i am wondering if Purple Primer has become a not well tested standard. please tell me if i am wrong. i was shocked when i found i could actually break pvc and cpvc connections with just torsional stress. i expected the pipe or fittings to fail but to my shock the glue joints themselves actually failed.

we decided to sacrifice a newly installed system. after a cure time of 2 weeks we sawed apart and put the connections under torsional stress. we found 10 failures in that house. we decided to re-plumb the house but how you do that is a real question.

the failure in all cases was between the glue and the purple primer. these connections depend on fusion to work. that is, the mixing of the two plastic parts that have been temporarily liquefied by a solvent. the plastics mix and becomes a hard continuous material after curing. a good fusion bond will not break. the part itself will break in the thinner walls outside of the double layered bond area.

when purple primer is used, it does what primer usually does. it prevents the solvent glue from getting to the plastic at all. you could see that under a microscope. you can prove that by painting purple primer on a plastic part. then paint a thick layer of solvent glue on top of that. after curing you can see that the solvent glue can be easily pealed off the primer. it simply becomes a not so strong glue joint. not a fusion joint.

the purple primer itself has a little better bond to the plastic but that only extends a few thousandths into the plastic. that's because the primer evaporates very quickly.

there is a short lived advantage to that combination. the solvent effected area of the plastic is very shallow so cure time is very fast. but the joints made with just cleaner then solvent glue were in my tests much much stronger after a reasonable cure time. and none of those joints failed from glue failure.

it was seen that the glue without primer made fusion welds about 0.03 inch deep .. where the purple primer depth was only 0.002 inch. the penetration of solvent glue into the primer did not happen.

purple primer is the law here and in most places. but has anyone actually made sure this is something that works. the best you can say from my tests are that it shortens cure time but with terrible long term results.

now i don't like spouting off if my data is wrong. so we went to the hardware and had their "experts" teach my people the "right" way to do things. but nothing changed. we made sure we had the proper materials and were doubly careful about everything. still we could make failures.

i got advice from many. the young guys and the store experts all said you will have failures unless you use purple primer and its a code requirement. you have to do it. but some old plumbers with years of experience said. don't ever use purple primer, it will weaken your joints. well now i don't know what to believe other than my own experience.

i haven't found any federal or local testing of this combination. but i am thinking old experience trumps the established way of doing things. still you are stuck. you have to follow code and it hurts to know that you have possible failures in the making.

obviously the glue with purple primer has been working for years but i am thinking that doesn't prove the joints are as good as they can be. it only says its good enough maybe.

it would be good to have someone duplicate my experiment and tell me i am wrong and give me a reason. i would love to see the thinking that went into the purple primer/solvent glue combination. if it was for short term fast cure times then that's not a good reason.

we tried applying solvent glue to still wet primer and that worked better but nearly impossible to do since dry time is very fast with the primer. that did however improve results. that still limits fusion depth so connections were faster curing but not as reliably strong eventually as cleaner/glue combination.

it was found that the greater depth of penetration was needed so that the plastic parts fluidly conform to eliminate problems with out of round, burrs, texture and even contamination. when the plastic can be deformed then it mates perfectly with the other surfaces. with the primer/ glue combination you are depending on the glue to fill in gaps. not good in my opinion. you end up with a layered glue joint. that combination may not even have the same temperature coefficient as the plastic alone or fusion.

i welcome comments. it seems the only way to do this properly is to get code enforcement involved if that's possible. not here they don't make the rules they just enforce them. who then do i contact. this is my first stop. this looks like a good venue to iron this out.



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Try editing this post with some paragraphs

quote..
" went to the hardware and had their experts teach my people the right way to do things"
that is mistake number one.
sorry to insult hardware store people but I have yet to find an expert there.
in my long career of putting pvc together I can't remember one joint that was properly primed and glued coming apart.
of the thousands I have done, what I can remember is putting (maybe a couple of dozen) together and within 30 seconds realizing I had made a mistake. I uttered a few words that are banned from this site and tried rotationally and every other direction I could think of without getting the joints apart.

I agree with Packy on this.

In my experience using quality fresh purple primer and then immediately after applying primer using quality fresh cement, naturally following the directions from the manufacturer (length of drying time, temperature and humidity, cleanliness, etc) makes for a very strong solvent welded joint.

Quote: " I was shocked when i found i could actually break pvc and cpvc connections with just torsional stress."

You do say you are using PVC and CPVC pipe.

However is there "ANY" chance that you are using ABS (black) pipe. I am not a plumber but from my understanding you do not use Purple Primer on ABS pipe. I have read that in many articles.

I write this just to clear up any question as to what pipe you are using. (I now stand by to be corrected by any licensed plumber.)

Quote "I uttered a few words that are banned from this site and tried rotationally and every other direction I could think of without getting the joints apart."

Same here. IF I caught the mistake within a few seconds, it MIGHT come apart.
After 30 seconds, saying "Dagnabbitsonofawitchonabroomfromell" didn't do any good.

Wrong magic word, maybe?

well who are you going to go to for advice. is there anyone else?. granted i had to choose among the unwashed to find one with "experience" at the hardware. but what he said is just what you are saying. he defended purple primer. in fact got angry that i would question it. he also has years of experience and has "never" had a failure. although one of his customers said he did have at least one.

so i had the "expert" make me a bunch of connections for test. he was very reluctant but did so when told to by the boss. when i tested his joints all passed my tests. but under a microscope you could see that he did not use purple primer until after the joint was made. he expected us to fail his joints and wanted to show us how wrong we were. that backfired of course when they all passed. he refused to make more.

now you cant tell much about a single connection. even ours, out of a whole house of plumbing we found only about 10 failures. its not a matter of all failing its a matter of how close to failing are you. we stressed the parts beyond what they would normally see in service. but the point is none failed without primer some did with it. so is there a better way. there is no fusion of plastic material when purple primer is used if the primer is allowed to dry. and that happens way to fast to be reliably overcome. you can prove all this easily. just paint primer on the outside of a pipe. then paint on solvent glue. if you can peal off the glue then the glue did not penetrate the primer and you will not have a fusion connection.

