How to create a hidden plug for PVC pipe

Question

I'm working on building a semi-permanent set of full-size soccer goals. Full-size in this case means 6' x 18'. Because of the size and spans, I'm planning on using 1.5" PVC pipe and fittings. And in order to help keep the goals from tipping over from strong winds, I plan on adding 25-50 lbs of sand in the base support tube for each goal.

While not to size, this picture gives a good idea of the general layout for the goals.

The sand will go in the longer, horizontal pipe that is on the ground.

Normally, this would be a fairly straightforward project. The challenge is that I want to make sure the sand remains in the bottom pipe. Unfortunately, I can't rely upon the wonderfully consistent draw of gravity as the goals are meant to be taken apart and taken off of the field during the winter. And I don't want the sand spilling out when the goals are disassembled.

The goals are meant to last for at least 5-10 years, and the hope is that by storing them during the winter they'll have a better chance at lasting that long. I'll be disassembling the goals the first few years, but will eventually pass that task along to someone else.

My initial thought had been to install a concealed plug of some sort on the inside of the pipe. So after adding the sand to the bottom pipe, I would plug it and keep the sand from getting out. I added a red line to this example image to give a better idea.

My problem is that I couldn't find anything at the local hardware store that would serve as an inline plug like that. I checked a number of fittings from other pipe dimensions, but they weren't fitting.

My question(s):

• Are there any general guidelines for knowing which pipes or fittings can slip inside a different dimension of pipe. For example, is the outer diameter of a 1" fitting supposed to fit within the inside diameter of a 1.5" pipe?

  • If so, what type or size of fitting should I look at in order to create this interior plug?

• Is there a better approach to solving this type of a problem? Would a different type of material slip inside of the 1.5" pipe more readily / consistently?

Answer 1

Given all the ideas, the obvious solution would seem to be don't use sand.

Instead, fill the bottom pipe with cement. Or fill it mostly with gravel with a few inches of cement or silicone sealant to hold the gravel in place.

Answer 2

Two ideas...

1. Fill the pipe with sand, and then use an expandable foam like "Great Stuff" to fill the last several inches of the pipe. The polyurethane foam should stick well to the inside of the PVC, and the sand will not be able to pass through.

2. A standard coupler has a lip in the middle to stop the pipe from sliding all the way through. Cut a disk of metal or other sturdy material that will fit inside the coupling and put it against that lip. Gluing the coupling onto your pipe will lock that disk in place and create a seal for the sand.

Answer 3

If the hardware store lacks a rubber stopper section, try a homebrew supply store, unless you happen to have a handy source of lab supplies. Some size of rubber stopper will jam-fit nicely - probably an #8 or #8.5.

But I sincerely doubt that the material and size will work. 4" schedule 80 will flop when 18 feet long - 1-1/2" schedule 40 will act like a wet noodle, or darn near to it. Judging by the noise a standard 6x6" (roughly) square-tube aluminum goal frame makes when struck by a ball, I'd expect this to break frequently.

If the budget does not permit standard goals you might do better to look at wood.

Answer 4

If you plugged the inside of 1 1/2 inch Tee fitting (S x FPT x S) and installed one on each side of the horizontal legs you could than tighten a thread 1 1/2 inch plug to access the sand. To seal one end of the Slip hub of the tee: insert and epoxy an appropriate shaped disc (flashing metal, rubber gasket stock?).

Answer 5

Cut a chunk of sponge from one of those big yellow tiling sponges and jam it into the pipe, leaving about 1/2" of space between the sponge and the end of the pipe.

Stand the pipe on end, sponge side up, and pour in some flex-seal, about 1/4" deep. Repeat until the sponge doesn't soak any up (the tighter you compress the sponge the better) and let it cure. You'll have a nice rubber plug.

My application is in an open loop, like a fountain, where there's no significant pressure on the plugs, so I don't know what would hold up to a higher pressure, but this method was one option.

Answer 6

Use foam sealer to plug both ends of the pipe from the inside.