Any opinion

Best solution to do what?

Hi Auozkan -

"there is a sliding on the tank basement and tank" - Do you detect movement or displacement of the tank on the base? Is the base failing? or is the tank bulging?

Please give more detail!

The concrete base(30 years in servis) is failing.Tank is ok.

Hello auozkan

You evidently expect readers to be able to read your mind.

I shall attempt to interpret your problem:

<"CS storage tank"> = You have a Caustic Soda Storage tank.

<"(15m height,25 m diameter)"> = 15 Metres high, and 25 metres diameter.

<"has 6500m3 costic"> = The tank contains 6500 cubic metres of Caustic Soda.

<"there is a sliding on the tank basement and tank"> = the tank is sliding across the floor???

<"what would be the best solution"> = How can this sliding be stopped ??

Please advise the following:

1. Tank Material:
2. Concrete
3. Steel
4. Plastic - Specify please
   
5. Other - Specify please

Basement (Floor material):

1. Concrete
2. Steel
3. Other - Specify please

Existing method of preventing the tank from sliding: Specify please.

Is the Caustic Soda:

1. Dry Flakes
   
2. Dry Powder
3. Liquid in solution?

Floor slope:

1. Level
2. Sloping to drains
3. Other - Advise please
   

It is possible your tank has developed a leak in the underside, the Caustic Soda leaking out, thus lubricating the tank, and allowing it to slide, because Caustic Soda is greasy in nature.
I have done my best to interpret your question, please advise here, with so you may be properly helped.

Kind Regards....

Sorry,

Tank Material:

C.Steel

Basement (Floor material):

Concrete (30years in servis)

Caustic Soda:

Liquid in solution?

Floor slope:

Sloping to drains

Thank you for your consern.

May I suggest to you that if you want Engineers to give you free advice ( all of us are in the main always ready to do so ) you must have some respect for those willing to help.

Thus it is essential that you precisely answer the questions you have been asked. It is not only a question of politeness but very importantly for any of us who have had similar experience to give you accurate answers and suggestions. So that you may reliably and safely correct the failings or failure of the tank. Besides what you have been asked I would even go further in seeking answers from you on the following questions:

1.As the tank is obviously an old one ,is it welded or rivetted ( I am presuming it is welded .)

2.Are you aware of the thickness of the steel plate on:

-bottom,

-shell plate of the first strake ?

-Has the tank been properly maintained and regularly painted ?

-Do you have the means of fully emptying the tank or is that impossible ?

3.Has the original pad been made up of a circular re-inforced concrete ring . Or is it a fully concreted pad and, if so : what is the estimated thickness of the concrete ?

4.a.If the base has been made up of a circular concrete ring, what is the material that makes up the balance of the surface of the pad ? What is the thickness therof ?

b.Can the tank be emptied in order to perform adequate , thorough and : safe remediation ?

5.Have you consulted with the Insurers of the installation and /or relevant Municipal or State Authorities ? Will you need their prior approval before doing anything ?

When you have answered these additional and basic questions then I am reasonably certain we will collectively or: individually, give you proven methods of correcting your problem.

Labor Omnia Vincit

.It is welded

.the thickness of the steel plate on:

-bottom(not measured yet)

-shell plate of the first strake is 6 mm

-Has the tank been properly maintained and regularly painted ? I'm not sure only the last for years we are using it and haven't any documents.

-That has just been fully emptied (There was seen deep pittings and leaks on the bottom plate)

- it is a fully concreted pad and,the estimated thickness of the concrete is app.1mt

north side of the tank base concrete cracked and destroyed because of costic corosion.(Costic rate;costic %50,water %50)

-We have been consulting it reconstaction of all basement or particalar north demaged side repair and tank bottom,first plate changing.This tank also next to other tanks nearly 12-15 mt away and at the midle side,it is difficult to lift from its place.

We haven't yet decided on.That is why your thread very helpfull for me .

Thanks for everybody who threads, spending his value time.

