Note: Descriptions are shown in the official language in which they were submitted.
CA 02196523 2000-09-27
TEST PLUG FOR PIPES
This invention relates to a test plug for pipes.
BACKGROUND TO THE INVENTION
In the fabrication of fluid flow systems, whether they be for the purposes
of conveying liquid such as petro-chemicals, or gasses such as natural gas, or
even
fluidized cereals as is common in the cereal processing industry, the use of
conduits or
pipes is common and replete. From a fabrication point of view, pipes can only
be
manufactured to a finite length and therefore, various lengths or elbows must
be
connected together in order to structure the conduit fluid conveyance means.
This is
accomplished by welding butt ends of pipes together or to elbows etc., or
alternatively, to
weld the end of a pipe to a butt flange and to juxtapose two butt flanges
together by
means commonly known, for example, use of bolts through each juxtaposed
annular
portions of each butt flange. Generally, such flanges co-operatively employ
gaskets as
sealing elements.
It is increasingly desired to have these welds tested for the purposes of
determining whether these welds tested for the purposes of determining whether
there is
any leakage. Particularly, in the petro-chemical industry, it is now being
mandated that
the amount of fluid evaporating or escaping from any weld or flange/flange
interface be
reduced to allowable limits which, up to now, have been about 2 liters per
annum to less
than a 1/4 of a liter per annum per flange/flange or weld interface. When one
considers
that in petro-chemical plants there are thousands of such welds or butt
flanges, the task of
testing each of them becomes onerous and costly.
THE INVENTION
We have conceived a simplified test plug which
is used to test pipes, with an internal diameter of approximately %2 inch
(1.75 cm) and
with modification to as great as what is desired, say even 6 to 10 feet (300
cm), or more.
CA 02196523 2000-09-27
It is an object of the invention to provide a simplified test plug which can
be hand carried by one or two workers, assembled within the diameter of a pipe
to be
tested, temporarily sealed therein so as to allow a testing step to take place
which tests
the integrity between an annular pipe segment and the test plug, the annular
pipe segment
generally including a welding interface or a flange interface, or other
surface, in order to
determine if this region leaks at all, and if it does, to what extent.
The invention therefore contemplates a test plug assembly for testing the
internal integrity of a segment of pipe having an internal diameter, the
assembly
comprising (a) an annular body with opposite annular faces and defining on its
outer
perimeter, a peripheral recess, (b) a pair of bosses (c) a pair of resilient
annular members
adapted to be respectively juxtaposed between a boss and an annular faces, (d)
means for
urging the bosses respectively against an adjacent resilient annular member so
as to cause
the same to frictionally engage and to seal against a boss, and its adjacent
annular face,
and the internal diameter of the pipe segment, and (e) means communicating
through the
assembly to that plenum now defined by said recess, the annular members, and
the
internal diameter of the pipe, whereby the integrity of the pipe segment may
be
determined. Particularly, the urging means (d) is a shaft which extends
between said
bosses, preferably with one of the bosses being integral to the shaft, the
opposite end of
the shaft being threaded so as to provide means for urging the resilient
annular members,
respectively between an adjacent annular face and boss in order to seal the
diameter of
the pipe, there to define the plenum. In one embodiment, the communicating
means (e)
communicates through the shaft from its threaded end and provides
communication
means to the recess in the annular body, which preferably is a peripheral
annular recess or
race.
In another embodiment, there may be a pair of communicating means to
the peripheral annular recess defined by the annulus and the urging means
being a
plurality of axially oriented circumferentially disposed bolts, in which case
each boss
may be an annulus. In order to further reduce weight, the annulus may be
aluminum
wherein the outer annular recess is milled from cylindrical aluminum stock;
and the
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CA 02196523 2000-09-27
bosses, fabricated wither from steel or aluminum solid rod or square stock and
appropriately milled.
