Hauv Offshore Platform Hydraulic Systems Heating Fire-Resistant Fluids (95/5 Dej-Glycol) ntawm 80℃, Dab tsi Phab ntsa Thickness ntawm Titanium Tube tiv thaiv Pinhole Leaks Tom qab 10,000 Thermal Cycles?

Hauv cov chaw sab nrauv, hluav taws kub - cov kua dej tiv taus yog siv los txo qhov kev pheej hmoo ntawm hluav taws kub hauv siab - cov kab hydraulic siab. Cov kua dej no feem ntau muaj 95% dej thiab 5% glycol (ethylene lossis propylene). Cov kua dej no yog siv rau ntawm 80℃thiab raug rau kev caij tsheb kauj vab tsis tu ncua thaum lub twj tso kua mis hydraulic raug kaw thiab kaw thiab raws li qhov kub thiab txias hloov ntawm nruab hnub thiab hmo ntuj. Titanium Qib 2 raj yog siv rau hydraulic kua dej sov vim lawv corrosion kuj nyob rau hauv dej -glycol sib tov thiab siab zog rau qhov hnyav piv. Txawm li cas los xij, ib qho kev ua tsis tiav tshwj xeeb, thermal qaug zog tawg, ua rau lub qhov dej ntws tawm tom qab rov ua kom sov dua. Thermal qaug zog, tsis zoo li lub siab tawg los yog tsis zoo corrosion, ua rau microscopic kab nrib pleb tsim thiab loj hlob los ntawm lub raj phab ntsa yam tsis muaj kev ntsuas phab ntsa thinning. Kab lus no nthuav qhia qhov tsawg kawg nkaus ntawm phab ntsa tuab tsim nyog rau Qib 2 titanium raj kom tiv taus 10 000 thermal cycles ntawm 20℃(ambient) thiab 80℃(ua haujlwm) yam tsis muaj pinhole leaks, raws li kev ntsuas qaug zog thiab kev txheeb xyuas qhov kawg.

Hydro-Txoj kev qaug zog ntawm Tubes ntawm lub rhaub dej Hydraulic
Lub titanium rhaub tube nyob rau hauv lub hydraulic kua system yog raug rau cyclic thermal stresses tshwm sim los ntawm txawv expansion ntawm lub raj thiab ib puag ncig ib puag ncig. Thaum lub rhaub yog nyob rau, lub raj phab ntsa yog rhuab los ntawm 20℃mus rau 80℃(ΔT=60 degree). Sab hauv phab ntsa hauv kev sib cuag nrog cov khoom cua sov ua kom sov sai dua li cov phab ntsa sab nrauv hauv kev sib cuag nrog cov kua dej hydraulic. Kub gradients thoob plaws phab ntsa ua rau compressive stresses rau sab hauv phab ntsa thiab tensile stresses rau sab nraum phab ntsa. Lub voj voog ntawd thim rov qab thaum lub tshuab cua sov tua. Txhua lub voj voog kub induces strain amplitude ntawm lub raj phab ntsa.

Rau ib tug raug Qib 2 raj, 25 hli txheej txoj kab uas hla nrog 1.65 hli phab ntsa, lub thermal strain ib lub voj voog ntawm sab nrauv phab ntsa yog nyob nruab nrab ntawm 0.08 mus rau 0.12% (nyob ntawm seb cov cua kub npaum li cas thiab cov kua convection). Qhov no zoo hauv qab cov txiaj ntsig ntawm titanium (0.5-0.7%) yog li qhov deformation yog elastic. Tab sis txawm tias elastic cyclic kev nyuaj siab ua rau tsub zuj zuj ntawm qaug zog puas. Tom qab lub voj voog txaus, cov kab nrib pleb me me tshwm sim ntawm qhov chaw tsis zoo, suav nrog lossis thaj chaw muaj kev ntxhov siab (tube khoov, welds, raj ntawv txuas). Cov kab nrib pleb no txhim kho transgranularly thiab thaum kawg perforate phab ntsa los ua tus pinhole leak. Hydraulic kua xau los ntawm pinholes ua rau poob dej thiab siab.

