Note: Descriptions are shown in the official language in which they were submitted.
WO 93/08012 -1 - 21 16 7 8 !1 PCT/GB92/01937
Descri~tion
This in~en~ion relat~s to a hea~ recoverable wraparound art~cle
r for bond~g to aIl ob~ect such as a pipe, eg to seal agains~ in~ess of
wate~ ~o protect aga~st p~ysical dam~ge or to make a ~oint between
the ob~ect and aDother ob~ec~. In par~icular. ~che in~e~tion relates to :;
a wraparolmd art~cle ~cluding heatiI~g meaIls along at leas~ o~e
long~ al edge and alc)ng t~e circu~feren~al edges as considered
in the wrapp~d con~gura~o~.
A wrapar~und ~cle includ~g hea~g means along 'chree
edge~ is known from D~:-A-3712356. This descr~bes a sheet of ~;
thermoplastic material for covering a ~o~nt between plas~c pipes in
which the sheet is pr~ided w~th at least two parallel heating wires
on three edg~ r~gion~. The ar~cle is not heat recovera~le.
.
A heat-reco~rera~le a~a~le is one whose d~erlsio~l
c~n~tion can be made to cha~ge substantlally when sub~ected to
heat tre~tmen~. A he~t-reco~e~able ar~cle will usually reco~rer
towards an orig~al shape from ~vhich it has previously been
: ~ ~ deformed but the term as used herein also ineludes ar~cles w~ch
adopt a new conflguration when su~ected to heat treatment, e~en if
it has not pr~viou~ly been deformed.
.
HLeat-recoYerable ~cles are well }m~wn ~nd may be used ~n
t~e se~g o pipe ~oints. the repair of polymeric coatings on pipes
arld s~m~lar structures. the protection f~om chemical ~d physical
at~ack of pipes and ot~er s~ucb~res. o~ten metaLlic. Th~y IIlay also be
used to ~eal cable splices.
When a ~oint ~5 made between two leng~hs of ther~ly
insula~ed steel pipe. a~ used for e~ca~ple ~n a district he~ffng system.
the insula~ion is remaved (~plcally In the factory) from the end
.: .
Wo 93/08012 PCI/GW2/01937
-2-
regions o~6~ng~ of pipe in order that the insulation is not burnt
when the pipes are ~oined. for example by welding. After the weld
has been comple~ed. the ~aninsul~ted portion of the pipe in the
region of the joint must be reinsulated in order to minimise heat loss.
It ~s important ~ha~ the insulation in $he re~ion of the ~oint is sealed
against mois~ure ~ngress which migh~ otherwise eause degradation of
the insu~a~don. not only ~n the 3O~nt region but possibly also along the
plpes to ~ome dl~tance f~om the ~oint. arld cause also corro~on of the
pipe~.
. .
Severe physical c~rlstraint$ are placed upon the seal of t~e
insul~ at a ~o~ betwee~ Insulated pipes in a distr;lct heaffng
~y~tem. As a result of i~equent and w~de temperature cy~ng, the
plpe c~ be sub~ected to ~x:p~ion and con~as~on cydes and to
lo~ ud~al and transv~se m=en~s. For example~ lt ha~ been
determ~ed that forces of up to lON.mm~2 can be exerted on the
outer protecthre ~acket of aD in~ulated pipe as a result of temperature
c~rcles e~erie~ced ~ a plpe ~ Ynnter before ~t 18 burled. The se~l
~usS be abl~ ~tad~these cy~les ~d movemen~s wlt:hout
bre~g. Fbrth~ ~ is preferred that the 5eal be able to -
wiehstand ffle preS~eB :exerted when the ca~i~y arourld ~he
insul~ted port~on of p~pe ls relnsulated bY~r ~aming in situ.
One ~pproach '~hat ~ha~; met wit~ conxidera~le succes~ is the
su~ect of GB-A-2108~i25. In one aspect it involves creating a fle~fible
~seal. be~en the ~sula'don surroundlng each p~pe and a rigid casing
which spans the unlnsulated por~on of pipe. by means of a heat- :
rec~vable polymeric~sb~e co~ted w~th a sealant. To pFeValt
m~vemeIlt of:the sealant coated s~eve of (}B-~-2l08625 re~a~ve to
~e pipe. the sle~ve is pro~ided wi~ adhe5~ve m~terial at spe~fled
regions to bond ~e sleeve to the p~pe insulation ~d to ~e cas~slg.
Ano~; approæh wh~ch has met with considerable success is
described ln EP-B-245067. This des~r~bes a ~gid sy~tem for sealing
the insula~on al: a pipe Joint which is sufflcien~y strong to wlthstand
the forces encountered durlng lnstallation wl~out stretchlng or
WO 93/OB012 ~ 8 ~ pcr/GB92lol937
., 3--
fle~nng to any sign~ficant extent. or breaking. E;P-B-0245067
describes an article comprising a heat recoverable polvmeric layer~ a
layer of bondirlg matenal ~or forming a bond between the recoYerable
material and the ob~ect, and a larninar me~al heating elemen~ having a
pluralit~r of apertures through its th~ckness inbuilt in one of the
layers. The sleeve is multlwrapped for some embodiments. especially
for large pipe or cable cove~g, so t~a~ it builds up a th~ckness of.
~or ~mple, from O.S ~o 3.5 mm. lncreased thic~ness enhances the
s~en~, which is reguired of a r~gld seal.