In above noted embodiments, the hydrostatic testing media is a fluid-like
liquid, preferably water, which is inserted into the plug after its sealing
engagement
within and communicating with the inner diameter of that selected pipe space
which now
defines the testing plenum is itself defined by the plug and the internal pipe
space
diameter. Into the testing plenum, the testing media is flowed, via conduits
through the
plug; then, pressurized to test the integrity of that portion of the pipe that
is in juxtaposed
communication with the hydrostatically filled testing plenum.
In a variation of the aforesaid embodiments, the "test plug" is also an
isolating-monitoring plug; namely, one that isolates pipe space from a region
or interface
while allowing monitoring of that pipe space on the obverse side to the test-
isolation
monitoring plug from that pipe interface that is to be either tested, or to
which a weld is
to take place, for instance, the creation of a pipe-weld-pipe interface or a
pipe-weld-
flange interface or any other similar interface that is to be tested.
In its broadest application, the invention contemplates a method of testing
the internal integrity of a pipe segment having an internal wall defining an
internal bore
having an internal bore diameter comprising the steps of (a), selecting a
resilient annular
member having an outer diameter less than the internal bore diameter, two
bosses, each
with an outer diameter less than the internal bore diameter, at least one
being a disk (b),
positioning , within the internal bore, the bosses on opposite sides of the
resilient annular
member (c), moving the bosses, relatively closer to each other to compress the
resilient
member therebetween into sealing engagement with the internal wall of the pipe
and (d),
conveying a fluid into the internal bore and against a boss to test the
internal integrity of
that pipe segment, juxtaposed therewith. Particularly, and in the preferred
embodiment,
the method of testing comprises the steps of (a), selecting an annular body
with an inner
annular diameter and outer annular diameter that is less than the internal
bore diameter,
the body having an outer peripheral race of diameter less than the outer
annular diameter,
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two resilient annular members, each respectively having an outer diameter
greater than
the outer annular diameter and an inner diameter less than the outer annular
diameter, two
bosses, each with an outer diameter less than the internal bore diameter (b),
positioning,
at opposite ends of the annular body, one of the resilient annular members,
then a boss
(c), moving the bosses, relatively closer to each other to compress the
resilient member
adjacent thereto into sealing engagement among the annular member and the
internal wall
to thereby define an annulax space among the outer peripheral race, its
adjacent
communicating internal wall of the pipe segment, and the annular resilient
members and
(d), conveying a fluid through the annular space thereby to test the internal
integrity of
the pipe segment communicating therewith. Either one or two annular bosses may
be
selected, if one, the opposite boss is a disk boss with front and obverse
faces and, when
the diameter is quite large, the disk boss may be supported on its obverse
face.
DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example and with
reference to the accompanying drawings:
Figure 1 is an assembly perspective view of a test plug, according to the
invention, particularly suited for pipe diameters up to 3.5" (8.9 cm),
approximately;
Figure 2 is a sectional view in preliminary application of the plug of
Figure 1 into a butt flange pipe weld interface, the integrity of which is to
be tested.
Figure 2A is the same as Figure 2 showing the fitting of the plug in sealed
position;
Figure 2B is an orthogonal cross-section to that of Figure 2 and 2A further
showing testing;
Figure 3 is a cross section along lines III-III of Figure 2;
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Figure 4 is a partially axially cross-sectional view of an alternative
embodiment of pipe plug with venting, particularly suitable for larger
diameter pipes of
up to about 8" (125 cm);
Figure 5 is a partial section illustrative of the testing sequence for testing
the integrity of the pipe flange welded interface;
Figure 6 is an end plan view of yet a third embodiment of test plug,
allowing a central cavity through the plug and particularly adapted to test
pipes of
internal diameters of 8" or more;
Figure 7 is an axial section along lines VII-VII of Figure 6; and,
Figure 8 is a diametrical cross-section of another embodiment of test plug,
wherein one annular boss substantially occupies the total internal diameter of
the plug,
and hence is a disk, while providing an aperture therethrough communicating to
a
channel therewith for pressure or content monitoring of internal pipe space,
the opposite
boss being an annulus.
Figure 8A is a section of the flange-weld-pipe interface of Figure 8 buy
illustrating an annealing step to anneal the weld, the test plug shown in
phantom.
