Bonding PVC Pipe

[GarethR]

Have cut and fitted a 45deg 100mm PVC pipe to my main 150mm PVC pipe. I have some old PVC glue which cost around $20 for a fairly small tub, it's been sitting on my shelf for over a year since I last used it and is now useless.

While $20 doesn't seem like much I'm getting tired of forking out $20 for sealer, glue, etc only for it to be unusable several months later. So, ideally I'm after a method that uses something that has a decent shelf life.

Any preferred recommendations on how best to bond the two together keeping in mind product shelf life?

Thanks,

Gareth

[CMB]

I duct tape all my joins.

[GarethR]

I duct tape all my joins.

Interesting, how strong are your joins? Are they able to hold some heavy duty flexi pipe weight for example?

I'll be using the 100mm to run some flexi to my TS blade guard and it needs to take some weight.

Talking about tape. I purchased some double sided carpet tape (Norton, "good" $20 stuff), used some strips for a router job, and then about a year later went to use some more on a similar job and guess what...the tape was no longer adhesive!!

It had obviously got tired of watching me beavering away over the year and decided to forget about it's primary object!!!

[CMB]

Interesting, how strong are your joins? Are they able to hold some heavy duty flexi pipe weight for example?

I'll be using the 100mm to run some flexi to my TS blade guard and it needs to take some weight.

Talking about tape. I purchased some double sided carpet tape (Norton, "good" $20 stuff), used some strips for a router job, and then about a year later went to use some more on a similar job and guess what...the tape was no longer adhesive!!

It had obviously got tired of watching me beavering away over the year and decided to forget about it's primary object!!!

That can happen with double sided tape. Only super expensive commercial grade will last while sitting on the shelf.

As for duct tape, it's commonly used in commercial workshops here in Vic. Personally, I haven't had any problems to date on both rigid or flexi. Also easily removed as it's not permanent. Will leave behind some adhesive residue though that is quickly cleaned off. I don't use foil or webbed tape, just good old stretchy silver/grey duct tape. I'm sure others will agree, but happy to stand corrected if need be.

[BobL]

The joint the OPs is referring to is non-standard (a 45º entry of a 100 mm duct in a hole cut into a 150 mm Y) with very little to zero overlap (i.e. largely unsupported at the join) and not a smooth joint, so stuff like gaffer tape is not going to work and neither is PVC glue.

What works best is something that provides some support via a build up of material around the joint which is why I suggested a hot glue gun or plastic welding with plastic rod. This method will also fill any holes resulting from an imperfect fit. If the 100 mm duct is going to be under stress with say 100 flexy hanging off it I recommend adding some gussets for extra support.

[rwbuild]

Sikaflex, run a thick bead around it, smooth out with finger, 24hrs later same again, then in a weeks time you wont budge it, support it temporary for first 48hrs then good to go. You can reinforce it with 3 aluminium tabs about 100mm long x 20mm wide bent to the required angles and pop rivet to PVC

[BobL]

Sikaflex, run a thick bead around it, smooth out with finger, 24hrs later same again, then in a weeks time you wont budge it, support it temporary for first 48hrs then good to go. You can reinforce it with 3 aluminium tabs about 100mm long x 20mm wide bent to the required angles and pop rivet to PVC

Sikflex is good stuff but there are zillion different kinds - which one would you recommend?

It also tends to be expensive and the amount that would be used for this job is small so you'd want the tube to last
I heard putting sikaflex silicone in the freezer is one way to prevent an opened capped tube hardening - anyone know if that is correct.
What about the other types?

BTW for extra strength.I would use the Al as gussets rather than tabs.

[GarethR]

Thanks Guys.

Hot glue gun seems an attractive option. I'm guessing glue sticks have a reasonable shelf life?

Bob, did you have any recommendations what glue sticks to look out for? I'm guessing something with a medium to high viscosity and ability to bond with PVC, and depending on the gap something that can fill it?

Also, will a standard craft hot glue gun do or do I need something a little more industrial?

Thanks,

Gareth

[rwbuild]

Sikflex is good stuff but there are zillion different kinds - which one would you recommend?

It also tends to be expensive and the amount that would be used for this job is small so you'd want the tube to last
I heard putting sikaflex silicone in the freezer is one way to prevent an opened capped tube hardening - anyone know if that is correct.
What about the other types?

BTW for extra strength.I would use the Al as gussets rather than tabs.

Sikaflex Pro

[BobL]

Thanks Guys.
Hot glue gun seems an attractive option. I'm guessing glue sticks have a reasonable shelf life?
I bought an elcheapo kit that came with a box of sticks about 10 years ago that are still working


Bob, did you have any recommendations what glue sticks to look out for? I'm guessing something with a medium to high viscosity and ability to bond with PVC, and depending on the gap something that can fill it?
Also, will a standard craft hot glue gun do or do I need something a little more industrial?

Unfortunately I can't help here, I'm not a big hot glue gun users.
One of the members posted about ducts and junctions using a hot glue gun - hopefully he will pop up and chip in

[steamjunkprops]

Acetone, works the same way the normal glues work.

Sent from my GT-I9507 using Tapatalk

[GarethR]

Acetone, works the same way the normal glues work.

Sorry, not sure I understand this comment?

[BobL]

Sorry, not sure I understand this comment?

What he's saying is that acetone works like regular PVC glues (they dissolve some of the PVC from both pieces) and when it dries it bonds the two pieces.