We have c~scove~ed ~at par~cular advanLtage~ can be achi~ed
by provl~ng a heat re~erable fabric wraparo~nd sleeYe, preferably
impreg~ated or eoated wlth~ polymeric materlal,, which ~leeve 1s
pr~rlded ~lth heat~$lg mean~ in or on ~ts in~er surface. along at least
three edges. be~g one lo~gl~edge and botb annular edge~
when t~e sle~ve is ~n its wrapp~d con~gurat~o~.
The e~dstence~ o~ heat-recoverable ~ c sle~es is krl~wn.
E~ference may be made~: for exa~ple~, to EP-A-0~16393, GB~A-
2133639, GB~-2133740. GB-~-21343~4, C;B~-21356~2. GB-~-
21358~6 and GB-A-213942. the di~osures of which are
incorporated herein by refer~ce.
Thus the prese~t invention provltles a wraparound ar~ele for
~oncllng to an elorlgate obJect such as a pipe or cable or for ma~ng,
:: or bonding to, a ~o~t or spllce be~weer~ such a~dcles. the article
~: co~prl~fflg a layer of a fabrlc t~a~ is heat-recoverable, preferably heat
shrlnkable. ~t leas~ in part~, whlch is in the for~ of a sheet ~at can be
apped arouIld the ob~ect. aDd which is provlded with elect~ical
hea~g ~e~s in andlor o~ its inner ~ e when Yvrapped. along at
least three edges of the shee~, being at least one of ~e lon~tudinal
edges aT~d bo~ an!lular edges when the shee~: is in lts wrapped
conflg~
:
.~
~:
:
WO 93~08012 PCltGB92/01937
2,~ lG7 ~4 -4-
One. some or all of the healing means can be at least partially
embedded ~ the reco~rerable fabnc. or ~hey can lie on the surface of
the fabric layer.
The electrical he~ting rneans may be of any suitable type. For
example an open mesh of the type descnbed in EP-53-Q245067 can
be used. Such a s~cruc~ure c~ a~van~ageously follow the recoYery of
the slee~e. In another embodiment certain fibres of the fabr~c may be
conduc~re, or extra conduc~re fl~res or w~res can be inserted in the
fabric and connected to a power supply to act as he~t~ng elements.
For ~ple~ c0nduc~ve copper w~ may be inserted. Mi~ures of
di~erent hea~g means naay be used. Elec~ical power to the
electr~cal he~g means tWhich heat by I2R heat~ng a~ a result of
e~ecbical ~e~t pa~sage) may be p~rided by ~y su~table
electrodes. For OEample. metal s~ips or conduc~lre braid ~ips may
be ~ed to, or ~n~exwoven ~, the fabric.
~ e sle~e preferably also comprises a bonding layer, on i~s
inner surface lwhen w~pped) at leas~ e reg~on of ~e hea~Lng ~ -
means. l?~ef~ab~ he bond~ng layer c~mprises a~y o~ thg mater~als
m~ti~ed f~r the boIlding layer of EP-B~24506~, ~e di~closure of
which i~ incorpora~d herein by refere~ce.
.
The bonding material may be selected from mate~als whlch
:pro~de arl adhesive bond and: ~rom mate~s which pro~ride a fusion
bond. The selection ~ depend on the :m~tenals of the recoverable
l~yer and on:the ob~ect to which ~ is ~o bond. Pre~erably the bonding
ma~erlal ~ be heat-ac~vatable. t~at is for example a mater~al w~ch
can pr~vlde a fi~sion; bond. or ~ a material wh~ch provide~ an adheshre
bo~d (ie. asl adhesive) a hot-melt ~&esi~e or a heat-curable adhe~ive.
has the adtrantage of p~lding an ar~cle w~th a layer of bonding
m~ter~ that is 1~1:ent uD'Lil t~e heati~g elemeIlt is powered in order
to cause ~ yer o reeo~erable ma~erial to recover and to ac~ate
the borlding matenal~ a~d wh~ch ls t~e~efore particularly con~renient
du~ing storage arld during manipulation of the article prior to
inst~Llatiorl.
wo 93/080l2 pcr/Gss2/ol937
5 211678~
A heat-acti~ratable adhesive (as the te.,l~ is used herein) forms a
bond that is based on chesI~ical and physical interaccions which are
initiated when the adhesive is in its liquid phase and are retained on
solidi~cation, Examples of hot-melt adhesives which may be used as
bonding mater~al in the article of the invent~on are disclosed in US-
418177~ and US-4018733, w~ich disclose formula~ons comprising
polyam~des modii~ed wlth hydrocarbon waxes. and Ix~tures of acidic
et~ylene polymers and tac~ers. Also su~table are composi~ons
based on etheylene vinyl-acetate copolymers. bIended with
h~rdro~on waxes ~nd optionally butyl rubber. A par~cularly
preferred adbesive. especially for use on untreated surfaces and in
low temperature applicatlons. is that disclosed in GB-A-2075991.
whlc~ IS a blend of a polya~de. an acryli~ rubber and preferabl~ a
small amount of arl e~ylene/acry~ic acid/bu~ri acrylate terpolymer.
In order to obta~n satlsfactory shear performances in such adhesives.
it may be ad~lantageous to cross-l~ e adhesiYe. although the
degree of c~ss-~g must not be so high as to reduce the abllit~r of
t}se adhesive to l~quify. and tl~ to flow and to wet the ob~ect to be
bonded. and therefore to form a bond to the ob~ect wlth good ped
skengt~.
