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Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & AnonBrass Connector Corrosion, Leaks, Dezincification in PEX Piping Systems
Current corrosion, links, meringue dezincification reports for PEX connectors in Ohio & Michigan

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PEX Piping Brass Fitting Corrosion, Leaks, & dezincification failures:

Current field reports & photographs of corrosion, leaks, & obstructive corrosion build-up inside of brass elbows, tees, & adapters used with plastic PEX water supply piping. This article reports on current observations of corrosion & leakage in PEX piping systems in recently-constructed homes in the U.S., particularly in Ohio & Michigan.

This article series discusses  the properties of Pex Tubing or Piping, Cross-Linked Polyethylene (PEX). We address pex tubing & fitting failures and leaks reported for some U.S. states: field photographs & reports of brass connector leaks, corrosion, blockages possibly ascribed to dezincification of brass connectors used with PEX plumbing systems. Symptoms include visible corrosion, water leakage, & possibly obstructed water supply piping resulting in reduced water flow at fixtures.

Updates on Pex fitting de-zincification problems reported from the field. Pex dezincification research citations.

We discuss the uses of PEX tubing for water supply & in heating applications and we describe several different types of PEX tubing connector systems used including PEX crimp fittings, PEX compression fittings, PEX expander fittings, PEX Press-Fit connectors, and PEX Shark-Bite fittings and connectors.



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PEX Dezincification Update & Research: field failure photographs of Brass PEX Pipe Fitting Corrosion & Leaks

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

[Click to enlarge any image]

Article Contents

Above left: perforation corrosion visible on two brass Tee-connectors installed on PEX water supply piping observed in a midwestern U.S. home constructed in 2009 (orange arrows). Above right, brass tee corrosion appearing both on the Tee-fitting body (red arrow) and around the end of the PEX tubing (green arrow) on water piping in a 2009 home. [Click to enlarge any image]

Definition of Brass, Gunmetal, Dezincification, & Meringue Dezincification

Brass is a generic term used to describe a family of alloys made principally from copper and zinc where zinc is alloyed with copper in percentages ranging from 15% to 40%. Some "brass" fittings sold worldwide, including plumbing fittings, may also contain lead, tin, and zinc and would more properly be called "gunmetals".

Gunmetal alloys are used only in the manufacture of cast items. The U.K.'s Foundation for Water Research explains that the function of lead in castings is to reduce the porosity of the final product: as lead is the last ingredient to solidify when casting a part, the lead can be drawn into openings or pores in the product to reduce the chance that it has a pinhole leak.

What this means to a builder, home owner, inspector or investigator of plumbing systems and water supply piping is that the observation of cast brass plumbing fittings (as opposed to machined fittings) means that the fittings may contain lead that particularly in the presence of low pH water (acidic water) may leach into the water supply. We discuss this concern
at LEAD LEACHING WARNINGS.

Dezincification (shown below) refers to the loss of zinc from a brass plumbing fitting by dissolution, ultimately leading to leaks or broken fittings. Zinc present in the brass alloy dissolves leaving pores or openings that can become water leaks. Dezincification also weakens the remaining fitting, increasing the risk that the fitting or other brass parts such as the stem of a water control valve might break.

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

Meringue dezincification (shown below) is a special case of corrosion of brass plumbing fittings that occurs in high pH water (above 8.2 or basic water), leaving corroded material as a white deposit (probably salts) that clogs brass fittings and reduces water flow rates. Meringue dezincification might explain some reader reports we receive of a decrease in hot water flow rate at some plumbing fixtures, particularly those used most-often and at highest-temperatures.

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

Since both clogging (meringue dezincification) and perforation leaks may occur at the same time on water supply systems, another step in identifying the type of dezincification occurring might be to test the water pH level.

