Polypropylene VS. Polyethylene
I have heard this debate before in the boat tank industry. To put the facts straight, based on my 20 some years in the plastic fabrication field, polypropylene if welded with an inert gas such as nitrogen will not oxidize. C.C. Tech is an equipment manufacturer for the metal finishing industry. We manufacturer equipment for electroplaters such as complete lines that hold anything from hydrochloric acids to 50% sodium hydroxide and at temperatures up to 160º F. In my 20 years of experience I have never seen one of our tanks fail due to oxidation. Furthermore the company's history of equipment manufacturing dates to 1980. We still visit our customers shops and service the process systems, and the tanks themselves are intact and running fine. That's 20 years of operation! Some of the plastic yellows, however that is from UV light waves in their florescent lighting. Today most plastics have UV inhibitors that stabilize the plastics to discourage the yellowing. We have spent thousands of dollars on our nitrogen feed systems and have deliveries twice a week on liquid nitrogen to our facility. I understand the confusion with which plastic is used, and how it is determined. We are applying our expertise based on an industrial standard. Simply if the tank is used for water, polyethylene. Polyethylene is approved for water holding by the FDA. For waste we use polypropylene. It will handle any thing that might end up in contact with it. As for molding tanks, any tank molder will tell you that polyethylene is far easier to mold that polypropylene.