:
A fuslon bond ~as the term is used hereln) on the other hand is
one that ls based on physical interac~ons lni~ated by intimate
contact between compa~ble materlals in thei ~isco-elastic state. and
is more akin to a weld. ln m~y Ibut not all) cases. compatib~lity of
two or more polymeric composi~ons arises from substan~al amounts
of comm= recurring units in the polymers of the mate~ials. such as
for ~le whe~ ~t least 50~6. preferably at least 70%. of the
recurrfng units of a~ polymer of a flrst csmposltion are the same as at
~least 50%, preferably at:least 70%, of ~he recurring units of a
polymer of the ot}ler co~post~on. these percentages being based on
the total nu~ber of recurTir~g units.
. ~ ~
Polymerie mate~ t}lat may be used for the fusion bonding
layer ~nclude. for example po~eth~lene, polypropylene. polybutene.
W093/08012 ~'~,.6~S4 -6- PCI/GB92/01937
copolvmers of ethylene~ propylene. butene and hexene. copolvrners
of ethylene w~th ethyl acrylate. ~rinyl acetate, acrylic acid. methacrylic
acid, acrylic esters or methacrylic esters in which polyethylene
predominates, blends of these polymers. and blends of these
polymers w~th elastomers~
, :',
We have found ~hat a slee~e af a certain thlckness when made
from the recoverable fabric of the present in~renffon pro~ides the
same strength eg parffcular~ ag~st internal or external pressure. or
aga~nst tensile stre~ a much thl~lcer sleeve made from a
recover~le sleeYe of the mater~al described irl EP-B-0245067. For
many appl~ ons ~ is very desirable s~nce lt allows the the~mal
mass of the ar~ciie to be le~s than tha~ of t~e he~ted reglon of the
p~pes so that, if the ~ lcle during heat reco~ery rea~hes hlg~
temperature~ d~ to the ~oint ls m~mised. Thl~ 1s par~cularly
usefi~l ~n the ca~e of d~s~dct he~g pipe ~oirlts a~ explained below.
~ Di6t~ hca~ng pipes 1 yp~cally compdses a een~al steel plpe1,
an outer~ thick insula~on and aD outer pol~meric coa~g. I~ loi~g
such plpe~ the :9tcel: iS bared aDd a weld made. It is ~en necessa~y
tQ make good t~e iDsula~oIl. Tbls may be done by Sl~Ollndi~lg the
outer p~bmer~c coadngs on e~t~er slde of the plslt with a casirlg (one
o r mul~-p~ sealed to the polymerlc coverlng, ~nd then
i~nmed~ately adding~foam lnto the~ annular gap around the steel pipes
in ;~the ~oi~t reglon wlthin:the ca~ing. The ~pes of foams used
callydecompose~at~tempaturesofabout140Corhig~er.
Therefore if a heat recoverable sleeYe ~s used during the reinsulation
of: ~strlct; heat~g ~oints.~ er as a sin~e part casing or as seals
onto a r~gld: cas~ng,~ t~en t~ tnstaller must ensure that the sleeve
does not heat to temperature~ at wh~ch the foam w~ll decc~mpose. In
situat~ons where the ~cknes~ of ~e sleeve is high. s~ that the
thermal ~ass~of the sleeve is greater than th~t of the region of the
pipe wh~ch }~ durlng the :ins~ ation. then it is ~rery dffl~cult to
con~ol o~rer-hea~dng of the sleeve and consequent dam~ge to the
foam. Thus the present applica~on, which allo~ws the use of ~inner
d hence l~wer t~ermal mass sleeves. provides signi~cant
: .
WO 93~08012 P~/GB92/01937
7 21167~1
advantages compared to the pnor arc soiutions. Preferably ~he sleeve
used has a wall thickness less ~an that of ~e pipes to be joined.
preferably less ~ 0.75 times the wall thickne~s of the pipes to be
joined. As an exa~ple~ according to our ~ven~on a sleeve of
appro~dmately 1.7 mm ~ckness can provide appro~dmately the same
strength ~when tested by a~dal pull out of a 160mm diameter, 0~5m
length tubular ar~cle) as a double wrap slee~re according to EP-B-
0245067 of about 3.2 mm total thickness. ~gh s~e~gth slee~es are
par~cularly required where large pipes are used, eg of the order of
400 mm diameter or larger. p~ci~lar~y if subiect to high stress
d~ng ~nstallatio~s. Suc~ stresses may be generated for ea~mple
when a p~pe line is ~g la~d i n soil. This typical3y takeB several days
so ~e ~oints may be ~osed to night/day temperature cycles wh~ch
may create stres~ on tbe~)Di~lts.
In a preferred embodiment according to ~che invention part
o}~r of the fabr~c is heat recoverable, pre~erably heat shrinkable.
preferablyrad~ . a ces~tral nrtllarre~on oft~e sleev~
when ~ l~cs wrapped- co~tlon is not ~ieat re~overable. Tbis may
be ashl~, for example. ~ a wea:ve, by arran~g for the flbres ~n
:the w~ ~to run ~==P~I~ and ~o provide rows of heat
recoverable fl~*es at eithe~ end of the wr~ped ~lee~re and non-heat-
recovable, ie. heat stable flbres in the central region. The use of a
fabric according to the ~nven~on, par~cularly one ha~g a central
h~t:stable sec~on has~been found to be a par~cularly advantageous
structure in appllcatlons where the ar~cle is sub~ected to stress eg
when empl~yed as a 30int be~cween distr~ct hea~ng pipes, slnce the
sleeve is able to "glve" a small amoun~ due to straigbtening of f~bres
~de~ tension and~ rdax~tlon of fibres when tension is released. Such
stralgh~é~ng and relaxadon occurs due to the nature of the fab~ic. in
which. at least ir~ the unrec~rered state. ~bres pass o~er arld under
each: o~er in a shallow slllulso~dal con~guraffon and hence, unless in
a ~rery ffgbfweave or other fabrlc con~gurat~on. car~ straighten and
tigbten in response to stresses.