Phab ntsa Thickness vs. Fatigue Life
Kev ntsuas ntsuas cua sov ntawm Qib 2 titanium raj (25 hli OD, ntau cov phab ntsa tuab) hauv dej -glycol (95/5) ntawm 80℃tau nthuav tawm nrog cov ntaub ntawv qaug zog. Cov raj tau rhuab los ntawm 20 mus rau 80℃nrog tus nqi ntawm 10℃/ min (zoo ib yam li hluav taws xob cua sov) thiab txias los ntawm 80 mus rau 20℃nrog tus nqi ntawm 5℃/ min (natural convection). Cov voj voog tau txuas ntxiv mus txog thaum pinhole xau pom los ntawm lub zog lwj.

Rau 1.0 hli phab ntsa tuab (BWG 18) lub neej qaug zog yog nyob rau hauv thaj tsam ntawm 2,000 txog 4,000 cycles. Kev ua tsis tiav yog nyob rau ntawm lub raj khoov thiab qhov chaw weld nyob rau hauv uas cov residual stresses concentrated lub cyclic strain. Pinhole leaks tshwm sim yam tsis muaj qhov pom tseeb thinning ntawm phab ntsa.

Rau 1.2 hli phab ntsa (BWG 16) lub neej qaug zog tau nce mus rau 4,000-7, 000. 8,000 cycles yam tsis muaj kev ua haujlwm, tab sis qhov tawg tau loj vim qhov sib txawv ntawm qhov sib txawv ntawm polishing thiab residual stress.

Lub neej qaug zog yog 8,000 txog 15,000 cycles rau 1.65 hli phab ntsa (BWG 14). Lub neej nruab nrab yog 11,000 cycles, zoo dua li 10,000-cycle aim. Kev ntxhov siab txo cov welds thiab cov leeg polished ua rau nws tshaj 15,000 lub voj voog.

Rau 2.0 hli phab ntsa, qaug zog lub neej muaj ntau dua 20,000 cycles thiab tsis muaj kev ua tsis tiav tau pom txog 25,000 cycles thaum kuaj. Cov phab ntsa tuab sib npaug sib npaug ntawm qhov sib npaug ntawm qhov sib npaug vim qhov ntsuas kub ntawm cov phab ntsa tuab yog qis dua rau tib qhov cua sov (kub diffusivity tsau, phab ntsa loj txhais tau tias me dua ΔT ib chav tsev tuab).

Kev qaug zog lub neej rau 2.5 hli phab ntsa yog ntau tshaj 30,000 cycles, zoo tshaj qhov yuav tsum tau ntawm cov offshore platforms.

Kev sib raug zoo ua raws li txoj cai lij choj lub zog: mus rau qhov tsis ua haujlwm ~ (phab ntsa thickness) ^ 1.8 txog 2.2. Kev nce phab ntsa thickness ntawm 1.0 hli mus rau 2.0 hli ua rau 3.5-4.5 quav nce hauv lub neej qaug zog.

Nto Finish thiab residual stress influence
Tab sis lub neej qaug zog tsis yog nyob ntawm phab ntsa tuab xwb; qhov chaw saum npoo thiab qhov kev ntxhov siab seem kuj ua lub luag haujlwm tseem ceeb. Kev ntsuam xyuas ntawm 1.65 hli phab ntsa thickness raj nrog sib txawv nto polish qhia:

Raws li -kos ( zeb tiav, Ra 1.6-2.5 µm) 8,000-11,000 cycles ( nruab nrab 9,500)

Pickled (Ra 0.8-1.2 µm): 9,000-13,000 cycles (qhov nruab nrab 10,500)

Polished (Ra.2-4 µm): 11,000-15,000 cycles (qhov nruab nrab 13,000)

Cov raj kho nrog tom qab-weld stress relief (540℃rau 1 teev hauv argon) muaj lub neej qaug zog 20-30% ntev dua li cov raj welded. Qhov kev ntxhov siab txo qis qhov seem tensile stresses ntawm welds los ntawm 150-200 MPa mus rau tsawg dua 50 MPa, tshem tawm cov chaw feem ntau rau qaug zog tawg pib.

