Norma ASME B31.3 se vztahuje na n\u00e1vrh, v\u00fdstavbu, kontrolu a \u00fadr\u017ebu procesn\u00edch potrubn\u00edch syst\u00e9m\u016f pou\u017e\u00edvan\u00fdch k p\u0159eprav\u011b chemik\u00e1li\u00ed, ropy nebo plynu v pr\u016fmyslov\u00fdch odv\u011btv\u00edch. Tyto potrubn\u00ed syst\u00e9my mohou zahrnovat kotle nebo v\u00fdm\u011bn\u00edky tepla.<\/p>\n
Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) sni\u017euje pravd\u011bpodobnost vzniku k\u0159ehk\u00e9ho lomu u sva\u0159ovan\u00fdch ocelov\u00fdch d\u00edl\u016f a je vy\u017eadov\u00e1no podle ustanoven\u00ed 331.1.1 a tabulky 331.1.1.<\/p>\n
Postupy pou\u017e\u00edvan\u00e9 p\u0159i sva\u0159ov\u00e1n\u00ed trubek podl\u00e9haj\u00ed r\u016fzn\u00fdm norm\u00e1m, kter\u00e9 p\u0159edepisuj\u00ed jejich n\u00e1vrh podle konkr\u00e9tn\u00edch po\u017eadavk\u016f. Ka\u017ed\u00fd postup p\u0159edlo\u017een\u00fd k schv\u00e1len\u00ed technikem pro sva\u0159ovac\u00ed postupy mus\u00ed b\u00fdt posouzen, aby se ov\u011b\u0159ilo, zda spl\u0148uje v\u0161echna nezbytn\u00e1 krit\u00e9ria; na z\u00e1klad\u011b sv\u00e9ho odborn\u00e9ho \u00fasudku m\u016f\u017ee technik ur\u010dit, zda bude dan\u00fd postup p\u0159i re\u00e1ln\u00fdch sva\u0159ovac\u00edch \u00fakolech fungovat efektivn\u011b.<\/p>\n
Sva\u0159ovac\u00ed postupy slou\u017e\u00ed jako n\u00e1vody, kter\u00e9 sva\u0159ovac\u00edm technik\u016fm pom\u00e1haj\u00ed p\u0159i prov\u00e1d\u011bn\u00ed dan\u00e9 pr\u00e1ce. Tyto dokumenty popisuj\u00ed sva\u0159ovac\u00ed proces, po\u017eadovan\u00e9 parametry a specifick\u00e9 vlastnosti sva\u0159ovan\u00e9ho spoje \u2013 jedn\u00e1 se o dokumenty nezbytn\u00e9 pro zaji\u0161t\u011bn\u00ed vysok\u00e9 kvality svar\u016f vznikl\u00fdch p\u0159i sva\u0159ovac\u00edch operac\u00edch. Spolu se specifikacemi postup\u016f a z\u00e1znamy o kvalifikaci pro sva\u0159ov\u00e1n\u00ed (WPQR) tvo\u0159\u00ed z\u00e1klad pro kvalitn\u00ed sva\u0159ovan\u00e9 spoje.<\/p>\n
PWHT spo\u010d\u00edv\u00e1 v oh\u0159evu trubky na nastavitelnou teplotu po libovoln\u011b dlouhou dobu. P\u0159esn\u00e1 doba a teplota mohou z\u00e1viset na typu materi\u00e1lu a tlou\u0161\u0165ce trubky. P\u0159ed ochlazen\u00edm je v\u0161ak nutn\u00e9 trubku izolovat, aby se svary chr\u00e1nily p\u0159ed nadm\u011brn\u00fdmi tepeln\u00fdmi ztr\u00e1tami b\u011bhem ochlazov\u00e1n\u00ed.<\/p>\n
WPQR mus\u00ed obsahovat \u00fadaje o ka\u017ed\u00e9m svaru: \u010d\u00edslo svaru, polohu, typ dr\u00e1\u017eky a typ elektrody, jako\u017e i \u00faplnou specifikaci materi\u00e1lu a \u00fadaje o jakosti ka\u017ed\u00e9ho druhu materi\u00e1lu pou\u017eit\u00e9ho p\u0159i sva\u0159ov\u00e1n\u00ed. Krom\u011b toho mus\u00ed b\u00fdt v souladu s p\u0159\u00edslu\u0161n\u00fdmi normami uvedeny tak\u00e9 teploty p\u0159edeh\u0159evu a teploty mezi jednotliv\u00fdmi vrstvami.<\/p>\n
Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) je \u0159\u00edzen\u00fd proces, p\u0159i kter\u00e9m se materi\u00e1ly sva\u0159en\u00e9 b\u011bhem sva\u0159ov\u00e1n\u00ed zah\u0159\u00edvaj\u00ed na teplotu ni\u017e\u0161\u00ed ne\u017e jejich doln\u00ed kritick\u00e1 teplota transformace a v t\u00e9to teplot\u011b se udr\u017euj\u00ed po stanovenou dobu. PWHT slou\u017e\u00ed k odstran\u011bn\u00ed zbytkov\u00fdch nap\u011bt\u00ed a zm\u011bn mikrostruktury; vy\u017eaduj\u00ed ji v\u011bt\u0161ina norem, v\u010detn\u011b ASME sekce VIII divize 1; mezi jednotliv\u00fdmi normami v\u0161ak mohou existovat zna\u010dn\u00e9 rozd\u00edly, pokud jde o jej\u00ed po\u017eadavky.<\/p>\n
Rozd\u00edly v po\u017eadavc\u00edch vypl\u00fdvaj\u00ed p\u0159ev\u00e1\u017en\u011b z provozn\u00edch podm\u00ednek, na kter\u00e9 se jednotliv\u00e9 normy vztahuj\u00ed. Zat\u00edmco drobn\u00e9 odchylky nemus\u00ed b\u00fdt d\u016fvodem k velk\u00fdm obav\u00e1m, v\u00fdrazn\u00e9 rozd\u00edly by mohly potenci\u00e1ln\u011b vyvolat v\u00e1\u017en\u00e9 bezpe\u010dnostn\u00ed obavy. Nap\u0159\u00edklad nep\u0159im\u011b\u0159en\u00fd po\u017eadavek na tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) p\u0159i teplot\u011b 1100 \u00b0F by mohl v\u00e9st ke sn\u00ed\u017een\u00ed tvrdosti a hou\u017eevnatosti, zat\u00edmco teplota 1200 \u00b0F by vedla k podobn\u00fdm v\u00fdsledk\u016fm.<\/p>\n
Potrubn\u00ed syst\u00e9my jsou vystaveny n\u00e1ro\u010dn\u00fdm vliv\u016fm prost\u0159ed\u00ed i provozn\u00edm nam\u00e1h\u00e1n\u00edm. Aby byla zaji\u0161t\u011bna jejich bezpe\u010dnost a \u00fa\u010dinnost, mus\u00ed je in\u017een\u00fd\u0159i a dodavatel\u00e9 navrhovat s ohledem na vhodn\u00fd v\u00fdb\u011br materi\u00e1l\u016f, sva\u0159ovac\u00ed techniky a kontroln\u00ed postupy, a nav\u00edc je podrobit d\u016fkladn\u00fdm zkou\u0161k\u00e1m. Norma ASME B31.3 poskytuje ide\u00e1ln\u00ed r\u00e1mec pro hodnocen\u00ed t\u011bchto z\u00e1t\u011b\u017e\u00ed a spln\u011bn\u00ed v\u0161ech nezbytn\u00fdch po\u017eadavk\u016f \u2013 in\u017een\u00fd\u0159i i dodavatel\u00e9 mohou vyu\u017e\u00edt znalosti t\u00e9to normy k navrhov\u00e1n\u00ed bezpe\u010dn\u011bj\u0161\u00edch syst\u00e9m\u016f s vy\u0161\u0161\u00edm v\u00fdkonem, kter\u00e9 z\u00e1rove\u0148 spl\u0148uj\u00ed v\u0161echny p\u0159\u00edslu\u0161n\u00e9 bezpe\u010dnostn\u00ed normy.<\/p>\n
