Will PVC bond to CPVC?

Users who are viewing this thread

Messages
51
Reaction score
1
Points
6
Location
North Carolina
I have a 3/4" PVC to 3/4" CPVC adapter. I know that I have to use CPVC cement (as PVC cement is not strong enough to work on CPVC).

Having said that, will CPVC pipe actually bond to PVC? I assume it would, since they make an adapter for that very purpose. The slip adapter itself is made of PVC.
 

Gary Swart

In the Trades
Messages
8,101
Reaction score
84
Points
48
Location
Yakima, WA
Many folks do not understand about how the various plastic pipes are joined. There are 3 basic kinds of plastic pipe; ABS, PVC, and CPVC. They are chemically different. That much is easily understood. The problem comes in the fact that what we all commonly call pipe "glue" or "cement" is neither of these. They are solvents that melt the top surfaces of the pipe and fitting briefly. When the two surfaces are joined, the liquid surfaces combine into what is actually a chemical weld. So, it's not a matter of bonding, strength, or sticking. Each type of pipe has its own solvent, so the answer to your question is, No, you can't join different types of plastic pipes, except by using appropriate adapters. Not known what you are doing and why you would need to join CPVC to PVC, it's hard to advise you on what you may need to do. A couple of problems with PVC and CPVC pertain to why you are mixing media and size incompatibility. In other words, 3/4 PVC is not the same size as 3/4 CPVC.
 
Messages
51
Reaction score
1
Points
6
Location
North Carolina
Here's my situation. . .

The water line that comes into my garage from underneath the house is PVC. I'm installing a water filtration system, and I want to add a brass hose bib to the PVC line before it goes into the filtration system (that way I can draw unfiltered water for yard maintenance).

This is how I want to install the hose bib: 3/4" PVC main line -> 3/4" PVC to 3/4" CPVC adapter (this adapter is specifically made to transition 3/4" PVC to 3/4" CPVC) -> 3/4" CPVC pipe -> slip CPVC/threaded brass transition adapter -> brass hose bib.

I considered using a brass hose bib with PVC, but I know you're not supposed to use a male brass thread with a female PVC thread. So, I ultimately want to use the CPVC/brass transition adapter to attach the hose bib.

Here's what I don't understand. . . Why would they specifically make an adapter for PVC to CPVC if there's no way you can successfully join the two materials?
 

Cacher_Chick

Test, Don't Guess!
Messages
5,458
Reaction score
213
Points
63
Location
Land of Cheese
They are not commonly found in stores, but such a transition fitting normally has a brass nipple between the 2 types of plastic. There are also plastic fittings with brass or stainless steel threaded inserts.
 

Laurihill

New Member
Messages
1
Reaction score
0
Points
0
Location
Minnesota
I need to find an adaptor that will tie 3/4 inch PVC to 3/4 inch CPVC. Is that a common adapter? I can't come up with a connector....
 

Terry

The Plumbing Wizard
Staff member
Messages
29,946
Reaction score
3,460
Points
113
Location
Bothell, Washington
Website
terrylove.com
PVC and CPVC don't mix. Inside a home, only CPVC is legal. PVC is for cold water pipes underground.

Since they are not the same size, the only way to connect the two pipes is with threaded fittings. The post above by the inspector mentions that.

cpvc-female-2.jpg
 
Last edited:

john sherwin

New Member
Messages
1
Reaction score
0
Points
1
Location
cocoa beach
PVC and CPVC don't mix. Inside a home, only CPVC is legal. PVC is for cold water pipes underground.

Since they are not the same size, the only way to connect the two pipes is with threaded fittings. The post above by the inspector mentions that.
In Florida we use pvc water supply and then it transitions to cpvc inside the house (used for hot and cold). Where the pvc is stubbed up out of the slab you would put a male adapter and then use a cpvcxbrass female adapter and this set-up would be exposed?

Also, following the question above - the cpvc to pvc adapter is a pretty common part on supply shelves - how or should it ever be used?
 

Sylvan

Still learning
Messages
2,757
Reaction score
689
Points
113
Location
New York
Wow all of the above seems so complicated

