Chidule ichi chikupereka malingaliro okhudza kapangidwe kotetezeka ka mapaipi kuti agawidwe a haidrojeni.
Hydrojeni ndi madzi osinthasintha kwambiri omwe amatha kutuluka madzi ambiri. Ndi kuphatikiza koopsa komanso koopsa kwa zinthu zomwe zimapangitsa kuti madzi azituluka mosavuta, madzi osinthasintha omwe ndi ovuta kuwalamulira. Izi ndi zinthu zomwe muyenera kuganizira posankha zipangizo, ma gasket ndi zisindikizo, komanso mawonekedwe a makina otere. Nkhani izi zokhudza kufalikira kwa mpweya wa H2 ndizo zomwe zikukambidwa kwambiri, osati kupanga H2, madzi a H2, kapena madzi a H2 (onani mbali yakumanja).
Nazi mfundo zingapo zofunika kukuthandizani kumvetsetsa kusakaniza kwa haidrojeni ndi mpweya wa H2. Haidrojeni imayaka m'njira ziwiri: kusungunuka kwa mpweya ndi kuphulika.
Kuchepa kwa mpweya. Kuchepa kwa mpweya ndi njira yodziwika bwino yoyaka moto yomwe malawi amadutsa mu chisakanizocho pa liwiro la subsonic. Izi zimachitika, mwachitsanzo, pamene mtambo womasuka wa hydrogen-air mixture wayatsidwa ndi gwero laling'ono loyatsira moto. Pankhaniyi, lawilo limayenda pa liwiro la mamita khumi mpaka mazana angapo pa sekondi. Kukula mwachangu kwa mpweya wotentha kumapanga mafunde opanikizika omwe mphamvu yake imafanana ndi kukula kwa mtambo. Nthawi zina, mphamvu ya mafunde ogwedezeka ikhoza kukhala yokwanira kuwononga nyumba ndi zinthu zina zomwe zili m'njira yake ndikuvulaza.
Kuphulika. Pamene kunaphulika, malawi ndi mafunde odabwitsa anadutsa mu chisakanizocho pa liwiro la supersonic. Chiŵerengero cha kupanikizika mu mafunde ophulika n'chokulirapo kuposa mu kuphulika. Chifukwa cha mphamvu yowonjezereka, kuphulikako n'koopsa kwambiri kwa anthu, nyumba ndi zinthu zapafupi. Kuphulika kwabwinobwino kumayambitsa kuphulika kukayatsidwa pamalo opapatiza. M'dera lopapatiza chonchi, kuyaka kumatha kuchitika chifukwa cha mphamvu zochepa. Koma kuti kuphulika kwa chisakanizo cha mpweya wa hydrogen kuchitike pamalo opanda malire, gwero lamphamvu kwambiri la kuyaka limafunika.
Chiŵerengero cha kuthamanga kwa mpweya kudutsa mafunde ophulika mu chisakanizo cha haidrojeni ndi mpweya ndi pafupifupi 20. Pa kuthamanga kwa mpweya, chiŵerengero cha 20 ndi 300 psi. Pamene kuthamanga kwa mpweya kumeneku kukagundana ndi chinthu chosasuntha, chiŵerengero cha kuthamanga kwa mpweya chimawonjezeka kufika pa 40-60. Izi zimachitika chifukwa cha kuwonekera kwa kuthamanga kwa mpweya kuchokera ku chopinga chosasuntha.
Chizolowezi chotulutsa madzi. Chifukwa cha kukhuthala kwake kochepa komanso kulemera kwake kochepa kwa mamolekyulu, mpweya wa H2 umakonda kutulutsa madzi komanso kulowa kapena kulowa muzinthu zosiyanasiyana.
Hydrojeni ndi yopepuka ka 8 kuposa gasi wachilengedwe, yopepuka ka 14 kuposa mpweya, yopepuka ka 22 kuposa propane ndipo yopepuka ka 57 kuposa nthunzi ya petulo. Izi zikutanthauza kuti ikayikidwa panja, mpweya wa H2 umakwera mofulumira ndikutha, zomwe zimachepetsa zizindikiro zilizonse za kutuluka kwa madzi mofanana. Koma ukhoza kukhala lupanga lakuthwa konsekonse. Kuphulika kungachitike ngati kuwotcherera kukuchitika panja pamwamba kapena pansi pa kutayikira kwa H2 popanda kufufuza kuti kutayikira madzi kukuchitika musanawotchetse. M'malo otsekedwa, mpweya wa H2 ukhoza kukwera ndikuwunjikana kuchokera padenga kupita pansi, zomwe zimapangitsa kuti uzitha kusonkhanitsa mpaka kuchuluka kwakukulu usanakhudze magwero oyatsira moto pafupi ndi nthaka.