you can argue that the captive parts trap solvent glue so that might be more effective than exposed to air drying. but remember you can put on as thick a coat as you like extending penetration time but in the actual joint nearly all glue material is squeezed out if it has not already combined with the plastic. that leaves you with a very thin coating of solvent.

we did buy all fresh products "again" to make sure we didn't have just some bad component. the hardware management was interested in our test so contributed pipe and parts for an extended test.

while its hard to do what we did, that is, destructively test a whole house. its easy to see that fusion welding is not happening, even if primed joints often work, a glue only joint without fusion is not as strong as it could be.

i cut apart a few of the strongest purple primer samples that did indeed pass my tests. i found that for whatever reason the glue did penetrate the primer. in some because the primer was missing deep inside or in a small area. on others i would guess the primer was not dry when assembled. at any rate the strong connections all had fusion welds, if only over a small portion of the joint.

the question to be answered is... are these primed joints indeed fusion welds. i say not in my tests. and i worry not in many. if a glue joint instead of fusion is acceptable then that's a different story.

in my tests the primer/glue works but is not a good thing. how am i wrong. i really want to know. it would clear my mind if i could say with confidence all those connections we made to code are as good as they can be.

i am an electrical engineer so granted not a plumbing expert however as in all projects i do i consult those that have expertise. i checked with my chemical and mechanical engineering people. they are confused about why primer is used in view of the test results. the fact that it "works and has always been done that way" doesn't answer that question. i expect criticism and hope for constructive ways to prove primer is a good thing.

the mechanical people tried to find a reason for primer. it minimizes the solvent affected zone thus reducing the peripheral damage to the part. but the fact that a penetration of only 0.03 in the case of no primer, that is considered of little consequence to the overall strength of the part. the chemical people point out that there is a zone of plastic that has a mix of adhesive that might not be as strong as pure plastic but in no case is that weaker than the adhesive bond alone to primer.

at this point i want to find some dumb thing (other than consulting the "experts" at the hardware) that i and my workers have done to cause this problem.

its easy for anyone to see if the solvent glue actually penetrates the primer. i say it doesn't and if that's true then you do not have a fusion connection. you have a glue joint. is that what you wanted ??

if the solvent does not penetrate the primer into plastic then there is little if any softening of the plastic surface. that softening is needed to allow the plastic to conform and fill in surface imperfections, pipe size, roundness and other problems that are eliminated when softening is allowed.

the parts are able to conform within the dept of the solvent affected zone. if that's zero then there is no flow of material to fill gaps. the relatively weak adhesive has to fill in where plastic should be.

sorry about that. some blogs delete paragraphs. not sure why

you might be right in what you are doing. indeed that's the only way i got purple primer to work. but that's difficult to do reliably especially for one not skilled in the art. i have seen suggestions to not allow the primer to dry but that's not easy. so DIY would not know how to do that. and by the time they paint the last part the first one or at least a part of it is dry.

one of the guys i talked to had 40 years experience. he always used purple primer. i asked him if he has had any failures. he said not very many. one he remembered was a hot water line to a washing machine. it lasted some 10 years then blew causing incredible damage to the finished basement. the hot water line has both thermal cycle stresses and mechanical thumping as water is turned on and off (water hammer) . he did think it was strange to see the parts come apart not break. he couldn't remember the other failures but in 40 years he has seen a few. i sure wish i had those parts to test.

however looking at other failures brought to me i noticed many violated some rules. some were not cut off square. some had burrs folded back on the pipe. some were not inserted all the way. a few had contamination like saw dust. but all had purple primer and none had solvent penetration of the primer and almost all failed at the glue interface to the primer. one had only primer.

so i am thinking if you are really good and really fast then you might get away with purple primer. but if you are a DIY person or one without years of experience then i think purple primer is a risky way to go. i doubt any of the failures i saw would have happened with cleaner/solvent glue only ..

i cut off a pipe at an angle with even a false cut mark then i banged up the end on concrete to make burrs, then i dipped the thing in sawdust. i glued it without primer and without cleaning then purposely pulled it back from fully seated a little. i made every attempt to make this thing fail. it worked anyhow. that tells me we have increased margin when fusion is allowed to happen.

the only thing i see that primer helps is cure time. it becomes strong very quickly and maybe that's important when it has to be pressure tested too soon. but at what cost.

if the primer is blocking the solvent from doing its job then that's all we should have to prove. unless someone comes up with a more important reason for using it, it seems to be a real detriment.



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quote..."so i am thinking if you are really good and really fast then you might get away with purple primer. but if you are a DIY person or one without years of experience then i think purple primer is a risky way to go".

NO!! It is not risky! It's the proper method! You got good advice from PRO! plumbers. don't be stubborn. Get yourself some quality primer and glue from a plumbing supply house. Don't be afraid to give your fittings or pipe a little twist as you set. Hold together for 30 seconds and be done. Just like with anything the more you do it the better you get.

yes we are using pvc cpvc and other materials. we follow all instructions to the letter on each.

if you are in doubt that this problem happens. then just do my simple experiment. paint purple primer on the outside of a plastic part. let it dry now paint on the solvent glue. if there was indeed a fusion type connection with the plastic then you will not be able to peal the glue off after curing. indeed you cant if you have not used primer. it will take some of the plastic with it when forced to peal. but with the primer it will simply peal right off leaving the primer undamaged.

the primer itself can be pealed off of the plastic but will take a very small amount of plastic with it. you can measure its depth of penetration by what comes off with it. but you will notice the plastic under the primer will still have its shine. if you keep the primer wet for awhile then it increases its depth of penetration. and if you can keep it wet long enough then the glue will somewhat mix with the primer.

you still wont necessarily have fusion of plastic to plastic but a whole lot better than a typical dry primer connection.

under the microscope you will see plastic fused to primer a little. then that primer layer fused to solvent glue. then that solvent glue layer fused to the other side primer and that primer fused a little to the other plastic. that works but its not fusion of plastic to plastic. its a multi-layered complex structure. and even that happens only if you can keep the primer wet until glue is applied on all parts at the same time.

you can do that experiment any way you want. using pressure or multiple parts or even several coats of solvent. the only place you will see fusion to the plastic is where there is no primer.

