Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
86~
METHOD 0~ ~OCATING A F~ULT I~ ~ PRESSURE PIPE
SYSTEM ;~
~ield o~ the In~ention
Th~ pre~ent invention is concerned wlth pipeline
~uper7i~ion technique~9 and more specifically with
methods of locating a ~ault in a pressure pipo ~ystem~ ;
Background of the I~ve~tion
In one known method ~cf. U~S~Rr Inventor'~ Cer~
ficate No~ 380909 publi~hed in 1473) a fault in the pipe
Qy3tem is located b~ measuring9 on the surface of the
pipeline route, acou~tic ~ave~ produced in the point o~
the leak and propagating through the ground. In Rccordance
with thi~ known mothod, two ~tanding wa~e maxima of equal
amplitude, being adjacent to one another, if po3~ible, are
detected on the ground surfaoe above the leaky pipeline,
a~d the coordinate~ of the leak are calculated by halvi~g
the di~tance between the t~o mQxima.
The above method does not make it po~iblo to locate
a ~ault in the pipeline in the daytime~ on a~count of
noise induced by traffic And by YariOUS indu~trial plant~;
on the other hand9 in c~e the method i~ employed for
locating a fault in comple~ branched pipe ~y~tem~, even
in relatively noi~e-~ree condition3, the proc~ of fauIt
lo¢ation tend~ to be ~ery time-consuming~ 3ince the route
of the pipeline ha~ to be determined7 ~ollowed by the
scanning o~ the route ~ith a t~ter.
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Al~o known in the prior ~rt i~ a method o~ locating
a fault in a pipelin~ (c~. U.SO Patent No. 3.691.819 publ.
in 1972~ based likewise on measuring ~ound wave~ but dif-
ferent from the previou~ly de~cribed method in that the
mea~uring ~et i~ inserted into the pipeline wnere it i~
displaced by force of tha produet being tranæferred along
the pipeline. This method generally invol~e interruption
in the product transfer along the pipeline ~or ln~ertion
there into of the mea~uring et, which present~ certain
di~ficultie~ when operating a branched circular pipe
system.
I~ another known method of locating a fault i~,pre~-
sure pipelines (c~. U.S.S,R. Inventor's Certificate
~o. ~27.425 publ, in 1972), there are provided ~t the end~
of the pipeline to be checked pick-up~ respon3ive to pres-
~ure fluctuations of the product trans~erred, in the audio
frequency range, the fluctuation being due to vibration o~
the jet e~c~ping through the pipeline leakg and the fault
i~ located by measuring the phase difference between the
fluctuations ~en~ed.
The implementatio~ of thi~ method nece~itQtes a com-
munication channel between the pick-ups and the mea~uring
set, and due t~ inadequate accuracy vf determining the
pha~e ~hift angle, it bring~ about a con~iderable error
in fault location, while the application o~ the method to
complex branched ~y~tem~ add~ to the camplexity o* the
equipment employed for implementlng ~he method~
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There i~ Ql~O known ~ method of locating Q fault i~
a pipeline avoiding the use of a ~pecial com~unication
channel, wherein the latter i~ 7eplaced by the action o~
the fluid pumped along the pipeline, the in~ormation being
carried by ~n artificial di~turbance wave developed by an
electromagnetic valve appropriately ~paeed from the measur-
ing set. (c~. a paper by A.B.Sturmin et Q~ Automatic f~ult
location in pipeline~ without using a ~pecial communication
channel" in "Water Supply and Sewer System Desi~n" publi~h-
ed by CINIS o~ Gos~troy of the U.S.S~R.~ ser.IV, i~ue
2/71, Moscow 1971), The valve is opened by a pressure drop
wave reaching it from the fault area, ~imulating a leak in
the position o~ the valve. The fault i~ located by detect-
ing the difference between the arrival times of tho two
re~pe~tive pre~ure drop wave~ reaching the measuring set.
This method i~ impracticable in complex pipe ~ystem~,
its realization requiring complex equipment, which re~ult~
in a relatively ~mall reliability o~ the method.
In a further known method o~ detecting leak in pipe
system~ (c~. U.S.S.R. Inventor'~ Certificate No.403920
publ. in 1973 ) ba~ed on the preliminary study of the
specific pipe ~y~tem, the faults are located by specifying
the ~equence of ~canning the pre~ure pick-ups and allow- --
able pre~ure drop rate~, mea~uring the pres~ure in the
te~t points, calculating the pre~ure change between the
mea~urements in each poi~t, and comparing it with the
allowable pres~ure cha~ge rate. By detecting the point in
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which the pre~sure change rate e~ceeds an allowable limit,
a fault in the pipe ~ystem is indicated. In order to
locate the leaky section3 two mutually adjacent point~
with ma~imum pre~qure drop rates are ~elected out of all
the point~ to be checked, which defi~es the leaky 3ectio~.
