be the other possible solution of above mentioned situation...................

or what are the recommended practises for repair of reduced cladding thickness in pressure vessels .....is there any code or standard

[ashfaqanwer]

mechengr,
You may be interested in looking at the following thread also:
http://www.thepetrostreet.com/forums/vi ... ?f=18&t=44

[mechcolor]

It depends upon the actual data of the pressure vessel.
Before attempting any repair in a cladded or weld overlaid pressure vessel, some important factors are to be considered.
1. Original thickness of base metal
2. Extent of metal loss in cladding
3. Local loss or general
4. Vessel post weld heat treated or not
5. Service conditions (pressure, temperature, service fluid)
6. Code of construction
After looking into all this then a repair procedure in accordance with post construction codes is applied.

@mechcolor

But what could be the other possible solution of above mentioned situation...................

or what are the recommended practises for repair of reduced cladding thickness in pressure vessels .....is there any code or standard

[irish]

Cladding can be recovered by making weld overlay depending upon the chemistry of base material and the thickness.
Otherwise, butt welded insert plates in corrosion resistant material is a workable option.