ABSTRACT
After 8 months of Commissioning, a series of leaks were
observed under Contract C2015-80 – Renewal of pipeline at
Riche-En-Eau, Grand Bel Air and Ville Noire. Upon
investigation, the ferrules were found to leak.
The quantity and type of leaks rendered everyone perplex.
This paper through some research works attempts to
explain the leaks.
Firstly, it should be noted that the Ferrules supplied is made
up of an alloy of Copper: CW615N with chemical
composition CuZn39Pb3Sn while our bidding document
specifies Gunmetal (as per BS 1400-LG2) and Ductile Iron.
The existence of Ductile Iron Ferrules is doubtful. Gunmetal
is another alloy of Copper:CC491K and chemical
composition CuSn5Pb5Zn5.
CW615N contains 39% zinc as compared to 5% in CC491K
which is Gunmetal.
Beyond the threshold of 15% Zinc, the alloy is prone to
- Stress Cracking Corrosion and
- Dezincification.
Both thrive in certain environments.
FERRULE
ALERT
Workmanship cannot be overlooked. Over-tightening leads
to excessive stresses in the threads and contributes to the
occurrence of stress corrosion cracking failures.
Colleagues are invited to give their views and for discussion.
This ferrule problem is very real, their replacement should
not be considered as the only solution.
Equipped with the right knowledge, proper care and
precautions, these ferrule failures can be avoided.
A.Baldan (T.O)
Jan 2020
C2015-80 – RENEWAL OF PIPELINE FROM RICHE EN EAU TO GRAND BEL AIR & VILLE NOIRE
July 2019
PART 1
REPORT ON LEAKS (SADDLES AND FERRULES)
CONTRACT FEATURES:
Contract Price
Contractor
Commencement Date
Duration
Scheduled Completion
Revised Completion
Mobilisation on Site
Excavation Starts DI 100
Excavation Starts DI 200
Connection Ch 00
REE Res.
Testing Starts
Rs 119 844 021.00 (excl. vat)
Sotravic Limitee
27-Sep-2017
20 Months
26-May-2019
17-Jun-2019
30-10-17
26-02-18
Grand Bel Air
07-03-18
CH OO Stretch A
19-06-18
Ch 00 - Ruisseau Delices on both DI 300 from Cluny and
Tapping Starts
17-04-18
18-05-18
19-06-18
09-07-18
21-06-18
Laterals DI 100
Main DI 200
Laterals DI 100
Laterals DI 150
Main DI 200
Shifting Starts
27-08-18
Jauferally St – Grand Bel Air
PRV Set
17-09-18
4.8 / 2.0 bar
Commission GBA
18-09-18
Final Lat Connections
25-09-18
01-10-18
End V-Noire to Mahebourg - PE 160 at Bridge
Start Petit Bel Air - PE 160
FULL COMMISSIONNING
11-10-18
Last Connection to NHDC Ville Noire
No of HH
1033
111 HH at Debarcadere shifted on this System.
Previously supplied from Ruisseau Delices.
Taking Over
21-11-18
Permanent Reinst- Asphalt
19-02-19
Cite Ville Noire Start
RDA Reinstatement End
25-06-19
District Council - 11-06-19
Appearance of Ferrule Leaks
25-04-19
Leak Detection Exercise
Sept – Oct 2019
Ferrule Replacement
07-10-19
(Full Fledged)
Shifting started on August 2018 and leakages started to appear on 25 April 2019. Therefore, the pipeline
run for 8 months until the first sign of leaks appears.
Upon repairs, cracks were found on the ferrules where water spurts out in jets. This continuous action
eventually eroded the ferrule and even the adaptor.
The following pictures illustrate the leaks:
ORIGIN OF FERRULES:
Contractor Sotravic supplied the ferrules for this Contract.
The manufacturer is Ningbo Bestway M&E Co Ltd. From China.
Note: ‘’NB’’ is embossed at the Top of the Ferrule.
The following documents were submitted.
1.0
2.0
3.0
4.0
5.0
Certificate of Registration/ISO certification
Manufacturer Authorisation
Statement of Origin
Product Catalogue
Project References (Local)
5.1
Supply and Replacement of Mains in John Kennedy DMA (NRW), contract CPB/20/2014
5.2
Supply and Replacement of Mains in Curepipe & Lislet Goeffroy DMAs (NRW)
The above 2 projects were under progress at Bid Submission.