Offshore Hydraulic Heater Tubes Daim Ntawv Thov Matrix
Thermal Cycle Requirement Tube Outside Diameter Pom Zoo Phab Ntsa Thickness Surface Finish Stress ReliefEstimated cycles to a pin-qhov to
25 hli 1.2 hli Pickled 5,000 cycles (nruab nrab 5 xyoo lub neej, 2-3 cycles / hnub) Tsis tas yuav 5000 txog 8000 cycles
10,000 cycles (10 xyoo tsim, 3 cycles / hnub) 25 mm 1.65 mm Polished Pom zoo rau welds 11,000-15,000 cycles
10,000 cycles (10 xyoo tsim) 25 mm 2.0 mm Pickled Tsis tsim nyog 15,000-20,000 cycles
20,000 cycles (20 xyoo lub neej) 25 mm 2.0 mm Polished Yuav tsum tau rau tag nrho cov welds 20,000-25,000 cycles
20,000 cycles (lub neej ntawm 20 xyoo) 25 mm 2.5 mm Raws li kos Tsis xav tau 25,000-30,000 cycles
High vibration platform (ntxiv rau txhua yam kev nyuaj siab cyclic) Ntxiv 0.5 hli mus rau saum toj no Txhua Polished Yuav Tsum Tau Txo cov kev xav tau los ntawm 20-30%
Cov lus pom zoo rau 10,000-Cycle Service
Qhov tsim kom muaj cua sov 95/5 dej-glycol hluav taws kub resistant kua ntawm 80oC rau offshore platform hydraulic systems yog 10,000 thermal cycles (txog 10 xyoo ntawm 3 cycles ib hnub twg). Rau Qib 2 titanium raj, polished nto tiav thiab kev ntxhov siab welds, qhov tsawg kawg nkaus phab ntsa thickness yog 1.65 hli (BWG 14). Xwb, 2.0 hli phab ntsa pickled tiav yam tsis muaj kev ntxhov siab nyem muab qhov sib npaug lossis zoo dua lub neej qaug zog. Pom zoo specification:

Khoom siv: ASTM B338 Seamless Tube, Titanium Qib 2

Phab ntsa thickness: min . 1,65 mm (BWG 14)

Sab nraud txoj kab uas hla: 25 mm (los yog raws li xav tau rau lub rhaub tsim)

Nto tiav: Polished Ra 0.4 µm max (sab hauv thiab sab nraud)

Welds (yog tias muaj): Tag nrho kev nkag mus GTAW nrog kev ntxhov siab tso tawm ntawm 540℃rau 1 teev

Tube khoov: Min khoov vojvoog 3x OD, mandrel khoov kom tiv thaiv tsis muaj zog ntawm phab ntsa

Rau kev txhim kho tshiab uas qhov hnyav tsis muaj kev txhawj xeeb, 2.0 hli phab ntsa muab qee cov npoo ntxiv thiab tshem tawm qhov yuav tsum tau ua rau kev ntxhov siab, uas ua rau nws yooj yim rau kev tsim khoom. Yog hais tias tus pinhole leaks tshwm sim ntawm cov cua sov tam sim no tom qab 5,000-7,000 cycles, ib qho kev hloov ncaj qha rau 1.2 hli lossis 1.65 hli raws li -cov raj yog 1.65 hli polished raj nrog kev ntxhov siab welds.

Rau cov tshuab hydraulic nrog ntau tshaj 3 cycles / hnub (xws li platforms nrog ceev twj tso kua mis cycling rau siab tswj) nce phab ntsa thickness raws li: rau 5 cycles / hnub (18,000 cycles tshaj 10 xyoo) qhia 2.0 hli phab ntsa yam tsawg kawg nkaus. Xav tau cov ntaub ntawv ntawm qhov chaw tiav (Ra ntsuas) thaum yuav khoom. Yuav tsum tau ntawv pov thawj ntawm kev ntxhov siab annealing nrog lub sijhawm- daim ntawv ntsuas kub rau cov khoom welded. Nrog rau txoj cai phab ntsa thickness thiab deg mob, qib 2 titanium tubing yuav ciaj sia 10,000 thermal voj voog yam tsis muaj pinhole leaks nyob rau hauv offshore platform hydraulic rhaub kev pab cuam.