Thi~ method prevents the preci~e location of the
qpecific point o~ the leak and i8 restricted to locating
the lsaky sect~on.
Al~o known i~ a method of locating a fault in a pre~-
sure pipe ~y~tem di~closed in the U.S,S~R. Inventor'~
Certificate No. 1912~4 publiahed in 1967. In this known
method, there are provided, Qt opposite end~ of the pipe-
line ~ection supervi~ed~ pick-ups responsive to the preR-
sure drop wave produced in the point o~ the leak and
travelling along with the product being tran~ferred in the
pipe sy~tem, and the leak i~ located b~y measuring the di~-
ference between the pick-up re~pon~e t ~e~.
When thi~ prior art method of fault loc~tion is
Qpplied to a bra~ched circular pipe ~y~tem, practically
every ~ection of the system needa to be checked~ Each ~ec-
tion m~y be considered a~ a~main line with the mlnimum
number o~ branches, and a complex ~y~tem may con~i~t of a
large number of ~uch ~ection~ with pick-up~ neces~arily
pro~ided at the end~ o~ each ~ection and a communicatio~
channel connecting the pick-up~ with the mean~ for imple-
menting the method~ Con~equently, it re~ult~ in a oumber-
~ome~ impracticable, and uneconomic~l ~u.pervi~ion ~tem~,
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and the nPce~ity of providing a large number of communl- :
cation channela and detecting de~ice~ (pick-ups) cause~
the reliability of the ~upervision system to be sub-
~tantially raduced,
Summary of the Invention
~ here~ore it i~ an object o~ the pre~ent ~v~ntio~
to provide a~method for locating a ~au~t in a pre3~ure
pipe ~y~tem which can be comparatively eaqy to realize
~nd which ha~ a better reliability when operated in a
branched and looped pipe ~ystem.
With thi~ principal object in view, there is pro~id-
ed a method of locating a fault in a pres~ure pipe sy~tem, ~.
residing in that there are provided pick-up~ re~ponsi~e
to the pres~ure drop wa~e produced in the point of ~he
~ault and propagating with the product being tran~erred
in the pipeline 9 and the ~ault ig located u~ing the dlf-
~erence b~tween re~ponse time~ o~ the pick-up~7 wherein,
according to the invention~ the pick-up~ are mounted in a
lea~t three teat po~nt~ of the pipe ~y~tem9 ~paced apart
by ma~imum distance~ mea~ured alo~g the pipeli~e, such
that with a specified value of minimum le~kage the pre~-
sure drop wave generated in a particular test point ha~
an amplitude in t~o adjacent test points ~uf~icient to
operate the pick-ups di~posed in ~aid two points~ the rB~
ponse times of the pick-ups neare~t to the ~ault point
which the pr~s~ure drop wa~e will reach ~ir~t ~re recorded,
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a first ~et of possible point~ of the ~ault iJ determined
by measuring the di~ference be~een the re~ponse time~ of
the ~irst and the second of the three abovementioned pick-
ups, a second set of possible points of the fault i8
determined by mea~uring the di~ference bet~esn the re~
pon~e timeq of the first and the third of said pick-ups,
a third group of possible point~ of the fault is deter-
mined by mea~uring the dif~erence bet~een the re~ponse
time~ of the second and the third of said pick-up~t ~nd
the point of the fault i~ located by coinoidence of one
of the possible leaky points of one group with one of the
pos~ible leaky points of,at lea~t one of the other group3.
With the choice of the pick-up positions indicated
sbove, their number will ~e just sufficient for location
o~ a leak in any point of a comple~ branched pipe ~ystem,
the comple2ity of the ~y~tem entailing but a ~mall in-
creQ~e in the number of pick-ups. Owing to the fact that
the number of pick-up~ i~ at a minimum, the number of c~-
munication channels between the pick-ups and the device~
for proces~ing the data coming from the pick-up~ will be
al~o minimQl~ thus re~ulting in a greater reliability and
a lower cost of the sy~tem embodying the propo~ed method.