Figure 9 is a diametrical cross-section, along lines IX-IX of Figure 10, of
yet a further embodiment of the test plug of Figure 8 wherein the disk boss
has no
aperture and is supported by a brace structure that is particularly suitable
for large
internal diameter pipes, say 54" (135 cm) or more of internal diameter.
Figure 10 is an end plan view installed, of the test plug of Figure 9.
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Referring to Figures l and 2, one embodiment of test plug is generally
shown as (10) and is suitable for testing the integrity of a welded
discontinuity (3) like a
flange (31) -weld (3) pipe (32) interface. The flange (31) generally is a
standard butt
flange, as will be apparent hereafter, while the pipe or conduit (32) is
generally of a
diameter up to approximately 18" (82.3 cm). The welded discontinuity (30), is
a weld
which holds the flange (31 ) to the end of the pipe (32) so that a
corresponding flange of a
next pipe run may be bolted thereto each butt annular surface (33) of each
flange (31)
juxtaposed. Initially, it is the weld interface (30) whose integrity is to be
determined;
whether or not there are unseen fissures or apertures which may allow leakage
of a fluid
which will pass through the conduit (32) when in application as in the petro-
chemical
environment or otherwise. A bolted flange-flange interface could similarly be
tested, as
could any other pipe discontinuity.
In the first embodiment, the plug (10) includes a cylindrical shaft (11) that
at one end has a threaded shank (12) and at the other end, an integral boss,
plug or disk
(13) so as to form an integral shaft component (14); the disk (13) has an
inner bevelled or
truncated cone-like peripheral surface (13'), as shown. The shaft (11) defines
an internal
bore (15) communicating with a flaring outer or distal end (16) that acts as
an attachment
means to communicate the bore to a water pressure source that, during testing,
acts a
pressure media as will be explained. The bore (15) extends approximately mid-
way into
a along the longitudinal axis of the shaft ( 11 ), as more clearly seen in
phantom in Figure
2 and in the cross section Figure 2B, and communicates with diametrically
oriented
channels (17), which communicate to the outside surface of the shaft (11) -
see Figure
2B.
The shaft ( 11 ) is adapted to pass through an annular piece, sometimes
referred to as the annulus, generally referenced as (20) having an internal
bore (21) sized
larger than the external diameter of the shaft (11) and having at least a
radial bore, shown
in figures 1 and 2 as two racially oppositely disposed channels (22) that
communicate
between a stepped annular recess (23) exteriorly circumscribing the center
portion of the
annulus (20) with the inner bore (21 ). The opposite ends of the annulus (20)
are integral
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radially protruding disks (24) and (25), with their respective outer truncated
annular
surfaces (24') and (25') being bevelled inwardly from center to perimeter.
In order to complete the other rigid components of the plug (10), there is
an annulus (26) whose inner bore is larger than the outer diameter of the
threaded shaft
( 12) so as to accommodate its passing therethrough with space, the annulus
having an
interface (26') as a reversibly bevelled annular conical surface, and its
outerface,
preferably orthogonal to the longitudinal axis of the bore, yet having a
stepped bore of
slightly larger diameter at the interface between this space and the inner
bore of the
annulus so as to define a channeled race (26r) which accommodates a smaller
elastomeric
ring (R3), as will be explained. The obverse surface (26') is a reversibly
bevelled annular
conical surface, which might also be "truncated", as are clearly seen in
Figures 2, 2A and
2B.
1 S A second boss in the form of an annular collar (27) has its inner bore
sized
to accommodate the threaded shaft, to mate with a threaded nut (28) which is
adapted to
thread onto the shaft and to compress all the components of the plug referred
above into
one integral unit. In order to provide annular sealing between juxtaposed
bevelled
surfaces (13') and (24'), there is an elastomeric annular ring (Rl);
similarly, there is an
elastomeric annular ring (R2) juxtaposed between truncated conical annular
surfaces (25')
and (26'), the elastomeric annular seal (R3) which nests into the annular race
(26r). The
inner diameter of the annular race is sized to frictionally engage the outer
diameter of the
shaft (11) so as to provide a sealing fit as will be explained.
