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Basic Common Sense Rules for Safe and EffectiveCryogenic MaintenanceFEBRUARY 19, 2013

By Keith Hall 

• Never use carbon steel wire brushes or carbon steel wirewheels to clean stainless steel! an" never use

a stainless steel wire brush or a stainless steel wirewheel, or a scotchbrite #a", on stainless steel i$ it

was #reviousl% use" to clean carbon steel&

• Never cut or 'rin" ne(t to a #ainte" sur$ace& )he hot *etal will e*be" into the #aint an" rust s#ecs will

a##ear&

• Never s#ra% #aint ne(t to another tan+ or vehicle, an" never #aint in the win", col", or rain& hen

#aintin' beware o$ overs#ra%&

• )o #revent subse-uent rustin', the insi"e o$ an% hole "rille" in carbon steel *ust be #ri*e" an" or 

#ainte" be$ore installin' a bolt, screw, or rivet&

• Never "rill holes in the to# or botto* $lan'es o$ a truc+ chassis. $ra*e rail& /oles *a% onl% be "rille" in

the si"es o$ the $ra*e rail& Avoi" ali'n*ent o$ holes or too *an% holes in one area&

• Never wel" on a tractor chassis $ra*e rail&

• Be$ore wel"in' a co*#onent on a vehicle, or on a trailer with a #on% en'ine, alwa%s "isconnect the

batter% or cla*# an electronic #rotection "evice to the batter%& You *a% ruin the en'ine.s electronic

control *o"ule i$ %ou "o not "o this&

• Never wel" on the outer ac+et o$ a cr%o'enic tan+ un"er vacuu* as %ou can easil% *elt throu'h an"

ruin the vacuu*& /u*i" air enterin' the annulus *a+es the subse-uent evacuation o#eration "i$$icult&

• Be$ore wel"in', alwa%s veri$% the correct wel" #roce"ure to be use", as #er the en'ineerin'& Alwa%s

veri$% that %ou are usin' the correct wel" wire an" shiel"in' 'as an" are $ollowin' the correct wel"

#roce"ure&

• hen wel"in', be care$ul o$ $ans or o#en "oors that *a% blow the shiel"in' 'as awa% $ro* the *olten

wel" #u""le the sa*e $or heliu* when lea+ chec+in'&

• nce an% co*#onent, #i#e, or tan+ has been o(%'en cleane", it *ust sta% #ro#erl% #rotecte" or 

covere" while %ou are wor+in' on it, an" covere" whenever %ou are not& 4arts that have been o(%'en

cleane" $or $uture use *ust be seale" in a #lastic ba'& 567 8leane", b% who*, the "ate, an"

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the :ualit% 8ontrol ins#ector.s si'nature an" "ate *ust be written on the ba'& Follow the in"ustr%

stan"ar"s an" %our co*#an%.s o(%'en cleanin' #roce"ures& ;ee# %our han"s an" tools clean&

• )here *ust be a #ressure relie$ valve installe" between an% valves or chec+ valves where li-ui" coul"

be tra##e"&

• Never o#erate e-ui#*ent %ou have not been traine" on or authori<e" to use&

• Never enter a con$ine" s#ace without $ollowin' all %our co*#an%.s sa$et% #roce"ures air test, air 

ventilation, hole watch, entr% #er*it, etc&&

• Never use carbon steel blac+ #i#e, 'alvani<e" #i#e, or #lastic #i#e or tubin', etc&, $or cr%o'enic service

it will e*brittle an" catastro#hicall% $ail& Use onl% stainless steel, alu*inu*, brass, or bron<e

allo%s, rate" $or the e(tre*el% low use te*#eratures an" wor+in' #ressure as "esi'nate" b% en'ineerin'&

• Never use a $ittin', valve, hose, etc&, that is not rate" $or the o#eratin' #ressure an" te*#erature&

• Never a"a#t 8=A $ittin's or connections&

• >t is the in"ustr% stan"ar" that the interior o$ all cr%o'enic tan+s, #i#in', an" #ressure buil"in' coils, no

*atter the inten"e" 'as service, be o(%'en cleane"& )an+s, #i#in', an" #ressure buil"in' coils inten"e"

$or o(%'en service *ust also be ins#ecte" $or o(%'en service& All *aterials use" in o(%'en service *ust

be 5o(%'en co*#atible, o(%'en cleane" an" o(%'en ins#ecte"&

• Alwa%s wear #ro#er sa$et% #ersonal #rotection e-ui#*ent when wor+in' aroun" cr%o'ens i&e& $ace

shiel", 'loves, lon' sleeves, ear #lu's, etc&&

• All shar# corners or e"'es on *etal obects %ou $abricate shoul" be 'roun" roun" or s*ooth&

• Never $ill or a"" en'ine oil or h%"raulic $lui" to an% e-ui#*ent without *a+in' sure %ou have the correct

oil $or the a##lication or custo*er re-uire*ent&

• Never 5s#in, 5bu*#, or o#erate a cr%o'enic #u*# "r% or without 'ivin' it su$$icient ti*e to #ro#erl% cool

