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@Anil Jain • 10 Jun, 2009
Hi All,

This thread is the part I of the "Can you Design" series. In this series you all guyz need to decide on, from where you need to start, what will be the materials, which force/design you will like to see for designing the product/monuments. Anyone of you can start another thread with the product of your interest.

A few rules:-
1. Anybody can post in this thread, Specially I would like to see more posts from Non-civil engineers. Just think what all forces/material you will compute for designing a Overhead Water Tank. I am assuring you it would be a fun and good learning exercise.
3. I will keep giving my inputs in this thread..

Lets see how near we can reach in designing a Overhead Water Tank

-CB
@Differential • 10 Jun, 2009 I would consider following points while designing this.
1) Output pressure required. This will decide elevation of tank.
2) Purpose and Quantity of water required. Also frequency of refilling. This would help to decide its size.
3) Type of refilling. eg, If input presurre is low, one might have to use pump.
4) If water is too hard, one might have to stress on material of tank. One might have to use inside coating to avoid rusting.
5) Depending upon decided size, one has to decide if to provide manhole for cleaning.
6) Depending upon availability of space, its final parameters can be decided. e.g. If less space, one would go with less radius and more height. If plenty of space, one would go with more radius and less height.

Anything else?
@Anil Jain • 10 Jun, 2009 Excellent start / answer Buddy!!!

Covered many of the all. Here goes my inputs...
1) Output pressure required. This will decide elevation of tank.
This is not the only factor in deciding the elevation. Waiting for others to give some other factors in deciding elevation.

2) Purpose and Quantity of water required. Also frequency of refilling. This would help to decide its size.
I doubt, this is probably not important in designing; this is part of requirement. Generally you get requirement that you need to design a overhead tank with (XYZ ltr) capacity.

3) Type of refilling. eg, If input presurre is low, one might have to use pump.
May be you can add type of pumps... or will it depend on refilling type?

4) If water is too hard, one might have to stress on material of tank. One might have to use inside coating to avoid rusting.
5) Depending upon decided size, one has to decide if to provide manhole for cleaning.
Excellent, out of box for a non-civil student.

6) Depending upon availability of space, its final parameters can be decided. e.g. If less space, one would go with less radius and more height. If plenty of space, one would go with more radius and less height.
I am sceptical about it. Will explain it later after getting a few more responses.

@ Other CEan's - Its just start, you only can made it a success. In other words its for your learning only, its not compulsory that only civil engineer should know how to design structure; or that civil engineer should not learn how to design a chip. Engineering is all about learning.
Waiting for responses from different engineering stream.

-CB
@raj87verma88 • 10 Jun, 2009 1) The type of liquid i.e. will the tank store water or petrol or anything else. This will define the type of roof and bottom of the tank (Flat, cone, dome etc) and the insulation to be provided if any.
2) Materials to be used and it's stress bearing properties i.e permissible stresses (These are needed in all design calculation whether structural or mechanical)
3) Shape of tank, i.e. Cylindrical or square.
4) Number of supports
5) Capacity of the required tank
6) The tank walls will be designed such that they are thickest at the bottom and the thickness reduces as we move upwards.
7) The total structure should have a solid foundation of reinforced concrete.
8) The seismic activity of the area should be taken into account.
9) A pump for refilling, preferably a centrifugal pump.
10) The tank should not have too much height as that would put a lot of pressure on the bottom of the tank.
11) A manhole for cleaning the tank

Will add on to the points as I come with new ones.
@raj87verma88 • 12 Jun, 2009 Where is crazyboy? Dude, have you left this thread?
@Anil Jain • 12 Jun, 2009
1) The type of liquid i.e. will the tank store water or petrol or anything else. This will define the type of roof and bottom of the tank (Flat, cone, dome etc) and the insulation to be provided if any.
OOps !! you missed that

As per the thread You are going to design the OVERHEAD WATER TANK 😁
stress bearing properties i.e permissible stresses (These are needed in all design calculation whether structural or mechanical)
This is Useful
3) Shape of tank, i.e. Cylindrical or square.
Bingo.. right suggestion
4) Number of supports
5) Capacity of the required tank
Volume must be desided before designing tank
6) The tank walls will be designed such that they are thickest at the bottom and the thickness reduces as we move upwards.
Up to a certain limit its correct but Not Always... we will discuss this in detail. Though good point Patty !!
7) The total structure should have a solid foundation of reinforced concrete.
Superb, this should be the first point.
8) The seismic activity of the area should be taken into account.
Was not expecting from a non-civil guy... Superb, Why didn't you considerd Wind Force man...
9) A pump for refilling, preferably a centrifugal pump.
Rightooo..

Till now no body added anything about material... foundation... forces (inner and outer),
Suggest design (Looks) also.. Area, Soil dampness, Water level...

Think more.. think big... Crazy ideas are welcomed.

