Repair of Crude Column without Shutdown

[nickypaliwal]

Is it possible to make an extra layer of material on the corroded section of a pressure vessel to delay the shutdown?

 

[A clark]

The NBIC permits external weld build up of corroded areas. Look at Part 3 Section 3, 3.3.4.3 (3). This paragraph gives the requirements.

 

[metengr]

Are you are talking about an external weld build-up while the column is in operation? Repairs of this type are not addressed by the NBIC because you need to verify defect removal and integrity of the repair. On line repairs are case-by-case and should be discussed with the Jurisdiction or Insurer of the equipment, or look at the API code on repairs and alterations.

 

[weldstan]

I recall two instances of weld repairs to Crude columns in service that led to catastrophe. Do be extraordinarily careful!

 

[every_name_is_taken]

Also use ASME PCC-2 as a resource to help guide you. Article 2.2 speaks to external weld build up. I also urge caution if you plan on doing this with the vessel online, especially if it's the vacuum tower. You should do AUT across the entire area you plan on welding to check for any low spots where burn through is a real possibility. Alternatively to weld build you could try and weld a fillet patch over the corroded area, welding the seam where you know you have good metal. See PCC-2 article 2.12. Also look to API 2201 and PCC-2 article 2.10 to get your mind jogging about what to consider for welding on in service equipment. You can do this kind of repair, you just need to make sure you are very careful. And do not commit to something outside of your technical experience. If you need to, seek help from someone who can come to your site, not just some people on an internet forum. Profit is never more important than the safety and well-being of people.

 

[MJCronin]

Is this repair going to be covered by a HAZOP (or similar) review ?

This will be one of the first questions asked by the authorities if things go wrong ....

Where is the location of this column ? Inside the United States ????

MJCronin
Sr. Process Engineer

 

[nickypaliwal]

Thanks for all your responses. The location is Oman and I believe it is a populated area inside the city.

As I am not specialized in pressure vessel design so should study it based on your comments and come back.

 

[nickypaliwal]

To update, nothing has been finalized for forward action and we have regretted the project as we don't specialize in it.

Still I will try to gather information and share with you, if I get any.

 

[PMCap]

The NBIC does not currently prohibit restoration by encapsulation of a degraded area which is a means of implementing an ASME code restoration without breaching pressure boundary. let me know if you need additional information on this method of restoration. The method can be implemented in a timely fashion and is quite cost effective.

 

[nickypaliwal]

@PMCap Please send me some details of this method for my study.

 

[jte]

nickypaliwal-

Welded Encapsulations are one of many topics addressed in ASME PCC-2 Repair of Pressure Equipment and Piping Part 2. They're used commonly enough, and easy to fabricate out of materials readily available at most refineries and upstream facilities. Nothing secret or special about them, but it does help to have a pretty thorough understanding of vessel design, and occasionally, design by analysis.

 

[PMCap]

nickypaliwal - go to

http://www.pmcengineering.com