~:
~ ~ .
;
WO 93/08012 PCI/GBg2/01937
8- ;
The fle~bility of a joint between district heating pipes pro~ridea
by the use of a he~t recoverable fabric also forms part of the present ~:
inYention. ThUS another aspect of ~he irl~ention prt~rides a method of
reinsulating a bared ~oint bel:ween district hea~ng pipes each of
which co~pr~ses a ce~tral pipe ha~ring an outer insulation. the
me~hod compr~sing
~1) pos~oning a wraparound article either to bridge the insulation
on e~ther side of the pipes or to bridge from a pipe to a central
cas~g position~d over the ~oint. t~e ~cle comprising a wraparound
~abxic sleelre ~vhlch has end annular regions which are radially heat
~hrlnl~le, d a ceiltral tubular portio~ which is radlally l~eat stable.
and
~21 a~ply~g hea~ to shr~; the ends of the ~r~cle.
whereby aft~ shrinkage tbe sle~e i5 longitudinally ~ble.
..:
Ihe slee~e co~pri~es a ~absic. which i~elf pre~erably
comprlses recoverable. prcferably cros~-l~kedt f~br@s arranged in
one of t~ warp or t~e weft of t~e fab~ic. so tha~ ~e f~ic ls
:recovera~le ir~ subseantlally ne directlon. Preferab~r ~ls is the
circumferen~ direc~on whe~ the sle~ve is in a wrapped
conlguratlosl. .
l~e term "fibre" as used herei~ includes filaments eOg.
mono~lament~ or ~ents, and a~so staple fibres, and tapes.
Th~ fabr~cs used iD;the articles accord1ng:to the in~ren~on preferably :~
empl~r the heat-shrinkàble fibres in the ~orm of fllaments. espec~ y
mo~of~l~ents. In ~a~other preferred embodiment 1:he recoverabillty
~is hi~est. espedally preferably significarlt~y highest. in the direction
of tl~e rec~YeraWe ~bres.
Cross-lin~g of the fibres enables the ~abric ~:o be heated aboYe
their recovery temperature wit~out mel~ing. Higher recoYery ratios
~an be a~ie~red w~t~ cross-linked flbres thar~ would be possible with
-
W0 93/08012 ~ 2 I 1 6 7 8 ~ Pcr/GBg2~01g37
non-cross-lirlked stretched fibres. and in addition fabric containing
cross-l~nked ~bres is not so sensitiYe ~o overheating.
As examples. any of t~e fabrics descnbed in EP-B~0116393.
EP-B-024398S. EP-~-0430377. :E:P-A-022S152. US 4816328~ US
4816309, U.K. Pa~e~t ~pplicatlon Pllblication Nos. 2133639,
2133740. 2134334. 2135632. 2135836 and 2139142 carl be used ~n
the article and method of the presen~ rentlon.
Whllst the ~abric may be tlsed alone. it is often ad~tag~ous for
it to be emplc~red in con~ tlon wlth an adhesive or seala~t or ot3her
po~lc m~te~ ~t reIlders ~t ~ubs~antially impe~v~ous to fluids~
the ~e~lve. sealallt or o~er mater~al either being a~pl~d in sib~
whOEl the fabr~s~ 18 ~stalled or applled in the ~actory. Thus~ for
e~ple, ~e fab~c may be ~mpregnated Y i~ a curable adbe~ve
composltio~, e.g a ~le epoxy composi~on and espeeially an
~3ptlo~ b-staged ~pox~ re~ bat is c~ed by me~s of a pol~mide,
arl ar~hydrlde ~r an ~so~ate al~holl~bL other mate~ials may be used
~u~h ~ ph~c~ resins~ or i~te/phe~llc re~. The re~i$ L may
y be lamlna~d on to t~e f~bFic or ~t may be employed i~
partlculate fo~ as desc~ed in U.K Pate~c Pub~at~o~ 0. :21~300.
Alte~ an adheshre suc~ ~ a h~t-~elt adhe~i~e and espec~lly
an ad~e~1ve based :on a polyam~de or anL e~ylene-~nyl aceta~e
copolyme~ may be appl~ed el~her to the ~ c or to ~e substg~te
during~nstalla'don.
,
P~os~ preferably, howeYer~ the heat-reco~rerable fabric is used ~n
comb~ lon wl'lh a matrix polymer layer which softens when he~ted
to aecommodate recovery of the fabric. to ~orm a s~gle co~po~ite
stru~ture.
The heat-recover~le fabric is pre~era~ly bonded to. mo~
preferably. c~mbedded in. the polymer matrix mater~al. At or abo~re the
reco~r~ry temperature of the flb~es. the polymer mat~ix material
sh~uld be capable o~ limi~ed flow under pressure so that it ~etains the
in~egri~ o ~e composite struch~re without substan~lly imped~g
:
W093/08012 2~ 4 -10- PCr/GB92/01937
recovery of the fibres. It preferably has. at the aforesaid temperature.
an elongat~on to break of greater than 50%. most preferably greater
than 100%, and a ~O% secant modulus of pre~erabl~r greater than
100%, and a 20% secant modulus of preferably at least 5 X 1O-2 MPa.
most preferably at least lo-l MPa, measured at a strain rate of
300%M per mirlute.
