Design Process for a Polyethylene Chemical vertical storage tanks

[fasboater]

I am trying to get through the process of designing a Polyethylene tank. These are no large tanks and the external loading is calced easy enough using ASCE however this industry seems to be using an ASTM D spec.. I am not really sure of the process and how that all fits into the ASCE load combo's. For example the specs call out for a simple hoop stress calc to design wall thickness (totally ignoring any other stresses due to external loading. Also per the ASCE there is an API 620 that I don't have and I don't know if it is even relevant.

 

[JStephen]

Can't help you on the tank, but will point out that API-620 is applicable to large steel tanks and wouldn't be of much use on a polyethylene tank.

 

[JedClampett]

I'm not sure why you're designing a Polyethylene tank at all. We use them for chemical storage every once in a while and we specify the chemical, capacity, diameter, etc. The supplier does the design. There's a cottage industry of engineers who do these (and/or FRP tanks) all the time. The know the ins and outs of designing them. No need to learn this yourself when there are experts, who work closely with the manufacturers and know their processes, to do them.

 

[fasboater]

Jed,

I am looking at this for a small manufacturer (no in house engineering). According to their spec these tanks are designed per UBC witch is quite outdate. So I am trying to bring them up to current IBC codes, however I am struggling a bit trying to integrate this ASTM D spec into IBC loading.

My first thought is to just combine the hoop stresses from the liquid and horizontal stresses derived from ASCE 7 loading. Or should these be considered separately.

thanks,