you can notice that joints made with dried primer will become strong very fast. that's the reason you cant take them apart right after assembly. that's actually a bad sign. if there was proper fusion then there will be a semi liquid phase between the parts until some curing. the connections will remain weak until at least a couple of seconds curing has happened. that happens pretty fast but full strength takes a while. the primed joint reaches its maximum strength very quickly because there is very little material involved. everything squishes out that can. what is left is only a few molecules thick.

in the case of no primer then the solvent glue actually penetrates the plastic before the parts are even assembled. you can control the depth of that penetration by a delay time before assembly. the longer you wait within reason the deeper the solvent penetration and the more forgiving the joint will be but the longer it will take to cure.

if you join the un-primed parts quickly after applying the solvent glue then you will have a relatively thin solvent affected zone in the plastic. that means cure time is short but strength will still be high because its is fusion. but conformance to flaws in the plastic is not as good as below.

if you wait after applying the solvent glue for say 5 seconds then the depth of the fusion weld goes up and conformance to surface irregularities is better but cure time is lengthened.

one skilled could actually modulate that time for the circumstances. if you are dealing with perfect parts, skilled workers and have a deadline before pressure testing then assembly quickly after applying the solvent glue will help that. it still wont be as fast as primed but will be a lot stronger and faster than deep fusion.

if you have "not so perfect" parts or not so skilled labor but have plenty of time for curing then it looks like a 2 or so seconds wait after applying the solvent glue before assembly is in order. that's more forgiving in my tests. you do have to hold the parts together for a couple of seconds since early fusion is in a liquid state for a short period. the thicker the fusion layer the longer it takes. its a good idea to hold the parts anyhow even with the primer since there is a tendency to back out for a second or so.

with the primed parts you can get away without holding the parts together, so many skip that important rule. but with deep fusion you cant ignore that. it only takes a couple seconds to do it right.

since there is plastic flow with fusion then the parts always bottom out (insert all the way) when assembled. but if the primer prevents softening of the plastic then i saw some connections that were in as far as they could go but not bottomed out. if the parts wont comply then it depends on how precise the parts were to start with.

chances are the taper in the fitting will not comply elastically to a pipe on the high side of its spec. but if you avoid primer then you have some semi-liquid area that can easily mold to whatever shape it needs. it allows bottoming out and actually encapsulates foreign material to some degree.

i estimate that quick assembly gives you about 0.01 inch of acceptable error in parts or contamination. a 5 second wait before assembly gives you over 0.03 tolerance. the primed parts gives you only tolerance within the elastic limits of the components. it takes a lot of force to bottom out worst case parts with dry primer.

i have done a lot of work on this and at the same time am hoping someone can tell me why i am wrong. not that i am but why i am. surely someone has done all this before it became a standard. was it done just to speed assembly or sell primer? i hope not.

i can see perhaps early failures caused by not understanding the process, prompt regulators to seek a solution. but was primer the solution to an immediate problem at the detriment of the process ?

i am listening to all your comments and hope we can all work together to resolve this long argued point.

quote; paint purple primer on the outside of a plastic part. let it dry

I thought you said you read the directions. You do NOT "let it dry", since the cement is supposed to be applied IMMEDIATELY after the primer.

quote; however looking at other failures brought to me i noticed many violated some rules.

WHY are "failures being brought to YOU"? Are you an ambulance chasing attorney trying to institute a class action suit?

quote; and by the time they paint the last part the first one is dry.

How many connections are they trying to make at one time? If you do them one at a time you would not have the problems you are citing.



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quote; but under a microscope

I am impressed. Few people would think to take a microscope with them to the hardware store. AND, if the joints did not fail, how could you inspect them with the 'scope? Again, I think you have an ulterior motive, or agenda, to be spending this much time on a problem that FEW people have. HOWEVER, I have had PVC connections fail after many years when they did NOT use the purple primer. I hope the person who had the washer line fail had used CPVC, or it should have failed a lot sooner than it did, regardless of whether it had primer or not.



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Primers are an important piece of the solvent cement process and are required by building codes for most applications. They help to prepare the pipe and fitting for solvent cementing by cleaning and softening the pipe and fitting making sure that the final joint integrity is maximized. For most cases, a cleaner should be used, followed by a primer and then the solvent cement. Additionally, after application of the primer, the solvent cement should be applied immediately before the primer dries. Note that primers should NOT be used for ABS pipe and that cleaner should be used in its place.


Oatey

Read pages 8 and 9.
[www.tchristy.net]

hi doug e. we of course did everything by the book. we even tested what that little twist does. then we measured time to freeze. that's how long it takes for the joint to become self immobile. that varied a little with the depth of fusion and part tolerance. i don't remember what the specifics were for that but they were no where near 30 seconds. once the softened material conforms to its new position and shape then there is no longer an internal force to push it back out. in our tests that took only a few seconds. strong adhesion of course increases with time.

my installers would shriek if they had to hold on 30 seconds for every connection. what we did find is that no external stress should be placed on the connection for at least several seconds . 30 seconds would be nice if production allows.

alas we did all the work to local code and exactly the " proper " way. there is no choice in that yet until regulators do a second look at this. but one thing we know is that the intended fusion welds of these pipes and fittings is not happening the way we are doing it. and we think we are doing everything by the book unless someone can show different.

one thing i did notice is that purple primed joints have a stronger tendency to back out in certain cases. when the parts fit tightly then the primed joint does not comply well. when you push it in it elastically stretches the tapered connector to accommodate the fully inserted pipe. that stretch is reversible in that it tends to push the pipe back out. since freeze time is very short with primed parts that isn't much of a problem but can be for fast workers.

parts assembled without primer however start with softened plastic that quickly conforms to the diameter of the fitting and the spring force is no longer present. however the joint remains semi-fluid for a second or so. it becomes sensitive to external forces for a few seconds. its actually much better than the primed part as far as pushing the pipe back out is concerned.

if you really meant "hold the parts for 30 seconds" then i will have to try that. i doubt it will help since freeze time is so short. but i will try anything that has a chance of helping with the understanding. remember that damaged no primer test part with no hold time and even purposely backing it out a little still, even sawdust, survived and made connections stronger than the part itself. how can primer improve on that forgiving nature.

and as far as taking the experts advice. that too is a problem i found that some say the book is right don't question it. others say its dead wrong and even more say they don't have a clue and have never been able to understand the why.

wouldn't it be nice to have one cohesive voice that brings it all together with physical proof and proper unbiased science based results one way or another. we need someone in authority and with plastics, mechanical and chemical expertise to revisit this. if you know such a person then i will contact them if possible.

this is one of those things that should be resolved not just accepted if there is new information that shows a problem. if i am wrong, it wont be the first time. if i am right then maybe we can fix this.

i will try to be open minded and i would hope you will also. the idea is to solve the problem not to assume anyone is right or wrong.

