hydrogen blistering ion Amine stripper

[rsauk]

The plate material for this amine stripper is A516-grd70.
38mm.thk. (presumably laminated)
The bottom of this column has blistering which has cracked.
The blisters are contained in a band approx 12feet (circumferentially) x 3feet blisters are linear (top and bottom) each blister being 200mm.plus.dia. Cracks are fully exposed and approximate to mid wall thickness.
The suggestion is that (the damage) is typical for this condition. and the worst is past.
This situation has been identified during retraying exercise and we would obviously like to put this back into service until such time as a replacement section can be fitted.
Is this possible and what monitoring would be necessary throughout and how long could it stay in service.
Operating pressure is 5.6kg/cm2 and temp of 70-80 degrs.C.
diameter of vessel is 4.1metres.

 

[rustbuster]

rsauk,

Sounds like your solution is degraded and or your rich loading is to high.
I would say the worst will continue if solution quality is an issue, i have seen 30 year old strippers in fine condition while others were destroyed after a few years.

Oxygen ingress is one of the highest culprits in degrading amine solutions. Make up water should be with steam condensate.

Based on your description, your rich piping, if carbon steel is likely in poor condition. If have seen damage in 300 series stainless systems (preferential weld) where solution quality is poor. Also damage in lean systems under these conditions.

Check the solution for degradation products. Replace or reclaim if this is the case.

Good Luck

 

[flames]

Depending on the conditions, the assumption that the worst has past could be dangerous. I suggest you preform a fitness for service assessment (API 579 or a similiar process) using someone experienced in this type environmental cracking.

If you decide to operate this vessel you should definitely monitor the known blisters using UT methods (combinations of shear wave, straight beam and TOFD). The regular external inspections will provide data to continually update the fitness for service assessment.

Did your inspection also try to assess SSC concerns in the welds?

 

[mqreis]

for the assessment of the blistered areas we have to know
1- the max. blister dia
2- the min distance between the closest blisters and the distance from nearest structural members like nozzle, attachement,...etc.
3- are all blisters at the same level
4- dia of the vessel
5- is the vessel Heat treated
Nowe if the remaining thickness is half the design thickness then you may run ((if the production is needed urgently)) provided U/S scanning from outside is monitored.
check SCC in amine service which is also critical in such service

 

[pickuw]

The following could be done:
1. Checkfor the degradation of MEA and change it if required.
2. Use treated boiler water for make up.
3. Perform UT (preferably) or RT in the blistered as well as satisfactory areas. Interpretation to be done by levelIII holder.
4. Rerate your equipment from company like Lloyd's Rgeister and obtain certification from them for using the equipnment for a fixed period.
5. For your new equipment insist on stress relieve of the welds irrespective of thickness.

Regards
Surya ssp
pic, kuw.