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East Alligator district centre water supply assessment : Kakadu National Park



East Alligator district centre water supply assessment : Kakadu National Park

Other title

D . Pidsley


Jamieson, M.; Pidsley, D.; Paiva, Jerome


E-Publications; E-Books; PublicationNT; Technical Report ; 26/1991




Made available via the Publications (Legal Deposit) Act 2004 (NT).






Water-supply -- Northern Territory -- Kakadu National Park; Groundwater -- Northern Territory -- Kakadu National Park; Kakadu National Park (N.T.)

Publisher name

Power and Water Authority

Place of publication



Technical Report ; 26/1991


1 v. : ill., maps ; 30 cm.

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Technical Report WRD91026 Viewed at 15:07:48 on 29/07/2010 Page 104 of 107. !2zincificatiat (Figure 5) is the selective raroval un&! r acidic condi t.icns of zinc fran brass 1oihi.d1 gene~ally contains ,3rCt.1OO 30% zinc and 70t ccpper.. 'Ihe camonly accepted theory of dezincification is that the brass dissolves" the zinc ions stay in solution ar:d the ccp~r.. being m::Ire noble .. plates back on (Fontana and Greene, 1967) .. The result is a POraJs (.~per st...'"Uct.ure havin; little st..-ength. Comen grade brass ~ seats suff,~r rap id failure t grcovirq, =idered to ]'" due to a cancination of initial dezincifil:at:ion and t.~en erosicn corrosicn of the residual PO.rOJS ~;er st..."Ucture (AMI:EL. 1984). Corrcsicn of galvanised iron sel:vice piQes has occ:Jrred as for retiOJ.l.aticn !Ie-ins crentioned above.. However, ultimate failure is 51-ewer than for cq;per because of. tbe tetter adherence of the corrcsicn layer. ?ranatlJre failures of t..~e standaJ:"d o:pper solar collec+"-e.tS arxi steel arx:I cq;:per hc,t 'IGlter stora;re tar.ks are a regular OCCJr:-ence. O.I;lrcsolvenc.l attadc. en. !:he ~per pipeworl;., dezincification corttBicn of brass fitti..rT;s and WLLCSicn of steel ccmponents apt=ear to be t..~ :min causes. 4.7 Coc:m:icn llesistant PllmIbirq Galv.mizeC iron and c-:::pper pipes" and ccmcn brass tubes and fittirgs a...""e nOI!:. ~ori tted in hOJSe plLmbin; in the coastal cclrrasive supply areas. '!he fol!Otfirq cor=csion resistant :naterials are nc:w used: L Tappin; saddles: Reir.orced plastic (e.g. Hardii=llas) with dezincification :-esistam: (DR) brass ferrules to AS 2345" 2.. Service p i~ fran the nain to l:he lee.: Class 12 P'.l:. 3. Meters: Cezinci!icati.cn :::-esistant. and !.o::a:t:.ed undergr~nd in a 9recast /::ox ",it..'1 a 4. 5. mm 05101520 1 , , !)R brass cre'l:er cock. eelC1lol grcund eliminates ara suscep !:able to darr..age. FUtt:'ng the rretets ?V:. upstands which fbt and cold pip~rK within t1.lildings: Class 16 polyi:::uty!.er:.e CPS) to AS 2642.2 wit."1 canpressicn union type joints and acetal fittin;s in non-e.:<posed locations" or DR brass tubing to AS 1572 in exposed locations.. Class 16 E9 has a pressure rat..in,; of 0.48 MPa at 95C. '!'apware, val V'eS and. brass. Q.J.arter-turn preferred. cornbiraticns: DR ceramic disc tapware Rei.'"'lforced. :Jlastic t.appin;; saddles have been used satisfactoz:-il.y for Sate ti.me as has Class 1.2 ~ se!;'V'ice pipe. Bec3use of t..'1e high ccrrcsivity of t..~e '-.laters it is not kncwn at this stage it: DR brass to AS 2345 and tube to AS 1572 ...,il1 be totally adequate. Installations are :::ein; :ronitored and. no failures have t::een obset";ed over a 9 ilDnt.;" pericxi to date. !:R prq;::erties of brasses can be .reduced Cy ovemeatirq. Consequently, joinin; brasses to PB or.PVC is by rteehanical r:eans '..n.thaJl: brazitxJ. '!he several PS jointir'g systems available have .been st'..tdied and carpression union t:,;pe fittin;.s are the only !:yf:e pe::mitt.ed. .. ~ has a CUr:::rreter har-i....ness of 60 ;,hich is just wi thin the te:cn.i te attack ra.nge ~ Tests conducted by the CSIRO in 1984 ccnfi!:M that termites in the Darwin area are able to oenettate l?9 pipe ext.ensi....-elv. Consequently, it is only installed within l::ui1.dings and under :e.t:m..ite treated sl.at:s .. At this stage euOed:IEnt. of PB in concrete is not: pe::r.'.itted. However, it is ;;::cssible that after exnerience is gained ~nt ..,ill be all~ beCause P.B is unders tcod. to ;.edom satisfactorily in such situations .. Q.Jidelines for the use ot: materials in the coastal corrosive supply areas have been !?rcduced tv l1illin; and Partners (1986;.