MANY years ago while a plumbing apprentice and taking a plumbing class at L.A. Trade Tech College we had a representative come in from Spears mfr and we did tests directed by him.

Using primer and not using primer before using cement and the difference was very significant as far as the strength.

We cut away sections of fittings and where primer was used the joints were solvent welded and the connection was strong as the pipe/fitting itself.

Now about 40 years later quite possibly the cements today have improved in formulation however I saw in class where the primer both cleaned and importantly softened the fitting/pipe and so I'm still a firm believer in using primer with PVC and CPVC.

thanks steve. very informative directions.

hello HJ


quote WHY are "failures being brought to YOU"? Are you an ambulance chasing attorney trying to institute a class action suit?

no i have never sued anyone even when it was justified. when i went to one hardware with this problem and demonstrated it. one of of the managers became interested. he then with my permission steered other plumbers with similar problems to me. i welcomed the additional input. pretty soon several people came to me with samples.

i have always been a trouble shooter. in the army i made a difference in our missile defense system. i worked with suppliers and tech reps. believe it or not a soldier can do that. i did. my missile sites across the country ran better and were more reliable than ever before. i made huge cost reductions by working with suppliers to make modern versions of troublesome circuits. i can say i worked hard in the military and did my part.

after military service i became a senior engineering trouble shooter for a large company. i was in charge of teams of sometimes PHDs to solve the most difficult problems for that company across the country. now i sometimes take on problems for free from small businesses to large. i have never asked for a penny but often get a crate of nice things in my front yard.

quote; How many connections are they trying to make at one time? If you do them one at a time you would not have the problems you are citing.

typically my experienced people would do a T connection all at once. that would be 6 surfaces total. the less experienced would do just one at a time and would take much longer but with the same results. most failures had little to do with the skill of the person doing the work.

when i say the primer was dry, its just chemically not wet enough to do much mixing with the solvent glue. its only as dry as it gets when you put down the can of primer and pick up the parts to be assembled and the glue.

the dry time is very fast for primer. for our purposes its no longer fluid enough to prevent blocking the solvent glue from doing its job in just seconds. while it can be done its not a reliable thing in my opinion for most DIY people. but indeed if you can assemble with still wet primer you get better connections. i would love to test samples from others to see if there really is fusion of plastic surfaces going on with what ever method they use to keep the primer wet.

the instructions say to use the primer twice on the connector. once before the pipe and once after. that's an attempt to keep it wet.

there seems to be a new version of low VOC primer that may have a longer wet working time. but haven't tried that.

If your joints are pushing out on you then I,m guessing your not remeaming the outside edge,this also part of a proper joint.try one of your experiments doing it that way.please let us know..dan

hello steve .. very nice article. www.tchristy.net i would agree with everything they are saying. i get that they are saying the solvent glue alone is all you need but if you have to use the primer by code then you must use it wet and that i also agree with.

my problem is its easy to make good fusion welds with solvent glue alone but more difficult to do so with primer first. to what degree can you let a portion of the connector dry. there is always some drying around the top of the target. so where does it become a problem. the fact that we saw failures while using the primer but did not while using just the solvent glue even under worst case conditions should be saying there is a reliability hit without benefit by using the primer.

thanks for a good article steve.

now Vics article about his time as plumbing apprentice is appreciated. it looks like a good recommendation for primer. i would love to see the test results to see why they differ from mine. maybe materials have changed over the years. i have seen good primed connections but i have not seen any that were stronger than the solvent glue connections without primer. and i haven't seen significant fusion of plastic when primer was used unless the primer was very wet. my cross sections show very nice plastic flow and mixing using just solvent glue. very little using primer.

thanks vic. your input helps with the bigger picture.

hello PlumerDan

quote "If your joints are pushing out on you then I,m guessing your not remeaming the outside edge,this also part of a proper joint.try one of your experiments doing it that way.please let us know..dan"


good point dan.
the joints made with just solvent glue don't push out. its only some of the ones with primer that do that.

we do cleanly cut the pipes and clean them of burrs inside and out. if the primer is not liquid enough to soften the plastic deep enough then the pipe is actually bigger than the tapered hole in the fitting. if you force it in, then it wants to spring back out for a second or so. until its glue bond starts to exceed the push back forces.

there will always be push back forces unless the plastic is softened enough to deform to the smaller tapered hole. (or the hole deforms to accommodate the pipe or actually both). it can do that if the solvent softened zone is deeper than the required deformation.

the primer typically dries so fast that it only penetrates a couple of mils. so the parts don't plastic flow enough to remove that push out force. you might not notice it because the cure to freeze time is so short with primer.

you will really see the difference if you take a pipe on the high side of its spec and put in in a fitting on the low side of its spec. now with primer you will feel a strong push out immediately after insertion. that is, if you can even get the parts fully inserted. the push back only lasts a second or so but can be a problem if not held in place for that second of freeze time.

using the same spec parts without primer you will likely not feel any push back. that's because the pipe and fitting are already softened before insertion. and the soft surface depth is enough to allow the plastic parts to blend together when assembled. there is no spring force available to do push back in that case.

the solvent glue does a much deeper penetration of the plastic surface because it has a much longer wet time. it will however not penetrate primer unless the primer is still liquid everywhere in the connection. even then its penetration is slowed considerably.

you would like the depth of that softened surface to be enough to accommodate normal size tolerance, slight out of round errors and surface textures. its far better to let the plastic flow into those areas instead of filling in voids with adhesive.

hello hj
quote; I am impressed. Few people would think to take a microscope with them to the hardware store. AND, if the joints did not fail, how could you inspect them with the 'scope? Again, I think you have an ulterior motive, or agenda, to be spending this much time on a problem that FEW people have. HOWEVER, I have had PVC connections fail after many years when they did NOT use the purple primer. I hope the person who had the washer line fail had used CPVC, or it should have failed a lot sooner than it did, regardless of whether it had primer or not.