The ab~Lt~ of the matr~x materlal to flow ~hen heated need ~ot
necessarlly apply afte~ recovery. T~us, for ~ple. the polymer
matrix mate~lal may eventually c~e to a the~mo~et Oll hea~g,
although it is p~eerred that th:e cure rate is suf~c~ently slow under
the reeo~ y cond~t~ons not to af~ect adYersel~ e above men~isned
physlc~l prop~le~ of ~he polymer ma~ material du~ g t~e
rec~y of the flb~es. Th~s, ~or example~ t~e po~mer form~g tbe
ma~ materlal may con~ain graft2d hydrol~ab~e ~llane g~up5 whlch
are capa~le of cross-~g t~e m;~te~al subsequently i~ the
p~seslee of moisbure. Alten~ the mat~lx materlal may include a
po~mer. preferabb a rubbcr ar~d espe~all~ a~ylle n~bber, w~eh
eor~ s ep~ group~: and a roo~ tgmperab~e insoluble cur~ng agent
e.g. dl~a~diamlde. Preférred mal~ materlals are descr~bed in U.
Patent ~ppllcation Publicat~on No. 2135632. Thus a partieular~y
; ` ~ pre~eITed slee~e eomprlse~ a ~ompos~te structure of a heat-
:~ recove~We fabrle a~d~ a polyme~ mam~ mate~al ehar~c~r~ed in
.
(a) the hea~-reco~erable fab~c comprises fibres that wil~
recover when heated. ~: fl~re~ ~g a recove~y s~ess Y of at least
5 x lO-~2 MPa at a temperab~re above their c~y~talline melting
Sransitlon temperaturc: and
(b~ t~e polymer mat~i~ material has an elongat~o~
temperature profEle such tbat there e~dsts a tempera~ure O wh~ch is
at~ or ab~e ~e crysta~ne meltlng transltlon temperature of the
flbres at whlch temperature ~t~e poIymer matrix materiaI has an
elong~a~on to break of greater ehan 20% snd a 20% secane modulus X
;:
: ',
WO 93/08012 pcr/GB92/ol937
211 678~
of a~ leas~ 10-2 MPa (measured at a strain rate of 3~0% per minutes~,
and at which temperature the inequali~ (1) is satisfied:
(1-~)
is less than orle.
Y R
wherein R is ~e mearl effective vo~ume fra~on of he~t-recoverable ~:
fibre~ in ~e compo~ite structure along a glven d~eeffoIl baS@Cl 0~ t~e . ~:
total ~rohLme o~ t~e compo~te s~:ructure. or rele~t p~rtlon thereof.
Ihe ~abric ca~ be ~t~d, W~ " noIl-wo~en~ braided. or ~che l~e. It
is prefOEred ~t ~che fiab~ic 1~ a woven ~abric. Ihe ~abrlc can be wove~
in a~ ~u~table p~ or =ple, twlll~ bro~en twill. ~a~n~ satee~. :
I~o, EalaiD" ~op $ack. sa~k and vaho~ e c~mlbi~tio~ in si~le
or ~ul~ple p~r ~eave~ for ~ple two or three ply weavesr The
c may be lmitted if des~ed, eit~er ~ k~i~ted or weft ~nitted.
Whe~e ~ f~ric ~s~ a brald the tlYms '~arp" and 1~ are ~o$
strl~b app~ le. but whe~3L used i~ ~h~s Sped~ R t~ey cas~ be
co~sld~ed t~ r~ate to braid~ b~r arbltaIy sele~ioIl of ~Ibre dire~i~s.
~he fablic m~y CD}ltai~l 0~1}31' heat-recove~Lble flbre~, o~ as is ~:
prefe~ed i~ m~y colltain bo~ heat -re~overable f~bres a~d non he~t- :
recaverable flbr~s. I~ may al~o compIise conduc~ve ~bres ~h~ch naay
provlde th~ heati~g me~,: ~e ~bres may be = ged i~ any
patt~rn irl aceorda~ce wlt}l~e ~n~e~on~ but it i~ especially --
pre~erred th~t all t~e ~b~e~ ~end~ng Irl the dire~on of t~e
rec~le fi~re~ are recoverable. a~d t~at all the o~e~ flbre~ ~e
norl-h~t-rec~le. Where the ~a:b~ic i~ en it preferab~ has
heat-rec~rable fibre~ ~ one direc~oIl and d~si~all~ heat stable
~res iIi ~e ot~er directio~ so t}lat t~e fabric as a w~ole is
reco~able i~ a 8i~ e dirCC~t)Il O~lly. WhOEe the fàb~ic is ~ted. if
sric i~iade sQlely ~m heat reco~rerable ~bre~ ~t will be
r~coverable ~ dlmension~. b~t if. ~s is preferred ~ is kn~tted
from a he~-stable flb~ and a ~eat-rec~erable fibre ~Lhat is either
warp or weft inserted. it will be recove~able in only one direc~on.
wo 93/08012 2 ~ ~ 6~ 8 ~ ~12 - PCI /GB92/11 1937
The reco~erable fibres preferably form part of the fabric itself.
T~e recoverable fibres may instead be additional. and be
incorporated, for example, inser~ed after production of the ~asic
fabrio.
Sin~larly, if coIlductive ~bres are included, they may form part
t~e fabrlc i~self or be add~onal. and ~neorporated. for e~ample
~n~e~ed after produc~on of the baslc fabric.