In order to insert the assembled plug (10) into the pipe interface so as to
test the integrity of the internal diameter of the interface (30), and now
referencing Figure
2, the assembled plug in its relaxed mode is placed into the pipe flange with
the interface
(30) occupying or communicating with the area defined by the annular recess
(23). The
nut (28) is turned down, as shown by the arrow in Figure 2A, and the
respective annular
bevels (13') and (24') forced into closer proximity; and similarly, with
juxtaposed bevels
(25') and (26'), respectively forcing the respective annular rings (Rl) and
(RZ) outward in
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the direction of their respective arrows (Ra). At the same time, fluid in the
direction of
the arrow (F), floods the bore (15), the oppositely disposed radial channels
(17)
communicating water flow into the foreshaft regions referenced (40) in Figure
2B, out the
radial channel (22) of the annulus (20) so as to flood the annular space (S)
defined by the
plug (10) in the internal diameter of the pipe flange interface. Some of the
fluid would
escape, flowing in the direction of arrows (60) during initial purging of any
air within the
space or plenum (S) while the nut (28) is turned down in the direction of the
arrow (50)
eventually sealing with the space (S). The annular ring (R3) isolates the
annular space (S)
between the internal bore (21) and the outside shaft diameter (11) so as to
create a
watertight environment.
Additional water pressure is applied so as to increase the pressure of water
within space (S). The pressure of water within space (S) can be measured by a
hydrostatic device, not shown, while observing the outside of the weld
interface (30) to
see whether any leakage occurs.
In the embodiment of Figures 4 and S, which is particularly suitable for
internal pipe diameters up to approximately 125cm because test plugs with
larger
diameter than about 90cm, Figures 1 through 3, become too heavy for workmen to
carry
thus, the same consists of a shaft (41 ) having an external end boss or disk
(42) at one end
and a threaded portion (43) at the opposite end, the shaft and disk defining a
central bore
(44). The disk (42) is welded at (45) to an annular end disk plate (46) whose
inner
margin (46') is a bevelled annulus to accommodate "O" ring (R1). There is an
opposite
annular end disk (47) with a similar inner annular bevel (47') to accommodate
annular
ring (RZ) but the disk (47) also has an aperture therethrough (48) which
allows passage of
a hydrostatic flooding and testing circuit, generally shown as (50) to extend
therethrough.
The plug (40) includes an annular piece (60) defining an inner bore (61) which
accommodates the shaft (41) and an outside circumferential race (62), which
includes a
hydrostatic filling channel (63) communicating with the testing circuit (50)
in the fashion
shown. As such, the circuit (50) has a threaded hose (51 ) whose distal end
threads into
and sealingly mates with a corresponding thread (T) defined by the outer
extremity of the
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bore (63) to make a fluid channel passing through the disk (47) and
communicating with
the race (62). The bore (44) acts as a venting channel to allow venting of the
internal
pipe (32) when the plug (40) is being inserted into the flanged pipe bounded
by the
peripheral weld (30) which is put in place to sealingly attach one to the
other - see Figure
S. It may also be an advantage to conduct a second testing circuit which is
referenced
(65) to test everything that is to the right of the plug (40), as shown in
that figure. Thus,
the same bore (44) serves to vent the interior of the pipe (33) during
insertion and
removal of the plug (40) or, alternatively, accommodates a second circuit for
testing the
interior of the pipe (32), if required, by utilizing testing circuit (65).
If the space (S) which is bounded by the plug (40) and the internal pipe
(32) flange (31) and circumferential weld (30) is to be tested, then
preferably threaded
hose (51) is positioned so as to be vertical over the bore (44) and the
testing circuit (SO)
includes a hydrostatic pressure gauge (P) communicating with the hose (51), a
venting
valve (V) having a switch (Vl), and a hydraulic fluid control valve (H) with
its
corresponding switch (H~). Water is periodically allowed to flow through valve
(H) into
space (S) by opening (H~) and closing (V~) and venting of the air within the
space (S) is
achieved by reversing valve positions (H~) and (Vl) so air vents out of valve
(V) in
accordance with the arrow thereabove. This cycling occurs until the space (S)
is filled
with water and then pressuring of the water takes place so that the pressure
gauge (P)
registers the hydrostatic pressure on the circumferential weld seam (30) to
test the
integrity of the same.