actually i do have a digital microscope i carry frequently with my laptop, but of course why would i be doing lab work in a hardware store. i could but that makes little sense. i take photomicrographs with me to demonstrate what i have found in the lab if needed.

the joints we tested were FMA. we, of course took them apart to find out why they failed or passed tests. if i stress tested it why would i leave that potentially damaged part in place. of course it would be replaced and the failure or passed stressed part brought back to the lab for further study. when i stress test a part its usually until it fails one way or another. the glue joints failing is my interest right now. then i am also interested in any that pass when i expected them to fail.

and of course the man used CPVC. if he didn't it would be obvious why it failed. i think it should be obvious why it did fail. that man claims he has always used purple primer and i have no reason to doubt him. i also don't doubt the failure was caused by exactly what i am talking about. with primer you have a probability of at least a portion of a joint having purple primer that has blocked the solvent glue from making a good fusion weld. its the same failure i am seeing now.

what ulterior motive could i possibly have spending all this time trying to clear up confusion for you and everyone else.

while i am disappointed in the negativity i can see where it comes from. everyone seems to have an agenda today. there is a scam around every corner. and no one does anything that is difficult just because its the right thing to do.. do they ?

according to the latest data i am looking into, purple primer is not required outside of some areas that still have that on their books or in special cases. also parts made without primer are perfectly acceptable with many manufacturers and in many areas. in fact according to one company engineer its the preferred method now to not use primer unless forced by code or special needs.

there is nothing to show that areas that don't require purple primer have any higher failure rates than those that do. more on that after i contact a few more people. in fact i suspect the opposite will be shown true.

For what it's worth, I have only seen 2 failed glue joints. One was on a 1/2" CPVC hot supply line to a bath lav underneath the floor, NO insulation on pipe, no insulation in crawlspace, and an open access door in the cold winter. The pipe had the orange CPVC solvent; no purple primer.

The other was Black ABS kitchen sink drain pipe in a heated space. Could not tell if purple primer was used.

I cannot say if primer or lack of it caused the problem. I cannot say if the solvents/or primers were new and fresh. I cannot say if any cleaner was used. I do not know who made the union or how.

What I can say is every single solvent weld I've made by de-burring the pipe end, using fresh cleaner, primer, solvent with a 1/4 turn twist and holding for 30 seconds has never failed.

Never had a call-back on any solvent welds I have made. But then again, I never go back any apply torsional stress to failure just to see how many foot-pounds of torque it takes to break it loose.
My 2 cents.

I am not a plumber but was curious to follow this thread.

My question to you is you kept saying PURPLE primer. Are you singling out the purple primer as producing the weaker joints you saw or are you saying all primer but purple primer is the sample you used in your tests?

The primer softens the surface, as long as it is a liquid. Once it dries IT becomes the surface of the pipe that you glue to, NOT the PVC/CPVC itself. It is like fastening to a painted surface. The bond is no better than how good the paint adheres to the underlying surface.

quote; the idea is to solve the problem not to assume anyone is right or wrong.

Who is this "WE"? There is no "problem" other than one you are trying to create.

quote; the less experienced would do just one at a time and would take much longer but with the same results.

I guess that I am a "less experienced" plumber even after 60+ years in the trade because I have SELDOM had a situation where I had to make all three tee connections at the same time. AND making one at a time does NOT "take much longer". This posting has gone on much longer than necessary. In my opinion, and based on my experience, your whole premise is faulty. IF you are getting that many failed connections from "users", then THEY are the problem, not the materials.

HLee (OH)

Have you approached companies like Spears, Lasco and SolderSeal regarding your destructive testing results? I would be interested in what they have to say regarding their various formulas, as solvents. Besides, it would give them an opportunity to further explain to you and us.

Best Wishes

quote; The other was Black ABS kitchen sink drain pipe in a heated space. Could not tell if purple primer was used

"Primer" of any kind is NOT used on ABS pipe or fittings.

to: sum (FL)
quote: "I am not a plumber but was curious to follow this thread".

"My question to you is you kept saying PURPLE primer. Are you singling out the purple primer as producing the weaker joints you saw or are you saying all primer but purple primer is the sample you used in your tests?"

since purple primer is code in my area that's the only thing i tested. i don't think there is a specific defect in purple primer but my tests do show that it can be the cause of problems.

purple primer is just clear primer that a dye has been added to make it easy to see. it was added for code compliance reasons only. the dye is not suspected as a cause of any problems that i know of.

i was just handed an article that claims purple primer should not be used for drinking water. yikes. i better check more on that. that's a new one on me.

we did try just cleaner then solvent glue and that worked great. first it does pre-soften the plastic a little. i don't think that is needed but it doesn't hurt unless too much is used or its pooled. but at least the solvent glue is not adversely affected. its a less aggressive solvent and that's good for cleaning. making a sticky surface is not a good way to keep particles from sticking. i consider it just a nice way to wipe the surfaces clean. you can let it dry or not. it wont change the results. one difference you can quickly wipe the cleaner off to remove contamination. you don't wipe off purple primer without making a mess.

purple primer on the other hand has a profound effect on joints. as someone "point out" "it is a primer and it prepares the joint for gluing". i would agree with that. my disagreement is... is that what we want to do ? a glue joint and a solvent based fusion joint are two different things.

judging from the number of really good people that are disagreeing with me here then i would say to listen but don't do what i say except for testing. wait until we (or me if i am the only one) gets more and better information and approaches code compliance with that result.

but surely tuck this in the back of your open mind as a possibility. so far i am getting some minds ticking on this. some others outside this blog are scratching their heads at least.

i feel its worth looking at since it involves a whole lot of plumbing in a lot of houses. of course its a moot point for most since you have to go by code right or wrong. if i am wrong then i will have just irritated some people and maybe gotten a few thinking. but if i am right then there is a real reason for doing something about it. difficult as that may be.

i feel my tests are showing something important and i haven't yet seen any scientific tests that show otherwise. although one person did show, not tests but, results he remembered from years ago. so that "proof of concept" may actually be out there somewhere. also good plumbers are having good results which would tend to say maybe its good enough the way it is.