-CB
@shalini_goel14 • 12 Jun, 2009 1. Some automated mechanism for its regular cleanliness.
2. Its capacity as well as weightage on the set up base.
3. Mechanism for avoiding leakages in long run.
4. Some different build. Why all tanks have same kind of shapes? Can anyone tell me?

* Will add more if striked any 😔 *

[ PS: Good work Raj 😀 ]
@raj87verma88 • 12 Jun, 2009
OOps !! you missed that

As per the thread You are going to design the OVERHEAD WATER TANK 😁
I had read somewhere that the shape of tank is also selected. There are different types of roofs like fixed roof and floating roof and it depends on the type of fluid to be stored.

The ones supporting the the whole tank. Over which the tank is kept.

Volume must be desided before designing tank
Aren't capacity of tank and volume of tank the same thing.

Was not expecting from a non-civil guy... Superb, Why didn't you considerd Wind Force man...
On second thoughts I should have said, natural activities of the area.

1) I mentioned about stress bearing properties in the earlier post. We should no the allowable stress of the material which has to be used. There are different grades of concrete and each has different values of allowable stresses bearing capacity. The materials are chosen accordingly.

2) The joints should be leak proof

3) Vapour pressure or gas pressure on the walls should also be taken into account along with liquid pressure.

4) Hoop reinforcement.

5) Vertical reinforcement of walls.

6) Rigid base tank or a flexible base tank.
@raj87verma88 • 12 Jun, 2009 Thank you Shalini. Waiting for more points from you. Nice to see you in the Mechanical and Civil Section. :smile:

@CB: I guess both Shalini and me are waiting for the feedback. The ball in in your court now.
@Anil Jain • 14 Jun, 2009 Here come my inputs about what you need to consider before designing a water tank. I won’t go in deep down the technicalities; as this is not my motive. My motive was to explain/realize you that how near you can reach in designing a structure which is not your cup of tea. You guys (PattY, Differential and Shalini) did a marvelous job.

Material:
In water retaining structure a dense impermeable concrete is preferable therefore, proportion of fine and course aggregates to cement should be such as to give high quality concrete. Generally we avoid steel or metallic material for Overhead water tank... (Not always; but most of the times.)

The design of the concrete mix shall be such that the resultant concrete is sufficiently impervious. Efficient compaction preferably by vibration is essential. The permeability of the thoroughly compacted concrete is dependent on water cement ratio. Increase in water cement ratio increases permeability.

Joints:
Strange!!! No one discussed this.
I won’t go in detailing of joints; however, we do consider them as causes of leakage in concrete are defects such as segregation and honey combing. So, all joints should be made water-tight as these are potential sources of leakage. A few types of joints
a) Contraction joint
b) Expansion joints
c) Sliding joints
d) Temporary joints

Foundation: Decide on type of foundation, following are the two main points in deciding that.
1) Soil type
3) Structure shape

Shape:
Based on load/area a few other parameter we need to decide on shape and elevation of tank

Stress:
Design of liquid retaining structure is different from ordinary R.C.C, structures as it requires that concrete should not crack and hence tensile stresses in concrete should be within permissible limits. A reinforced concrete member of liquid retaining structure is designed on the usual principles ignoring tensile resistance of concrete in bending. Additionally it should be ensured that tensile stress on the liquid retaining face of the equivalent concrete section does not exceed the permissible tensile strength of concrete. A few points we should consider while calculating stress for material.
a) Shrinkage, expansion and contraction of concrete due to temperature or shrinkage and swelling due to moisture effects.
b) Vibrations
c) Difference between inner and outer pressure
d) Erosion
e) Temperature
e) Wind Force
g) Vapor and gases
h) and a few other parameter (explaining them will eat out my whole time. so keeping myself till this point only)

Floor of tanks resting on supports:
a) Supported by columns
b) Supported on wall
c) Ground

Walls:
Before designing walls following points should be considered:
a) Provision of joints
b) Pressure on Walls.
c) Walls or Tanks Rectangular or Polygonal in Plan.
d) Reinforcement
e) Beam designs

Filling style:
This section should cover with how and what frequency we should fill the Tank. What should be the pump station, what is the input/output Type

Distribution:
Strange no one mentioned this point. We are designing water tank means we must think of a way how we are going to distribute the stored water. This would decide the laying of pipelines for distribution.

FEW OTHER PARAMETERS WHICH AN ENGINEER MUST CONSIDER ARE AS FOLLOWS:
a) Cleaning
b) Way to clean
c) Type of Manhole
d) Earthquake bearings
e) Bearings which will control the movement of water

All the queries are welcomed. Meanwhile I will keep on updating this thread when I will feel that there are some important points I missed in this.

Analyze yourself how close you reached in designing a structure.