The flbres are preferably formed ~rom a polymerlc heat-
recaverable maLterial which recover when heated to over and above
th~ rec~ emperature. By "~he r~co~rery te~per~ture" of
p~lymesic heat-recoverable ~t~lal~ 1~ mearlt t~t ~e~perature at
~lch the recovegy of ~e polymerlc materlal ~ill go substantlally to
comple~o~. In general~ the ree~e~y temperature w~ll be ~he
~ e mel~g transltlon t~mperature if the polymer ~s
ery~talli~e or ~e ~ tra$~ffl~ temperature if the polymer ls
amorp~ous.
:
The he~t-recoverable flb~res are preferabl~ ~rmed ~om a
polymerl~ mat~ial that ~mparts good physical prope~es and. in
part~cular. good creep re~ ce to ~e f~br~s. Olef~n polymers such
a~ polyethylene and e~lene copolymers. pol~amides. polyesters~ :
a~rylic pol~rmers ~d other polymers may be employed and pregerably
~hvse t~at are capable of: be~ng cros~-l~ked. A par~cul~ly preferred
polymerlc material for ~e flbres i~ ba~ed o~ polye~ylene ha~ring a
~enslqr of fi~m 0.94 t~ 0.97Jgms/cc~ a weig~ average molecular
glat ~ ~f ~om :80 ~ 103 t~ 200 X 1~ and a number a~erage
molecular wdgbt Mn of firom 15 X 103 to 30 X 103.
Pr~fera~ly the recovery ~emperature of $he fibres is 60C or
more. mosf~ from 809C to 250C ~uch a~, for çxample, 120
to 150C.
WO 93/08012 21 1 6 7 ~ ~ pcr/GBs2/ols37
- 1 3 -
When ~he ~ibre is cross-linked bv irradi~tion it is convenient
to incorporate the cross-linking step into manufacture of the fibre.
The ~bre ean be extruded, s~retched at a temperature below its
melting tempera~ure, preferably by an amount of from 800 to 2000%, :
then sub~ected to irra~atlon to effect cross-link~g. A less prefe~Ted
way of maki~g t:he ~bre is to ~de the ~bre. irradiate to cross-link.
then heat the ~bre, preferably to above ~ts ~eltlng temperature.
stretchlng t~e fibre, and then COQI~Ilg the stretched flbre. High
density polyethylene flbres are preferably ~rad~ated with a dose of
~om about 5 to about 3S megarads. preferably ~om about 5 to about ~ ::
2S megarads and ~n par~cuiar ~om about 7 to about 18 megarads.
especially firom 10 to about 18 meds. Usually the gel content of -
the cross-linked flbre ~s gre~ter than 20~6, preferably greater tban
30%. most preferaby greater than 40%. In prac~dce. gel contents ~:
greater ~ 90% a~e not easlly achlevable. Fibres produced i~ ~Lhis
way can have a hi~h strength after reco~y.
: .
Any sultable: ~: may be used for any norl heat-~bres
i~cluded~ e fabrlc. As~e~nples there may be menelo~ed glass
bre. polyester.Rayon:~Iraoe Mar~). cotton and tinsel metal.
Pa~ of all of the hea~ recov~y~ fabric may be lined u~ith a
bon~ng layer as aforesaid such as an adhesive for bondlng to ob~ects
and/or~ bonding the~overlapping longltud~al edges~ of the ar~cle. in
the~:wrapped conflgura!~on. to each~o~er. Alterrathely bonding may
be by fusion.: The preferred: steps and order in which bond~g is
carried out:is~descr~bed ~ respect of the ~method according to the
inven~on. : :
Th~s ~other aspect of ~e invent~on provides a me~od of
c~ering n elongate ob~e~t or bonding two such ob~ects in end to
end relat~onshl,p us~ng a u~raparound ar~cle accordirlg to the first
aspect of the ~nventlon. t~e method comprising connect~ng the
hea~cing means to a power:suppl~r to heat and to recover those reg~ons
into contact wi~ the underlylng ob~ect.
WO93/08012 ~ 6 18 4 14- pcr/GBs2/ol937
Pre~rably the article is wrapped around Jche ob~ec~ so that
longitudinal edges o~Te~lap and electrical power applied initially to
the electrical heat~ng means on the at least one longitudinal edge to
bond the edges to each other. Then. the longltudinal seal ha~ring
been made. heat is pre~erably applied to the hea'dng means at the
end~ to complete the seal. In a prefelTed method for joining two
elonga~e ob~ects or for co~e~ing a ~oixlt be~wee~ the two elongate
ob~ects" the a~cle ~ wrapped arou~d a piece of relea~e paper
po~ttoned arou~d one of ~e elongate ob~ects. before heat is appl~ed
to t~e hea~ng mean~ on t~e longitudinal edge,. The underlying pipe
or cable 'lherefore act~ as a support. The loIlgltud~nally sealed article
i~ then prefesably slid from the release paper, which is rem~ved.
Then electr~al po~r is preferab~ supplled to t~e ~l~lar heating
means at eac~ e~d of the wrapped ar~cle to co~plete ~e seal.
Where t~e artlcle i5 used to.loin two elongate ob~ects. ~t ls preferably
wrap~ed around ~ piece of release paper on one of ~e ob~ec~ to one
side of the Jolnt. before heat is applied to ~e hea~dng mea~s O~ e
lw~ al edge. Ihe ar~cle ca~ t~en s~ply be pu~hed over the
~oislt b~o~ e~e dectrlcal~ power i~ supplled to ~e annular hea~dng
mean~ to cog~plete the seal. Thls i~ made pos~ible becau~e of t}~e
prese~ce of the rele~se paper.