"own with li-ui"& )he 'eneral rule o$ thu*b is seven *inutes $or a #u*# ? an" s*aller! 12 *inutes $or a

10 #u*#&

• )o #revent 'allin' when a stainless steel co*#onent is threa"e" into another stainless steel co*#onent

or alu*inu* into alu*inu*, a##l% a thin coat o$ li-ui" o(%'en co*#atible 'rease to the threa"s

be$ore installin' note@it is ver% e(#ensive@use s#arin'l%& For e(a*#le, a##l% to stainless steel bolts

bein' threa"e" into a stainless steel valve bo"%&

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• hen runnin' electrical #ower to electronic "evices i&e& $low *eters, totali<ers, =4, *o"e*s, etc& "o

not tie into trailer li'htin' circuits& Electronic "evices shoul" be #owere" on their own #ower su##l% circuit

with an easil% accessible $use or brea+er&

• hen #re#arin' $or, an" #er$or*in' a #neu*atic or h%"ro #ressure test, "o not insert #lu's into theoutlet #orts o$ the #ressure relie$ valves on a tan+ or #i#in' circuit& >nstea", screw a sa$et% relie$ valve,

with a sli'htl% hi'her #ressure relie$ ratin' than the test #ressure, into the outlet #ort o$ the e(istin' relie$ 

valves on the tan+ or #i#in' circuit& )he test shoul" never be le$t unatten"e" until vente" an" the hi'her 

rate" relie$ "evices re*ove" Coreover, never #er$or* a #ressure test without $irst chec+in' the

en'ineerin' calculations "ocu*ent to be assure" o$ the correct test #ressure&

• 6a""ers *ust be #ro#erl% tie"o$$ be$ore %ou ascen"& )ie the base o$ the la""er so that it cannot sli#&

You *ust wear a harness an" tieo$$, in accor"ance with co*#an% tieo$$ #roce"ures, when not wor+in'

at 'roun" level&

• >nstall cr%o'enic valves so that the $low "irection is #er the en'ineerin' #i#in' sche*atic& Note@a 'lobe

valve 'enerall% shoul" be oriente" so that the col" li-ui" is hel" below the seat when close" an" not

on the u##er or ste*D#ac+in' si"e o$ the valve& =enerall% a 'ate valve is oriente" so that when close",

the u#strea* #ressure #ushes a'ainst its seatin' sur$ace&

• An% ball valve use" in cr%o'enic service *ust have a s*all vent or wee# hole "rille" into the internal ball

itsel$, or be o$ another vente" "esi'n, e&'& vente" $lan'e #iece& )he ball valve *ust be oriente" so that the

"irection o$ $low #er*its li-ui" tra##e" insi"e the ball to be vente" when the ball is close", either bac+ into

the tan+ i$ there is no chec+ valve in the line, or to vent "ownstrea*&

• An% valve use" $or cr%o'enic li-ui" service shoul" never be *ounte" with the ste* e(ten"in' lower than

30 "e'rees above the hori<ontal #lane& alves use" $or va#or service are 'enerall% never *ounte"

with their ste*s oriente" *ore than 30 "e'rees below the hori<ontal #lane&

• hen ti'htenin' a lea+in' #ac+in' on a valve, ti'hten onl% enou'h to sto# the lea+, an" no *ore& )hen

veri$% that the valve can still turn nor*all%&

• hen o#enin' a 'ate or 'lobe valve in cr%o'enic service, $ull% o#en the valve, then close it a $raction o$ 

a turn& )his #revents the valve $ro* $ree<in' in the o#en #osition, *a+in' it easier $or %ou to close when

it is col"&

• Never "rive over hoses or e(tension cor"s with $or+ li$ts or other sho# e-ui#*ent&

• n *obile e-ui#*ent, or on e-ui#*ent subect to vibration, #rotect hoses an" wirin' that coul" rub an"

cha$$ b% wra##in' an" securin' with s#lit loo* an" or rubber& ecure e-ui#*ent $ro* win" an"

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other *ove*ent with loo* cla*#s, tau$$ cla*#s, etc& Avoi" the overuse o$ <i# ties the% "e'ra"e in

ultraviolet sunli'ht an" can brea+ in the col"&

• hen runnin' an au(iliar% #neu*atic "evice o$$ a truc+.s, tractor.s, or trailer.s air s%ste*, i&e& $or electro

#neu*atic valves, alwa%s install a #ressure #rotection valve 44 on %our su##l% air line at the air tan+& houl" an au(iliar% air line ever brea+ the 44 will close i$ the air tan+ #ressure "ro#s below a set

#oint e&'& G #si&

• )horou'hl% #ur'e hoses an" lines be$ore connectin' the*& )he #ur'e #roce"ure will #revent "ebris or 

hu*i" air $ro* 'oin' into a cr%o'enic vessel& )he #ur'e also hel#s #recool the hose&

• a$et% relie$ valves shoul" be oriente" so that the en'rave" label can be easil% rea"&

• )he e(it si"e non#ressuri<e" o$ the vent #i#in' on a cr%o'enic tan+, inclu"in' the vent #i#in' $ro*

relie$ valves, *ust have a wee# hole at the lowest #oint $or con"ense" water to "rain&