The invention will be herein~-fter di~clo~ed in a
detailed deQcription of preferred embodiment thereo* taken
in conjunction with the accompanying drawing,
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Brie~ De~cription of the Drawing
The dr~wing illu~trate~ a ~chem~tically view o~ ~
pres~ure pipe ~y~tem where a fault i~ located using the
method accord~ng to the invention.
Deta~led Description o~ the Pre~erred Embodiment
.
Suppo~e that it is nece~3ary to pro~ide ~upervi~ion
for a complex pre~sure pipe system ~hown i~ the drawing.
The pipe system i~ composed of pipeline~ ~hown a~ ~traight
lines connectad in node points, of which point~ 1~ 2, 3...
19, 20, 21 are indica~ed in the drawing ~or the ~ake of
clarity o~ the description, A leak in the pipe ~ystem is
located by detecting a pressure drop wave originating in
the point of the leak and propQgating with the liquid or :;
ga~eou~ product propelled along the pipelines ~uch a~
water, crude oil, petrol, g~s ~uel, etcO). ~or detecting
the pressure drop wave, in predetermined, so-cQlled te~t,
point~ of the pip9 ~y~tem, pick-up~ are disposed re~pon-
sive to the action of the wave, such a~ pre~sure pick-upa
mounted on the walls of the pipelines and contacting the
product tran~ferred~ or vibration pick-up~ mounted on the
wall~ of the pipelines but not in contact ~ith the product
tran~ferred. The ~election of the test poirlt~ indicated
ag encircled in the drawing, accordin~ to the invention,
i~ made using the following procedure.
A predetermi~ed minimum leakage ~alue i~ a~sumed
which is to be detected by the pick-upc ~nd interpreted
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~5~86~
as ~ fault9 e.g. the leak of ]0% of the total flow rate
of the product across the pîpeline.
The first te~t point i~ selected in any point of the
pipeline, ~uch as a node point 3. The ~econd test point,
such as a test point 9 i~ spaced from the test point 3 by
~uch a distance that the pressure drop wave originating
in the test point 3 has an amplitude sufficient for record-
ing thi~ wave ~s it appr~ache~ the vicinity of the test
point 9 by means of a pick-up providsd in the test point 9,
It appears that since the pressure drop wave is propagated
with the product transferred in the pipeline, the diqtance
between th~ points 3 an 9 mu~t be measured along the pipe-
lines connecting the two Point~. It is also evident that
this di~tance must be selected along the shorte~t of all
possible path~ of propagating the pre~ure drop wave
between the test points 3 and 9, nQmely, one of the paths ~;^
3-2-1-5-9, 3-2-6-10-9, 3-7-6-10-9, etc. The ~hortest way
of propagatio~ o~ the pressure drop wa~e with the product
tran~ferred bet~een two points is determined by an ap-
propriate method, such as the Ford method. Suppose that
the ~hortest path of propagation of the pres~ure drop w~ve
between the test points 3 and 9 i~ the path 3-2-6-10`9.
Thus, as the te~t point 9 for mounting the pick-up~
i~ selected, we are intere~ted in the first, the ear-
liest of all, operation of the pick-up mounted in the te~t
point 9 in respon~e to the pressure drop W8Ve originating
in the test poi~t 30 In ca~e the above conditio~ of ~elect-
ing the te~t point 9 is observed 7 thi~ pre~ure drop wave
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will not cause the pick-up mounted :in the point to be
repeatedly operated as it approaches the point Rlong other~
longer~ sections of the pip9 sy~tem~ Similar considera-
tions co~cerning the first operation~ of the respective
pick-ups hold for the selection of the subsequent test
points.
A third te~t point 18 i~ selected with a maximum
spacing from the test points 3 and 9 where the pres~ure
drop wave originating in the test point 189 a9 it appro-
aches the te~t point~ 3 and 9, has an amplitude sufficient
for operation of the pick-ups disposed in these test
point~. The condition for selection o~ maximum distances
along the shortest path o~ propagation o~ the pre~sure
drop waves also holds for the third test point 18 a~ well
a~ for the ~ubsequent test points. Suppose, for instance,
that the ~horte~t path for the presqure drop wave propa-
gated from the point 1~ to the point 3 lies along the
~ection~ 18-13-B-4-3, while for the wave propagated ~rom
the point 18 to the point 9, it is along the ~ection~
18-17-16-15-10-9.
