Chuyn i dn v N/mm2 =145,0377 PSImmHg=0,019 PSIKg/cm2=0,098
N/mm21at=14,696 PSI1m=39,37 inchTnh chu p sut trong theo ASME Bc 1
Xc nh p sut tnh ton p, psi:= (chuyn sang PSI) Bn knh trong Rt ,in :
ng sut cho php Sy , psi : Trong : S: ng sut cho php tiu chun, psi
E: h s hiu chnhTra Sy ca vt liu theo nhit lm vic t t Table Y 1 in
ASME 2013, Section II, Part D ( trang 567 749) Dng thp SUS304 ( bng
tra ) v tr s 11
Bc 2 Chn trc gi tr b dy t, in. Dung sai cho php UT
(undertolerance allowance), in: UT = t. UTP ( thng ly UTP = 12,5% )
B dy danh ngha c iu chnh theo dung sai cho php v n mn ta, in: Vi C
l h s n mn C, in T (gi tr mnh chn trn)Bn knh trong ( tnh n mn), in
: Bc 3 B dy ti thiu theo chiu dc thn tr:
B dy theo phng bn knh thn tr:
Chn gii tr t ln hn => b dy yu cu tr = tmax Nu tr < ta :
chp nhn t chn ban u Nu tr > ta : chn li t n khi thu c tr < ta
Bc 4 iu kin theo chiu dc thn tr:(t so vi gi tr tr tnh ra c) iu kin
theo phng bn knh thn tr: (t so vi gi tr tr tnh ra c)
Tnh chu p sut ngoi theo ASMEChn trc t theo tiu chun tm thpTrng
hp: Do/t 10 Bc 1: Lp t s: L/Do v Do/t Bc 2:T th ta suy ra c h s A
(794) ( bng tra A )
Bc 3:T h s A, s dng cc gin tip theo trong Section 2-D, subpart 3
(Figure) tra h s B (bng tra B)
Bc 4:Tnh: ng vi h s A ri vo vng tri gin : ng vi h s A ri vo vng
phi gin : Bc 5: So snh cc gi tr Pa trn vi P. Nu Pa nh hn P th chn
mt gi tr t ln hn ri lp li cc bc tnh ton cho ti khi P P a H s A: c
quyt nh t Figure G subpart 3 ca Section 2, part D v c s dng vo bng
vt liu trong subpart 3, Section 2, part D trong trng hp Do/t <
10 xem (c)(2) trang 786 . H s B: c xc nh t bng material trong
subpart 3 ca Section 2, part D cho nhit kim loi (UG-20(c)) Do : ng
knh ngoi ca v tr E : h s n hi ca vt liu ti nhit thit k L : di tng
cng ( UG-28.1 figure) P : p sut ngoi thit k Pa : gi tr tnh ton p
sut ngoi lm vic ti a vi cc gi tr gi nh ca t t : b dy ti thiu. (mm)
R0 : bn knh ngoi (mm)Trng hp: Do/t 0.1 th xem nh A=0.1 Bc 2: S dng
B bc 1 tnh: Bc 3: Tnh: = Vi: S = 0.9B v c tra theo ng cong nhit khi
tm gi tr B tng ng Bc 4: So snh 2 gi tr Pa1 v Pa2 ,gi tr no nh hn th
c dng nh Pa . So snh cc gi tr Pa trn vi P. Nu Pa nh hn P th chn mt
gi tr t ln hn ri lp li cc bc tnh ton cho ti khi Pa P
