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Silicone pipe to bulkhead


cocojakes

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Okay, so heres the situation. I'm in the process of finishing a custom 40B AIO. I drilled the back of the tank to allow for installation of drain for easy water changes. The issue is that the length of the bulkhead, plus thread to slip converter, plus street elbow, is too much. It results in about 3 inches of distance behind the tank, but I only have 1.5 inches of space to work with between the tank and the back of the stand (which encompasses the entire tank, the hood and stand are connected)

 

My potential solution, which I want opinions on, is could I saw off the extra inch of bulkhead, and get rid of the thread to slip fitting, and just use a generous amount of SCS1200 silicone to bond the two fittings, without being constantly worried that it will leak, and I won't notice because its inside the back portion of the stand, up against the wall.

 

I have all these countering thoughts on silicone, that I know its incredibly strong, I mean, its holding together the glass of the entire aquarium, yet it seems so flimsy, as I can often apply enough force to separate silicone from whatever its stuck to, especially with enough torque. Am I being unreasonably concerned, and the silicone will be more than sufficient? Or am I being overly trusting in silicone, and need to find a more solid means of connecting the CPVC to the PVC Bulkhead.

 

 

 

Afterthought, would PVC cement be a better idea?

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cement is a far better idea

how would I go about that? I use cement for all my PVC fittings, but thats slip on slip, it seems like it would be kind of iffy using cement for slip to thread, since it won't very easily fill the gaps in the threading, so it would only bond with the tips of the threading, which seems kind of, not very solid bond? It would be able to attach face to face easily enough, but again, that wouldn't be much surface area for bonding

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yes it will, that stuff expands a bit. just make sure you put in a generous amount and cover any visible holes. What makes you think silicon will even stick to plastic all that well?

 

You could try putting silicon into some scrap pieces of pvc and see how long that holds up.

 

alternatively, just go buy the proper equipment (male elbow) and not jury rig a stress point. Or use teflon tape, whichever

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The pipe should slip in the bulkhead, Not on the treads. 1" bulkhead accepts 1" pvc INSIDE the threads. Get it? I Think. I did that on mine anyway.

thats what I'm talking about, I have a street elbow, which is one side the same dimensions as regular pipe (accepts fittings onto it) on the other side the same dimensions as a corner fitting (accepts a piece of pipe into it) and it slips in fine, but would need to be bonding to the threads on the inside of the threaded bulkhead.

 

 

yes it will, that stuff expands a bit. just make sure you put in a generous amount and cover any visible holes. What makes you think silicon will even stick to plastic all that well?

 

You could try putting silicon into some scrap pieces of pvc and see how long that holds up.

 

alternatively, just go buy the proper equipment (male elbow) and not jury rig a stress point. Or use teflon tape, whichever

does that exist? I've never seen a thread to slip pvc elbow? If it exists that would be an ideal solution. My major issue is the added length of the thread to slip connector

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Got ya. My bulkhead isn't threaded on the inside.

 

 

But you can do something like this. Just use teflon tape on the threads and get an elbow like this. No need for silicone or cement on the bulkhead.

 

 

 

bulkhead-return.jpg

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okay, so I noticed that the threading only goes part way, then it becomes slip, so I have sawed off part of the thread, to expose the inside slip. It seems to be about an 1/16th of an inch bigger interior diameter, than my cpvc exterior diameter. Any ideas? Should just a LOT of PVC cement do the trick? Or how do people generally feel about just using teflon tape to seal a loose slip fitting? It will be about 5 inches below water, in the return section of the back "sump" area of the tank, so not a TON of pressure on it, but I still want it to be pretty solid, such that I don't need ever worry about it

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I wouldn't use a slip bulkhead if someone gave it to me free.

I always recommend thread x thread bulkheads and LaCo PVC thread lubricant to seal the threaded fittings. Once you glue a slip bulkhead you have to cut it apart with a hack saw if you even want to change anything, with a threaded bulkhead you just unscrew it and screw something else back in so it can be reused over and over.

 

http://www.reef2reef.com/forums/equipment-lighting-hardware-aquarium-filtration/34973-installing-bulkhead-tips.html

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The teflon tape was for the threads. The part you cut off. You can pvc cement the slip you have left assuming its the same size as one that doesn't have threads. I've done it. The pipe was loose before the cement but melted and sealed just fine with the cement. But like AZDesertRat said you will have to cut if off if you ever have any problems or have to replace something.

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