See DE-ZINCIFICATION vs WATER CHEMISTRY

Definition & Causes of "Dezincification" & "Meringue Dezincification" of Brass Plumbing Fittings

The process of dezincification of brass water piping system components includes at least the following contributors

  1. Water chemistry - Water pH: water of chemistries that are that high in pH (basic) or low in pH (acidic) and even water that is neutral in pH all ultimately are expected to corrode brass plumbing fittings. However just how the corrosion is manifested (leaks, blockages, breakage failures) varies by water chemistry and time.
  2. Water chemistry - level of Chlorine: water that is high in chlorine is likely to experience faster dezincification. Chlorine is added to both public and private water supplies but in our OPINION is likely to be less carefully controlled to be kept within recommended levels in private water supply systems.
  3. Water temperature plays a role in dezincification too . Though dezincification occurs in both hot and cold water piping, the dissolution of zinc from brass fittings by dezincification is more rapid in hot water piping and systems than in cold water piping. Combining hot water, high chlorine and low pH with brass fittings increases the risk of dezincification and leaks in the plumbing system.
  4. Alloy composition of the brass fitting:The percentage of zinc in brass varies according to the manufacturing process and most likely the intended use of the product. A brass fitting using a lower percentage of zinc is likely to suffer dezincification at a lower rate than a high-zinc fitting. A "pure brass" fitting containing only zinc may be less prone to perforation that an alloy that includes lead.
  5. Manufacturing process of the brass fitting: gunmetal components intended for manufacture by casting are likely to contain lead and thus may pose a risk of lead leaching into the water supply.

    Brass that does not include lead and that is fabricated into final product form by machining is still vulnerable to dezincification depending on water chemistry and temperature. Experts such as the Foundation for Water Research in the U.K. point out that while both brass and gunmetal alloys are vulnerable to corrosion and dezincification, brass alloys are more vulnerable to dezincification than gunmetals.

Dezincification Propensity of the Water Supply Chemistry

Zhang (2009) ranked water supplies in different areas of the United States according to the propensity of the water supply to encourage leaching of zinc, copper, and lead leaching over a 100-day test period. He ranked the following water supplies from highest to lowest.

[Table construction & excerpting shown below are adapted from the author's original text - Ed.]

Effects of Water Chemistry on Leaching of Metals from Metal Components: Copper or Brass Piping & Fittings

Propensity for Dezincification [1][4]

Selective Leaching of Zinc vs Copper [2]
Ordered by ratio of Zn:Cu

Comments

Rhode Island Santa Clarita  
San Diego San Diego  
Santa Clarita Chapel Hill  
Las Vegas Las Vegas  
Chapel Hill Seattle  
Seattle Blacksburg  
Blacksburg Rhode Island [3]  
     

Notes:

Original source: Zhang, Yaofu. "Dezincification and brass lead leaching in premise plumbing systems: effects of alloy, physical conditions and water chemistry." PhD diss., Virginia Polytechnic Institute and State University, 2009. - http://scholar.lib.vt.edu/theses/available/etd-12182009-203827/unrestricted/Zhang_Y_T_2009.pdf

[1] Zinc leaches into the water supply; 100-day test; note that this same effect can cause corrosion and leaks as are illustrated and reported in this article.

[2] Focused on the last 1200 hours as indicative of a longer-term trend the table order is revised as shown in this column

[3] Zhang noted that Rhode Island water has a low pH, allowing copper to dissolve together with zinc. The author points out a consideration important for inspectors testing the water supply: don't just test for high chlorine. A low pH water supply may cause brass fittings to fail by general corrosion rather than dezincification.

[4] Interestingly the author found that either a focus on the last test period (when corrosion was most advanced and presumably the rate of corrosion was accelerating) or on the total weight loss of the metal components (how much material has been lost) gave the same ranking after loose scale material was removed to leave just the brass intact.

 

Water Chemistry: Effects pH on Brass Fittings

Effects of Low pH Water on Brass Fittings: Corrosion

Zhang (2009) observed that water that is low in pH (such as in Rhode Island in the U.S.) is likely to cause brass fittings to fail by general corrosion rather than meringue dezincification. That's because low pH allows both copper and zinc to dissolve together. Water with a low pH means that the water is "acidic" to use a term familiar to many people.

The significance of Zhang's observation is that we might find PEX brass fittings or other brass piping or fittings failing and leaking "prematurely" on water supplies that are of low pH regardless of the chlorine level, or exacerbated if the water supply is low in pH and chlorine is being added at high levels.