Refernng Figures 6 and 7 and to the third embodiment of the invention,
the same consists of an annular plug (80) consisting of mirror end annular
bosses or
plates (81) and an annulus (82) with an outer circumferential race (83). The
juxtaposed
faces of the annular plates (81) and the annulus (82) are respectively
bevelled at (81') and
(82'), as shown, so as to accommodate the seating of "O" rings (R~) and (R2)
therebetween. Each of the annular disks (81) have a plurality of apertures
(84)
therethrough circumferentially disposed so as to permit the passage
therethrough of a nut-
bolt arrangement, generally shown as (85) consisting of a bolt head (86) which
is welded
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at (89) to the exterior face of one of the annular disks (81 ), the opposite
end of the bolts
(85) having a threaded shaft portion (86) accommodating a nut (87) which can
be turned
down onto an underlying washer (88). The annulus (82) may have appropriate
diameters,
as may the disks (81) to accommodate internal pipe (32) diameters over 9", as
may be
required.
The annulus (82) defines a filling and pressure channel (90) which
communicates through the annulus (82) to the outside annular race (83), and
diametrically opposite thereto a venting channel (90'). The plug (80) can be
inserted into
large diameter pipes exceeding 8", the bolts (87) tied down so as to force "O"
rings (R,)
and (Rz) against the inner diameter of the pipe-flange interface to be tested.
Liquid media
is channeled into the space (S) defined by the race (83) and the inner wall of
the pipe
flange interface while venting of any air exits the diametrically disposed
venting channel
(90").
Because of the great weight of the annular plug (80), particularly when
made of steel, or steel alloys such as stainless steel, each annular plate
(81) has four
adjusting heads (95) diametrically paired and consisting of a protruding butt
(96) having
a threaded bore (97) accommodating a threaded bolt (98) which extends
therethrough and
whose distal end is adapted to turn against the internal diameter of the pipe
(32), to locate
the plug (80) co-axial with the pipe (32). Locking nuts may then be turned
down to lock
each bolt (98), as shown in phantom in Figure 7, against the internal diameter
of the pipe
(32) that is being tested. Thereafter, flange nuts (87) are turned down to
apply the
pressure on the "O" rings (R,) and (RZ) sealing them against the inner walls
of the pipe
flange interface so that the annular space (S) occurs as above noted, and
pressure venting
in the fashion, as earlier described, can take place. It is convenient to make
the annulus
(20), (60), (82) from aluminum in order to reduce its weight, and in certain
applications
even the bosses (13), (26), (46), (47), (81) may be made from appropriate
stock but in
some applications, particularly in the cereal industry, the whole plug will
have to be made
from stainless steel in order to meet health standards.
CA 02196523 2000-09-27
Referring now to yet a further embodiment and to the Figures 8 and 8A, a
test plug (190) also acts as an isolation and pipe space monitoring plug, and
has an
annular boss flange (81) and an opposite (annular) flange (181) in the form of
a disk
defining a central axial aperture (182) therethrough which communicates to a
monitoring
conduit reference (65') and into the internal pipe space diameter, referenced
(PS), of the
pipe (32) to the left of the flange (181) which can be perceived to be a long
continuous
pipe space of a fluid conveying conduit in an existing installation to which
it is now
desired that there be affixed onto the end of the pipe (32), a flange shown in
phantom as
(31). Thus, particularly in instances where the pipe space (PS) is part of a
conduit, in a
petro-chemical plant, it must first be drained of contents; nevertheless,
there are residual
airborne hydrocarbons in the pipe space (PS) and also embedded into the inner
surface
walls of the pipe space (PS). When welding to such existing pipe space (PS),
present
safety standards require that the pipe space (PS) walls first be cleaned; this
is expensive.
With the isolation test plug configuration (190), this is not necessary.