i am in touch with engineers that should be able to answer to this before long. so be patient.
discussing it is good, ignoring it might not be the best thing considering my test results. you can duplicate those and see what you find for yourself,

hello Wheelchair (maybe we have something in common there)

quote: "Have you approached companies like Spears, Lasco and SolderSeal regarding your destructive testing results? I would be interested in what they have to say regarding their various formulas, as solvents. Besides, it would give them an opportunity to further explain to you and us."

no i haven't but that's a great idea. i will see if i can find an engineer to talk to at those places.

thanks for the good wishes.

to hj
quote; "I guess that I am a "less experienced" plumber even after 60+ years in the trade because I have SELDOM had a situation where I had to make all three tee connections at the same time. AND making one at a time does NOT "take much longer". This posting has gone on much longer than necessary. In my opinion, and based on my experience, your whole premise is faulty. IF you are getting that many failed connections from "users", then THEY are the problem, not the materials."

hi HJ watching my really good guy is like watching a master artist. he is smooth and has a theory that makes sense to me. he has only 30 year experience so he yields to your seniority but maybe it would be good to listen to what he has to say.

he point out that you cant really align an elbow for instance unless both parts are in place. the angle magnifies itself and what seems like a dead on alignment might be a few degrees off if you are sighting only the elbow. that adds permanent stress to the joint when the assembly is finished if its off very far. when both parts are assembled at the same time then precise alignment is much easier. he has neat ways of supporting thngs while they cure.

then if you make one glue joint then continue to add on to that joint you are stressing that first uncured part unless you wait a long time. that could really slow things down unless you have multiple areas started, where you could hop back and forth to allow one to be curing while the other is being worked on. but i see that can cause confusion and errors with the less skilled members.

so i can see his point and unless there is a reason to not do that then he ends up with less stressed and better aligned parts than at least i could do one at a time. and he is so fast that i doubt primer drying would be any less making one joint at a time.

its not a matter of me forcing failures. that's only demonstrating what i am questioning.

if someone gave you parts and you tried to break them assembled one way and you found that you cant break them until the limits of the other structures are reached. then you would have to say that's a good joint.

then you assemble them another way (the way its always been done) and you can break the actual glue joint with stress well below that which would damage the other parts. why would you insist on doing it the old way without giving the new way a chance. or at least considering it as a future possibility. why put it down before the facts are in.

i would say you are convinced the way it has always been done is right. and you could be dead on with that, but shouldn't we have more to show why that's the right way. especially if someone notices that it might not be. i say lets find out.

so far i haven't found anyone with a lot of "in service" failures, but everyone including you has likely seen failures that maybe others had installed. what is wrong with bringing those to someone interested in finding out why they failed. don't we want to know. do we already know everything there is to know about this. i think we should all want to make improvements wherever they can be done. we should all join in identifying and solving problems. why not.

why would it be the "users fault" when they run across a failure. and why would we not blame the material if it was a material failure. we wont know that until the part is tested. if the failures all turn out to be workmanship then that area should be improved with better instruction and education. but if the failures turn out to be a weakness that can be corrected. or a procedure that can be improved then why not find that out.



all of my people say they would love to learn from your experience. that's something you cant buy. its a shame our only connection is this forum. we have a lot to learn and you have a lot to teach. it would be great if you could help prove this one way or the other. we need your experience. the whole world does.

quote; then if you make one glue joint then continue to add on to that joint you are stressing that first uncured part unless you wait a long time.

That "first uncured joint" has cured almost immediately, IF it was assembled properly. AND it does not take a rocket scientist to align fittings properly while assembling them.

Just a sharpie

Disclaimer - I am not a plumber who knows code (just a former pipefitter).

Following Info from "Christy's" product link (link submitted on post by steve (CA)

"The recommendations presented here are based on the knowledge and experience of Christy’s team of chemists, technical experts and field support personnel."

While inserting pipe into fitting, TWIST pipe 1/8 to 1/4 turn until pipe has bottomed into socket of fitting. Do NOT rotate after the pipe has reached the socket stop. ---EXAMPLE of "set" time for 1/2" to 3" pipe is from 2 to 15 minutes depending on size and temperature range. (Larger size "set" times are longer.)

PlumerDan (CA) Remarks using a "sharpie". -- (For alignment.) (After pre-fit, during final assembly.)

Actually following ALL "Christy's" instructions for using their product, someone would have to be a REALLY smooth worker to (clean?), prime, apply cement to pipe, apply cement within fitting, apply cement to pipe SECOND time, assemble, TWIST pipe/fitting, bottom out pipe, hold pipe and each fitting together for at least 30 seconds at same time while completing correct final alignment of "many" multiple joints connected/attached together all at SAME time before primer dried (before applying cement). ALL of the joints should be completed as stated. S/he would have to be busier than the proverbial "One armed paper hanger". One section pipe and one elbow at a time maybe - - but a tee, three sections of pipe into tee, twist, align, hold etc. -- maybe with additional fittings? "Maybe" on a PVC furniture or factory assembly line, but a actual home/industrial construction site? Again, not a plumber but how often in a home would "many" such multiple joints "NEED" to be finial cemented at same time? My working experience is all with metal pipe. The only experience I have had with PVC was for personal needs. So far the only problem I have with the purple primer is the ugly stain which shows. (Of course I do know that the stain is to show any inspector that a primer was used.)

The point is, even though "Christy's instructions mentions solvent cementing "can" be done without a primer on water systems depending on size, pressure, code etc it also mentions "Extra Care" and additional instructions must be followed when NOT using primer to assure adequate penetration and softening of the pipe and fittings. To "Side Step" the "Extra Care", the fall back position appears to be to use primer on PVC / CPVC (and of course never on ABS).

Getting back to the very first post "we found 10 failures in that house." If "multiple joints were assembled and cemented at SAME time, IMO "ALL" (100%) of the aforementioned assembly instructions may not have been completed, especially ---"While surfaces of fitting and pipe are still wet or tacky from priming, use the proper size applicator to aggressively apply a full even layer of solvent cement -----".

