I have a question about standard AWWA D100? 1

[luiseduardo]

[pre]first of all I’m from peru work for company AQUAFIL this company is specialized in wastedwater treatement plants,we biult steel tank for wastewater. acoording to awwa d100 standard say that should use thickness of 0.25" all parts of the structure in contact with water But we’re using thickness of 3/16”. Acoording to what I’ve read AWWA d100 standar say : the awwa standard usally contain options that must be evaluated by user of the standard, in other words could have trouble with awwa standard . keep in mind we’re using this standard five months ago

Thank you very much for your reply

 

[JStephen]

Smaller-diameter tanks can use 3/16" shells, find the section giving minimum shell thickness.
Bottoms plate is normally 1/4" minimum regardless.

 

[bimr]

Not really sure what your question is.

The AWWA Standard is a voluntary standard. Were you required to construct this tank to the AWWA D-100 standard?

There are other aspects to be considered, foundation, seismic, etc.

 

[luiseduardo]

Thank you very much for the info, but keep in mind it's a baby tank, the company has standard size for the steel tanks for instance : maximun diameter 9.85'(3.0m)x lenght 32.81'(10.0m) and minimun diameter:6.56'(2.0m)x lenght 18.7'(5.70m) they are baby tank if I comapare with the U.S steel tanks for water. I think that smaller-diameter tanks can use 3/16"

On the other hand most steel tanks for wastewater are put horizontal form. Adjunct a picture about steel tank

 

[bimr]

If this is a wastewater application, you probably should be using a corrosion allowance. Wastewater will tend to be more corrosive that potable water.

 

[JStephen]

The tank bottom is essentially treated as an unstressed membrane for design purposes. The 1/4" thickness is mainly for corrosion and practical construction. Note, for example that API-650 allows stainless steel tanks to use 0.1875" bottoms, even though allowable stress is lower. Anyway, it's not an issue that will make the tank fall down, but may affect longevity.

 

[luiseduardo]

Jstephen thanks for your reply.

I know it's much better to use thickness of 0.25" than 3/16".But keep in mind If I use thickness of 0.25" the budget of cosntrucction steel tanks will be high.but don't worry, when the construcction finish must be tank surface preparation internal and external acoording to SSPC-SP5 STANDARD, after that we have to cover whole the part internal of tank with FIBERCLASS, so getting a thickness of 1/8" this process is standard for the company.on the other hand here in peru we use thickness of 3/16" steel tanks for wasted water storage is standard

anyway thank you for your tip


best regards