Welding of non pressure parts(external cleats) after Hydrotest

[John121]

Equipment: Pressure vessel
Thickness: Thickness More than 200mm
Code: ASME section VIII Div 2 and U2 stamp.

As code said that No welding is allowed after Hydrotest.

But piping modeling design progress is far ahead and other hand vendor is worked out the all the possible roller position but there are some cleats on roller path. At progressive design stage we are not prefer relocate the cleats position since it have serious major piping design rework. Also roller position can not changed before hydrotest. Vendor also denied to use RF pad on those clashing cleats since obstruction in rolling path.

So only option balance is that to weld cleats after hydrotest prior to shipment. so it is permissible to weld non pressure attachments on DIV 2 Code stamp vessel after Hydrotest? If permissible then what are the additional requirement.

Also, Any alternative to deal such issue?

 

[racookpe1978]

Have you evaluated the locations sufficiently to estimate where the pads will be placed?

Seems like the critical (metallurgical-affecting) weld will be pad-to-pressure vessel wall. Not support to pad.
If so, then weld over-sized pads to appropriate locations with an fillet weld all around. The actual support (cleat) then goes to the welded pad, but does not touch or affect the PV steel underneath the pad.

Pads may need to be over-sized, over-thick, more expensive, but you can have it three ways: Quick, cheap, or high quality. Pick two.

 

[John121]

As said earlier, Rolling operation not allows RF pad on rolling path. So we are not using RF pad, instead checking the code acceptability of the welding of cleats directly on shell after hydrotest.

 

[XL83NL]

Please refrain from double or multiple posting on the same topic next time. I have RF-ed the other threads for deletion.

Huub
- You never get what you expect, you only get what you inspect.

 

[racookpe1978]

No. Rolling the tank walls is a fabrication step - a very early fabrication step well before welding.

Surely you are not pretending to plan on rolling a fabricated pressure vessel after the hydrotest?

 

[weldstan]

Could rolling be involved with sub arc welding the circ seams? If the pad welds are made to the shell (pressure part), PWHT is required prior to hydro. I can see no real problem with doing so. The complete vessel is hydro tested.

 

[david339933]

I think an explanation as to roller and roller path is needed. If it is as weldstan indicated, then this should be established prior to fabrication. You cannot use that as an out to weld post hydro.

 

[0707]

IMO after the PWHT conclusion and the final hidrotest nothinng can be welded directly to the vessel shell.

luis