NYC is much easier.... Copper type K for under ground and type L for above
 

Layla-Gail O'Brien

New Member
Messages
14
Reaction score
0
Points
1
Location
Galveston County, Texas
Website
www.linkedin.com
Many folks do not understand about how the various plastic pipes are joined. There are 3 basic kinds of plastic pipe; ABS, PVC, and CPVC. They are chemically different. That much is easily understood. The problem comes in the fact that what we all commonly call pipe "glue" or "cement" is neither of these. They are solvents that melt the top surfaces of the pipe and fitting briefly. When the two surfaces are joined, the liquid surfaces combine into what is actually a chemical weld. So, it's not a matter of bonding, strength, or sticking. Each type of pipe has its own solvent, so the answer to your question is, No, you can't join different types of plastic pipes, except by using appropriate adapters. Not known what you are doing and why you would need to join CPVC to PVC, it's hard to advise you on what you may need to do. A couple of problems with PVC and CPVC pertain to why you are mixing media and size incompatibility. In other words, 3/4 PVC is not the same size as 3/4 CPVC.
Many folks do not understand about how the various plastic pipes are joined. There are 3 basic kinds of plastic pipe; ABS, PVC, and CPVC. They are chemically different. That much is easily understood. The problem comes in the fact that what we all commonly call pipe "glue" or "cement" is neither of these. They are solvents that melt the top surfaces of the pipe and fitting briefly. When the two surfaces are joined, the liquid surfaces combine into what is actually a chemical weld. So, it's not a matter of bonding, strength, or sticking. Each type of pipe has its own solvent, so the answer to your question is, No, you can't join different types of plastic pipes, except by using appropriate adapters. Not known what you are doing and why you would need to join CPVC to PVC, it's hard to advise you on what you may need to do. A couple of problems with PVC and CPVC pertain to why you are mixing media and size incompatibility. In other words, 3/4 PVC is not the same size as 3/4 CPVC.

I beg to differ... PVC and CPVC have different applications, so they are not typically used in the same types of applications. CPVC goes through an extra chlorination process, which lets it withstand high temperatures much more effectively than regular PVC. While PVC starts deteriorating at 140F, CPVC stays strong up to 200F, which makes it perfect for water supply lines. PVC, on the other hand, is most often found in drain lines since it’s cheap and doesn’t rust.

The first thing to consider is size. Are the sizing systems even compatible? All major brand PVC pipe is made to NPS (Nominal Pipe Size) standards, or “schedules.” Schedule 40 and 80 are the most common NPS schedules. The schedule determines how thick the wall of the pipe will be. The size name (given in inches) is just a nominal size, so the measurements will not be exactly that size. A 1” schedule 40 pipe, for example, will have a 1.029” ID (inside diameter) and a 1.315” OD (outside diameter). Sch. 80 PVC and sch. 80 CPVC will fit together because they have the same ID and OD. The same is true of schedule 40 PVC and CPVC, but that type of CPVC is rarely used.

One major difference between these two types of piping, when it comes to sizing, is the fact that CPVC is made in two different sizing systems: NPS and CTS. CTS (Copper Tube Size) is, as the name suggests, the same size as copper piping. This is a source of confusion, as CTS CPVC and copper are both commonly used for the same jobs. CTS pipes and NPS pipes are not compatible. Usually CTS CPVC is yellowish in color, while NPS CPVC is gray (sch. 80) or off-white (sch. 40). They are also marked on the outside, so telling different types of piping apart should not be difficult

Just because CPVC and PVC can fit together, this does not necessarily mean they can actually be implemented into a working system.PVC cement (or glue) does not work like regular glue. It breaks down the surface of the pipe it is applied to and chemically bonds pipes and fittings together. For this reason, you cannot use just any PVC cement to join these two materials together. CPVC, as we explained earlier, is a stronger version of PVC pipe with a higher melting point and tougher chemical structure. This means old-fashioned PVC cement will not be fully effective on CPVC.

**So, NO; There is no special “CPVC to PVC glue,” and chemically joining CPVC and PVC requires solvent cement and primer that are strong enough to fully bond CPVC pipe. To connect PVC to a CPVC fitting (or vice versa) follow these steps:
  1. Brush CPVC primer on the outside of the pipe and inside of the fitting about 2 inches deep.
  2. Immediately apply a light layer of CPVC cement to the area that is primed outside the pipe and inside the fitting.
  3. Slide and twist the pieces together then hold them together firmly for 30 seconds.

...HOWEVER; interchanging the TYPES this will not pass inspection if the plumbing line REQUIRES CPVC because of line pressure or temperature, because you have to use the specification of the lesser pipe/fitting type - in this case being PVC.

Additionally, PVC and ABS can also be joined with solvent connection [ ;) no more "rubber boots" to blow out! :|) ] ...https://www.homedepot.com/p/Weld-On-4-oz-ABS-PVC-794-Transition-Cement-in-Green-13369/203111088

Anyway...wasn't trying to be a wise-a$$ but a lot of people don't know about the new solvents and standards for the pipe fittings... I guess inspectors finally red-tagged enough jobs that plumbers and piping companies took notice...
 

Layla-Gail O'Brien

New Member
Messages
14
Reaction score
0
Points
1
Location
Galveston County, Texas
Website
www.linkedin.com
PVC and CPVC don't mix. Inside a home, only CPVC is legal. PVC is for cold water pipes underground.