Effects of High pH Water on Brass Fittings: precipitation & clogging - Meringue Dezincification

The Foundation for Water Research (FWR) points out that high pH water (water that is basic or has a pH above 8.2) causes corroded ingredients of a brass fitting to precipitate out of the water supply and to settle in the fitting itself. This effect leads to clogging: reduced water flow through the system, and is referred to throughout contemporary brass fitting failure literature as "meringue dezincification".

Effects of Neutral pH Water on Water Piping Systems

Neutral pH water is water with a pH in the range of 7.6 to 8.2. When the water supply is maintained within this neutral pH range brass fittings and other brass components in water supply systems (such as control or stop valve stems & gate valve components) will still experience corrosion, but at a slower rate. The FWR report we cite
at RESEARCH on DEZINCIFICATION states that in this neutral pH range there will be no build up of a corroded material deposit (no meringue dezincification) and that "... it takes in the region of 15 years for the walls of the fittings to become penetrated. The snapping of tap and valve spindles ... is another manifestation of the problem." - Foundation for Water Research (2003).

See WELL DISINFECTANT pH ADJUSTMENT

The FWR concludes (for U.K. Readers - as recommendations in other countries may vary) that plumbers should use only dezincification-immune (gunmetal) or dezincification-resistant (marked DR in the U.K.) brasses on water supply systems that initiate or propagate dezincification corrosion.

Watch out: since gunmetal fittings may contain lead there could still be a lead leach-out and water contamination concern. In the E.U., a 2013 EC directive restricts the allowable level of lead in drinking water to 15 mcg/L (micrograms per litre).

In the U.K. and the rest of the E.C., see

Simple Inexpensive Methods of Testing the Water Supply for Chlorine & pH

For investigators of dezincification who are including water testing in their inspection procedure, we suggest that In addition to testing for the chlorine level, investigators should test the water pH.

Hydrion pH test strips from MicroEssentialsLab Water testing for chlorine as an indicator of risk of merengue dezincification of brass PEX fittings (C) InspectApedia BB

Testing the pH of a water supply is as easy as testing its chlorine level as simple litmus paper strips will suffice to make a general test of the pH of a water supply.

While our correspondent, an inspector discussing dezincification, described using pH testing in the field, he warned that most field inspectos are not attempting the same level of testing as might be performed by a more-expert water testing laboratory.

However simple pH testing by litmus paper or by instrument is widely used by water test services as well as those building inspectors who perform basic investigation services. And if conducted properly (for example using fresh, uncontaminated litmus paper tests), measuring water pH using litmus paper strips is an accurate approach. Both litmus paper and pH meters can be used to perform this test and have been in wide use for a over 100 years since Sorensen (1909) first proposed this test. Contemporary pH meters and litmus paper are in fact similarly accurate. Kahn points out that

The significance of changes in pH level, for instance, differ slightly depending on whether pH is measured by litmus paper or the more accurate pH meter. - Kahn (1985)

while Thomas (discussing measurement of soil acidity) points out that

As recently as two decades ago, the use of the small, handheld portable pH meters then available to determine pH in the field was a very imprecise and hazardous undertaking because both electrodes and meters were subject to sudden failures but this has changed rather abruptly in the last few years. Microcircuitry and plastic have contributed to rugged pH meters and electrodes that witstand ... - Thoms (1996)

Watch out: What about pH variations over time? A single pH test of a water supply can be taken only as a reasonable estimate of the water's chemistry at the time the test was taken. While the pH of most water supply systems is probably rather consistent over time, environmental, weather, or other variables might cause pH values to vary in private water supply systems and possibly even in municipal water supplies.

In addition to the RESEARCH on DEZINCIFICATION in this article, also see the water pH testing research found at this article's REFERENCES section.

If you decide to make some tests including pH I hope you'll report the results to us.

See CHLORINE TESTS, WATER for an explanation of methods to test the chlorine level in water
and/or
See WATER DISINFECTANT QUANTITY.

See WELL DISINFECTANT pH ADJUSTMENT for a discussion of the relationship between chlorine and water pH.

 

Reader Reports PEX piping brass fitting dezincification in Ohio & Michigan, U.S.