ASME B31.3 je pr\u016fmyslov\u00fd standard, kter\u00fd stanovuje pokyny pro n\u00e1vrh, v\u00fdstavbu, kontrolu, provoz, zkou\u0161en\u00ed a \u00fadr\u017ebu potrubn\u00edch syst\u00e9m\u016f. C\u00edlem t\u011bchto p\u0159edpis\u016f je zajistit bezpe\u010dnost t\u011bchto syst\u00e9m\u016f pro u\u017eivatele a jejich odolnost v\u016f\u010di environment\u00e1ln\u00edm a mechanick\u00fdm nam\u00e1h\u00e1n\u00edm. Obsahuj\u00ed podrobn\u00e9 pokyny t\u00fdkaj\u00edc\u00ed se sva\u0159ovac\u00edch technik pou\u017e\u00edvan\u00fdch p\u0159i v\u00fdstavb\u011b t\u011bchto syst\u00e9m\u016f, jako\u017e i postup\u016f, kter\u00e9 je t\u0159eba dodr\u017eovat p\u0159i zkou\u0161k\u00e1ch a \u00fadr\u017eb\u011b.<\/p>\n
Dodr\u017eov\u00e1n\u00ed normy ASME B31.3 vy\u017eaduje d\u016fraz na bezpe\u010dnost, d\u016fkladn\u00e9 pl\u00e1nov\u00e1n\u00ed a kontrolu kvality v ka\u017ed\u00e9 f\u00e1zi v\u00fdroby, aby se p\u0159ede\u0161lo nehod\u00e1m a z\u00e1rove\u0148 byly spln\u011bny po\u017eadovan\u00e9 normy kvality a v\u00fdkonu. Tato norma je obzvl\u00e1\u0161t\u011b d\u016fle\u017eit\u00e1 v pr\u016fmyslov\u00fdch procesech, p\u0159i nich\u017e se pracuje s nebezpe\u010dn\u00fdmi l\u00e1tkami.<\/p>\n
Norma ASME B31.3 m\u016f\u017ee pomoci p\u0159i pln\u011bn\u00ed po\u017eadavk\u016f na instalaci energetick\u00fdch i technologick\u00fdch potrubn\u00edch syst\u00e9m\u016f a z\u00e1rove\u0148 poskytuje pokyny pro bezpe\u010dnou manipulaci s vysokotlak\u00fdmi syst\u00e9my, kter\u00e9 by p\u0159i nespr\u00e1vn\u00e9m zach\u00e1zen\u00ed mohly p\u0159edstavovat nebezpe\u010d\u00ed.<\/p>\n
Vyd\u00e1n\u00ed normy ASME B31.3 z roku 2014 bylo revidov\u00e1no s c\u00edlem zahrnout nov\u00e9 po\u017eadavky na tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT), up\u0159esnit sva\u0159ovac\u00ed postupy, aktualizovat z\u00e1kladn\u00ed p\u0159\u00edpustn\u00e1 nap\u011bt\u00ed a doplnit dal\u0161\u00ed uveden\u00e9 materi\u00e1ly. Krom\u011b toho nesm\u00ed svary na n\u00edzkolegovan\u00fdch ocel\u00edch obsahovat v\u00edce ne\u017e 1,5% Cr a 0,5% Mo a u svar\u016f z nerezov\u00e9 oceli 2,0% Ni; tato zm\u011bna byla zavedena s c\u00edlem sn\u00ed\u017eit riziko k\u0159ehk\u00e9ho lomu u t\u011bchto typ\u016f ocel\u00ed \u2013 jedn\u00e1 se o bezprecedentn\u00ed v\u00fdvoj, kter\u00fd ovlivn\u00ed zp\u016fsob, jak\u00fdm budeme v budoucnu pracovat na projektech tohoto druhu.<\/p>\n
Tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) uhl\u00edkov\u00e9 oceli pom\u00e1h\u00e1 sn\u00ed\u017eit zbytkov\u00e1 nap\u011bt\u00ed v oblastech svar\u016f, a t\u00edm v\u00fdrazn\u011b sn\u00ed\u017eit riziko prask\u00e1n\u00ed pod vlivem vn\u011bj\u0161\u00edho prost\u0159ed\u00ed, co\u017e \u010din\u00ed z PWHT nezbytn\u00fd krok p\u0159i sva\u0159ov\u00e1n\u00ed sestav z uhl\u00edkov\u00e9 oceli. Po\u017eadavky na PWHT z\u00e1vis\u00ed na norm\u011b a typu materi\u00e1lu; u n\u011bkter\u00fdch svar\u016f nemus\u00ed b\u00fdt PWHT nutn\u00e9, pokud tlou\u0161\u0165ka svaru nep\u0159esahuje maxim\u00e1ln\u00ed mezn\u00ed hodnotu uvedenou v tabulce 331.1.1.<\/p>\n
PWHT nejen\u017ee sni\u017euje riziko prask\u00e1n\u00ed zp\u016fsoben\u00e9ho vlivem okoln\u00edho prost\u0159ed\u00ed, ale tak\u00e9 posiluje a zvy\u0161uje hou\u017eevnatost svarov\u00fdch oblast\u00ed \u2013 jedn\u00e1 se o nepostradateln\u00fd proces pro jak\u00e9koli potrub\u00ed \u010di tlakovou n\u00e1dobu, kter\u00e1 je vystavena drsn\u00fdm podm\u00ednk\u00e1m okoln\u00edho prost\u0159ed\u00ed. Nav\u00edc je jeho prov\u00e1d\u011bn\u00ed relativn\u011b jednoduch\u00e9 a ekonomick\u00e9.<\/p>\n
Zpr\u00e1va EPRI (odkaz 1) doporu\u010dila sn\u00ed\u017eit teploty p\u0159i dodate\u010dn\u00e9m tepeln\u00e9m zpracov\u00e1n\u00ed (PWHT), av\u0161ak sou\u010dasn\u00e9 normy B31.1 a B31.3 stanovuj\u00ed maxim\u00e1ln\u00ed teplotu PWHT, kter\u00e1 je pro tento \u00fa\u010del p\u0159\u00edli\u0161 vysok\u00e1. Jej\u00ed sn\u00ed\u017een\u00edm pod doln\u00ed kritickou teplotu pro materi\u00e1ly t\u0159\u00eddy P \u010d. 4 by bylo mo\u017en\u00e9 vytvo\u0159it dodate\u010dnou rezervu.<\/p>\n
Po\u017eadavky na tepeln\u00e9 zpracov\u00e1n\u00ed po sva\u0159ov\u00e1n\u00ed (PWHT) u potrub\u00ed a tlakov\u00fdch n\u00e1dob jsou stanoveny p\u0159\u00edslu\u0161n\u00fdmi p\u0159edpisy a normami, kter\u00e9 obvykle vych\u00e1zej\u00ed z n\u00e1rodn\u00edch \u010di mezin\u00e1rodn\u00edch centr\u00e1ln\u00edch certifika\u010dn\u00edch program\u016f, jako je nap\u0159\u00edklad ASNT Central Certification Program (ACCP). Aby z\u00edskal certifikaci v r\u00e1mci t\u011bchto program\u016f, mus\u00ed technik NDT absolvovat komplexn\u00ed zkou\u0161ku, kter\u00e1 m\u016f\u017ee zahrnovat radiografick\u00e9\/neradiografick\u00e9 zkou\u0161ky, kontrolu magnetick\u00fdmi \u010d\u00e1sticemi, ultrazvukov\u00e9 zkou\u0161ky nebo jakoukoli jejich kombinaci.<\/p>","protected":false},"excerpt":{"rendered":"
ASME B31.3 covers the design, construction, inspection and maintenance of process piping systems used for transporting chemicals, oil or gas within industries. These piping systems may include boilers or heat exchangers. Post weld heat treatment (PWHT) reduces the likelihood of brittle fracture in welded steel components and is required as specified by Clause 331.1.1 and … <\/p>\n