FREQUENCY OF LEAKS
Leaks on Ferrule
10
9
9
8
8
7
6
5
4
4
4
4
3
3
2
3
2
3
2
2
2
1
4
3
3
2
1
4
2
2
2
1
1
23-07-19
19-07-19
17-07-19
11-07-19
04-07-19
26-06-19
21-06-19
20-06-19
19-06-19
12-06-19
17-06-19
07-06-19
04-06-19
31-05-19
30-05-19
28-05-19
24-05-19
22-05-19
20-05-19
17-05-19
13-05-19
10-05-19
25-04-19
0
Leaks started to appear after 8 months that the ferrules have been put into service
The above graph illustrates the no. of leaks/repairs on the corresponding dates for the period April to
July 2019
A very small drop is observed in the Trendline.
ACTION TAKEN:
Since the occurrence of leaks, PMO is liaising closely with Ops as well as the Contractor.
Once the complaints are received, same is immediately communicated to the Contractor who promptly
organize for the repairs.
Contractor has already used All of the ferrules supplied under the Contract. So as not to delay reparation
works, ferrules were taken from Contract C2016-34 – Renewal of Pipeline in Magnien. (60 Ferrules were
therefore transferred)
These 60 ferrules will be deducted from Contractor’s claim.
Contractor was informed that no more ferrules would be obtained from Plaine Magnien site and that he
would have to supply his own for future repairs.
Consequently, the upcoming repairs were done using ferrules supplied by Contractor Sotravic for their
Riviere du Rempart Contract.
1- A Site visit was effected on the 31st May 2019 where Mr Soocheta – EE PMO and Mr Bundhoo
CWO OPS were present to assess the leaks de-visu.
2- A meeting was convened on the 10th June at St Paul to discuss the issue of leakage on ferrules.
3- It is known that after commissioning the pressure at end of Grand Bel Air and at the end of the
pipeline at Ville Noire was around 4 to 5 bar.
4- Furthermore, a plan showing the location of leaks has been produced.
The leaks are more prominent at end of Grand Bel Air and end of Pipeline in Ville Noire where the recorded
pressure at commissioning were 4 to 5 bar.
Another pressure monitoring carried out on Thursday 25th July 2019, the pressure has subsided to 2.5bar.
Further pressure readings have to be taken during the night where pressure builds up where demand is
lowest.
C2015-80 – RENEWAL OF PIPELINE FROM RICHE EN EAU TO GRAND BEL AIR & VILLE NOIRE
Nov 2019
PART 2
REPORT ON LEAKS (SADDLES AND FERRULES)
LEAK DETECTION EXERCISE.
From the meeting of 10 June 2019, the Contractor mentioned that he would submit a report after some
investigation works.
Meanwhile, the leaks kept on cropping and the Contractor attended to the repairs promptly.
A Leak Detection exercise was carried out on the newly laid pipeline from the 25 Sept 2019 to the 08 Oct
2019.
RC Mamad from Ops South arranged and monitored the exercise. Contractor was represented by one of
his Foreman, Mr Kamlesh Seebah. As for the PMO, myself, TO Baldan was present.
A summary of the qty of possible Leaks detected per Agglomeration is given in the following table:
ROADS
AREA
Grand Bel Air
Cite Ville Noire
Fresonge
Fabien
Debarcadere
LEAKS
DETECTED
65
11
56
3
16
151
L/m
9045
It is worth to be noted that 70/151 probable leaks were detected on the RDA Classified road.
On the 06 August 2019, samples of the leaked ferruled were handed over to the Mauritius Standard
Bureau (MSB) for analysis in terms of their Chemical Composition.
MSB does not have the accreditation to test for copper and its alloys and they sent it to South Africa for
the Tests.
NOM 10 October 2019.
Based on the Leak Detection Exercise and previous repairs, it was found that 30% of the ferrules are
defective and therefore ALL THE FERRULES SHOULD BE REPLACED.
The Contractor requested to the CWA to supply him the ferrules which he will bear the costs.
Ferrule supplied by La Cure StoresCompression Type.
The Copper insert is pushed inside
the PE 20mm.
Ferrule supplied by Contractor
Note: It is supplied with a Brass Adaptor
to connect the PE 20mm externally
FINDINGS DURING REPAIRS WORKS.
From the Leak Detection Exercise, 151 leak spots were identified.
We should appreciate that one leak spot may include several tapings, hence several ferrules.
During Excavation works, up to now, Leaks have been found at the Leaking Spots (69 spots).
