Its a question just for academic interest, do not know if this condition will occur in reality. Request your opinion/ advise on following;

How do we comply to code requirements (UG 99-g) of inspecting all the joints and connections during hydrotest for a jackaeted vessel falling under lethal service category.
One option of considering partial jacket leaving weld joints accessible for inspection comes to my mind but this may be very difficult considering all the long/ circ seams and nozzle attachments.

Regards

It happened to me when I was inspecting glass lined pressure vessels. Being special items for pharmaceutical and advanced chemical (and war, I am afraid) industry, it happened few times to have inner chamber in lethal service. This was not a problem because the jacked had only an apron (the closing ring welded to the shell) for glass lining purposes (heat treatment for glass consists in 3 or more cycles at temperature 920 - 950 °C).
The inner shell was hydrostatic tested after glass lining without the jacked. The jacked welded and hydrostatic tested afterwards. You can do the same.
Mauro

Dear Mauro,

Thanks for your reply. I still have one confusion on the same;

We are supposed to carryout hydrotest after completing the welding/ fabrication, did you repeat shell hydrotest after jacket closing ring welding on the shell and considered that shell welds (which are not accessible after jacket is in place) have already been checked during hydrotest before jacket was in place?

Thanks again

Regards
Sanjeev

Repeat,
shell was complete
the closing ring of the jacket (apron) was welded to the shell
shell was glass lined
shell was Code hydrostatic tested (for glass lined pr.vessels need not to be more than MAWP, they did at 1.1 x MAWP)
jacket was welded to the "aprons" (are called aprons the closing ring of the jacket welded to the shell), therefore no weld done on the shell itself (glass lining would crack).
jacket was hydrotested
shell did not need repetition of hydrotest (done already). However repeating is not prohibited.
mauro