The ~et~od according to the ~mre~ation is par~icularly
appllcable where :t~e ob~ect~s ~ pipes or cables or ~oints
~erebetween~ p~e~ably distrlet heating pipes or ~oints
therebet~een .
mbod~s of the ~vention w~ll now be descr~bed. by way of
example. w~th referenc~ to 'che accompanying ~aw~ngs. wherein:-
Flgure 1 sho~vs a first ar~cle acc~rding to the i~yeIltiorl:
Fig~ s 2 and 3 show se~uen~al steps in the installaffon of
.
-:
WO 93/08012 pcr/GBg2/ol937
-~lI678~
F~gures 4 and 5 show other em~odimen~s o ar~lcle according
to the i~ven'don
Referring to ~he drawings Figure 1 show~ a first artlcle
acco~g to the inveIltlorL. The ar~cle comprises a fabric sle~e 2
wh~ch is lamina~ed with a polymer matrlx (not shown). The slee~e 2
has lo~gU:udinal edges 4 arld circumferen~al edge~ 6 v~ewed when ::
the sleeve i~ ~ it~ wrapped con~gurat~on as sh~wn. The longitudi~al
edge~ 4 can be overlapped in order to hold the ~paround ar~cle in
a tubular closed cor~i~tlon. ~e sleeve also comprlses three
hea~dng eleme~ 8, 10 and 12 ~n the fon~ of copper meshe~ :;
e~tendlng al~g one longltu~ edge and both circumferentlial clr
lar edges of the sleeve 2. The me~ heater 15 also covered on ~ts
~n~lde s~ce ~vi~ a bonding layOE a~ de~cribed ~ EP-E~-0~245~367.
~vhlch bonds t~e mesh heater to t~e ~ ic sle~ve 2. arld ~ use, will
bond the aleeve 2 to tbe underly~g elo~gate ob~ect. II1 the drawlngs
the mesh heater~ are not ~h~ n detall. a~d ~he bond~ng layer is
not shown (for s~plLcity). Ihe ar~cle al~s) comp~lse~ two elongate
elecrode~ 14 ~g along e~ o~ the` lo~gitud~al edges o~
sle~ve 2. a~d fi~the~ elonge~e ekstrodes 16 ~t~d~ng arolmd the
cl_=lere~l edges of ~e sleeve 2.
Th~ construct~on of ~e fab~c is such as to prQ~rlde
e~r~u~e~t~al sh~ge at the e~ds only of the sle~re. Thus i~ two
e~rcumferenUal zoIles at t~e ends of the slee~ 2. beneath the mesh
hesters 10 and 12. t~e sleeve compr~ses heat shrinkable polyethlene
fl~res e~endl~g~ the cirn~ferexltial direction~ while in the
circumfe~tlal ~r~ctioIl in tbe entral reglon bet:weeIl the two end
~gions of l~e sleeve 2 the sleeve comp~ses non-shrin~able
po~r~thyle~e f~bre~. In the longltudinal d~eetion t~oughout. the
~fabrie comprise~ a ml.cta~ of ~lass ffbres and non-shrinkable
po~retlyle~e ~bres. The e~fest of this cDns~uc~on is that if
electrieal ci~T~nt is applied to tbe me~h heater it eau~es the
shrinkabb polyet~ylene flbre~ at t~e en~ regi~ns in contact ~nth
mesh hea~ers 10 asld 12 to:shrlnk. whi:le ~he een~al reg~on be~veen
e encl regio~s of $he slecve does not shrink. When electrical
,
WO 93/08012 ~ " 16 Pcr/cs92lolg37
current is applied to the mesh heater 8 it causes che ~onding layer
ad~acent to that mesh heater to bond to the overlapp~ng edges of the
sleeve, although there is no longitudinal shrinkage. ~:
Figures 2 ~nd 3 are seque~tial steps showing the instaL1ation of
'che article.
In Figure 2 the sleeve 2 is showIl wrapped ar3und two district ::
heat~ng pipe~ 18 and ao wh~ch h~ve been ~oined toget}ler by a weld
21~. Each of the di~trlct heat~g pipes I8 and 20 comp~lses an inner
steel pipe 22 arld an out~r ~tion 24. The steel pipes 22 are
welded at 21. but t~e insula~on 24 around t~at reg~n has belslg
bared. It ls ~at reg~o~ ~h~ t i~ necessary to r~nsulate. The
sleev~ a ~B posi~ed to orle side: of the weld 21. I~ 1~ po~ orled
around a release paper a6 wrapped around the outer ins~on 24 of
o~e o~ ~e pipe~ 18. The l~ngltu~al edg~s of t~e sleeve 2 are
ov~apped. ~d ~he~ ele~t:r~e~ 16 are con~ectetl ~o a 5Upp]y of
power 80 that elç~rlcal curr~nt ~ t~r~u~h the ~esh heater 8~
y hea~g t~e b~d~ng layer a~acalt t~t me~ hea~ 8. aDd
thereby for3DIng a seal between t~e lox~ dlnal edges of ~e ~abrie
~leeve 20
Fai~lc sleeve 2 is therefore at ~s stage in ~e shape o~ a
tub~ar sleeve. arld this ls the~ slid f~om the release paper 26 over
: t~e ~eld region 21 which~ls to be reinsulat~d. The ~v~tage of
form~ig ~e longltudinal ~eal to one side o~ the ~oirlt ~er a release
p~per 26 is th~ the pipe to one side of the ~oint pro~ndes a ~uppo~ ~-
fo~ t~e sleeve while the longltud~ seal is made. The lo~gitudin~l
seal eoul~ be ~ade ~ the slee~e 2 posi'doned arousld t~e bared
reglon sround weld~ 21, but ~ thls were done it wo~ld be desirable to
include an i~sert support member while t~e long~tud~nal seal were
: made.
