Wall penetrations on a cast in situ concrete tank 1

[ashtree]

We are getting an above ground concrete tank built at one of our wastewater plants to store treated effluent. Its about 50000 USG capacity with a wall height of 9 foot and a wall thickness of about 6 inches.

We have a number of pipes to go through the wall , two four inch and two 10 inch. These will be made of stainless steel.
I assume that these pipe stubs should have what i would call a puddle flange welded on the pipe that is located in the middle of the wall or perhaps bolted on one side of the wall. This prevents a pathway for water to flow between the wall and the pipe as well as positively locating the pipe in the wall.
This is not my area of expertise and the contractor although supposedly very experienced in tank building does not seem to have any preference just saying that we have to provide the pipes and they will install them.

Am i correct in saying that the pipe stubs should have puddle flanges and if so should this be cast into the concrete or bolted onto and sealed on one side of the tank?


Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[dik]

Is the plate rolled to accommodate the radius of the tank? Can you use bentonite 'rope' with the effluent? and if so, can you put a couple of wraps of 'rope' on the pipe extension through the wall? I've not seen 6" walls used for this type of containment and it may be that a curved plate on the inner surface will work. It is also possible that a gasket can be provided with the plate.

Dik

 

[ashtree]

Thanks for the reply.
Bentonite would be compatible with the effluent. Are you proposing to wrap the pipe in the rope so that the rope effectively forms a sleeve around the pipe through the full depth of the wall?
The plate could be curved but would only have to be slightly as the tank is about 32 feet in diameter.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[dik]

Done that often... the rope is contained within the conc wall.

Dik

 

[ashtree]

Have you used the non bentonite style like Hydratite?
Would you propose to wrap spirally the whole length going through the wall ie: 6 inches?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[JedClampett]

I'm worried on several levels. Six inch walls are not thick enough to waterstop, much less carry a 9 foot head of water. Maybe your tank is round and can carry the water pressure as a hoop stress. Even so, six inches is a thin wall. Your Hydratite will likely spall the concrete as it develops considerable pressure when it swells and three inches of concrete are not enough to resist it.
I'm not familiar with the terminology you're using about the puddle flanges being welded to the stubs. If you had a thick enough wall, your pipe would have a weep ring welded to it at roughly mid-depth.
Is this an engineered tank and, if so, has your engineer done these type structures before?

 

[dik]

Just a turn and a half... should not interfere with thin wall... and, concur with Jed regarding the 6" wall... see my first post. I was thinking that if you had a plate, curved to match the inside surface with a blueskin or neoprene gasket between the plate and the wall and secured it with some anchors... had the pipe extend through the wall with a wrap and a half of bentonite 'rope'. that would provide a liquid tight connection... Typically for this type of work... wall thickness is generally in the order of 10" min...

Dik

 

[ashtree]

It is engineered and these people build lots of these tanks.
Weep ring is the same as a puddle flange.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[dik]

Do they have a detail for a pipe penetrating it... keep the responsibility in one court...

Dik

 

[ashtree]

I don't know, as i have not seen any design drawings yet. These i believe would only be very generic anyway as its just a standard design with just slight modifications. I went and looked at the documentation that i have and they do what they call a "box out" around the penetration so am i correct to assume that this is a wall thickening at that point.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[ashtree]

Sorry. I got the wording wrong. It is actually a block out around the pipes.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[LittleInch]

Difficult to know what they mean by block out workout a drawing. Could mean more reinforcement or no reinforcement.

Normally I would expect a puddle flange stub but 150 mm isn't thick. Alternatively you could core drill a hole of near enough exact pipe OD. Seal it with flexible epoxy filler and slide on a slip on flange, Weld it then bolt it to the tank wall with a neoprene gasket.

Is the tank going to be lined?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[gerhardl]

Wall-ducts as solution

Let us assume that the tank supplier and installer can guarantee that the necessary holes in the tank will not damage the tank over
time. (Insurance, guarantee?). Also that he is able to strengthen and cast necessary additions (mainly from outside of tank) to give constructional correct fastening support and framing for proper mounting of wall-ducts.

Let us also assume that the borderline between the two supplies is described and clarified. Example: Pipe properly laid, supported, fastened, any stress relieving devices (if necessary) etc.

On your side the task will then be reduced to your original question: finding a good solution, giving minimum of pipeline stress transferred to the concrete.

In attached catalogue you will find examples on five different constructions of wall-duct devices (pages 34 - 38), German with English sub-text. I have personally repeatedly used solutions from this company for Scandinavian plants, but am sure you can find similar suppliers locally.

https://www.marlener-metall.com/files/content/download/Katalog_englisch.pdf

 

[ashtree]

No the tank won't be lined.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[nackra]

The wall seems thin as noted above. Link seal could work for your application:

http://www.gptindustries.com/en/products/link-seal

I have used sleeves cast in the wall forms and also cored penetrations.

 

[bimr]

Puddle Flanges are used to seal around the outside of pipes that are required to pass through concrete structures. They are installed during construction. Pipes passing through concrete will not bond to the concrete and water can pass along the external surface of the pipe. Puddle Flanges act as a barrier to this flow. The seal is clamped onto the pipes and stops this direct route. The seal body is compressed during the pouring process and should the concrete shrink during curing the rubber relaxes and maintains a seal against this flow path.

The rule of thumb for manholes it 1" thick for 1' of water depth. Agree that 6" is not thick enough.

 

[cvg]

they do what they call a "box out" around the penetration so am i correct to assume that this is a wall thickening at that point

a box out (block out) means that they leave an opening in the structure and that eventually later on in the construction sequence they will install the pipe with the puddle flange, waterstops and any other penetrations and place concrete or grout to fill in the blocked out area. it does not imply a thickened section. This is done because exact location of the pipe is not always known by the concrete crew and to avoid cutting through rebar. better to block it out and finish it later in coordination with the mechanical crew.

 

[ashtree]

Thanks for the discussion and input everybody.
We all agree that 6 inches seems too thin. However the design has been engineered and well tested because this outfit have built many of these tanks around the country. Part of the process is that they have an engineering inspection during construction. The contract has been awarded already and we will have to accept it.

Back to my original question. Should the pipe stubs have a puddle flange attached and cast in with the pipe?
Or should we go with a turn and half of hydratite or similar?
Or do we do something else?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[LittleInch]

If the tanks have a box out as described (basically a square hole) or you can cast them in as it's being poured then yes I believe a stub pipe with a puddle flange is best, but might also need some sealant around the outside / surface penetration to prevent weeping of water through the penetration.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[gerhardl]

Hi all,

Seems that my references in previous postings have not been studied. I try again with more direct links.

In my opinion one of these two constructions, properly adapted to the existing concrete construction, will solve your problems and answer your questions. It is else, as commented by all, a question of what the supplier can guarantee for necessary bolting and adaption.

Several variants of the proposed solutions exist on the market, or can easily be fabricated.

https://www.marlener-metall.com/files/content/download/Typ_PM5.pdf

https://www.marlener-metall.com/files/content/download/Typ_PM3.pdf