This represent 100% successful detection and credits goes to the Detection Team.
TYPE OF LEAKS ENCOUNTERED.
PIC 1
PIC 2
PIC 3
Fully holed
Crack in Brass Adaptor
Hairline Crack Sookye
Rd, Ch 14
The above RHS picture (PIC 3) shows a hairline crack which was undetected during the Leak
Detection Exercise. However, it was weeping. With time, the hairline will erode the ferrule into
a wider and wider gap. (PIC 1)
PIC 2 shows a hairline crack in the Brass Adaptor.
The above scenario justifies the decision to change All the ferrules, as in some point in time, they
will start to leak if the cracks have already been formed.
SUMMARY OF FERRULE REPLACEMENT UP TO DEC 2019.
Contract C2015-80 - Renewal of Pipeline at Riche En Eau Grand Bel Air and Ville Noire
SUMMARY of Replaced Ferrules
From
25-04-19
25-09-19
27-09-19
16-10-19
25-10-19
31-10-19
15-11-19
25-11-19
05-12-19
09-12-19
To
24-09-19
15-10-19
24-10-19
30-10-19
14-11-19
22-11-19
04-12-19
06-12-19
17-12-19
Total Remaining
12-01-20
Nonleaking
Leaking
District Council
9
104
27
85
28
71
40
41
26
66
68
71
15
105
64
86
17
40
73
86
33
114
103
80
29
76
393
570
55.18
%
594
PIT
113
95
156
44
175
104
127
43
106
963
1033
70
Replaced before Leak Detection
Leak detection starts
Replaced after leak Detection
Replaced after leak Detection
Replaced after leak Detection
Replaced after leak Detection
Replaced after leak Detection
Replaced after leak Detection
Replaced after leak Detection
Replaced after leak Detection
Total Replaced
Asphalted
RDA
PIT
Asphalted
27
27
17
17
22
11
18
22
11
18
95
95
Total Qty of Ferrules
Total
550*
POTABLE WATER RECOVERED TILL DECEMBER 2019 FOLLOWING FERRULE REPLACEMENT
15-Oct-2019
4395 m3/d
26-Dec-2019 2909m3/d
TECHNICAL SPECIFICATION OF SUPPLIED FERRULES.
The supplied Ferrules are from NINGBO BESTWAY M&E CO LTD, China. (ANNEX 1)
As per the Bid Submission, they meet the requirements of ISO9001:2008.
9001:2008 is the standard that outlines the requirements an organization must maintain in
their quality system for ISO 9001:2008 certification.
The technical aspects mention a Brass/Bronze construction ferrule for an HDPE Outlet.
Contractor informed that these ferrules have been used at
1.0 Supply and Replacement of Mains in John Kennedy DMA (NRW), contract CPB/20/2014
2.0 Supply and Replacement of Mains in Curepipe & Lislet Goeffroy DMAs (NRW)
Both are CWA Projects.
MISSING USEFUL INFORMATION
From the submission, the following important data cannot be found:
1.0
2.0
3.0
4.0
Working Pressure
Temperature
Type of Ferrule (Push fit or Compression)
Material percentage composition as per which Standard / BS/ISO
Grade of material.
Installation Instructions.
Resistance to Corrosion.
5.0
6.0
CWA’s REQUIREMENT.
As per our document Contract C2015-80, pg 325, APPENDIX TO SPECIFICATIONS:
4.0
CLAUSE 2.22: DUCTILE IRON PIPES, FLANGES AND FITTINGS
For Swivel Ferrules to be supplied, both Gunmetal (as per BS 1400-LG2) and Ductile Iron (BS EN 545/ ISO 2531: 2000),
will be accepted under this Contract.
Also, it should be noted that our item in the Supply BOQ is as follows:
2.16
SWIVEL FERRULE (PRISECOCK)
NIL
0
2.16.1
BRASS SWIVEL FERRULE TO ACCOMMODATE TRANSITION COUPLER 20 MM HDPE/BRASS WITH
MALE THREAD
UNIT
900
CAUSE OF LEAKAGES.
From the above background information, 2 avenues will be explored to investigate the most
plausible cause of the Leaks.
1.0 - Material Supplied (Ferrule) in terms of its composition and Characteristics.
2.0 - Workmanship and Method of Installation.
1.0
MATERIAL SUPPLIED
CHARACTERISTICS.
