Repair against Chloride SCC in Tank

[RogerSAM]

Hello everyone,

We are currently facing an issue in our urea manufacturing plant. We have observed severe external chloride SCC in a carbamate solution tank. Design data is given below, and pictures of the cracks are attached for reference. There are currently two limiting factors:

1. Although we have recommended its replacement as soon as possible, but the logistics and planning are not allowing it to be replaced until 2-3 years later.
2. Wherever we attempt a repair, more cracks appear in the welds' HAZ.

I wanted to inquire if any of you have faced a similar problem and if so, what repairs can I undertake to ensure its safe operation for 2-3 more years?

Design Data
DP = 285 PSI
DT = 100 C
Service = Ammonia, Urea and Carbamate
Material = A240 Gr. 304L
Shell Thickness = 5mm
Bottom Plate Thk = 6mm
Design Code = BS 2654

 

[EdStainless]

There is no fix.
Tell planning that this tank will have to be taken out of service within a short period of time when it fails.
See how that impacts their plans.
You can clean and grind all that you want to.
But the stresses from the new welds will drive more CSCC.
If you needed to get a few months then there might be options.
Design a replacement tank in duplex and get it on order this month.
The duplex tank will be a bit thinner because of the higher strength.