Best way to prevent leakage when two pipes are screwed into each other?

June 4, 2023 10:09 AM

This is a picture of the plastic pipes that are screwed together, joining my inflatable hot tub to its "control center (heater, etc.)."

Right now they don't have the washers in there (I can't find them!) or anything else reinforcing their connection, and I'm afraid to fill the hot tub with water because, if anything leaks, I'll have to empty the hot tub in order to fix them.

I'm wondering what the best way is to PREVENT leaks where they are screwed together, BEFORE I fill up the hot tub. Are replacement plastic washers my best bet? Or Teflon tape? Or something else? thanks for suggestions.

posted by DMelanogaster to Home & Garden (18 answers total)

If they are supposed to have washers in there and there aren't any now, it will very likely leak significantly if you fill it up. Sounds like you need new washers. Teflon tape isn't a replacement for washers.
posted by ssg at 11:01 AM on June 4, 2023 [5 favorites]

If you didn't find washers among the parts that came with the unit, maybe they are not required. But you really need to look at the manual (Google it if you don't have it) and look at the parts diagram and list, which will show you whether those connections require washers. Without knowing the brand/model and with only one inconclusive image, we random people on the internet can't really answer this question.
posted by beagle at 11:09 AM on June 4, 2023 [4 favorites]

I'm a little confused by the picture. Do the hoses slip over the fitting, then squeezed by the two part collar, or is the two part collar threaded onto the tub fitting?
posted by Marky at 12:09 PM on June 4, 2023

Can you tell us the manufacturer and model number? Perhaps there's a service guide or parts replacement list that shows what should be in those connections.
posted by JoeZydeco at 12:32 PM on June 4, 2023

Best answer: I have an Intex spa/hot tub which looks very similar, if yours isn't an Intex model then they may be based on the same (or similar) parts. Mine came with a o-rings for the connections between the tub and the pump/header unit, and in fact also included spare o-rings in case they were damaged or over compressed. The o-rings (I think that's what you might mean when you're saying washers?) were contained in a clear plastic bag in the box, they're made from black rubber.

They're a critical part, needed to stop leaks. This is why the instructions state you have to only hand tighten the joints. This applies the correct amount of pressure to the o-ring and makes it correctly seal the connection. Too much pressure and it will deform, too little and it will leak. Leaving the o-ring out entirely would cause leaks. The hot tub is fairly deep and as the connection is near the bottom there is a decent amount of pressure.

If you have the manual you'll find a 3D exploded parts diagram which shows where the o-rings have to sit. If you don't have the manual then searching for the exact model number will probably find it online.

Good luck - we haven't been able to set ours up this year as local electricity pricing is prohibitive 😔

(Of course - there is NOTHING to stop your unit being a different design that doesn't have o-rings! I'm not saying they should be there, I'm saying my similar one has them and if you don't then its worth double checking in the manual)
posted by samworm at 12:36 PM on June 4, 2023 [2 favorites]

Response by poster: It's an Intex PureSpa for 6 people --- here is a photo of the parts, and, yes, they're called O Rings and they're supposed to be already-attached (parts 8 and 9, but what is 9 attached to? SO CONFUSING) , but we're not sure that they are! Last year the top connection leaked --but that one doesn't even seem to have an O-ring! - that's why I'm asking this question. It is so difficult to figure out what's going on and if it coincides with the manual.

But yeah, obviously I should have said O ring and I should have said that last year it leaked so we were wondering if there is something additional, like Teflon tape, that we should be doing to prevent the leak.

and sorry you can't afford to run yours this year!!
posted by DMelanogaster at 12:52 PM on June 4, 2023

Best answer: ...O Rings and they're supposed to be already-attached, but we're not sure that they are!

You really need to take the connection apart and visually check to see if the o-rings are there. They should be readily apparent. If they aren’t there, you should contact Intex for the correct o-rings.
posted by Thorzdad at 12:58 PM on June 4, 2023 [1 favorite]

Best answer: Ok, I have a very similar unit. 9 Isn't "attached" to anything. It sits between the two parts that you're screwing together, kind of inside the joint. It is held in place when everything is tightened up. When disassembling it can be easily lost as it'll just fall out if you aren't paying attention. But as I say - my unit came with a full set of spares because these are inexpensive, vital and easily lost or damaged. So if you've lost the one that used to be in the junction then you possibly have a replacement already. The inlet and outlet are different sizes so it should be obvious which one to use, its the same size as the pipe it's mating to.

If you can't find the ring then you could try teflon but I don't think that'll work. And there are shops like headseal.com that exist because these seals are pretty important.
posted by samworm at 1:50 PM on June 4, 2023

O rings work by sitting between two surfaces that are each designed to seal against them. Fittings like your hot tub uses typically consist of three parts: a compression nut with a female thread on one side and a flat face with a hole on the other, a flanged fitting that's captured by the flat face on the compression nut and on which that nut will spin freely, and a threaded fitting that engages with the compression nut's thread. Those last two parts each have sealing faces, and the O ring is supposed to go between those.