(FERRULE)
IN
TERMS
OF
ITS
COMPOSITION
AND
As per CWA Specs, the ferrule material should be Gunmetal or Ductile Iron.
Ductile Iron Swivel ferrules are not available.
ALLOYS OF COPPER/BRASS/BRONZE??
Copper is frequently used in alloys with tin, zinc, nickel etc.,
To put it simply,
Brass is a Copper-Zinc alloy in which Zinc is the Main Alloying element.
Bronze is a Copper-Tin alloy in which Tin is the Main Alloying agent.
Effects of alloying elements
Lead
The addition most commonly made to brasses to modify their properties is lead, up to 3% of which may be
added to alpha-beta brasses to provide free-machining properties. The lead does not form a solid solution
with the copper and zinc but is present as a dispersed discontinuous phase distributed throughout the
alloy. It has no effect on corrosion resistance. Lead is not added to wrought alpha brasses since, in the
absence of sufficient beta phase, it gives rise to cracking during hot working.
Tin
1% tin is included in the composition of Admiralty brass CW706R (CZ111) and Naval brass CZ112 (nearest
CW712R). As their names indicate, these brasses were developed originally for seawater service, the tin
being added to provide improved corrosion resistance.
http://herzmediaserver.com/data/01_product_data/06_broschure/eng/herz-brass-versus-bronze-inmaterial-selection.pdf
1.1
GUNMETAL (BS 1400-LG2) – As per our Contract Document
https://en.wikipedia.org/wiki/Gunmetal
Gun metal, also known as red brass in the United States, is a type of bronze – an alloy of copper, tin,
and zinc. Proportions vary but 88% copper, 8–10% tin, and 2–4% zinc is an approximation. Originally
used chiefly for making guns, it has largely been replaced by steel. Gunmetal, which casts and
machines well and is resistant to corrosion from steam and salt water,[1] is used to make steam and
hydraulic castings, valves, gears, statues, and various small objects, such as buttons. It has a tensile
strength of 221 to 310 MPa, a specific gravity of 8.7, a Brinell hardness of 65 to 74, and a melting point
of around 1,000 degrees Celsius.
Chemical Composition – CuSn5Pb5Zn5 and Alloy designation (UK) CC491K
BS1400 is the old BS Standard and has been replaced by BS EN 1982:2008
It is about Copper Alloy ingots and Copper Alloy and High conductivity copper castings
The UNS (Unified Numbering System) designation (US) is C83600
1.2
SUPPLIED FERRULES
On the other side, as per the Laboratory (Scrooby’s- South Africa) results, the ferrules supplied have
chemical composition – CuZn39Pb3Sn and Alloy designation (UK) CW615N
The supplied ferrules do not have any BS Standards but it has an EN 12165: 1998 which is about
Copper and copper alloys. Wrought and unwrought forging stock
There is no UNS designation for CW615N.
The nearest one is for CW613N is C48500 for CuZn39Pb2Sn and
CW614N is C38500 for CuZn39Pb3
https://books.google.mu/books?id=sxkPJzmkhnUC&pg=PA29&lpg=PA29&dq=CW615N&source=bl&ots=AKwu4bkx
l0&sig=ACfU3U0In1Sdbz5a_wfor9s6GgAylvxSGQ&hl=en&sa=X&ved=2ahUKEwibyc__PXmAhUEu3EKHTjVBPM4ChDoATACegQICBAB#v=onepage&q=CW615N&f=false
1.3
ALLOY DESIGNATION SYSTEM.
1.4
CHEMICAL COMPOSITION COMPARISON
Contractor sent samples of the defective ferrules used under the C2015-80 Contract as well as other
ferrules from different sources for chemical analysis to Scrooby’s Laboratory Service CC South Africa.
Contractor also performed tests on ferrules supplied from STR and METEX.
Most of ferrules in use are normally supplied by these 2 suppliers. Ferrules obtained from La Cure
Stores mostly are from them.
The tests consist of analyzing the % Composition in Mass of the different elements found in the
ferrules.
PMO also sent the defective ferrules for investigation to the MSB.
It is worth to note that MSB does not have the accreditation to perform Tests on Brass Materials.
Therefore, MSB sent our ferrules to one of their partners in South Africa. The results are still
pending.
1.41
MAJOR FINDINGS IN THE CHEMICAL ANALYSIS
As per the Test carried out by the Contractor, the % of the constituents’ present in the supplied
ferrules are within the range set in EN 12165.
