Composite Reinforcing Pad

[Alcinei]

We will need to increase the reinforcing area of some nozzles in an existing Pressure Vessel due to some modifications in the Operating Conditions. These nozzles are already reinforced with Pads nowadays. The easiest way would be welding another Pad over the existing one. Does anyone have experience on doing this? Is there anything in ASME Code Sec. VIII that doesn´t permit this type of solution?

 

[Merzi]

Alcinei,

I do not think you can weld a pad on top of another pad to make up for the reinforcement. ASME does not have any sketch highlighting this. However ASME does allow you to install a pad in the ID of the vessel, refer to UW 16.
1 a-3.
Regards

Merzi

 

[jazzer]

If conditions permit, and you do not need to add a lot of reinforcing material, you may consider weld overlay of the existing pad. This has been successful for me on several occasions. PWHT may be required.

 

[deanc]

The answer is no. The pad must be attached to the vessel wall. See Interpretation VIII-1-92-42,which sends you to
UW-16c & UW-16d.

 

[Alcinei]

Does anybody know if the material ASME / ASTM A-210 A1 is susceptible to pitting corrosion type when submitted to salty environment?

Thanks in advance!

Alcinei Nery

 

[bmoorthy]

To your first Question

Pad reinforcement can be by increasing the thickness, Increasing the dia, by providing internal pad.

Increasing thickness can be by weld deposition.

Increase in dia can be done by cutting a plate such that the ID of the new pad is OD of the old pad (With necessary Weld preparations). Then weld the Old pad tonew pad by a butt joint and weld OD of the New pad with the vessel Wall.

if you opt to provide inside pad, provide at least 2 holes, on at the bottom (Lowest portion of the pad) another at the top. This will ensur there is no retained fluid between the pad and the Vessel wall. If you do not provide relieving, it could lead to failures.