O ring seals work a little differently from the flat rubber washers you'd typically find in something like a screw-on garden hose fitting. Those, you just compress the hell out of; over-tightening is not really a thing. But with a typical O ring seal, you only need to screw the fitting tight enough to ensure that the ring stays nicely seated against both its sealing faces all the way around. Those faces are usually shaped in such a way as to create a tapered gap for the ring to sit in, so that when water presses directly on the O ring from inside the assembled fitting, the ring stretches a little and gets wedged more tightly into the taper; the higher the pressure, the tighter the wedging and the better the seal.

With the O ring in place and the fitting properly tightened, no part of the fitting outside the O ring is ever supposed to get wet. In particular, there's no point putting teflon tape in the compression nut's threads because those were never intended to be a sealing surface, and unlike threaded joints that are supposed to be sealed with tape, neither the nut's threads nor the male threads it engages with will be tapered.

If the O rings are missing, then water will escape past the place where they're supposed to be, and there's no other part of the fitting that's designed to contain it. Teflon tape in the threads of the compression nut might then be enough to stop it getting out through the threads, but it won't stop it finding its way between the compression nut and the flange on the fitting that it spins on, because that joint was never designed as any kind of seal.

Basically, if water is allowed into the compression nut, all bets are off. So you need to make the O ring seal work. That means acquiring O rings that fit between the sealing faces they're supposed to fit between, and tightening the nuts enough to compress but not crush those rings.

When an O ring seal fails, that's usually because the ring has cracked and/or hardened or been crushed or been eroded by chlorine to such an extent that water pressure can't stretch it any more. Fixing the seal requires replacing the O ring; screwing it extra tight or adding tape won't work. So when you do find a source of suitable O rings, buy more than you have an immediate need for.
posted by flabdablet at 2:40 PM on June 4, 2023 [1 favorite]

Response by poster: Here is a picture of the parts with two circled in red: the two parts, one on the spa itself, and the other in the control center, that join together. I have circled them because last year, when they were joined, THAT was the leak (at the place where they come together), AND I see that neither of those parts has an "O" ring!

So I still have my original question -- what are some things to try when you have a leak like that?
posted by DMelanogaster at 5:17 PM on June 4, 2023

I think that diagram is misleading. Those two connections, one above another, look like they are identical, so why would one have an o-ring and the other not? Indeed, if you look on the next page in the manual, you'll see that the quantity for part #8 is 2, which suggests that there should be one on each, but they are only showing one on the diagram for simplicity, which isn't uncommon.

If you look carefully at these two connections and they are indeed identical and one has an o-ring and the other doesn't, and the one without was leaking, then I think you have your answer.
posted by ssg at 5:35 PM on June 4, 2023 [1 favorite]

If you can't or don't want to order an o-ring from the manufacturer, try taking the existing o-ring to an auto parts store. They may have something that matches, if it is a standard part.
posted by ssg at 5:36 PM on June 4, 2023

Intex sells replacement parts including o-rings from what I can tell. Though if this is something you just purchased and it didn't include o-rings, I'd honestly call up the manufacturer and request them.
posted by Aleyn at 7:27 PM on June 4, 2023

Response by poster: I think that it says there are 2 O-rings because ANOTHER hose connection has an O-ring. (#9 on the diagram)

But I could be wrong!
posted by DMelanogaster at 7:45 PM on June 4, 2023

They list #8 SPA CONTROL INLET/OUTLET O-RING x2 and #9 SPA CONTROL AIR INLET O-RING x1, so there are a total of 3 o-rings, two of which are identical and one of those is for your leaky connection.
posted by ssg at 8:09 PM on June 4, 2023

That diagram is awful.

Here's what seems to be the same one on Intex's support site which also has links to the available spare parts.

Looks to me like you need two of part 8, 11699 Spa Control Inlet/Outlet O-Ring, and one of part 9, 11687 Spa Control Station Air Inlet O-Ring.

Also, despite what Intex is calling them, those are not O rings; they're specialist, proprietary, moulded rubber seals, so none of what I wrote above about how O rings work is applicable except the advice to stock more of them than you need immediately. And I doubt you'd be able to get them from anybody but Intex.
posted by flabdablet at 5:08 AM on June 5, 2023 [1 favorite]

Note that the diagram links part 8 to only the lower of two similar fittings, but the fact that the parts ordering list says you need two of those tells me that both of those fittings should have one.
posted by flabdablet at 5:15 AM on June 5, 2023

To add to flabdablet's excellent comment, it's good to know that Teflon tape is a lubricant but not a sealant. Its job is to help a tapered, threaded end advance further into its partner, and to keep that connection from seizing, but not to actually seal the connection.

You can buy sealant that includes Teflon, but it is a liquid, not a tape.
posted by Dashy at 5:16 AM on June 5, 2023