A fourth test point 19 is selected using the abova
considerations, i.e. with a magimum spacing from the teqt
points 9 and 1~, p~rmitting to record the pre~sure drop
wave~ ori~inating in the te~t point 19 by the pick-ups
dispo~ed in the test point~ 9 and l8, the pick-ups respond-
ing~ ju~t a~ in the case~ considered hereinbefors 5 to the
wa~e arriving thereat along the shortest paths between the
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respective test point~.
Sub~equent test points 20 and ~l are sImilarly
~elec-ted. Speaking of the gener~l ru1e o~ ~electing te~t
point~, it may be ~tated that each test point i~ ~paced
~rom the two te~t point nearest thereto by maximum di~-
tances ~o that the pre~3ure drop w~ve originating in thi~
point ha~ un amplitude, in the two of ~id te~t points,
~uf~icient for operation of the pick-up~ di~po~ed in these :~
te~t points, proYided that the pressure drop wave mo~e~
along the shortest path. The selection o~ the te~t point~
i~ continued until their nu~ber becomes large enough for
supervi~ion of the entire pipe sy~tem~ i.e. the number of
te~t point~ wherein the pick-up~ are mounted should be
such that wherever a fault occurs in the pres3ure pipe
system, the pressure drop wave origi~ating in this polnt
mu~t reach at least three te~t points. If the abovementioned
rule o~ selectin~ test points is ob~arved, the number o~ :
pick-ups used in the supervision ~y~tem will be minimi~edO
Suppo~e th~t in some point o~ the pres~ure pipe
sy~tem sho~n in the drawing a f~ult ha~ occured. A pre~-
~ure drop wave begin~ to prQpagate from the poînt o~ the
leak at a given speed depending on the hydraulic characte
ri~tics of the pipeline~ and the phy~ical properties of
the product being tran~erred, which wave cause~ three
pick-up~ to reepond, e.g. the pick-up~ mounted in the te~t
poînt~ 3,9~18, the pick-up mountsd in the te~t point 3
operating fir~t, followed by the pick-up mounted in the
te~t point 9, and finally~ the pick-up mounted in the
te~t poi~t 18.
According to the in~ention, xe~ponse times o~ the~e
pick-up~ are recorded. Let the respon~e time of the pic~-
up mounted in the te_t point 3 be tl, the response time
of the piok-up mounted in the test point 9 be t2, and the
re~ponse time of the pick-up mounted in the test point 18
be t3-
~ he di~ference A t~ between the respon~e times of
the pick-up~ mounted in the test points 3 and 9, the dif-
ferenca ~t2 between the respon~e time~ of the pick-ups
mounted in the te~t points 9 and 18, and the difference-
~t3 between the respon~e time~ of the pick-up~ mou~ted
in th~ te~t point~ 3 and 18 are then determi~ed:
~!~ tl = t2 - tl
~t2 - t3 - t2
~t3 = t3 ~ ~.1
Three ~et~ of po~ible point~ of the f~ult are furt- :~
her determined from the di~ference~ obtained d tl, a t29
and ~t3 9 based on the fact that the point oP the fault
to be detected mQy lie~ on the one hand, ~n any of the
~ection~ of the pipe ~y~tem bet~een the pointq 3 and 9p
Rnd on the other hand, either in any of the pipe ~ection~
between the point~ 9 and 18 or I~ any o~ the ~ection~
betwee~ the poi~t~ 3 and 18.
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On each i-th p~th o~ all possible paths of pre~f3~re
drop wave~ between the poi~s 3 ~nd 9 9 the di~tance ~i
from th~ midpath to Q possible poi~t of -the leak i9
found.
2 v ~ tl9 .,
where V i9 the ~elocity of propagatio~ of the pre~qqure
drop wave along the product being tran~3ferred in
a particular pipe ~ystem, and
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the number 'n' o$ po~3~ible path~ of propagation
of the wave between the point~ 3 and 9 depending
on the con~iguration o~ the pipe system concerned
between the~e two points.
The di~tande al, along each i-th path, ~rom one of
the te~t points 3 or 9, e.g. from the poi~t 3, to the
po~,qible fault, i3 then determined:
ai = SiJ2 - 2i
where ~i i8 the length of the i-th path.