Moto woyaka mwangozi. Kudziyatsa wekha ndi chinthu chomwe chisakanizo cha mpweya kapena nthunzi zimayaka zokha popanda gwero lakunja la kuyatsa. Chimadziwikanso kuti "kuyatsa kwadzidzidzi" kapena "kuyatsa kwadzidzidzi". Kudziyatsa wekha kumadalira kutentha, osati kupanikizika.
Kutentha kwa autoyatsa ndi kutentha kochepa komwe mafuta amayatsa mwangozi asanayambe kuyatsa popanda gwero lakunja la kuyatsa likakhudzana ndi mpweya kapena chinthu chowonjezera okosijeni. Kutentha kwa autoyatsa kwa ufa umodzi ndi kutentha komwe kumayatsa mwangozi popanda chinthu chowonjezera okosijeni. Kutentha kwa autoyatsa kwa mpweya H2 mumlengalenga ndi 585°C.
Mphamvu yoyatsira ndi mphamvu yofunikira kuti kuyatsa moto kuyambe kufalikira kudzera mu chisakanizo choyaka. Mphamvu yoyatsira yochepa ndi mphamvu yocheperako yofunikira kuti kuyatsa chisakanizo china choyaka pa kutentha ndi kupanikizika kwina. Mphamvu yoyatsira yochepa ya mpweya wa H2 mu 1 atm ya mpweya = 1.9 × 10–8 BTU (0.02 mJ).
Malire ophulika ndi kuchuluka kwakukulu komanso kochepa kwa nthunzi, nthunzi kapena fumbi mumlengalenga kapena mpweya komwe kuphulika kumachitika. Kukula ndi mawonekedwe a chilengedwe, komanso kuchuluka kwa mafuta, zimalamulira malirewo. "Malire ophulika" nthawi zina amagwiritsidwa ntchito ngati mawu ofanana ndi "malire ophulika".
Malire ophulika a zosakaniza za H2 mumlengalenga ndi 18.3 vol.% (malire otsika) ndi 59 vol.% (malire apamwamba).
Popanga mapaipi (Chithunzi 1), gawo loyamba ndikudziwa zipangizo zomangira zomwe zimafunikira pa mtundu uliwonse wa madzi. Ndipo madzi aliwonse adzagawidwa m'magulu motsatira ndime ya ASME B31.3. 300(b)(1) imati, "Mwini wake ali ndi udindo wodziwa mapaipi a kalasi D, M, kuthamanga kwambiri, ndi kuyera kwambiri, ndikuzindikira ngati makina enaake abwino ayenera kugwiritsidwa ntchito."
Kugawa madzi m'magulu kumafotokoza kuchuluka kwa mayeso ndi mtundu wa mayeso ofunikira, komanso zofunikira zina zambiri kutengera gulu la madzi. Udindo wa mwiniwake pa izi nthawi zambiri umakhala m'manja mwa dipatimenti ya uinjiniya ya mwiniwake kapena injiniya wotumizidwa kunja.
Ngakhale kuti B31.3 Process Piping Code siiuza mwiniwake kuti ndi zinthu ziti zomwe angagwiritse ntchito pa madzi enaake, imapereka malangizo okhudza mphamvu, makulidwe, ndi zofunikira pa kulumikizana kwa zinthuzo. Palinso mawu awiri oyamba a code omwe amanena momveka bwino:
Ndipo fotokozani ndime yoyamba pamwambapa, ndime B31.3. 300(b)(1) imatinso: “Mwini wa malo oika mapaipi ndiye yekha amene ali ndi udindo wotsatira Malamulowa komanso kukhazikitsa zofunikira pakupanga, kumanga, kuyang'anira, kuyang'anira, ndi kuyesa zomwe zimayang'anira kayendetsedwe ka madzi kapena njira zomwe mapaipiwo ali mbali yake. Kuyika.” Chifukwa chake, titakhazikitsa malamulo ena ofunikira pa udindo ndi zofunikira pakutanthauzira magulu a ntchito zamadzimadzi, tiyeni tiwone komwe mpweya wa haidrojeni ukugwirizana.