Unless you have practice with acetone, because it is colourless you can't always tell where it has been applied and some of it can dry before the two pieces bond so it won't make a complete seal. The way I use acetone is put the two pieces together and then squirt the acetone into the joint and turn the pieces until the bond. It can be a messy process and it's toxic stuff so it's safer and easier to use the PVC cements.

[GarethR]

It can be a messy process and it's toxic stuff so it's safer and easier to use the PVC cements.

Thanks Bob, will take the safer option.

[twosheds]

Sikflex is good stuff but there are zillion different kinds - which one would you recommend?

It also tends to be expensive and the amount that would be used for this job is small so you'd want the tube to last
I heard putting sikaflex silicone in the freezer is one way to prevent an opened capped tube hardening - anyone know if that is correct.
What about the other types?

BTW for extra strength.I would use the Al as gussets rather than tabs.

Hi BobL

I keep my opened sikaflex silicone tubes in the beer/bait fridge in the shed. One opened tube has been in there over two years and is still good. I just seal the end with a couple of layers of glad wrap. I haven't tried the freezer though - not enough room anyway with it being full of bait and ice for fishing.

Regards
Twosheds

[pjt]

I wonder how you would go if you cut a smaller hole in the 150 then heated the area around the hole (hot air gun or similliar) then pushed thru a piece of the 100 (ideally from inside the 150) this might form a bit of lap to give a bit of mechanical strength to the joint:?


Pete

[Robson Valley]

The solvent mix in PVC cement is every bit as toxic as acetone, if not moreso.
Realistically, how much do you need to use and for how long? 5 minutes with the door open?

Dry fit everything. Mark the registration of the pieces with a grease pencil. Slop in the PVC cement
and assemble 1/4 turn from final, count to 10 and twist = done.

The commercial process involves resistance welding: wrap one pipe with a thin paper tape containing a very thin copper "resistance wire." Attach the DC power leads, set the timer and wait. Power off and cut the protruding res wire ends. The two PVC pipes are physically melted together.

Hot glue might be OK but it chills & sets with very little working time.
Possibly a bead around the finished joint. Glue sticks last for decades, they are no more than
low temp, thermosetting plastic. I did theatrical F/X for 20 years;: masks, props, costumes, etc.
Not unusual to have 4 glue guns hot at the same time, 4 colors. Guns from 150W commercial
to dinky little craft guns. I built prototypes from cardboard & hot glue, then cut that up as patterns for products made of foam rubber, riveted aluminum sheet, etc.

The size, the capacity, depends on the volume of melt that you expect to express from the melt chamber
in the gun in one big squeeze.

[BobL]

The solvent mix in PVC cement is every bit as toxic as acetone, if not moreso.
Realistically, how much do you need to use and for how long? 5 minutes with the door open?.

I agree,exposure during working will be low.

I decided to look up the MSDS for acetone and PVC cement, the main component of which is butanone and it turns out that neither are that toxic and neither are classed by the US EPA as a hazardous air pollutants.

In terms of breathing toxicity, acetone is slightly less toxic than butanone but acetone is more volatile so exposure at room temperature will be greater.
By way of comparison both acetone and butanone have a breathing toxicity somewhere between methanol (lower) and ethanol (higher) - it might make you think about sniffing your whiskey too hard!

PVC cement also contains other "stuff" like hexanone and tetrahydrofuran.
Both have breathing toxicity levels similar to ethyl alcohol, but like Butanone they have higher boiling points than acetone so exposure at room temperature will be lower.

So nothing to worry about.

[John Samuel]

I wonder how you would go if you cut a smaller hole in the 150 then heated the area around the hole (hot air gun or similliar) then pushed thru a piece of the 100 (ideally from inside the 150) this might form a bit of lap to give a bit of mechanical strength to the joint:?


Pete
That's exactly what I did to make this three way junction. The smaller pipes had a flange formed on the end. The undersize hole in the larger pipe was heated with a heat gun and the smaller pipe forced through from inside and pulled out until the flange inside the bigger pipe was a reasonably smooth fit. The pieces were fastened together with short self tappers and sealed with silicon.

[BobL]

I wonder how you would go if you cut a smaller hole in the 150 then heated the area around the hole (hot air gun or similliar) then pushed thru a piece of the 100 (ideally from inside the 150) this might form a bit of lap to give a bit of mechanical strength to the joint:?
Pete

That's how I do mine as well.

I cut the 100 mm piece first so that it sits neatly on the 150 mm.
Put the 100 mm onto the 150 in the position where I want it and trace around it.
Cut the hole in the 150 about 2 mm smaller than the hole.
Heat the edges of the hole and force the 100 mm pipe through.
Keep applying low heat and pull the 150 mm lip back the other way.
I then plastic weld the join but any sealant or thick adhesive will work.

http://www.woodworkforums.com/attachments/f200/187439d1320976373-bobls-dusty-setup-modified-y.jpg

[GarethR]

Appreciate the suggestions.

I decided to go the heated glue gun route today after trying it out on a couple test pieces left for a couple days to fully set. After applying the glue via the gun I used the heat gun to remelt the bond which helped fill the gaps and smooth the rough edges of the glue job. I have undercut the 150mm by about 3mm, pipe wall thickness as the 100mm pipe. So, if the glue job doesn't work I'll heat it up and try your suggestions of pushing the 100mm through the undersized hole cut in the 150mm pipe.

Thanks again.

Gareth