Since they are not the same size, the only way to connect the two pipes is with threaded fittings. The post above by the inspector mentions that.

Actually, as long as you make sure you aren't using an inferior pipe/fitting for the job and the CPVC isn't CTS sidewall... they do! [see reply below]
 

Reach4

Well-Known Member
Messages
38,796
Reaction score
4,413
Points
113
Location
IL
CPVC stays strong up to 200F, which makes it perfect for water supply lines. PVC, on the other hand, is most often found in drain lines since it’s cheap and doesn’t rust.
PVC is commonly used for the down pipes on wells. Schedule 80 is the common minimum, and schedule 120 and 180 are used for deeper well use. This pressure rated pvc is strong and solid. The PVC sold as DWV is different. It is a foam core. It is lighter and weaker.

IMO, the codes should explicitly allow wells to use PVC pressure pipe up to the pressure tank, even if that is indoors.

ABS pipe commonly sold is all foamcore, and not suitable as pressure pipe.
 

Layla-Gail O'Brien

New Member
Messages
14
Reaction score
0
Points
1
Location
Galveston County, Texas
Website
www.linkedin.com
PVC is commonly used for the down pipes on wells. Schedule 80 is the common minimum, and schedule 120 and 180 are used for deeper well use. This pressure rated pvc is strong and solid. The PVC sold as DWV is different. It is a foam core. It is lighter and weaker.

IMO, the codes should explicitly allow wells to use PVC pressure pipe up to the pressure tank, even if that is indoors.

ABS pipe commonly sold is all foamcore, and not suitable as pressure pipe.

Actually, not all DWV is foam-core piping, but ABS DWV is...DWV PVC looks very similar to standard white schedule 40 and 80 PVC pipe and fittings. The only real difference is that DWV PVC is not made to handle pressurized uses like schedule 40 parts are. Instead, DWV PVC pipe and fittings are only made to handle Drain, Waste, and Vent (hence the name DWV). Drain, waste, and vent applications use gravity to create the flow of water and waste through the line. These applications cause minimal stress on the PVC parts, allowing for thinner walls and the elimination of pressure testing by the manufacturer.

The result is a less expensive product with a few specialized parts that are particularly useful for drain and vent uses. A few parts that are typically used for DWV applications are p-traps, drains, and cleanouts. Another difference between DWV and standard PVC parts is the end types. Standard schedule 40 and 80 PVC fittings have ends that are either threaded or socket (sometimes called slip). DWV parts sometimes come threaded, but their slip style fitting ends are called “hubs,” and are usually shallower than the deeper schedule 40 ends. For example, a slip coupling may be called “HUB x HUB” or “H x H” for short.

Threaded fittings for DWV PVC are made with the same NPT thread-type and size as standard PVC fittings; therefore, DWV and Schedule 40 and 80 pipe and fittings will fit together, but it isn't recommended that they are used together... and I'm not aware of any place it would pass inspection...because no DWV pipe or fittings (PVC or ABS) should EVER be used to carry pressurized liquids or gas!
 

davidxingyin

New Member
Messages
3
Reaction score
0
Points
3
Location
shijiazhuang
PVC and CPVC don't mix.

Differences between CPVC and UPVC

1. Plasticizing difference: UPVC is rigid PVC. A modified material is prepared by adding a certain amount of modifier on the basis of PVC resin powder. Therefore, the main difference between UPVC and PVC and soft PVC is that without plasticizer, there are more calcium powder and the material has high mechanical strength.



2. The difference of chlorine content: CPVC is chlorinated polyvinyl chloride, which increases the chlorine content in PVC materials through a certain process on the basis of PVC resin, thus improving the heat resistance, acid resistance, alkali resistance, salt, oxidant corrosion of the materials, and improving the thermal deformation temperature and mechanical properties of the materials.



3. Cost difference: CPVC increases chlorine content of PVC resin by chemical method, so the cost of CPVC is higher than that of UPVC.



4. Use difference: UPVC is suitable for producing valve pipes, etc. CPVC is mainly used in fire fighting pipes, chemical corrosion-resistant pipes and civil hot water pipes.



Precautions for PVC injection:



1. The product should not have sharp corners or sudden changes as far as possible, and the thickness should not change much in order to prevent degradation and deterioration of PVC.



2. The temperature of the mould should be controlled by cooling water control device, so that the temperature of the mould can be controlled between 30 ℃~60℃.



3. It is necessary to avoid the deterioration of other plastic PVC raw materials. Especially when other raw materials have been injected, the plastic in the barrel and screw must be cleaned before the PVC products can be injected.

If you want to know more, please visit https://www.pvcpipefitting.com/blog/
 
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