Procedure to add a 4" and 6" nozzle to pressure vessel

[mechtechmalech]

Hey Guys,

I have a oil treater pressure vessel I want to add in 2 nozzles. The reason I'm doing this is because we have some corrosion we want to cut out and replace it with a nozzle instead of a flush patch to waive the complete hydro test of the vessel and stick with a local hydro test. Could someone point me in the right direction as to where I would find and example procedure or something of the type to build a procedure for this.

 

[rustbuster]

You will need to submit a repair alteration to your AI for approval. If you already have a 2" nozzle on the vessel with no re-inforcement you should be in a good spot. If you want to put in larger nozzles you would need to submit design calculations.

 

[PMCap]

Perhaps the below may be of some help in resolving your issue:

Restoration by encapsulation without removal of the degraded area is not prohibited by the NBIC per Interpretation 04-01

This method of restoration can be very cost effective as the degraded area does not have to be removed thus saving fit-up, welding, and examination installation time and avoiding entry of foreign matter into the vessel.

The Encapsulation component attachment weld is typically classified as an ASME Category D weld that would not require volumetric examinations.

The AI has the authority to waive the hydrostatic pressure test.

Typically, a liquid penetrant or magnetic particle examination is performed on the root and final pass of the full penetration encapsulation to shell attachment weld. See NBIC Interpretations 98-33 and 98-38.

Alternatively, the encapsulation component can be supplied with a pressure port for local pressure testing – see NBIC Interpretation 01-15

I suggest you search the internet using the keywords such as asme - vessel - restoration by encapsulation, etc.

Let me now if you need any further help on this method of restoration for which I am extremely familiar

 

[mechtechmalech]

Could you please explain the process of encapsulation to me.

 

[PMCap]

Encapsulation process surrounds existing degraded pressure retaining material with a a new pressure retaining chamber that iw full penetration welded to the existing component and replaces the area of pressure boundary with new pressure boundary material. the encapsulated area would be considered to have completely wasted away in the new ASME Code calculations that support code compliance of the new pressure chamber and the existing component with the new chamber in the as-installed condition. Again I suggest you search internet using keywords such as "asme" - "vessel" - "restoration by encapsulation" - "nbic" - interpretation 04-01".