However, as mentioned earlier, the ferrules should meet the requirements set in BS1400 –
LG2 as per CWA Bid Document.
As per BS 1400, Gun Metals LG2, CC491K, has a much higher copper content than that of the
supplied CW615N ferrule. 84-86% as compared to 57-59%
The remaining main elements of Gunmetal, LG2, i.e. Tin, Lead and Zinc are evenly present
in the range of 5-6%, whereas in CW615N, Tin represents 0.2-0.5% and Lead is 2.5-3.5%.
Moreover, the supplied CW615N has a much higher % of Zinc (39 %) as compared to the 5%
in Gunmetal.
CONTRACT: CWA/C2015/80 - RENEWAL OF PIPE LINE FROM RICHE EN EAU TO
GRAND BEL AIR AND VILLE NOIR
Further to testing of ferrules carried out by Sotravic Ltd and the CWA, the table below describes
their chemical composition with respect to establised standards.
Elements (%)
Standards/Samples
REMARKS
Copper, Cu
Tin, Sn
Zinc, Zn
Lead, Pb
BS 1400 : 1985 (As per Contract)
84 - 86
4-6
4-6
4-6
EN 12165 (CUZN39Pb3Sn –
CW615N)
57.0 – 59.0
0.20 – 0.50
Remainder
2.50 – 3.50
A1
57.3
0.67
38.7
2.27
A3
57.8
0.86
37.0
2.76
Roche Bois
B1
57.6
0.67
38.5
2.26
(IN USE)
B3
60.0
0.89
35.3
2.66
C1
57.4
0.72
37.8
2.50
C3
59.6
1.27
34.8
2.63
Riche En Eau
D1
57.6
0.70
37.8
2.28
(IN USE)
D3
56.9
0.96
37.9
2.76
Riche En Eau
E1
56.9
1.04
37.9
2.77
(DAMAGED)
E3
59.0
1.05
35.7
2.67
STR
F1
58.4
0.73
37.0
2.07
G1
57.7
0.85
37.0
2.69
G3
57.9
0.87
37.1
2.62
Roche Bois (NEW)
Riche En Eau (NEW)
METEX
Results of Test
effected by CWA
PENDING
Compiled by EE Jeetoo
1.41
SIGNIFICANCE OF A HIGH ZINC CONTENT IN THE COPPER ALLOY BRASS.
There are numerous different types of brass specified by EN (European Norm) Standards.
Their
composition varies depending upon the properties required for a particular application. Brasses are
classified in a variety of ways, including by their mechanical properties, crystal structure, zinc content, and
color.
The main constituent of Brass is Zinc, but the latter’s proportion itself is usually modified to improve a
specific characteristic, such as strength, workability or Resistance to a particular type of Corrosion.
The type of Brass manufactured is determined by the copper to Zinc proportion by weight (%)
Brass types
Class
Proportion by
weight (%)
Copper
Notes
Zinc
Alpha brasses
> 65
< 35
Alpha brasses are malleable, can be worked cold, and are used in
pressing, forging, or similar applications. They contain only one phase,
with face-centered cubic crystal structure. With their high proportion of
copper, these brasses have a more golden hue than others
Alpha-beta
brasses
55–65
35–45
Also called duplex brasses, these are suited for hot working. They
contain both α and β' phases; the β'-phase is body-centered cubic and
is harder and stronger than α. Alpha-beta brasses are usually worked
hot. The higher proportion of zinc means these brasses are brighter
than alpha brasses.
Beta brasses[citation
50–55
45–50
Beta brasses can only be worked hot, and are harder, stronger, and
suitable for casting. The high zinc-low copper content means these are
some of the brightest and least-golden of the common brasses.
Gamma brasses
33–39
61–67
There are also Ag-Zn and Au-Zn gamma brasses, Ag 30–50%, Au
41%.[27]
White brass
< 50
> 50
These are too brittle for general use. The term may also refer to certain
types of nickel silver alloys as well as Cu-Zn-Sn alloys with high
proportions (typically 40%+) of tin and/or zinc, as well as predominantly
zinc casting alloys with copper additives. These have virtually no yellow
coloring at all, and instead have a much more silvery appearance.
needed]
https://en.wikipedia.org/wiki/Brass
1.42
ALPHA-BETA BRASSES (Double Phase or Duplex)
Based upon the composition of CW615N, we are concerned with Alpha-Beta Brasses.