Popeza mpweya wa haidrojeni umagwira ntchito ngati madzi osasunthika omwe amatuluka, mpweya wa haidrojeni ukhoza kuonedwa ngati madzi wamba kapena madzi a Gulu M pansi pa gulu B31.3 kuti ugwiritsidwe ntchito pamadzi. Monga tafotokozera pamwambapa, kugawa kwa madzi m'magulu ndi chinthu chofunikira kwa mwiniwake, bola ngati chikugwirizana ndi malangizo a magulu osankhidwa omwe afotokozedwa mu B31.3, ndime 3. 300.2 Matanthauzidwe mu gawo lakuti “Ntchito za Hydraulic”. Zotsatirazi ndi matanthauzidwe a ntchito yamadzi wamba ndi ntchito yamadzi ya Gulu M:
"Ntchito Yabwinobwino Yamadzimadzi: Ntchito yamadzimadzi yogwiritsidwa ntchito pa mapaipi ambiri motsatira malamulo awa, mwachitsanzo, siili pansi pa malamulo a magulu D, M, kutentha kwambiri, kuthamanga kwambiri, kapena ukhondo wamadzimadzi wambiri.
(1) Kuopsa kwa madziwo n’kwakukulu kwambiri kotero kuti kukhudzana ndi madzi ochepa kwambiri omwe amabwera chifukwa cha kutuluka kwa madzi kungayambitse kuvulala kwakukulu kwamuyaya kwa iwo omwe amapuma kapena kukhudzana nawo, ngakhale njira zochiritsira zitakhala zitatengedwa nthawi yomweyo.
(2) Pambuyo poganizira kapangidwe ka mapaipi, luso, momwe amagwirira ntchito, ndi malo, mwiniwakeyo amatsimikiza kuti zofunikira pakugwiritsa ntchito madziwo mwachizolowezi sizokwanira kupereka kulimba kofunikira kuti ateteze ogwira ntchito kuti asakhudzidwe ndi zinthu zina.
Mu tanthauzo la M pamwambapa, mpweya wa haidrojeni sukwaniritsa zofunikira za ndime (1) chifukwa suonedwa ngati madzi oopsa. Komabe, pogwiritsa ntchito gawo laling'ono (2), Malamulowa amalola kugawa machitidwe a hydraulic mu kalasi M pambuyo poganizira bwino za "... kapangidwe ka mapaipi, chidziwitso, momwe amagwirira ntchito ndi malo ..." Mwiniwake amalola kudziwa momwe madzi amagwirira ntchito bwino. Zofunikira sizikwanira kukwaniritsa kufunikira kwa umphumphu wapamwamba pakupanga, kumanga, kuyang'anira, kuyang'anira ndi kuyesa makina a mapaipi a haidrojeni.
Chonde onani Gome 1 musanakambirane za Kutupa kwa Hydrogen Kutentha Kwambiri (HTHA). Ma code, miyezo, ndi malamulo alembedwa mu tebulo ili, lomwe lili ndi zikalata zisanu ndi chimodzi zokhudzana ndi hydrogen embrittlement (HE), vuto lofala la dzimbiri lomwe limaphatikizapo HTHA. OH imatha kuchitika kutentha kochepa komanso kokwera. Poganiziridwa kuti ndi mtundu wa dzimbiri, imatha kuyambika m'njira zingapo komanso kukhudza zinthu zosiyanasiyana.
HE ili ndi mitundu yosiyanasiyana, yomwe ingagawidwe m'magulu awiri: hydrogen cracking (HAC), hydrogen stress cracking (HSC), stress corrosion cracking (SCC), hydrogen corrosion cracking (HACC), hydrogen bubbling (HB), hydrogen cracking (HIC). )), stress oriented hydrogen cracking (SOHIC), progressive cracking (SWC), sulfide stress cracking (SSC), soft zone cracking (SZC), ndi high temperature hydrogen corrosion (HTHA).