Wait for next “Can you Design: <XX>” thread soon.
@shalini_goel14 • 14 Jun, 2009 @CB Marvellous job and me - What a joke. Shame on us all CEans (so called engineers). Awesome design you explained to us Sir. Our quality of being an engineer is degrading day by day. So sad of me 😔

Thanks for sharing the very good design. 😀
@raj87verma88 • 14 Jun, 2009 Hey CB, I think I had got some points right on the second post too. 😎
@gohm • 14 Jun, 2009 I hadn't seen anyone mention what environment the tank & it's components will be exposed to. That will effect the design and materials used. Is it indoors? Outdoors? what substances will it be exposed to? What temperature and humidity ranges?
@Anil Jain • 14 Jun, 2009
gohm
I hadn't seen anyone mention what environment the tank & it's components will be exposed to. That will effect the design and materials used. Is it indoors? Outdoors? what substances will it be exposed to? What temperature and humidity ranges?
Oh Boy !!! you caught me...

Generally overhead water tanks are exposed to weather only. (I am talking about normal conditions). So I forgot to mention that its exposed one.

Other then that I mentioned temparature, vapour & gases. Also, I do agree that I had deliberately not mentioned a dozen of things which we do consider. The reson being going deep down into technicalities is not the motive of this thread. I just wanted that others should think that what and how to proceed for design of engineersing structure.

-CB
@Anil Jain • 14 Jun, 2009 Thanks for the good words and appreciating this idea.

@ Shalini - being a non- civil/mech guy you did a marvelous job. So don't be ashamed. Beleive me, I was not expecting this much from Non- Civilites.

raj87verma88
Hey CB, I think I had got some points right on the second post too. 😎
Hey Raj Buddy !!! I doubt your are from mechanical 😕

You almost covered everything ... Good show man.

Appeal to all other CEan's - sometimes its good that we stress out our mind (without thinking of advantage). Soon I will start a new "Can we Design: <XX>"

-CB
@adarsh1 • 20 Oct, 2009 hello all,
Regarding Water tank design i have few things which i like to share
a)in case of tank wall design one as to consider type of fixity given to wall at the supports to calculate the Moment coming on the wall for designing reinforcement.
b)the reinforcement has to be provided with proper detailing as per codal provisions and the more % of steel should be there at one third height of the wall at the tension side.
C) based on H/L ratio, coefficients can be obtained to calculate the moment over the length of the wall.
d) the limit of cracking in case of Water tank is order of 0.001mm as per code and in order to ensure it one must go for flowable, compact able concrete.
@ISHAN TOPRE • 26 Nov, 2010 I will consider the following
1)Height of tank.
2)Shape of tank.
As the shape if spherical can succumb to more pressure
3)Manhole
4)Outlet diameter
As this will decide The flowrate.Fitting with a nozzle will also serve the purpose
@Davina • 29 Nov, 2010 Why not try GstarCAD, it is a good CAD software, maybe it can help
@wenger230 • 24 Dec, 2010
The overhead water tank must be at least 60 cm (2 feet) above the uppermost slab and not touching the slab. There should be no leakage in the overhead tank as dampness in the south-west corner is not good.

water tank
@wenger230 • 25 Feb, 2011 Hey, I am using this Berkey water filter since 2 year and I must say that they are best in purifying water .. It is based on the 3 system level which purify water so that you can't find any bacteria or any harmful particle which cause you many disease.

Water Tanks
@ketul • 13 Jul, 2011 Dear all, I working with Plumbing and firefighting consultant from last 3 years i have joined this forum recently and want give some information.

we are designing OHWT and UGWT with simple rules which are as follows.
Total water requirement per day.
Water supply scheme Like ... Pressurized, By gravity or By Dead end system...
Water sources i.e. Water will available daily or not?
quality of water...Like Water will available from Sewage treatment plant or Bore or Corporation or tanker....
Requirement of Firefighting tank as per norms.

If water will supply through Pressurized than tank capacity will be less up to 50% compare to Gravity water supply system because it would use during emergency only...

I hope this data may helpful to for design OHWT.....

If fill something confusion i can give you example calculations .....
ketul
Dear all, I working with Plumbing and firefighting consultant from last 3 years i have joined this forum recently and want give some information.

we are designing OHWT and UGWT with simple rules which are as follows.
Total water requirement per day.
Water supply scheme Like ... Pressurized, By gravity or By Dead end system...
Water sources i.e. Water will available daily or not?
quality of water...Like Water will available from Sewage treatment plant or Bore or Corporation or tanker....
Requirement of Firefighting tank as per norms.

If water will supply through Pressurized than tank capacity will be less up to 50% compare to Gravity water supply system because it would use during emergency only...

I hope this data may helpful to for design OHWT.....

If fill something confusion i can give you example calculations .....

Hello,
My idea is to design 2 over head tanks each with a separate source of water ( say STP and bore well) with an interconnection between them. In normal condition, both tanks supply water for different purposes. Assuming that water from STP can be used for only some purposes and that from bore well cane be used for all purposes, the inter connection should ensure that water from bore well tank goes into STP tank in case the water in STP tank goes below a certain level.
Can you please provide me some sample calculations which are on the similar lines ? Is there a way to supply water to a higher level than what it is designed for, in future if required?

Thank you,
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