After t~e sleeYe 2: has been slid from the release paper into
positiorl o~er t~e bared region around weld 21. elec~:ric~l power
needs to be supplied to effect heat shrlnkage of the end reglons of
~ .
: :
`:
Wo 93/080l2 - 1 7 ? 1 1 6 7 ~ ~ pcr/s:iBs~/ol937
the sleeve 2. When the sleeve has been slid in~o position the edges of ::
slee~e 2 o~erlap the insulation 24 on either side of the bared weld
regi~n. Electrodes 16 are then discosmected from the power supply
and eleetrodes 14 connected to opposite l:erminals on ~he power
s~pp~y. Th~S causes elec~ical current to flow through mesh heaters
10 and lZ at either end of the sleeve ~. This hea~ ef~ec~ shrinkage
of ~e reco~rerable f~bres in those reglons of the f~bric sleeve 2.
there~y e~ec~ing radial he~t silrinkage of t~e ends of the sleeve 2.
Also t~e heat applied ac~ rates the bonding layer ad~aceIlt ~e mesh
heaters 10 and 12 in the end regions of ~e slee~r~. allowing the
slee~e 2 to fon~ a tl~t bond to ~e ~nsulation 24 on eit~er slde of
the b~ed weld re~on 21. Ihus ~e fab~c slee~re 2 is sealed to the
dlstrl~t he~dng plpes 18 and 18 on eit~er side of ~e weld 21. The
seal~d s~tem lS sh~ clearly in F~gure 3.
Figure 4 sh~s an alternati~ cle accord~g ~o ~e present
i~renlion. ~ dl~ers f~om tlle a~cle show~ in F~gure 1 irl ~hat t~e
me~h heater~ 8. 10 arld 12 are replaced by corlductlve ~bres or w~es
eg. copper ~vire~ g along the lo~l~ al edge and a~ou~d
the end~ of t~e sle~e~2. These are i~dica~ed a~ 8', 10' aDd 12'.
These co~duc~e ~ir~s or flbres may be interwaverl into the fab~c 2,
or they :may form par~ of the fab~c 2 itself. Thus ~ ~e end reg~ons
of the ~leeYe 2 the fab~c comprises polyethylene heat shrinkable
fibres, in the ~lrcumferen~al dlrec~on a~d in the cen~ral reg~on.
between the ends of sleeve 2. polye~chlerle non-shrinkable f~bres are
arranged ~ the ~rcumferent~al dlrection. ~lass fIbres e~ctend in th~ :
lo~gltud~nal d~re~tion throug}lout. A~ for t~e embodiment of figures
1-3 this means that the ce~tral region betweerl t;he t~o zones at the
e~ds will not be heat rec~erable. Simllarly along the lon~tudinal
edge of ~e sleeve where ~e mesh heater was posi~oned ~n ~he
a~cle vf Figure l. the mesh is replaced by conductive wires eg
copper WiJreB or by conduc~e fibres.
: , .
bre arrangement can be easily manu~actured by a wea.re
: ~ in whi~h t~e weft ~ctends longltudinall~- and the warp ex~ends
clrcumfentlally :~round the sle~ve.
wo 93/0801~ pcr/Gs92/ol937
~6~'~4 18-
For the embodiments of Figure 4 the electrodes 14 and 16 are
positioned as i~ Figure 1. In this case when electrodes 16 are
connected to a power supply they ca~se hea~ng of the copper wlre or
conductive f~bres 8' along the longitudinal edges of the sleeve 2.
When electrodes 14 are connected to the powcr supply they cause
hea'dng of the copper wires or conduct~ve flbres 10', 12' extending
arotmd the c~rcumference a~ the ends of the sleeves. The installation
steps of the slee~re of F~es 4 are the same as that for the sleeYe of
Figure 1 to 3. the longlt~dinal seal being formed before the
circumferen~al seals.
F~ure 5 ~hows a *~rther embodiment of ~r~cle according to
t~e inven~on. The flbre ~nd wire stn}cture of Flgure 5 is similar to
that of E4~ure 4. le it lnclude~ hea~ng wlres 8'. 10' and 12'
interw~ven in the fabrlc stru~e along t~e edges. Howcver in this
case ~vhere t~e wlres o~ conductive flbres 8' o~rerlap ~vith the w~res
or conduc~ bres lO'~and 12' th~y make electrical contact ~vith
ea~h ot~ ~ (~n tbe embodlme~t ~of Flgure 4 th~y do not). Ihi~ is
s}w~m at con~s 28 and 30:of~ . Ihu~ ln t~ ca~e. onlg two
electrodes ~32: and 34~are pruv~ded. belng eonnected to ~flbres 10' and :~
12' re~ at the opposlte eorners of:the wrapped s~eeve 2
fro~ e:omers 28 ar~d: 30.: When tbe sleeve is wrapped an~ power
suppl~ed -to :the deet~odes. eleetr~cal cl~rrent: therefore flows. say
f~ ~ele~trode 32. through condue~e w~res~or flbres 10'. then
throug~ eonductiye ~bres ~or ~wlres 8'. and fln~lly tbrough eonduet~e
flbres: 12'.~ Ihus by;this~a~rangement stmultaneous Ion~tudinal and
ti~l seals are: made.
It ls also envisaged ~at a U-shaped mesh heater could be used
-in the e~mbodlmen~ of Figure 5 to prov~de heating means 8'. 10' and
12'. ~n place of the conduct~ve fibres or wires.
;: '
: :
:, ~ ~ : :