Mwanjira yosavuta, kuphulika kwa haidrojeni ndi njira yowonongera malire a tirigu wachitsulo, zomwe zimapangitsa kuti kuphulikako kuchepe chifukwa cha kulowa kwa haidrojeni ya atomu. Njira zomwe izi zimachitikira zimasiyana ndipo zimatanthauzidwa pang'ono ndi mayina awo, monga HTHA, komwe kutentha kwakukulu ndi hydrogen yothamanga kwambiri zimafunika kuti ziwonongeke, ndi SSC, komwe haidrojeni ya atomu imapangidwa ngati mpweya wotsekedwa ndi haidrojeni. chifukwa cha dzimbiri la asidi, imalowa m'mabokosi achitsulo, zomwe zingayambitse kuphulika. Koma zotsatira zake zonse ndi zofanana ndi za milandu yonse ya kuphulika kwa haidrojeni yomwe yafotokozedwa pamwambapa, komwe mphamvu ya chitsulo imachepetsedwa ndi kuphulika pansi pa mulingo wake wovomerezeka, zomwe zimapangitsa kuti pakhale ngozi chifukwa cha kusakhazikika kwa madzi.
Kuwonjezera pa makulidwe a khoma ndi magwiridwe antchito a makina olumikizirana, pali zinthu ziwiri zazikulu zomwe muyenera kuziganizira posankha zipangizo zogwiritsira ntchito mpweya wa H2: 1. Kukhudzidwa ndi hydrogen yotentha kwambiri (HTHA) ndi 2. Nkhawa zazikulu zokhudzana ndi kutuluka kwa madzi. Nkhani zonsezi zikukambidwa pakadali pano.
Mosiyana ndi hydrogen ya molekyulu, hydrogen ya atomu imatha kukula, kuyika hydrogen pamalo otentha kwambiri komanso opanikizika, zomwe zimapangitsa kuti pakhale HTHA yomwe ingakhalepo. Pansi pa mikhalidwe iyi, hydrogen ya atomu imatha kufalikira m'zida kapena zida zopangira mapaipi achitsulo cha kaboni, komwe imakumana ndi kaboni mu yankho lachitsulo kuti ipange mpweya wa methane pamalire a tirigu. Polephera kutuluka, mpweyawo umakula, ndikupanga ming'alu ndi mipata m'makoma a mapaipi kapena zombo - iyi ndi HTGA. Mutha kuwona bwino zotsatira za HTHA mu Chithunzi 2 pomwe ming'alu ndi ming'alu zimawonekera pakhoma la 8″. Gawo la chitoliro cha kukula kwapadera (NPS) chomwe chimalephera pansi pa mikhalidwe iyi.
Chitsulo cha kaboni chingagwiritsidwe ntchito popereka haidrojeni pamene kutentha kwa ntchito kuli pansi pa 500°F. Monga tafotokozera pamwambapa, HTHA imachitika pamene mpweya wa haidrojeni umakhala pa mphamvu yayikulu komanso kutentha kwambiri. Chitsulo cha kaboni sichikulimbikitsidwa pamene mphamvu yochepa ya haidrojeni ikuyembekezeka kukhala pafupifupi 3000 psi ndipo kutentha kuli pamwamba pa 450°F (ndiye ngozi yomwe yachitika pa Chithunzi 2).
Monga momwe taonera kuchokera ku chithunzi cha Nelson chosinthidwa mu Chithunzi 3, chomwe chatengedwa pang'ono kuchokera ku API 941, kutentha kwakukulu kumakhudza kwambiri kukakamiza kwa haidrojeni. Mpweya wa haidrojeni pang'ono umatha kupitirira 1000 psi ukagwiritsidwa ntchito ndi zitsulo za kaboni zomwe zimagwira ntchito kutentha mpaka 500°F.
Chithunzi 3. Tchati cha Nelson chosinthidwachi (chosinthidwa kuchokera ku API 941) chingagwiritsidwe ntchito kusankha zipangizo zoyenera kugwiritsa ntchito haidrojeni pa kutentha kosiyanasiyana.
Pa chithunzi 3 chikuwonetsa kusankha kwa zitsulo zomwe zimatsimikiziridwa kuti zipewe kuukira kwa haidrojeni, kutengera kutentha komwe kumagwiritsidwa ntchito komanso kupanikizika pang'ono kwa haidrojeni. Zitsulo zosapanga dzimbiri za Austenitic sizikhudzidwa ndi HTHA ndipo ndi zinthu zokhutiritsa pa kutentha konse ndi kupsinjika kulikonse.
