3 replies to this topic

[fallah]

Dear All,

Considering 2nd item of section 7.3.6.3 of API 650 Ver. 2007 (2-Specifying the test water quality.....),
Could it be concluded that hydrotesting API storage tanks by sea water is possible?

Thanks

[Qalander (Chem)]

Dear fallah

Although I don't have the referred details right now in front, but recall many many API 650 design storage tanks tested with sea water many a times either after erection, repairs/ refurbishments at our previous employer's Near port terminal.

What are your concerns;as our Fire water was again Sea water stored in one such tanks.

Hope this helps

[fallah]

Dear Qalander,

Thanks for your response.

My main concern is corrosion due to hydrotesting by sea water on carbon steel tank.

Let me know if in the hydrotesting operations of API tanks you mentioned they had been tested with sea water,chemicals such as oxygen excavenger or PH increasing agent had been used?What were the materials of those tanks?If after operation, the tank had been rinsed by treated water?

Best Regards

[Qalander (Chem)]

Dear fallah,

Now since you want, I further elaborate but we had almost nil options to choose.

It's true that corrosion issues are there, but to the best of my knowledge and understanding we did'nt employ any chemicals, oxygen scavengers etc.

Most usually water used by gravitating under static head via suction pipeline system into the designated tank from Terminal's main fire water bulk storage in small small batches

Whereas Firewater tank was under simultaneous/ continuous sea water make-up from top via our Jetty submersible pump(as per high tide timings).

No extra ordinary corrosion rates were noticeable;

since usual routine immidiate to the water drain-out was complete manual cleaning to dry-off, then earliest in designated product service.

Wherever/ whenever possible we arranged for:

1) Appropriate intrnal epoxy coating inside roof/ shell roof adjoining areas & one feet of shell inside (after sand/ grit blasting)
2)also internal shell/bottom peripherial epoxy coating upto about one feet of shell inside.

This was mainly done to take care and protect:

(a)against in-breathing of salty water entrained dew induced corrosin on top areas and
(b)any cuude oil accompanied ballast sea water induced corrosion in bottom areas

Mostly an average life of 18~23 years was seen.

Hope this proves useful.