Alpha-Beta Brass is cheaper than single phase brass because of the larger amount of zinc used in it.
At the same time, it’s more prone to corrosion.
Still, the chemical composition leads to greater strength and hardness. Therefore, double phase brass
is suitable for hot forming and casting. Extrusion, stamping and die-casting are usable methods with
that type of metal.
.
1.5
CORROSION IN BRASSES.
Pure Copper is a noble metal and resists well to corrosion.
But the alloys depending on their composition are at the mercy of corrosion.
In the presence of some reagents certain alloys suffer from
1.0
Hydrogen embrittlement or Stress Corrosion Cracking and
2.0
Dezincification.
1.51
STRESS CORROSION CRACKING- SCC
Corrosion cracking most commonly occurs in brass that is exposed to ammonia or amines.
Brasses containing more than 15% Zn are the most susceptible. Copper and most copper alloys
that either do not contain zinc or are low in zinc content generally are not susceptible to SCC.
Because SCC requires both tensile stress and a specific chemical species to be present at the same
time, removal of either the stress or the chemical species can prevent cracking. Annealing or stress
relieving after forming alleviates SCC by relieving residual stresses.
Stress relieving is effective only if the parts are not subsequently bent or strained in service; such
operations reintroduce stresses and resensitize the parts to SCC.
Copper and Copper Alloys
Edited by
J. R. Davis
Davis & Associates
Prepared under the direction of the
ASM International Handbook Committee
SCC is commonly referred to as season cracking. In the case of copper alloy fittings, it is manifested
by the appearance of intergranular cracking, usually (but not always) disposed along the longitudinal
axis of the component. It is due to four essential factors:
• Residual Stress in the Fitting
• A Stress Cracking Agent ; Ammonia Derivatives ( http://www.conexbanninger.com/)
• Moisture
• An Alkaline Environment
HERZ Armaturen GmbH , Richard-Strauss-Str. 22, A-1230 Vienna
Failed ½ in. brass ball valve from HVAC system. Valve
split at male internal threads
https://www.valvemagazine.com/webonly/categories/technical-topics/5283-forensic-engineeringtracks-valve-failures.html
Broken Ferrule at
Soochit Store, Ville Noire (20-01-2020). This is a
probable case of SCC. This ferrule was issued by La
Cure Stores
Better resistance to SCC is possible if Brasses of Low Zinc are used.
Avoiding high stresses during the manufacturing, assembling and operation phase will also help,
As for operation, the following example is most relevant to our case:
1.51.1 USE OF PTFE AND OVERTIGHTENING
On site, when undertaking connection and assembly works with small fittings, PTFE Tape (Teflon),
is used at the joints and the plumber tighten the fittings TIGHTLY.
In doing so, a high level of stresses is introduced which may induce SCC.
When PTFE tape is used to seal the thread, it is all too easy to overtighten such joints to a point
where a very high circumferential hoop stress is generated in the female member. There have
been many examples of subsequent longitudinal stress corrosion cracking of the valve ends as a
result of contact with quite low concentrations of ammonia in service.
SITE PHOTOGRAPHS SHOWING
PROBABLE STRESS CORROSION CRACKING- SCC FROM SITE C2015-80
1.52
DEZINCIFICATION.
Dezincification is the leaching out of Zinc from brass. It can cause (meringue) build-up and pipe
blockage, fitting bursts, lead contamination events and pitting failure.
Dezincification can occur as a uniform or localized process, with or without meringue build-up. While
resistant brasses have been developed and are available for use in potable water systems, it has become
commonplace to use alloys susceptible to dezincification due to their low cost.
It is accepted that high chloride, low hardness and low alkalinity waters are especially prone to
dezincification.
Zhang Y. Dezincification and Brass Lead Leaching in Premise Plumbing Systems: Effects of Alloy,
Physical Conditions and Water Chemistry. [Thesis]. Blacksburg: Virginia Polytechnic Institute and State
University; 2009.
There are also health concerns due to links between dezincification and increased lead contamination of
potable water from brass (Triantafillou and Edwards 2007) (D. E. Kimbrough 2007) (D. Kimbrough 2001).
Preventing and Treating the Dezincification of Brass – Canadian Conservation Institute (CCI)
Notes 9/13
https://www.canada.ca/en/conservation-institute/services/conservation-preservationpublications/canadian-conservation-institute-notes/dezincification-brass.html
Brass containing less than 15 wt% zinc resists dezincification, but brass with more than 15 wt% zinc is
susceptible to the phenomenon. Duplex brass is even more prone to dezincification than alpha brass
(Scott 2002).
