Design of small plastic tank for rotomold and rapid prototype.

[nateconn]

Has anyone had experience designing a plastic tank with ¼” and 1/8” female npt threads or fittings. I would like to be able to install and remove NPT male threaded parts into this plastic tank but I don’t really know how to design these interfaces. I see that female NPT metal inserts exists but that might require a thicker wall thickness than I’d like. Right now I'd prefer to keep the wall thickness to .125 inch.

The tank will likely be rotomolded for production but I'd like to be able to rapid prototype it and use the same or similar features.

 

[btrueblood]

We buy a small HDPE rotomolded tank from a commercial manufacturer, and have our local rep spin-weld heavy-wall pipe fittings (female threads) into the wall in specified locations. I think it may also be possible to specify the fittings (which appear to be injection molded) to have metal inserts if that is a requirement.

 

[MikeHalloran]

We used to use a small metal tank that was a semi-custom version of a lawnmower gas tank; two halves with 1/8" npt drains, no filler neck, total capacity maybe a quart. Is that 'small'?

Rotomolding is normally used for containers larger than ~20 gallons; it's not competitive with blow molding for smaller stuff like milk jugs or jerry cans.



Mike Halloran
Pembroke Pines, FL, USA

 

[nateconn]

This tank is a little bigger, in the 3 gallon range.

"Rotomolding is normally used for containers larger than ~20 gallons; it's not competitive with blow molding for smaller stuff like milk jugs or jerry cans."

Really? this is going to be low qty only a couple hundred a year. I talked with a few different blow molders and they recommended I look into rotomolding due to the low quantity.