Vent hole for re-pad inside the vessel
Vent hole for re-pad inside the vessel
(OP)
All,
I have a situation that re-pad will be required inside the vessel for a beam seat. The re-apd and beam seat with be covered with 4" thick refractory to block heat from catalyst at 1000F so the CS vessel wall will be about 350F.
Do I need to put a vent hole for the re-pad ? My concern is it can trap moisture after hydrotest(this is a 15' dia FCC vessel), water and refractory may get in through vent hole during refractory installation( Note, vessel will be heated up to 1500F to dry out the refractory), and if refractory cracks during operation, catalyst may get in that will pop up the re-pad. Or shall I just plug and seal weld the vent hole after welding re-pad and leave it alone ? If plugged, will the little air or moisture trapped be a concern ?
I have a situation that re-pad will be required inside the vessel for a beam seat. The re-apd and beam seat with be covered with 4" thick refractory to block heat from catalyst at 1000F so the CS vessel wall will be about 350F.
Do I need to put a vent hole for the re-pad ? My concern is it can trap moisture after hydrotest(this is a 15' dia FCC vessel), water and refractory may get in through vent hole during refractory installation( Note, vessel will be heated up to 1500F to dry out the refractory), and if refractory cracks during operation, catalyst may get in that will pop up the re-pad. Or shall I just plug and seal weld the vent hole after welding re-pad and leave it alone ? If plugged, will the little air or moisture trapped be a concern ?





RE: Vent hole for re-pad inside the vessel
General Blr. CA,USA
RE: Vent hole for re-pad inside the vessel
Regars
r6155
RE: Vent hole for re-pad inside the vessel
Shell 5/8" thk, pad 5/8" thk, pad size about 18" x 30".
RE: Vent hole for re-pad inside the vessel
If tapped the pad can be air tested in the future if needed, although seal welding the plug will make this a little more difficult.
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Vent hole for re-pad inside the vessel
If you don't make Vent Hole, Reinf. Pad Inside will be sealed perfectly.
During Operation,High Temperature will expand Air inside Reinf. Pad due to Heat.
Finally, The Expanded Air will break Welding between shell & Reinf. pad.
As normal practice, All pad should have vent hole.
Regards,
Moon
RE: Vent hole for re-pad inside the vessel
Regards,
John
RE: Vent hole for re-pad inside the vessel
2) Beams should never be welded directly to the vessel wall because of the restraint they would impose on vessel growth.
Use beam sets, clips or support ring when design internal beams, they will allow for the radial expansion of the vessel due to temperature and pressure. Slotted holes in the clip or for the bolting attaching the beam to a beam seat allow for expansion.
See Pressure Vessel Design Manual 4th edition, by Dennis Moss
Regards
r6155