Chitsulo chosapanga dzimbiri cha Austenitic 316/316L ndicho chinthu chothandiza kwambiri pakugwiritsa ntchito haidrojeni ndipo chili ndi mbiri yabwino. Ngakhale kuti chithandizo cha kutentha pambuyo pa weld (PWHT) chikulimbikitsidwa kuti zitsulo za kaboni zichepetse hydrogen yotsala panthawi yowelda ndikuchepetsa kuuma kwa malo omwe akhudzidwa ndi kutentha (HAZ) pambuyo powelda, sichifunikira pazitsulo zosapanga dzimbiri za austenitic.
Zotsatira za kutentha kwa thupi zomwe zimachitika chifukwa cha kutentha ndi kuwotcherera sizikhudza kwambiri mphamvu za makina a zitsulo zosapanga dzimbiri za austenitic. Komabe, kugwira ntchito mozizira kumatha kusintha mphamvu za makina a zitsulo zosapanga dzimbiri za austenitic, monga mphamvu ndi kuuma. Popindika ndikupanga mapaipi kuchokera ku chitsulo chosapanga dzimbiri cha austenitic, mphamvu zawo zamakina zimasintha, kuphatikizapo kuchepa kwa pulasitiki ya zinthuzo.
Ngati chitsulo chosapanga dzimbiri cha austenitic chikufuna kupangidwa kozizira, kutenthetsa madzi (kutentha mpaka pafupifupi 1045°C kutsatiridwa ndi kuzimitsa kapena kuziziritsa mwachangu) kudzabwezeretsa mphamvu zamakina a chinthucho ku mtengo wake woyambirira. Zidzathetsanso kusiyana kwa alloy, sensitization ndi sigma gauge zomwe zimachitika pambuyo pa ntchito yozizira. Mukamachita kutenthetsa madzi, dziwani kuti kuziziritsa mwachangu kumatha kubwezeretsanso kupsinjika kotsalira mu chinthucho ngati sikugwiridwa bwino.
Onani matebulo a GR-2.1.1-1 Piping and Tubing Assembly Material Specification Index ndi GR-2.1.1-2 Piping Material Specification Index mu ASME B31 kuti mudziwe zinthu zoyenera kugwiritsa ntchito pa ntchito ya H2. Mapaipi ndi malo abwino oyambira.
Ndi kulemera kwa atomiki kokhazikika kwa mayunitsi 1.008 a atomiki (amu), haidrojeni ndiye chinthu chopepuka komanso chaching'ono kwambiri pa tebulo la periodic, motero chimakhala ndi chizolowezi chachikulu chotulutsa madzi, zomwe zingakhale ndi zotsatirapo zoopsa, ndingawonjezere. Chifukwa chake, dongosolo la mapaipi a gasi liyenera kupangidwa mwanjira yoti lichepetse kulumikizana kwa makina ndikukonza kulumikizana komwe kukufunikadi.
Pochepetsa malo omwe angatulukire, makinawo ayenera kukhala olumikizidwa mokwanira, kupatulapo maulumikizidwe olumikizana pazida, mapaipi ndi zolumikizira. Maulumikizidwe olumikizidwa ayenera kupewedwa momwe angathere, ngati si kwathunthu. Ngati maulumikizidwe olumikizidwa sangapewedwe pazifukwa zilizonse, tikukulimbikitsani kuti muwagwirizanitse mokwanira popanda chotseka ulusi kenako ndikutseka chosungunula. Mukagwiritsa ntchito chitoliro chachitsulo cha kaboni, malo olumikizira mapaipi ayenera kulumikizidwa bwino ndikutenthedwa pambuyo pa chosungunula (PWHT). Pambuyo pa chosungunula, mapaipi omwe ali mdera lokhudzidwa ndi kutentha (HAZ) amakumana ndi kuukira kwa haidrojeni ngakhale kutentha kozungulira. Ngakhale kuukira kwa haidrojeni kumachitika makamaka kutentha kwambiri, gawo la PWHT lidzachepetsa kwathunthu, ngati sichoncho, kuthekera kumeneku ngakhale pansi pa nyengo yozungulira.
Malo ofooka a dongosolo lolumikizidwa ndi flange ndi kulumikizana kwa flange. Kuti zitsimikizire kuti kulumikizana kwa flange kuli kolimba kwambiri, ma gasket a Kammprofile (chithunzi 4) kapena mtundu wina wa ma gasket ayenera kugwiritsidwa ntchito. Opangidwa mofanana ndi opanga angapo, phala ili ndi lokongola kwambiri. Lili ndi mphete zachitsulo zokhala ndi mano zomwe zimayikidwa pakati pa zinthu zofewa, zopindika. Mano amaika katundu wa bolt pamalo ang'onoang'ono kuti apereke kulimba kolimba popanda kupsinjika pang'ono. Lapangidwa mwanjira yoti lingathe kulipira malo osagwirizana a flange komanso kusintha kwa magwiridwe antchito.
