4'' UNISEAL Flexible Tank Adapter (Bulkhead)

Worked great on a septic tank. You drill a 5" hole with a holesaw (highly recommended you do it this way) and put the seal in the hole from outside the tank. Then you lube your pipe up (I used glycerin because I had some handy) and push the pipe in from the outside. It helps to spin and wiggle as you push it in. Based on how hard it was to get the pipe in there, I have no doubt it will seal.It is designed for pipe with an outside diameter of 4.5". That includes 4" ABS pipe and 4" schedule 40 PVC pipe.For low-pressure applications, you may also encounter SDR35 PVC pipe. I am not confident this would seal on SDR35 because it has a slightly smaller outside diameter. The same company makes an SDR35 seal, but I couldn't find it on amazon. This is why I opted to use schedule 40 pipe instead. SDR35 is used in low-pressure applications, and around where I live, it is often used in septic systems on the tank outflow side. Just make sure you know what kind of pipe you are buying and make sure it matches your seal.

i used them on a fiberglass septic tank. the holes in the tank were already cut to the right size. the seals installed right in the the tank holes. i tapered the end of the 4" abs pipe and used silicone sealant as a lube all over the entire length of inserted pipe . it took force and wiggling to to get the pipe started but once it started it slid in easy . The septic tank hole was at an slight upward angle but this was not enough to create a problem.

Uniseals are an inexpensive and effective solution to putting round pipe into other pipes, barrels, square sumps, round sumps, and square tanks, but they do have limitations. Follow the guidelines about size differences: you can't put a 3" uniseal into a 4" pipe. I've put in over 100 of these over the years, never a failure when I followed the rules (and including a few times when we didn't..... that's farmers for you.)Hints: When using larger diameter uniseals, use schedule 40 pipe, and chamfer the edge generously. You want to have a nice, SMOOTH, taper on the end of the pipe to slide into the seal, Thicker pipe allows for a longer taper, which makes it MUCH easier to slip through. I generally use a grinder with a flap disc to create the taper.Use good lube (my favorite is Crisco because it doesn't wash away in water like soap). Lots of it.Use a good hole saw. The whole needs to be EXACTLY one inch larger than the seal. A jig saw won't do.When pushing into a tank or other medium that will flex, support the back VERY well. Make sure your taper is generous, very smooth, use lots of lube, and then wiggle and push. It will take some force, especially on the larger diameters (4" and 6", particularly).

Easy to use and install and no leaks so far at all. This is made of a great quality material that seems to be doing a great job of holding up against any water leaking out of my rainwater collection totes.

Never used this before so for anyone else who isn't to on the up and up about pvc pipes and stuff let me just tell you this.. Not all 4" pipe is the same and the 4" pipe I originally bought this for was to small. I mean, it touched the ring but it just passed right through, no seal at all. However, another piece of 4" I had, had a larger OD size (not schedule 40 tho) and it fit these seals pretty good. I did go back and see that this says it will work on 4.5 inch OD pipe but doesn't really say what the minimum OD thickness should be. Pretty sure the pipe I bought it for was 4 inch OD and it was to small for it. Anyways. I made it work with some other stuff I had.

Went another way. Product looks good

These work SO well! I recommend this brand over the cheaper, Asian, knock off. No leaks and easy instal.

followed instructions but leaks. had to seal with flexiseal over the rings