Since it i8 not known on ~hich of lthe paths conneGt-
i~g the te~t point~ 3 and 9 the fault il3 located9 'n' po~-
sible points o* the fault of the ~ir~t ~3et are obtained,
such a~ the point al on the path 3-7-6-'L0-9, the point a~
on the path 3-2-6-10-9~ the point a3 on the path 3-2-1~5-9, ~:
~tc~
Similarly, a ~eco~d ~et o~ po~ib:La points of ~he
fault i~ found~ namely, on each j-th pat:h o~ po~ible
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paths o~ propag~tion of the pre~ure drop wave between
the point~ 9 and 18~ the di~tan¢e Y~ ~rom the centre o~
thi~ path to the possible poi~t of the fQult i~ given by:
Yj = 1/2 V ~2'
where j = 1, 2, 3 ... ~ m, :~
the number 'm' of pos ible path~ of propag~tio~ o~
the wave between the points 9 and 18 dependin~ on the con-
~iguration of the pipe ~y~tem between the two poi~t3.
The di~tance bj, along each j-th path, from one of
the point~ 9 or 18, e.g. ~rom the point 9, to a possible
point o~ the fault is then determined:
bj = Sj/2 - Ya ~
where S j i~ the length of the j-th path.
Since it is not known on which of the paths connect-
ing the test point~ 9 and 18 in the pipe sy3tem the fault
lies, 'm' pos~ible points of the leak of the second ~et is
obtained, such as point bl on path 9-10-6-7-8-13-18, poi.nt
b2 on the path 9-10-15-16-17-18, point b3 on the path
9-10-11-12-13-18~ etc.
A third ~e~ o~ pos~ible points of the fault 1~ ~urther
found, namely, on each k-th path of poss~ble paths of pro-
pagation of the pre~ure drop wave between the point~ 3
and 18, the distance Zk from the midpoint of the path to a
possible point of the leak is determined u~i~g the e~pre~
sion
Zk = /2 V ~ t
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where k = 1, 29 3 ...... 19
the number '1~ of po~sible paths of propagation of the
wave between the point~ 3 and 18 depending on the configu-
ration of the pipe sy~tem bet~een these point~.
The distance Ck along each k-th path, from one of the
points 3 or 18, e.g. from th~ point 3, to a po~ible point
o~ the fault is then calculated: -
Ck = ~k/2 ~ Zk
where Sk i~ the length o~ the k-th path.
Since it is not known on which particular path of the
path~ connecting the te~t point3 3 an 1~ with~n the pipe
system the fault is located, '1' pos~ible points of the
fault of the third ~et of point3 is obtained, such as
point cl on the path 3-4-8-13-18, point c2 on the path
3-7-12-17-18,.point C3 on the path 3-7-8-13-18, etc.
The exact point of the fault is determined, within
rea~onable tolerances, by the coincidence of one of the
po~sible point~ of the fault of one set with one o~ the
pos3ible points o~ the fault of another ~et or other ~ets.
In this particular example, the points al and bl approxi-
mately coincide, thus locating the fault in the pipeline
at ~ome point A lying.on ~ section de~ined by the point~
~1 and bl. Ideally ths length o~ the 3ection will be zero
~point~ al and bl coincide~ but in practical embod~nent o~
the method~ the point~ al and bl coincide to within the
maximum section length of 3 mO
Whether there occur~ the coi~cidence of the po~ible
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poi~ts of the fault of the first and ~econd set3, or of
the firæt and third ~ets7 or of the second and third sets,
or of all the three sets of point3, depends on the posi-
tion of the leak with respect to the three test points
where the pick-ups have operated~ as well RS on the con-
figuration of the pipe ~y~tem between these points~ If the
leak lay close to a point such as point 12, the coincidence
of three points would occur, i.e~ of one o~ the points of
the set 'a' with one o~ the points of the set tb' and with
one of the points of the set 'c'. In fact, the pressure
drop wave would tra~el, in thi~ case, from the point 12 to
test point 3 along the p~th 12-7-3, to the test point 18
along the path 12-13-18, and to the test point 9 along the
path 12~ 10-95 the length of the wave path bet~een the
test point~ 9 and 3, 9 and 181 an 3 and 18 equalling the
sum of the wave propa~ation paths from the point 12 to two
te~t points~ i,e. the paths 12-11-10-9 plus 12-7-3, paths
12-11-10-9 plus 12-13-18~ and path~ 12-7-3 plu~ 12-13-18,
respectively.
~ he in~ention can be advantageously utilized in muni-
cipal service for the purpose of superYising water supply
and heat supply systems o~ the cities, and in chemical
industry for supervision of comple~ pipe ~ystems o~ large
chemical plants. The invention is superior to the known
methods for similar applications in that it provide~ a
higher reliability9 a ~reater simplicity, and a compara-
tively lower cost.
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