manufacture them yourself, if you describe the application and which way they will be positioned and whether they need gaskets or any other particulars , could help as our company has built many many different style of tank lid covers
I'm going to ask a question.
You're speaking of "manways for non pressure storage tanks". Of course, "non pressure" means that the tanks will be subjected to atmospheric pressure. What kind of fluid will the tanks contain? Oil and/or oil products? Then the tanks should be designed and built to API 650, and the manway dimensions are clearly stated on it. For sure, the blind flange that covers the manway is thicker than 1/4 inches.
Or will the tanks contain water or other non flammable liquid? In this case, the tanks should be designed and built to AWWA D100, that also states clearly the dimensions of the manways. Again, for sure, the 36 inches blind flanges that cover the manways are thicker that 14 inches.
Or will the tanks be designed and built to some other standard?
Giovanni S. Crisi
Sao Paulo - Brazil