Dear Sir,

It looks as you have problems. However you may consider the following :

1.If the tank is empty you may use a series of stiffeners . Best ones would be ~ 200 m/m channel steel in lenghts of : 1m.80 . These should be prepared with a right angle lifting bracket extending, outwards, from the channel steel . The bracket would allow a jack to be fitted externally ( after the channel has been welded on the side of the 1st strake). The more jacking positions you have the less stress there will be on the shell of the tank. I would suggest at least six on the perimeter of the tank.

2.If you are going to replace the bottom of the tank then it is necessary for you to have internally stiffening cables with bottle screws. These will keep the shape of the tank from bulging out . I suggest these to be placed on the inside at exactly the position of the external " stiffeners-jacking-bracket "positions. Once this has carefully been done, you can start the jacking of the tank and lift it on to hard wood sleepers at each jacking station. (use hydraulic jacks with well co-ordinated workers . For safety use at least three levels to verify that you are lifting it in an even manner and to its final repair level

3.Before doing any jacking you should determine what you are going to do with the replacement of the bottom plates ?? If you intend to change it then you should commence cutting it by sections for removal and allow only a minimum jacking of the tank (not more than 200 m/m) off the concrete pad . This will allow you to remove the old plates in sections by sliding them out from under the shell plate. As well do the concrete remediation (see below).

4.I would suggest that the cheapest method you can use is for you to use a gunite concrete gun with high pressure air to fill all the voids of the failed section. After which you may consider to reline the bottom by pouring a new concrete pad . This I would suggest should have steel reinforcing mesh and be of the order of 150 m/m thickness.(One of the Engineers recommendation about rubber compound mixture is a most appropriate recommendation .Try and follow it . )

Once this has been done you can reweld the bottom plates. That is without as yet lowering the whole tank. (see below)

5.It is quite common that tanks steel plates (bottom and lower section of shell plates) are those that need renewal before anything else. ( Sometime as well if the upper frames and roof trusses have been subject to condensation ) these may also need replacement. In short you must determine at all times whether the extensive repairs are justified by the conditon of the rest of the tank itself. However should only the bottom of the shell plate (where it joins the bottom plates) be defective then you will have two options:

aa-cut around the perimeter a height of 500 m/m -or more- and replace it NB Do not forget that this must be determined before you weld the jacking channels so that all these possibilities are yours to complete the job safely and cheaply.

bb-Increase the height ( and capacity of the tank ) by increasing the renewal of the first strake and selecting a thicker steel plate for that section of the renewal. NB This also applies to the bottom plate thickness which I suggest you should seriously consider.

My experience with tanks that have been damaged by : faulty foundations,hurricanes, earthquakes etc allows me to give you the above advices. If these are followed carefully you can save your tank for another perhaps 20/ 30 years. Remember the above is far cheaper than a new tank IF you are carefull and follow the rules of safety.

Labor Omnia Vincit

Please specify the problem definitely. Sliding means horizontal movement, where falling means vertical down movement. Which movement you mean?

Dear A.H.Galala,

Tank movement is horizontal and vertical down on the north side because of bottom leakage.(Tank emptied and checked that was happened bottom plate leaks)

Thanks,

1^st : Check the tank annular plate (part of bottom under tank shell), make any repair required. Note: If it is necessary to replace the annular plate, there a special procedure and sum few calculations to be carried out to install small portion by small portion.

2^nd : Check the tank bottom. If there are a great corroded areas, it must be repaired or replaced. Note : If all bottom plates were totally corroded, I recommend :

1. Cut the bottom plates.

2. Make a soil exchange, and certain compaction must be carried out.

3. Install a new bottom plates.

3^rd : For point 2^nd and in case of there is no need to replace the bottom and in terms you construct a new concrete ring wall under tank shell which will hold the tank in position, I recommend to install a new bottom over the old one.

4^th : Such a study to be carried out to determine the need for anchorage of tank.

Important Note. A special attention must be paid at any stage to protect the tank shell from buckling/bulging due to wind or shell weight, and a temporary supports must be used.

Thanks for your opinions,When we come any decision,I will inform about it.

Is there any scope to put a liner inside the tank, made of, say, polypropylene?