8/19/2014 Anonymous said:

We are experiencing quite a lot of PEX brass fitting dezincification in Ohio and Michigan, with increasing issues with PEX brass fitting corrosion anywhere from 1997 through 2013 construction.

Our water is supplied from Lake Erie and you may be well aware of the water issues we have experienced since about 2008 with green algae blooms and the efforts to treat the drinking water.

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

At above left we observe multiple perforation & corrosion deterioration of this brass PEX pipe tee and yellow / green stains that suggest that the corrosion has advanced to the point of active water leakage (yellow arrow). At above right we can observe water dripping from this still more severely-corroded brass PEX pipe tee (yellow arrow).

From minor almost nonexistent corrosion on the brass fitting exterior to active leakage from fitting failure due to leaching out of the zinc. Is there any information compilation you are preparing for the public to educate themselves on related to zinc fitting issues from the late 1990's to 2013?

There is no one manufacturer whose fittings we see issues with. We do not see Kitec™ issues as there has been very limited usage in the region. We have seen Zurn - Qest™ and Nibco™ as the primary brands of leaky brass fittings in this application.

Thank you. Note I have photos etc. if interested in continuing this discussion. [Photographs of de-zincification in PEX piping connectors & fittings are reprinted herein with permission of contributors who requested anonymity, 12 Sept 2014 - Ed.]

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

At above left we see white corrosion creeping along the side of a brass elbow that was used to connect segments of Zurn® PEX white piping in a home constructed in 2004. At above right is an example of brass coupling corrosion connecting copper piping to PEX piping in a midwestern state home constructed in 2003. [Click to enlarge any image]

Reply:

It's worrisome that dezincification of PEX fittings continues as an ongoing issue. Please use my email found at our CONTACT link to send me whatever photos, reports, documents you can for publishing here both to inform other readers and to solicit additional field reports, research & advice regarding contemporary or ongoing PEX pipe connector & fitting corrosion, leaks or failures.

Below are identification photographs of a NIBCO brass PEX elbow removed from a domestic water heater piping installation. The readers made clear that the dezincification / brass PEX fitting corrosion and leak problems they are observing in Midwestern U.S. states do not appear to be confined to a single manufacturer or brand.

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

At below left the contributors illustrate perforation corrosion of a brass PEX Tee fitting.

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

At above right you can observe the considerable deposit of minerals / corrosion material built-up inside the body of this brass PEX Tee fitting. This particular form of dezincification is identified as meringue dezincification and produces clogging and reduced water flow rates.

Even before building occupants observe the effects of corroded leaky PEX brass pipe fittings they may report a symptom of reduced water flow rate and they may notice that effect first at the hot water side of plumbing fixtures.

Also see CLOGGED SUPPLY PIPES, DIAGNOSIS

PEX Fitting & Tubing Failures, Class Action Litigation Information

The PEX brass fitting manufacturing companies mentioned in the readers' observations include

More Reader Reports of Pex brass fitting dezincification:

(Aug 19, 2014 & atain 12 March 2015) an anonymous home inspector said:
We are experiencing quite a lot of PEX brass fitting dezincification in the NW OH, SE MI region. From minor almost nonexistent corrosion on the brass fitting exterior to active leakage from fitting failure due to leaching out of the zinc.

Merengue Dezincification of brass PEX fittings (C) InspectApedia BB Merengue Dezincification of brass PEX fittings (C) InspectApedia BB

Is there any information compilation you are preparing for the public to educate themselves on related to zinc fitting issues from the late 1990's to 2013? There is no one manufacturer whose fittings we see issues with. Nibco and Qitec are the top two that seem to be used in our market. Thank you. Note I have photos etc. if interested in continuing this discussion.

12 March 2015 Anonymous wrote:

Dan, I have a few additional photos of PEX fittings showing an interesting perspective. When you receive them, note the build up of the "meringue" corrosion inside the tubing that extends from the fitting.

The home was constructed in 1995 widening our area of concern to earlier than 1997 as we had previously identified through research and inspection findings. The PH levels in the regional public water supply have been found to be in elevated levels. We might blame some of this on the recent algal bloom issues we have been dealing with in the Lake Erie western basin. 

