Tank wind girder corrosion

[ER_Azza]

Hi All

I need a bit of pointers on the best repair option with the tank (fuel) remaining online. Therefore no hot work

There is corrosion on the wind girder of a tank. Look for ways to repair and arrest the oorrosion.

See photos.

Any feedback would be appreciated.

 

[IFRs]

blast and paint?

 

[ER_Azza]

You mean WET blast and paint?

 

[HTURKAK]

Apparently, the wind girder deails violates the rule of API 650 5.9.3.3 .

This is copy and paste of the relevant section ;

( Rings that may trap liquid shall be provided with adequate drain holes. Uninsulated tanks having rings shall have small
water-shedding slopes and/or drain holes or slots unless the Purchaser approves an alternate means of drainage. If drain holes are
provided, they shall be at least 25 mm (1 in.) diameter (or slot width) on 2400 mm (8 ft) centers or less. Insulated tanks where the
rings function as insulation closures shall have no drain holes or slots.

I will suggest you to consult with a paint expert and HSE .. IMO, acid pickling should be considered as an option.

 

[IFRs]

Er Azza - what is the liquid being stored? Is it gasoline (fuel) or #6 (fuel) oil, etc?
Would it be safe to power brush and paint?
Basically any way to safely remove the blistered paint and re-coat to stop further corrosion.
Is the tank in a desert or on the sea shore?

 

[r13]

You should consider sandblasting.

 

[ER_Azza]

Thanks All

Agreed that the tank girder did not have drain holes.
It was built awhile back.
Will definitely put in a couple of holes for draining.

But as you can see from the corrosion area, if not obvious, seems to be due to heat affected zone corrosion on the tank shell, just above the weld. Not on the girder itself.

My thoughts is to use brittle blast, kind of hand prep blasting which is very safe (no spark).
And get it painted. Only problem is that, will need two different contractors - one for the blasting and one for the painting.

Tank has diesel.

Appreciate the feedback, as all suggestions did get my brain to recollect from past experience. It's been awhile since I did work on tanks.

 

[HTURKAK]

These are my thoughts ;

- The corroded area implies dew fall is also effective rather than HAZ. Are the tanks located around seaside ?

- Still i will suggest corrosion removal with diluted acid . Any work which may produce spark or static electricity should not be considered. I know Muriatic Acid ( trade name ) is available at DIY markets etc.. The person shall use hand gloves and surface mask for personnel protection. I searched the web for muriatic acid and one of the outcomes;

https://www.youtube.com/watch?v=N3T61g1mjfU

 

[ER_Azza]

Thanks HTURKAK.

Very interesting. I wonder whether it's been used on storage tanks.
I would not be hesitant to try it on smaller water tank.

But a big conservative when it comes to big fuel storage tanks.
Concerned with the potential metallurgy degradation on using the muratic acid which might show over the years.
Would need to study further.

Thanks again. Good tip on using the acid which may could be practical for other application.

 

[IFRs]

Check with your safety team but diesel is not too bad for doing a brush blast and paint. Is this a fixed roof or external floating roof or internal floating roof tank? I don't normaly see the HAZ which in this case would be small from just fillet welds being a factor in coating failure, probably preparation, paint selection and application execution.

 

[Dhurjati Sen]

Belzona dear, the one and only saviour....

DHURJATI SEN