PVC pipe & fittings easy to insert last time but hard to insert this time

Users who are viewing this thread

Flapper

Member
Messages
516
Reaction score
27
Points
18
Location
California
About a week or so ago I did a PVC pipe project and I got all new materials. The pipe fit into the fittings easily, they bottomed out and didn't get stuck and were easy to remove. Likewise, while gluing, it was easy to insert the fittings.

Today I did another PVC project but this time it was different. The pipe didn't fit all the way to the bottom of the fittings, it got stuck like 2/3 in, and tended to stick together.. When gluing it was also rather hard to push the fittings in, I had to push hard to get them in. On the second to last connection, I looked in the piece of pipe to see the joint, and I saw this weird white thing; apparently the fitting scraped away some of the soft white PVC and made a shaving down there... :confused: I stuck my finger in and cleaned it out.

So first project, pipe and fittings fit easily and snugly without getting stuck, but a while later when I did this project, the fittings won't bottom out and they tend to get stuck and hard to remove. What could have happened? Does PVC absorb moisture and change properties or size or something? :confused:
 

Terry

The Plumbing Wizard
Staff member
Messages
29,946
Reaction score
3,460
Points
113
Location
Bothell, Washington
Website
terrylove.com
PVC and ABS will only bottom out when they have been glued up, both hub and spigot. We swerve them in. Push with a twist, and then hold until they stop trying to pop back out.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
How was it originally able to bottom out without glue?
The fittings or the pipe is out of spec! The fittings are tapered, and should only allow the pipe to bottom out when the cement melts it.
 

Flapper

Member
Messages
516
Reaction score
27
Points
18
Location
California
The fittings or the pipe is out of spec! The fittings are tapered, and should only allow the pipe to bottom out when the cement melts it.
The exact same fittings and the exact same pipe bottomed out when they were new, when I did the first project, but a while later they don't bottom out.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
It's supposed to be too tight to fit the pipe in dry. If you can, you're literally stretching the fitting, and typically, pulling it out again can be a bear; or, one or the other is not to spec. The cement has solvents in it and it makes what is called a solvent welded connection...to ensure it can work, things have to be tight when dry, as there aren't many fillers in the cement (there are some, just not huge amounts). If your cement isn't old (and lots of the solvent has evaporated), it should melt the plastic fairly easily, and the pipe should go into the fitting easily after properly installing the cement. The bigger the pipe, the harder, but still, easy to do.
 

Flapper

Member
Messages
516
Reaction score
27
Points
18
Location
California
It's supposed to be too tight to fit the pipe in dry. If you can, you're literally stretching the fitting, and typically, pulling it out again can be a bear; or, one or the other is not to spec. The cement has solvents in it and it makes what is called a solvent welded connection...to ensure it can work, things have to be tight when dry, as there aren't many fillers in the cement (there are some, just not huge amounts). If your cement isn't old (and lots of the solvent has evaporated), it should melt the plastic fairly easily, and the pipe should go into the fitting easily after properly installing the cement. The bigger the pipe, the harder, but still, easy to do.
I know but why was it able to be easily inserted before but not now?! It's the exact same fittings and pipe I used before!
 

Gary Swart

In the Trades
Messages
8,101
Reaction score
84
Points
48
Location
Yakima, WA
There's no way to explain what happened or why. The answers given have properly described how PVC and ABS pipe and fitting are supposed to fit. We can't dispute your experience, but it should not have happened as you describe.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
Variations from unit to unit imply lousy quality control. The bits are not in spec. FWIW, if you try to dry fit and then cut things with PVC, you'll almost always end up short and with things not in the desired position...you have to measure, and then ensure you get the pipe bottomed out in the fitting.
 

Flapper

Member
Messages
516
Reaction score
27
Points
18
Location
California
WIW, if you try to dry fit and then cut things with PVC, you'll almost always end up short and with things not in the desired position...you have to measure, and then ensure you get the pipe bottomed out in the fitting.
Of course; I don't measure with the dry-fit, I measure from the stops.
 

Terry

The Plumbing Wizard
Staff member
Messages
29,946
Reaction score
3,460
Points
113
Location
Bothell, Washington
Website
terrylove.com
Jim is right. I am right. You need to glue them if you want the fittings to bottom out and seal.
I never dry fit fittings, because you can't! Just saying. This is how those fittings are. Now get busy and start gluing.
 

Flapper

Member
Messages
516
Reaction score
27
Points
18
Location
California
Jim is right. I am right. You need to glue them if you want the fittings to bottom out and seal.
I never dry fit fittings, because you can't! Just saying. This is how those fittings are. Now get busy and start gluing.
What the heck, you think I am plumbing with dry fittings?! -_- You are completely missing my point! When I did my first project, the fittings inserted easily and bottomed out without glue, but this time they don't bottom out, like they are supposed to, but it was also hard to insert them with glue, and on one connection, it scraped away some soft pvc into a shaving in the fitting. I want to know why this is, which obviously nobody knows here.
 

Terry

The Plumbing Wizard
Staff member
Messages
29,946
Reaction score
3,460
Points
113
Location
Bothell, Washington
Website
terrylove.com
There were years I was plumbing waste and vents for five homes a week. That was one a day for five days, every week of the year.
That is a lot of pipe and a lot of fittings. I know exactly what I'm talking about.
And I've been doing this for fortytwo years. Ya might say yep, that's how it goes!

Oh Snap!
Look what I found here.......

4-Dry Fit
• With light pressure, pipe should go one half to two thirds of the way into the fitting hub. Pipe and fittings that are too tight or too loose should not be used.

8-Join Pipe and Fittings
• Assemble pipe and fittings quickly while cement is fluid. If cement has hardened, cut pipe, dispose of fitting and start over.
• Insert pipe into the fitting hub
• Without re-dipping the applicator in the cement, apply a medium layer of cement to the fitting socket aggressively working it into the surface. On bell end pipe do not coat beyond the socket depth.
• Apply a second full coat of cement to the pipe surface aggressively working it in.
• Do not allow cement to puddle or accumulate inside the system.
• Solvent cement should conform to giving a quarter turn as the pipe is being inserted, ensuring an even distribution of the cement within the joint. Do not quarter turn the pipe after contact with socket bottom.
• Once the pipe contacts the socket bottom hold pipe and fitting together until the pipe does not back out.
http://www.charlottepipe.com/Documents/PL_Tech_Man/Charlotte_Plastics_Tech_Manual.pdf

terry_football_01.jpg


I'm the guy on the left. The 70's
 
Last edited:
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks