Flushing of Weld surfaces of Pressure Vessels and Heat Exchangers

[DK44]

1. Is it necessary to flush the inside and / or out side weld surfaces of (L seams & C seams) of Pressure vessels and Heat Exchangers. If so for what reasons?
2. If such flushing (especially inside) is not done, leaving as welded surfaces , is it detrimental to the Vessel and in which way.
3. Does ASME Sec VIII div 1 / TEMA / API 660 provide specific requirements on this aspect.

 

[SnTMan]

Not sure what you mean by flushing. Probably can be found in TEMA & API 660 some language about internally free from grit, debris, etc.

Weld beads are usually cleaned of slag, etc. but generally otherwise left as welded.

Regards,

Mike


The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[metengr]

1. Is it necessary to flush the inside and / or out side weld surfaces of (L seams & C seams) of Pressure vessels and Heat Exchangers. If so for what reasons?

Section VIII, Div 1 does not require it. If the Purchaser's specification requires it you do it. Why do some require flushing, because of in-service inspection using PAUT.

2. If such flushing (especially inside) is not done, leaving as welded surfaces , is it detrimental to the Vessel and in which way.

As long as the reinforcement for the weld caps do not exceed the Code maximum, and the appearance of the weld is acceptable for examination, it is acceptable for service by Code. Note: The Code provides minimum requirements.

Does ASME Sec VIII div 1 / TEMA / API 660 provide specific requirements on this aspect.

Read the books......

 

[Trestala]

We request fabricators to grind flush the inside surfaces of welds on shell side for removable tube bundles. Or when plates (e.g. reinforcing pads) would be placed above butt welds.

 

[Vikko]

You have to clean after welding and remove material by grinding where necessary. I have seen doing small chamfers on internal side of the shell, after welding connections, but I do not think is necessary.

I see 3 problems on weld surfaces:
1) corrosion is higher on weld edges, which are not smoothed
2) stress is higher on geometrical shapes with sharp edges
3) there can be some stress concentrations inside the heat affected zone, which can in the long time develop cracks

Also, if external surface are not clean, depending on the materials used, there is possibility of oxidation on the weld surface, for atmoshperic exposure.

I am not sure on any particular requirement on any code.

 

[r6155]

This is the best design,including smoot finish in fillet welds, generally not required.
Welds shall be ground flush with the base material for pharmaceutical, food industries.
Also when coating / linning is applied.

ASME VIII Div 1 UW-13 (b)(4)(-a) The longitudinal weld within the area of the
offset shall be ground substantially flush with the parent
metal prior to the offsetting operation.

See: UG-82, App 21.3 , etc
Also I use in the longitudinal weld of nozzle in manhole.

Regards
r6155