The first sign of dezincification of brass is a change in colour, from the yellow typically found in brass to
the salmon pink of pure copper metal.
The pink colour may then turn reddish and then brown if the surface copper corrodes to form cuprite.
More severe dezincification produces a porous, weak metal, which is mainly copper (Dinnappa and
Mayanna 1987). Severe dezincification of brass plumbing fixtures can perforate the brass and cause leaks.
Larry Muller. The Basics of Dezincification - Director, Metallurgy and Technical Services
Chase Brass and Copper Company, LLC. Montpelier, OH; 201
Not all brasses are prone to Dezincification. Up to 15% of Zinc, the material is safe from Dezincification.
At ≤ 35% zinc, some additives and/or thermal treatments can prevent this corrosion.
Dezincification can be prevented by adding inhibitors like, 0.2% of Arsenic, Antimony and Phosphorous.
Adding 0.25%-2% of Tin, Nickel and Aluminum also help.
However, if the material contains > than 35%, the inhibitors cannot offer full protection.
Here, we recall that the supplied ferrule which is alloy CW615N has a 39 % of Zinc as tested by
Scrooby’s Laboratory Service CC - South Africa and the results submitted by the Contractor.
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WATER CONDITIONS FOR DEZINCIFICATION.
Water Conditions
High O2 & CO2, stagnant or slow-moving water
Slightly acid water & low salt content
Soft water, low pH, low mineral content
Waters high in chloride ions
Neutral / alkaline waters, high salt, ≥ room temperature
Type of Dezincification
LAYER - Progression is Slow and along a broad
front.
PLUG - Progression is faster and Localised
To summarize dezincification,
1.
Dezincification is the selective loss of zinc from brass.
2.
It’s an electrochemical reaction between zinc and some chemicals found in water.
3.
It results in a weak spongy copper layer at the water contact surface
4.
It can progress through the part causing leaks
5.
It can cause blockage of the water path if it forms a “meringue” deposit
6.
The loss of the wall’s cross section can cause mechanical failure by straight-forward fracture or
increased vulnerability to stress corrosion cracking (SCC)
Photographs of Dezincification
https://www.festoolownersgroup.com/hom
e-improvement-other-projects/thedezincification-of-brass-a-lesson-learned/
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DEZINCIFICATION RESISTANT BRASS
Standard Brass is widely used in the water industry. However, in certain conditions, when exposed to certain
pH values and Chlorides, they can suffer from dezincification.
The solution to this problem is a dezincification resistant alloy - DZR brass. This material is the ideal choice
when aggressive conditions prevail.
https://www.ldmbrass.com/en/product/4-0-0/4-39/dzr.htm
EN12165 also mentions the above at Clause (5c) when ordering.
SITE PHOTOGRAPHS SHOWING
PROBABLE DEZINCIFICATION FROM SITE C2015-80.
Totally Crumbled parts of a defective ferrules from
Site C2015-80 – July 2019 – This may be a
consequence of Dezincification.
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FURTHER READING
Zhang Y. Dezincification and Brass Lead Leaching in Premise Plumbing Systems: Effects of Alloy,
Physical Conditions and Water Chemistry. [Thesis]. Blacksburg: Virginia Polytechnic Institute and State
University; 2009.
Clement Cartier, Identification et traitements des principales sources de plomb en
eau potable - Département des génies civil, géologique et des mines école polytechnique de
montréal thèse présentée en vue de l’obtention du diplôme de philosophiae doctor
(génie civil) - UNIVERSITÉ DE MONTRÉAL - JUIN 2012
Moustafa Said Seleet , Electrochemistry of stress corrosion cracking of brass, Iowa State University, 1986
https://www.valvemagazine.com/web-only/categories/technical-topics/5283-forensic-engineeringtracks-valve-failures.html
Water Journal – Australian Water and Wastewater Association – April 1993
Aalco – The UK’s largest independent multi-metals stockholder.
BS1400
Copper Alloy ingots and Copper Alloy and High conductivity copper castings
EN12165
Copper and copper alloys. Wrought and unwrought forging stock
Ps : You must have noted that the workmanship aspect has not been fully scrutinized. This will be for
another paper after consulting more experienced colleagues.
Stress Corrosion Cracking, Dezincification or a
Lethal combination of Both.
adjeiB Jan 2020