Reply:

Anon: A search of InspectApedia for "Dezincification" will find this and other related articles on the topic.

It's worrisome to hear that even in 2015 dezincification of brass fittings used with PEX piping is a continuing issue. But the research in this field relating dezincification to water chemistry is both diagnostic and prescriptive.

Merengue Dezincification of brass PEX fittings (C) InspectApedia BB

Meanwhile in the article above I've added your 2015 merengue dezincification photos to your earlier report and some updated research citations on PEX and dezincification problems

We thus invite further comment from others.

Warnings About Lead & Copper Leaching into the Water Supply from Brass Piping, Fittings, Faucets - Water Chemistry Role

Watch out: some of the water conditions, particularly high levels of chlorine, that appear to play an important role in meringue dezincification of brass fittings on PEX piping systems may result in unsafe levels of lead as well as high levels of copper in the building water supply. Research by Kimborough (2007), Kumar (2007) and Zhang (2009) as well as other researchers warns that water chemistry combined with the properties of brass, copper, and lead and zinc-containing alloys can lead to trouble.

The following is excerpted from Zhang (2009):

Lead and zinc leaching from a range of brasses were negatively correlated. The mechanism behind this observation is not clear yet and needs future studies. But as a result DZR and red brasses release more lead to water, and a greater percentage of lead in the alloy to water.

Lead leaching is also found to be greatly influenced by water compositions. Higher chloride and lower alkalinity increase lead leaching. Orthophosphate at 1.4 mg/L decreases lead leaching, but the inhibitive effects are very sensitive to phosphate dosages.

Initially, dosing 40 mg/L of silicate also inhibited lead leaching, but the inhibitive effect of silicate diminished after 100 days of experiment. Adding 200 ppb of zinc slightly increased the lead concentrations in the water. Zinc does not seem to play a significant role in mitigating either dezincification or lead leaching from brass alloys.

When different water and the same alloy are considered, lead leaching was found to increase with higher zinc leaching. This result may help explain why some lead leaching cases were related with dezincification in practice.

Overall, there is a complex interplay between water chemistry and metallurgical composition that determines lead leaching to water. - Zhang, Yaofu. "Dezincification and brass lead leaching in premise plumbing systems: effects of alloy, physical conditions and water chemistry." PhD diss., Virginia Polytechnic Institute and State University, 2009.

See LEAD IN DRINKING WATER, HOW to REDUCE

DZR Brass: Dezincification-Resistant Plumbing Fittings

DZR or dezincification resistant fittings should be used to avoid future leaks and supply piping clogs due to dezincification, and are likely to be specified as the repair where water chemistry has already lead to brass fitting leaks or clogs.

Some companies already DZR-Brass fittings or alternatives including

Watch out: Danish researchers Andersen et als. found water damage due to corrosion even where DZR brass was used. The problems occur where the water supply has high conductivity - or as their paper cites, high alkalinity. Quoting:

In Danish drinking water installations, brass has been the most commonly used material for fittings such as stop valves and control valves; dezincification resistant (DZR) brass of the type CuZn36Pb2As being the dominating alloy.

DZR brass has traditionally been considered sufficiently corrosion-resistant to be used in all Danish water types, and previous experience has been good. However, today, an increasing number of severe water damage caused by corrosion of DZR brass in areas with hard, high conductivity ground water has increased the focus on corrosion of copper alloys and, as a consequence, recommendations have changed.

In the Copenhagen area and other areas with similar water quality, it is now recommended to use fittings of gun metal or stainless steel (AISI 316 or better).
...
Examinations confirm that the traditional copper alloys have unacceptably short life expectancy in the hard, high conductivity water types found in Denmark. A major reason is believed to be that the preferred pipe material has changed from hot-dip galvanised steel to stainless steel and plastic. - Anderson et. als (2015).

Research citations on PEX and dezincification problems

...


Continue reading at PLASTIC PIPE LEAK CAUSES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

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PLASTIC PIPING ABS CPVC PB PEX PVC - home page

PLASTIC vs. COPPER PIPES in BUILDINGS - separate article

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Kitek® PLASTIC PIPELEAKS & LAWSUIT - separate article

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