It has been posted " We are using pvc cpvc and other materials. We follow all instructions TO THE LETTER (by the book) on each." But it is also posted "my installers would shriek if they had to hold on 30 seconds for every connection" -- "the dry time is very fast for primer. For OUR purposes its no longer fluid enough to prevent blocking the solvent glue from doing its job in just seconds." Evidently to assemble multiple joints your installers will have to work even faster OR to do what is proper, really follow instructions and only assemble what is possible to stay within the manufacturers' recommended procedures and methods including ALL times,coatings etc.

Anyway - IMO to get "accurate" test results concerning need for use/non-use of primer. (Actual plumbers posts do not seem to have any problems with the proper use of primer and in fact recommend it.)

1. Random samples WITHOUT assembly documentation are of no use for purpose of proving primers effect or not.
2. Assemble 20 OR more joints using ALL (100%) of the products instructions WITH a inspector present during the assembly.
3. Then test and document in whatever way is desired.

the key is to use QUALITY TESTED products which meet SPECIFICATION

for primer the spec is ASTM F656

PVC ~ always use primer

ABS ~ never use primer

CPVC ~ there are 'some' types of solvent cement which do not 'require' primer

Quote

Purple primers made to ASTM F656 can be used on either PVC or CPVC piping products.

ASTM F 493 CPVC solvent cements used in residential construction are orange (require a purple primer) or yellow (... used without a primer in most jurisdictions).

HOWEVER

in some jurisdictions (Washington state, for example) purple primer is NOT acceptable for drinking/potable water

THEREFOR

drainage = PVC with purple primer

potable water = CPVC without primer and 'yellow' solvent cement

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 1 times.

I'm amazed at the extent to which some people go to look for a problem where none really exists.

All i can say is if you prime the pipe then fitting then the pipe again then apply the cement you will get a good strong solvent welded joint. I have seen many pipes assembled with just cement and that, in my opinion and experience (18yrs),is literally "gluing" the pipes together and in time the glue will harden and the joint will break to where the pipe can be pulled right out, I have never seen this happen with a primed joint.

As far as your 30 yr. experienced guy goes, it doesn't matter the amount of experience one has if they do not follow proper procedures.

I have heard it all such as you don't need to clean copper if it is new and shiny but those people evidently have no clue about the coating applied to it for shipping and storage purposes that can cause an imperfect joint. When they came out with the NoKorode type flux all the experience guys that were used to C flux said it wasn't as good then the same thing with the water soluble flux a few years ago but each of those flux types requires a different method of soldering basically and the techs were reluctant to change the way they had always done it.

- - - - - - -

PLUMBERS "Protecting The Health Of The Nation"

hello hj
quote: "The primer softens the surface, as long as it is a liquid. Once it dries IT becomes the surface of the pipe that you glue to, NOT the PVC/CPVC itself. It is like fastening to a painted surface. The bond is no better than how good the paint adheres to the underlying surface."

at last we agree completely on what you are saying above. only these are supposed to be fusion joints not glue joints. and even if glue joints were acceptable then its easy to prove that the glue bond to primer is not very good.

i consider a joint a failure not because its doesn't pass all inspections and even pressure tests. i consider it a failure if its not a fusion joint and the glue to primer bond can be broken.

you can't break a fusion weld. its stronger than the part itself. the glue joint might be strong, indeed strong enough to work, but no where near as strong as the part and not even close to a true fusion weld.

maybe i am wrong and glue joints are acceptable. if that's the case i would love to see that somewhere in the spec.

Your premise about a "fused joint" is faulty. You can carefully "peel" the pipe out of a fitting even if it is a PERFECT joint, without damaging the fitting's surface.

hello hj quote: "your premise about a "fused joint" is faulty. You can carefully "peel" the pipe out of a fitting even if it is a PERFECT joint, without damaging the fitting's surface."

if you can peel it off then indeed its a "glue" joint. a fusion joint cant be peeled. you will take plastic material from both parts if you try.

on a joint using primer then you are right. you can easily peel the two apart. just cross section a joint and you will see a very small interface zone between the two parts. and each layer can be stripped from its subsequent layer.

but without primer. you really do get a fusion joint. now the cross section will not have a very well defined interface. it will be a fairly deep mixing area. you will see mixing of the plastics and no well defined layering. you will not be able to peel the two parts. the two parts become one. that's the definition of a fusion joint.
once the solvent has cured then this connection should have nearly the same strength as the original plastic.

if you can peel it, its not a fusion joint.

if you paint primer on a test plastic part. then peel it off after cure, you will get the primer plus a little plastic. that's because the primer does fuse a little with the plastic. not very deep because its wet time is so short. but still it fuses. now paint solvent glue over that primer. you will see that it will easily strip off without damage to the primers surface.

now paint solvent glue directly on the plastic surface. after curing, try to peel it off. you will get a lot of plastic along with the glue if you can peel it at all. that shows that the solvent glue has mixed (fused) with the plastic surface.

perhaps the intent was to form a glue joint. but there are stronger glues available for that. the whole idea of solvent is to form a fusion joint. its difficult to pin down what the original intent was. a lot of people seem to agree that it was to form a solvent fusion connection. but if you can peel it off then that's not what you have.



Edited 2 times.

WC (VA) quote: "Actually following ALL "Christy's" instructions for using their product, someone would have to be a REALLY smooth worker to (clean?), prime, apply cement to pipe, apply cement within fitting, apply cement to pipe SECOND time, assemble, TWIST pipe/fitting,"

you are correct. its nearly impossible. but not as bad as it seems. its not the time after application of primer to finished assembly that counts. its the time from application of primer to the application of solvent glue. the cleaner doesn't matter. you can let it dry or not but it dries so fast that it will always be dry.

the glue has a much longer wet time. in fact in our tests we found a short delay after application of glue was beneficial. that's since any solvent action on the part happens before they are even assembled. once assembled the glue is squished out to almost nothing left in these tight fitting primed parts. so that leaves only application of primer to application of solvent glue the critical time factor.

yes there is a problem doing that on several parts at once but you can't do it on one part either. my best worker can make all connections at once faster then i can make a single one in a field situation. in both cases there will be dry spots in the primer by the time you apply the glue. his time between critical applications is actually as fast or faster than some others doing the same job one at a time. he made an interesting gizmo to hold all parts together while he prepares the next segment.