Chithunzi 4. Ma gasket a Kammprofile ali ndi pakati pa chitsulo cholumikizidwa mbali zonse ziwiri ndi chodzaza chofewa.
Chinthu china chofunikira pa umphumphu wa dongosolo ndi valavu. Kutuluka kwa madzi kuzungulira chisindikizo cha tsinde ndi ma flange a thupi ndi vuto lenileni. Pofuna kupewa izi, tikukulimbikitsani kusankha valavu yokhala ndi chisindikizo cha bellows.
Gwiritsani ntchito chitoliro chachitsulo cha carbon cha mainchesi 1. Sukulu 80, mu chitsanzo chathu pansipa, poganizira zololera zopangira, dzimbiri ndi zololera zamakanika mogwirizana ndi ASTM A106 Gr B, kuthamanga kwakukulu kogwira ntchito (MAWP) kumatha kuwerengedwa m'magawo awiri kutentha mpaka 300°F (Zindikirani: Chifukwa cha "... kutentha mpaka 300ºF…" ndichifukwa chakuti kupsinjika kololedwa (S) kwa zinthu za ASTM A106 Gr B kumayamba kuwonongeka kutentha kukapitirira 300ºF. (S), kotero Equation (1) imafuna Sinthani kutentha pamwamba pa 300ºF.)
Ponena za fomula (1), gawo loyamba ndikuwerengera kuthamanga kwa mpweya wa m'mapaipi.
T = makulidwe a khoma la chitoliro kupatula kulekerera kwa makina, dzimbiri ndi kupanga, mu mainchesi.
Gawo lachiwiri la ndondomekoyi ndikuwerengera mphamvu yogwira ntchito yovomerezeka ya Pa ya payipi pogwiritsa ntchito chitetezo S f ku zotsatira P malinga ndi equation (2):
Chifukwa chake, mukagwiritsa ntchito zinthu za 1″ sukulu 80, kuthamanga kwa kuphulika kumawerengedwa motere:
Kenako, Sf ya chitetezo ya 4 imagwiritsidwa ntchito motsatira ASME Pressure Vessel Recommendations Section VIII-1 2019, Ndime 8. UG-101 yawerengedwa motere:
Mtengo wa MAWP womwe wapezeka ndi 810 psi. inchi umatanthauza chitoliro chokha. Kulumikizana kwa flange kapena gawo lomwe lili ndi mulingo wotsika kwambiri mu dongosololi ndi lomwe lidzatsimikizire kupanikizika kovomerezeka mu dongosololi.
Malinga ndi ASME B16.5, kuthamanga kwakukulu kovomerezeka kwa zida zolumikizira zitsulo za carbon steel flange za 150 ndi 285 psi. inchi pa -20°F mpaka 100°F. Gulu la 300 lili ndi kuthamanga kwakukulu kovomerezeka kwa 740 psi. Ichi chidzakhala chiŵerengero cha kuthamanga kwa makina malinga ndi chitsanzo cha zinthu zomwe zili pansipa. Komanso, mu mayeso a hydrostatic okha, mitengo iyi imatha kupitirira nthawi 1.5.
Monga chitsanzo cha mfundo zoyambira za chitsulo cha kaboni, mfundo za mzere wa ntchito ya gasi wa H2 zomwe zimagwira ntchito pa kutentha kozungulira pansi pa mphamvu ya kapangidwe ka 740 psi. inchi, zitha kukhala ndi zofunikira zazinthu zomwe zawonetsedwa mu Gome 2. Mitundu yotsatirayi ndi yomwe ingafunike chisamaliro kuti iphatikizidwe mu mfundozo:
Kupatula mapaipi okha, pali zinthu zambiri zomwe zimapanga makina opangira mapaipi monga zolumikizira, ma valve, zida zolumikizira, ndi zina zotero. Ngakhale zinthu zambirizi zidzaphatikizidwa pamodzi kuti zikambirane mwatsatanetsatane, izi zidzafunika masamba ambiri kuposa omwe angathe kusungidwa. Nkhaniyi.