Hydrostatic Test of Storage Tank Using Sea Water

What materail is the tank made of?

if it is steel do you have any zinc plates in the tanks?

I just came across information on corrosion inhibitors....

May be you can use one but then you may have to use detergents to

clean the tank before use.

You also have to add a dye to the water you will use to make sure you can detect any leaks.

Check this two links

About corrosion: http://www.gim.bnl.gov/misc/envtest/dlcal/corrosion.html

About Corrosion Inhibitors: http://en.wikipedia.org/wiki/Corrosion_inhibitor

Note about my previous posting:

Make sure that the corrosion inhibitor you use does not mask leaks by

temporarily sealing them. That may give you a false integrity check.

CuNiFe may help to store water for people in your country.

Hi,

Hydrotest is carried out to find out any leakage at certain pressure. Sea water contains many corrosive salt, which may react immidiately with tank material , this way sea water corrode the tank also reduce life span. So, if you do hydrotest using sea water, then again you have to clean the tank using DM water or using other chemical, which may be expensive. This is the reason why International Standard like API suggest some specific rule for hydrotesting.

Depending uopn the use of tank, and nature of Hazard, you can decide whether to use sea water for hydrotest. But for Oil& gas, petrochemical, chemical, it is certainly not advisable.

Others have covered the corrosion aspect, but now let's think hydro efficiency. Seawater is heavier than fresh water and as such may not seek out leak paths as well as fresh water. Whilst using fresh water we use a surfactant to make the water 'wetter' so it will migrate out of small leak paths easier. Maybe some experts on fluid mechanics can comment on this aspect.

During my days of designing and constructing salinazation plants we used a spray on plastic liner to coat the inside of the salt water and fresh water tanks. I cannot remember the name of the manufacturer of the spray on liner, but start there, also try using all pvc as it lasts longer with quicker and less maintenence that steel.

Thanks for all the input.

Detail of the steel tanks

3 x Crude Oil Storage Tanks 80M dia x 23.6m

1 x Light Fuel Oil Storage Tanks 12M dia x 10.9m

3 x Potable Water Storage Tanks 101.5 x 20.9 m.

Contractor have plan to carried out the hydrostatic test with sea water which very corrosive and we can't accept it unless they can prove that no risk of corrosion to the tanks.

With best regards

arah

Thanks for providing the tank measurements. Could you also confirm the tank material and construction?

Thank,

The tank construction material will be mild steel.

Cheers

If the material is mild steel I don't recommend that you use ocean water. You can see corrosion in a very short time.

If the hydrostatic test is done only one time shortly after installation, I would go the extra mile and use fresh water. When you add the dye for the test you can also add an anti-corrosion product.

PS

If you need a holding tank for ocean water before it goes to the R-O, look into alternate materials. If the alternate materials (ie plastic) dont provide enough strength to build a large tank, consider a series of smaller tanks or a steel tank with polymer lining.

seawater is very corrosive to carbon steel and usually it should not be used, but in my personal opinion it all depends on the time of exposure of carbon steel to seawater. i mean that corrosion rate can be in ther order of 0.3-0.5 mm/y (millimeter per year) for a general corrosion rate and more for a very localized corrosion attack, and is a function of temperature, flow verlocity, salt content....

So if your test will take a short time, the effect of corrosion in my opinion can be negligile.

It depends also on the type of fluid that will be stored inside the tank in service..

you should look into API standard 653 "Tank Inspection, Repair, Alteration, and Reconstruction" you'll find information on hydrotest

Dear Sir

Vappro 844 Corrosion Inhibitor Powder in Seawater is what you're looking for. This is our new innovation from last year designed for as ballast tank addictive but ideal for hydrotesting using seawater. Our lab test with a mild steel in seawater added with Vappro 844 VCI powder show nil corrosion after 1500 hours. Please review www.tresolchemical.com.my for more information

Regards

Albert Lim

Corrosion inhibitor additives...cost?? Really, specifically sea-water?

Potentially, post-test purge with inert gas and monitor moisture content first, then O2 content(%). Depending on pressures involved, use a light oil or diesel, diesel fuel combusts in the region of >200bar. Pressire test circa 30bar are ok, operating conditions of the tank would be a main factor

HI,

YOU CAN USE SEA WATER PRIOR INTERNAL BLASTING & PAINTING OF TANKS,

MATEEN

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We have used sea water for years. There is very little corrosion. There will be a small amount of rust at the water line. Once you drain the tank its best to make sure the water is drained through a hose and no standing water be left around the out side of the tank. Once you fill the tank with oil, all will be well.

Thomas Beck

Sound Refining

Tacoma Wash. USA

This is not a problem. Corrosion takes time. If testing with sea water all you have to do is empty the tanks after the test. Just mop dry. You dont even need to rinse. This is done all the time throughout the world on tankers with No negative consequences.

Best Regards Bill Muirhead