Leakage was imminent at all locations with similar fittings in the hot water line where similar flow velocities were found. Heavy internal deposits resulted in localized corrosion cells where dezincification initiated. Energy dispersive x-ray spectrographic EDS micro-analysis identified the composition of the corrosion products to be zinc oxide. The attacked regions exhibited essentially pure metallic copper with only traces of zinc remaining. The heavy internal deposits were mainly zinc oxide due to the corrosion and aluminum oxide.
Two brass bras elbow fittings were received for analysis. Date range on this day between these dates. Smaller amounts of sulfur and chlorine were also detected in the deposits. Uniform-layer dezincification leaches zinc from a broad area of the surface. Further, manufacturers must be required Anal creampie video provide alloy ations design or chemistry for the materials used in their valves and Dezincification resistant brass fitting.
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Education Courses by program Register for a course Check your grades Certifications Training at your facility. Toggle navigation. Selective Dezincificatuon can be a problem when it weakens a fitting, leaving it vulnerable to failure and eventual leaks. There are several methods to increase resistance to corrosion and zinc leaching. It reacts with the other metal to form a different product. Continuous Cast Alloys. Figure An optical microscopic view of a cross-section through the fitting nipple tube. Abstract: The aim of this work was beass determine if the aging Dezincification resistant brass fitting polyethylene HDPE, PEX-A and PEX-B water pipes by exposure to chlorinated water altered polar and nonpolar contaminant diffusivity and solubility by analyzing new, laboratory-aged, Dezincification resistant brass fitting exhumed water-distribution system polyethylene PE pipes. That's because low pH allows Dezinicfication copper and Gary leffew bull riding to dissolve together. Figure 9: An over-exposed optical microscopic Dezincification resistant brass fitting of the cross-section fitting nipple tube, which revealed a thick ID surface deposit. Aviva Metals is the leading manufacturer of continuous cast bronze in North America.
Selective leaching , also called dealloying , demetalification , parting and selective corrosion , is a corrosion type in some solid solution alloys , when in suitable conditions a component of the alloys is preferentially leached from the material.
- Aviva Metals is the leading manufacturer of continuous cast bronze in North America.
- Dezincification is a process which selectively removes zinc from an alloy, leaving behind a porous, copper-rich structure that has little mechanical strength.
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Dezincification has become a buzzword in the forensic engineering world and the plumbing product industry. But what is dezincification? Brasses are a family of metal alloys whose main components are the elements copper and zinc.
There are numerous brass formulations, with varying ratios of copper to zinc, as well as the inclusions of other elements.
For instance, zinc is often added to aid in the machining, and provide strength to the brass. Many of the brasses used in plumbing products are commonly called yellow brasses. Figure 1 — Yellow brass with reddish discoloration on fracture surface. Dezincification is the selective leaching and removal of zinc from the brass, and into the water supply.
This corrosion process decreases the strength of the brass and increases porosity in the now copper-rich material. For brasses with increased zinc, the zinc available for removal is greater, and the corroded brass product experiences a greater loss of material and strength.
With the decreased strength and the water-pressurized working environments of plumbing products, brittle fracture failures of weakened brass plumbing products can occur. A reddish discoloration at the fracture surface of a brass product is a common characteristic of dezincification.
The loss of zinc creates copper-rich material that has a reddish hue. Some fractures will exhibit white deposits near the fracture surface. This may be a zinc oxide compound that is deposited after being leached from the brass. Figure 2 -White deposits and reddish discoloration of brass. A number of industry standards have been created in recent years to address the dezincification of brass.
In , NSF instituted Standard 14 which governs the physical and performance requirements for brass fittings and valves. In part, it states:. To meet this standard, brass suppliers and plumbing component manufacturers may add small amounts of other elements, such as tin, arsenic, phosphorus, and antimony.
These added elements offer increased resistance to the dezincification process, but do not completely prevent it from occurring. These brasses are commonly called red brasses, and their lower zinc content eliminates dezincification from occurring entirely. Figure 3 — Reddish brass layer on fractured fitting. WERC has analyzed thousands of failed plumbing products, including failed brass components.
Brass Failure , Dezincification. Name required. Email will not be published required. All Rights Reserved. Join Our Newsletter. Figure 1 — Yellow brass with reddish discoloration on fracture surface Dezincification is the selective leaching and removal of zinc from the brass, and into the water supply. Figure 2 -White deposits and reddish discoloration of brass A number of industry standards have been created in recent years to address the dezincification of brass.
Figure 3 — Reddish brass layer on fractured fitting WERC has analyzed thousands of failed plumbing products, including failed brass components. Subscribe Subscribe to our e-mail newsletter to receive updates. Hail Damage Assessment. Leave a Reply Click here to cancel reply. Comment Name required Email will not be published required Website. Structural Movement — Foundation Repairs.
We might blame some of this on the recent algal bloom issues we have been dealing with in the Lake Erie western basin. DZR brass has traditionally been considered sufficiently corrosion-resistant to be used in all Danish water types, and previous experience has been good. This type of dezincification uniformly reduces the wall thickness of the valve or fitting. Excessive corrosion deposits, stains and discoloration were observed on the OD surface of the fittings. Mildly acidic water pH below 7 without chlorine can also contribute to dezincification.
Dezincification resistant brass fitting. Case Study
EUROPRESS pressure reducing valve, dezincification resistant brass Italy - ITAP
Dezincification selectively removes zinc from the alloy, leaving behind a porous, copper-rich structure that has little mechanical strength. An in-service valve suffering from dezincification has a white powdery substance or mineral stains on its exterior surface.
What's the cure? Further, manufacturers must be required to provide alloy ations design or chemistry for the materials used in their valves and fittings. Over the past decade, an evolution in alloys has occurred, and yellow brasses that are dezincification-resistant do exist. However, specifiers who simply accept inexpensive yellow brasses without regard to whether they are standard alloys-or even meet the performance requirements of standard alloys-are vulnerable to potential dezincification problems.
Zinc is a highly reactive metal, as seen in its galvanic series ranking. This reactivity stems from the fact that zinc has a very weak atomic bond relative to other metals. Simply, zinc atoms are easily given up to solutions with certain aggressive characteristics. Not highly aerated, low rates of flow of the circulating liquid, relatively high tube-wall temperatures and permeable deposits or coatings over the tube surface.
This type of dezincification penetrates deeply into the sidewalls of valves and fittings. Common failures associated with plug-type attack include penetration through the sidewalls that causes water seepage or loss of mechanical strength in threaded sections to the point of fracture. Uniform-layer dezincification leaches zinc from a broad area of the surface.
This type of dezincification uniformly reduces the wall thickness of the valve or fitting. A complex set of conditions must be present for dezincification to occur, and the occurrence is often related to region of the country. The service conditions generally present where dezincification occurs include: Water with high levels of oxygen and carbon dioxide uniform attack.
Slightly acidic water, low in salt content and at room temperature uniform attack. Soft, low pH and low mineral water combined with oxygen, which forms zinc oxide uniform attack. Waters with high chloride ion content uniform attack.
Neutral or alkaline waters, high in salt content and at or above room temperature plug-type attack. Common signs that dezincification is occurring include: Presence of a loosely adhering white deposit of zinc oxide on the exterior of the valve. Presence of mineral stains on the outer surface of the valve. Check your grades. Get Reports. Join a technical committee. Work at NACE. Skip to main content Press Enter. Skip auxiliary navigation Press Enter. Skip main navigation Press Enter.
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