Code Repair

[jfoe]

If there is a repair done on the cladding of an atmospheric column around a nozzle, would this be considered a code repair requiring the useof an "R" stamp holder etc. There is a leak noted from the telltale nozzle which has a s.s. insert and is seal welded at both ends of the nozzle. The telltale is drilled in the c/s side up to the sleeve. Most likely the problem we think will be around the seal weld on the vessel I.D. If the cladding is not fully removed can the use of any welder perform the repairs to either overlay build-up or weld to the clad? Also is there a common procedure for doing this repair etc. Any help would be useful.BTW, the clad is 410 S.S. Thank you.

 

[metengr]

What type of vessel is this – operating pressure? When you refer to an atmospheric column around a nozzle are you referring to a separate pipe or sleeve that can contain pressure or vents to the atmosphere if the nozzle tell tale hole develops a leak? Is one end of the sleeve welded to the nozzle/vessel surface?

Just an FYI: The scope of the National Board Inspection Code (NBIC) deals with ANY repairs that effect the pressure retaining capability of the item. This would include any welds that join a non-pressure part attachment to a pressure retaining item or its appurtenances (that retain pressure).

 

[jfoe]

It is an atmospheric column in a crude distillation unit. It is a 4" c/s nozzle with a 3 1/2" s.s. pipe inside of it. The s.s. pipe has a plate around it that is welded directly to the clad lining on the vessel I.D. and seal welded at the nozzle flange end. I am not sure of the Op pressure and would have to look that up. The telltale hole is drilled all the way through the c/s nozzle so product is getting between the c/s nozzle and s.s. pipe.

 

[metengr]

Ok. From the sounds of your description, this would fall under the NBIC, which requires having an R-Certificate for weld repairs. The weld repair to the cladding at the location of the C/S nozzle and ss pipe would be part of the pressure boundary of the vessel.

For weld repairs to the cladding, I would use either E410 NiMo or ER410 NiMo filler metal. If you need to perform any PWHT, make sure that you allow the repair area to cool to ambient temperature prior to any PWHT.

 

[jfoe]

What about using E-309 if the repair is just on the inner nozzle plate welded directly to the cladding. The design drawings show the use of E-309 here. I am assuming that this is where the problem should be. I'll know more once the vessel is opened.

 

[metengr]

Yes, absolutely. I was going to mention this filler metal depending on where the weld repair would occur. At this point, if the seal weld is only cracked, I would definitely repair with the E309. However, if by chance you need to remove more of the cladding to chase flaws or cracks, I would go back with E410 NiMo to repair the 410 ss cladding, and use the E309 to restore the seal weld.

Also, after weld repairs are completed make sure you perform a Liquid Penetrant (PT) inspection of the repair area to assure compliance with RC-2051 of the NBIC.

 

[PAN]

jfoe and metengr,
Both nozzle plate and clad material are stainless steel type 410. This is not the dissimilar material. Should we use E308 instead of E309?

 

[metengr]

PAN;
If welding is being performed directly to the 410 ss cladding and the nozzle plate (which is also 410), I would use the 410NiMo. If welding is being performed between the 410 ss and the carbon steel base material, I would use 309 for this repair, not 308.

 

[jfoe]

Actually the plate is SA-240 TP321

 

[PAN]

metengr,
In case of welding 410 S.S. with 410NiMo, preheating and PWHT should be performed. I understand that E308 can be used without preheating and PWHT. Please comment.

However, the plate is 321 S.S. Therefore, E308 should not be used here.

jfoe,
This may out of topic. However, please advise us about the design to use several materials in your application. In my experience, 410 should be used at the upper part of column. Austenitic stainless steel (such as 321) should be used at the lower part of column. Where is the location of this nozzle?

For the repair work, I suggest you to check the original WPS before making decision about welding repair work.

 

[metengr]

PAN;
Correction in your first statement above; the application of preheat and PWHT requirements are a function of base metal(s) and weld metal. If one or both of the base metals to be joined is 410 ss, preheating and PWHT requirements will be followed for using 410 ss, regardless of weld filler metal.

 

[jfoe]

The nozzle is located at the bottom of the vessel.

 

[PAN]

metengr,
Thanks for the advice. I used to start a thread about welding 405 S.S. Please comment in thread725-73081.

 

[valero]

If it not too late you may think about removing the 410 sleeve and doughnut ring and go with an Inco A, or 182 overlay. I believe there are automatic welders that can handle 4” nozzles. Try GE welding. Another option is to remove the c/s nozzle and replace it with a 410 nozzle the overlay the i.d. shell area where you removed the doughnut ring with Inco A, or 182. Talk to your metallurgist for the best Inco filler for this application. This type of nozzle liner application has given me fits for a while in our Crude column. The overlay is far better and reliable. Another hint on your Crude column, or other insulated equipment with the same type nozzles is to insure you have some ¼” threaded piping that extends past the insulation if the nozzle weep hole is covered. I’m not sure of the operating temp at the bottom of you column, but it may be to high to use 309 filler. Also if you are performing an internal inspection pay close attention to the shell in the upper area where you transition from bare carbon steel to Monel clad. Do you closely monitor your overhead piping with ultrasonics? I am sure you have an injection up there and that is a place to look for elevated corrosion rates unless you have gone to a monel liner / overlay in that line.