in both cases the solvent glue will not penetrate the primer in at least some areas of the surfaces. in the lab i can actually do it. but its not as easy as it sounds and not likely a repeatable process in all but the most skilled people.

quote: "Getting back to the very first post "we found 10 failures in that house"

some question how we could have so many failures when they have none. none of my workers have ever had a failure for inspection or pressure testing that they can remember. that's similar to all the experiences i am hearing here.

when i say a part has failed, it likely would not have failed any conventional tests and i would expect a long and normal service life. there is no reason to believe any would have failed pressure test and the ones that were pressure tested all passed. eventually all redo work after experimenting did pass every required test even though they used purple primer.

that doesn't speak to thermal or mechanical stress cycling. probably no one likely tests for that or are even interested in doing so as long as their parts pass inspection.

what i noticed was a failure mode that should not happen. a good fusion weld should always be nearly as strong as the original plastic. and since its a double thickness it should always be stronger than other areas in the part.

the parts that we were able to break all failed stress, well before any other component limits were reached. that should never happen in a fusion joint. even if its "good enough", it may not be anywhere near as good as it can be.

the only "in service" field failures i have seen are ones that plumbers have saved for me as they encountered them or they just tossed in their tool box some time ago. the fact is, most failed for exactly what i am saying. they failed because they were glue joints not solvent fusion joints. and they failed in real world not my stress test.

at least some failed in high thermal swing areas. like hot water lines where the plumbing goes through unheated areas. they could go from freezing to hot water in seconds. some failures were from mechanically stressed areas. some we don't know why but we do know how.

the point is i doubt even those would have failed if they were fusion welds. they mostly failed at the glue primer interface. the same thing that i am seeing in my test.

i used to say unpopular things as an engineer like "if you think it works, then you just don't know enough about it .... yet." that might just apply here.

there might be a valid reason why some areas have outlawed purple primer. and also good reason to believe that areas where its not required might know what they are doing. maybe not, but how will we ever know if we are simply happy with the way things are. it may irritate a few for awhile but shouldn't we at least be looking and cooperating a tad better than our politicians.


thanks WC for some very good observations and helpful information.

thanks bernabeu for some good research

and PlumerDan (CA) that sharpie might just work

quote; if you can peal it, its not a fusion joint.

I am not "pealing" it like a bell, I am "peeling" it like an orange. In that case there are NO "fusion" joints because I have NEVER had a problem removing the broken PVC pipe from a fitting. In any case, it appears to boil down to the fact that YOU make PVC joints and they come apart. WE make them and they do not, so what does that tell you about your installation practices. This whole discussion has been about a problem that does not really exist.



Edited 1 times.

hj quote; " I am "peeling" it like an orange. In that case there are NO "fusion" joints because I have NEVER had a problem removing the broken PVC pipe from a fitting. In any case, it appears to boil down to the fact that YOU make PVC joints and they come apart. WE make them and they do not, so what does that tell you about your installation practices. This whole discussion has been about a problem that does not really exist."

we are having the same experience that you are reporting. we have never seen a failure to meet current requirements in any connection we have made. our forced failures demonstrate that there really is a problem even if you don't know about it. and field failures from others, no matter how rare, are showing that its a real problem.

it makes no sense to use a solvent glue if you are not going to allow it to make a solvent connection. much better glues are available if you were after just a glue joint. being able to peel the pipe out of a broken connection is proof that you are experiencing the same thing i am seeing. and i would bet every person commenting here can see the same thing in their connections.

you cant say that i am doing something wrong if you are seeing the same results.

you can continue to deny there is a problem at all or you can test it yourself. make a connection using only solvent glue. let it cure. now break it any way you like if you can. now try to peel it apart. you will see a remarkable difference.

first you will have a heck of a time breaking that connection and second you wont be able to peel them apart without breaking plastic.

and even that may not be optimized. orange solvent glue may or may not improve that further. but one thing you should notice, no matter what solvent glue you use, if you omit the primer then you will see a significant increase in joint strength.

one thing to remember. by definition a solvent fusion joint is where the two plastic parts are temporarily liquefied by solvent then combined in a liquid state. as the solvent dissipates you are left with a single plastic part. if the two plastic parts are not mixed together then it is not a fusion joint. if they are mixed than you will not be able to peel them apart.

your description of what you see tells me your connections are not fusion joints either. by definition you can't deny that.

so the question is, is that what was intended or is there some other reason a fusion joint is to be avoided. if there is a reason that outranks joint strength then the use of primer may indeed be the best compromise. but i haven't found that reason yet.

i have some meetings scheduled with material manufactures. that hopefully will answer a lot of questions.

one very old training manual shows how much better the fusion joint was when primer was used and how poor it was without primer. only the photos were switched or labeled wrong. i can duplicate those cross sections and those examples were backwards. i wonder if the entire industry wasn't influenced by that manual.

so i am still looking for legit information that justifies primer.

here is a definition of solvent welding of plastic from: [en.wikipedia.org]

In solvent welding, a solvent is applied which can temporarily dissolve the polymer at room temperature. When this occurs, the polymer chains are free to move in the liquid and can mingle with other similarly dissolved chains in the other component. Given sufficient time, the solvent will permeate through the polymer and out into the environment, so that the chains lose their mobility. This leaves a solid mass of entangled polymer chains which constitutes a solvent weld.



Edited 2 times.

Kudos to you, hlee for keeping your cool in answering all the letters from people that refuse to accept your evidence and insist that their way is the right way. You have done experiments to test a hypothesis, i.e., you have applied the scientific method. You have asked for input that may explain why your results contradict the common wisdom. The naysayers don't seem to be considering your data, but instead, have anecdotal evidence, to paraphrase, "in all my years of making joints, I've never had a joint fail." Personal anecdotes or experience, in the absence of real experiments, is something to go on. In the face of well-controlled experiments, anecdotal evidence just doesn't measure up.
What gets me is that some of the naysayers seem to be angry with you. They are saying, "How dare you go against what the manufacturers and the code are telling you?" Hey people, let's be a bit more open-minded.
Personally I am very happy to skip the extra step of using primer. I am on my way out to the garden to glue some PVC pipe joints in my sprinkler system and I am definitely not going to use primer.