Polymer PEX fittings

STEAM DOCTOR

Any experience with these fittings? Fraction of the price of comparable brass fittings. Comparing Viega to Viega. Any upside? Any downsides? Thanks.

STEAM DOCTOR

My particular application would be a high temperature baseboard heating system. 180°.

hot_rod

It is certainly possible to blend polymers to handle that temperature. 130C seems to be the high number for polymers, maybe the glass reinforced nylon blends.

You would hope the manufacturers did the homework and long term cycle testing

I'd be concerned about an over or crooked crimp putting a hairline crack in the fitting. Same for the thin brass I suppose.

Expansion would be my choice to use with polymer fittings.

Check back in 20 years. Nothing tests a product like on the job longevity test under expansion/ contraction and aggressive water conditions.

Mad Dog_2

The Uponor PROPEX fittings are well made and I've used them on Radiant and higher temp hydronic loops  25 years atleast.  That being said, I always preferred the heavy brass fittings instead.  Time will tell, but I just believe they will last longer   Mad Dog 🐕 

hot_rod

My preference is the copper Pex fittings, they have a smoother flow pattern. Brass ells and tees have sharp, right angle direction changes. Copper ells and tees have curved transitions.

We seem to have gotten through the brass dezincifaction phase with a minimal amount of lawsuits😎
That was a black eye for the brass Pex fittings

Expanding B Pex maybe the next ticking bomb🤔

ChrisJ

Doesn't it seem a bit strange questioning plastic fittings regarding temperature and performance when you're connecting plastic tubing to them?



From my experience there's several plastics I work with that handle very high temperatures.

For example,
Polycarbonate has a glass transition temperature of around 296F.
PEEK is 293F.
Nylon's GTT is right around 200-205F I think.

That means you could likely use polycarbonate and peek in steam heat applications. Nylon not so much..... I have run some plastics very close to their GTT without issue, but there's been times it's bit me.


For my plumbing I've been using Uponor plastic fittings. I honestly trust them more than brass regarding corrosion, longevity etc.

If I want to be able to re-use the fittings I go with brass just because that's their rule. And it certainly can be more difficult to cleanly cut pex away from a plastic fitting without damaging it.

GroundUp

I've not seen any issues with temp on polymer fittings, per se, but I have seen several of them break if there is any lateral stress on them. Uponor, Viega, and a couple other cheapo brands whether crimp or expansion all seem to have the same issue if care is not taken to support the piping and joints properly (meaning very little support so it has room to flex). Temp does seem to play a role as far as the expansion/contraction is concerned, which is usually the reason for the breakage, but I don't feel it's an issue for the polymer directly. I still use brass for almost everything, unless the water quality is really bad.

Mad Dog_2

Like everything else...ONLY time will tell which holds up longer.  Mad Dog 🐕 

mattmia2

ChrisJ said:

If I want to be able to re-use the fittings I go with brass just because that's their rule. And it certainly can be more difficult to cleanly cut pex away from a plastic fitting without damaging it.

The plastic fittings can be re-used but it is a surgical procedure that takes a fair bit of time and probably isn't worth the time for a professional if you have another fitting. Cutting the tube off without cutting the ridge off is difficult.

hot_rod

mattmia2 said:

ChrisJ said:

If I want to be able to re-use the fittings I go with brass just because that's their rule. And it certainly can be more difficult to cleanly cut pex away from a plastic fitting without damaging it.

The plastic fittings can be re-used but it is a surgical procedure that takes a fair bit of time and probably isn't worth the time for a professional if you have another fitting. Cutting the tube off without cutting the ridge off is difficult.

warming the tube with a heat gun or carefully with a torch is the best way I have found to reuse pex fittings. The tube and ring slides off easily when warmed a bit.

mattmia2

hot_rod said:

mattmia2 said:

ChrisJ said:

If I want to be able to re-use the fittings I go with brass just because that's their rule. And it certainly can be more difficult to cleanly cut pex away from a plastic fitting without damaging it.

The plastic fittings can be re-used but it is a surgical procedure that takes a fair bit of time and probably isn't worth the time for a professional if you have another fitting. Cutting the tube off without cutting the ridge off is difficult.

warming the tube with a heat gun or carefully with a torch is the best way I have found to reuse pex fittings. The tube and ring slides off easily when warmed a bit.

You can go a lot further with that with brass than with EP fittings.

hot_rod

mattmia2 said:

hot_rod said:

mattmia2 said:

ChrisJ said:

If I want to be able to re-use the fittings I go with brass just because that's their rule. And it certainly can be more difficult to cleanly cut pex away from a plastic fitting without damaging it.

The plastic fittings can be re-used but it is a surgical procedure that takes a fair bit of time and probably isn't worth the time for a professional if you have another fitting. Cutting the tube off without cutting the ridge off is difficult.

warming the tube with a heat gun or carefully with a torch is the best way I have found to reuse pex fittings. The tube and ring slides off easily when warmed a bit.

You can go a lot further with that with brass than with EP fittings.

Do you know the temperature rating or melt point of the EP fittings?

mattmia2

According to the spec sheet:
Maximum Temperature (no pressure): 320°F (160°C)
Max.Working Temperature/Pressure: 210°F (99°C) at 150 psi

https://s3.amazonaws.com/s3.supplyhouse.com/manuals/1295972159892/45170_PROD_FILE.pdf

ChrisJ

mattmia2 said:

According to the spec sheet:
Maximum Temperature (no pressure): 320°F (160°C)
Max.Working Temperature/Pressure: 210°F (99°C) at 150 psi

https://s3.amazonaws.com/s3.supplyhouse.com/manuals/1295972159892/45170_PROD_FILE.pdf

https://en.wikipedia.org/wiki/Polysulfone

Polysulfones are rigid, high-strength and transparent. They are also characterized by high strength and stiffness, retaining these properties between −100 °C and 150 °C. The glass transition temperature of polysulfones is between 190 and 230 °C.[9] They have a high dimensional stability, the size change when exposed to boiling water or 150 °C air or steam generally falls below 0.1%.[10] Polysulfone is highly resistant to mineral acids, alkali, and electrolytes, in pH ranging from 2 to 13. It is resistant to oxidizing agents (although PES will degrade over time[11]), therefore it can be cleaned by bleaches. It is also resistant to surfactants and hydrocarbon oils. It is not resistant to low-polar organic solvents (e.g. ketones and chlorinated hydrocarbons) and aromatic hydrocarbons. Mechanically, polysulfone has high compaction resistance, recommending its use under high pressures. It is also stable in aqueous acids and bases and many non-polar solvents; however, it is soluble in dichloromethane and methylpyrrolidone.[8]

Polysulfones are counted among the high performance plastics. They can be processed by injection molding, extrusion or hot forming.


Polysulfone has one of the highest service temperatures among all melt-processable thermoplastics. Its resistance to high temperatures gives it a role of a flame retardant, without compromising its strength that usually results from addition of flame retardants. Its high hydrolysis stability allows its use in medical applications requiring autoclave and steam sterilization. However, it has low resistance to some solvents and undergoes weathering; this weathering instability can be offset by adding other materials into the polymer.

Mad Dog_2

Uponor Propex brass vs  Polymer fittings.  I found the brass are more durable if you re use them as temps often.  I use a sharp pex cutter and slice the pex ring but not too deep. Then the pex will wiggle off. The ONLY leak I've ever seen on Propex is when I cut too deep and nicked the brass.  Mad Dog 🐕