29 Jun 02 9:52
I believe the weld in concern is the nozzle to shell weld.
As an inspector, one should always include visual inspections of the weep hole when inspecting the rest of the vessel anyway. In my experiences, I have seen several occasions where the nozzle to shell weld has cracked or even been subject to severe corrosion and began leaking. This allowed product to completely fill the gap between the repad and the shell causing severe corrosion to the shell. Eventually, the crack(having been exposed to the now corrosive environment) propagated about 3" into the shell which finally allowed enough product to reach the weep hole. No one knows how long it took for these events to occur but needless to say .....it did.
Recently, when inspecting large aboveground storage tanks, several clients are requesting Ultrasonic thickness testing of the repad looking for this type of corrosion.
As far as plugging the holes with grease goes, it is usually put there to keep water from being trapped behind the repad thus creating a corrosion problem. And, there will always be someone who sees the grease and assumes it to be a leak.
On painting the weep holes, that would only defeat the purpose of the hole being there in the first place! Now the hole is sealed up and product that might leak out, has no place to go.
Just my thoughts.....
Mechanical Integrity Specialist
Pharmacia Global Supply Arecibo-P. Rico