The test plug (190) has the two O rings (Rl) and (R2) which are urged
respectively against boss (81) and annulus (82) on the one hand, and disk
(181) and the
opposite end of annulus (82) to urge the O rings (Rl, RZ) against the inner
walls of the
pipe that is now defined as the plenum space (S). Cooling water may be
inserted into the
pipe space (S) by flowing water through conduit (90) into the plenum space (S)
to
outflow from conduit (90). When cold water is used, the temperature of the
pipe to the
left of the plug ( 190) maintains the pipe at a non-flammable temperature for
the
hydrocarbons that may reside in the pipe space (PS). Either a gas monitor, not
shown, or
other temperature sensitive device may be pushed into from right to left, the
testing
circuit conduit (65') through the conduit (182) into the pipe space (PS) for
monitoring
while welding of the weld (30) takes place.
After welding, another plug (290), similar to that of (190) is positioned, as
shown in phantom, on the inside surface of the pipe (32) and the integrity of
the weld
(30) tested by applying appropriate fluid pressures to the space, referenced
(5290),
defined by the O rings (R1 ) and (R2), the annulus (82), and the internal
diameter of the
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interface of the pope (32), weld (30) and flange (31). Throughout this testing
the other
isolation test plug (190) can be left in position. Once the integrity of the
weld (30) has
been assured, in some instances, it is also necessary to stress-relieve the
weld (30). This
is accomplished by applying an annular stress-relieving heater, referenced
(500) over the
S weld (30); the heater has an overcovering insulation (505). The pipe-weld-
flange
interface (30,31,32) is brought up to the annealing temperature while water is
still flowed
into channel (90) and out channel (90) for plug (190), keeping cool that pipe
juxtaposed
to the water-filled plenum (S) and maintaining a cool temperature of the pipe
to the left
thereof and particularly, to the pipe space (PS). It ahs been found that the
width of the
plug between bosses (81) is preferably about 6" and the position of the plug
(190) from
the weld (30) should be at least, for safety purposes, about 2'. In petro-
chemical
applications, the distal end of the conduit (65') which actually allows
venting and
monitoring of the pipe space (PS) is open ended and should be at least 35' or
more away
from the physical location of the plug (190). The cooling waterflow through
the circuit
(90), (S), (90') should be at a positive pressure of around 100 PSIG.
The operational sequence placing a flange, phantom flange (31), in
Figures 8 and 8A, would be as follows. Drain the pipe (32) and pipe space (PS)
of all
hydrocarbon liquids and then place the plug (190) into place in a fashion, as
earlier
described and then inflow water into the annular space (S) by flowing water
into conduit
(90) and out of conduit (90). The monitoring pipe or tube (65') extends at
least 35' away
from site of the flange (190) and monitors, the temperature and volatiles
within the pipe
space (PS), (the monitoring devices not being shown).
The flange 31 is then welded by weld (30) to the end of the pipe (32) after
the pipe end has been appropriately dressed. Leaving the plug (190) in place,
a second
plug (290), similarly configured, is positioned on the inside surface of the
weld to define
a testing plenum (S290) which is flooded with water in a similar fashion to
that of plug
(190) thereupon the integrity of the flange-weld-pipe interface is determined.
Thereafter,
the second test plug (290) is removed and the weld (30) stress-relieved, as
follows. Now
refernng to Figure 8, the test plug ( 190) is still left in place and the
water continues to
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flow into and out of the space (S) via the respective pipes (90) and (90'). An
annular
heater (500) is placed on the outside circumference of the weld (30) and an
overcoverlng
annular insulating sleeve (505) is placed thereover and the weld (30) brought
up to its
annealing temperature in order to stress-relieve the pipe-weld-flange
interface. After the
annealing step, the annular heater (500) and insulating annulus (505) are
removed; the
weld allowed to become cool and then at a time convenient, the plug (190) can
be dis-
assembled,
Referring now to Figures 9 and 10, and yet a further embodiment of test
plug, the same is generally indicated as (190'), all other reference numbers
being the
same as those of the embodiments of Figure 8 and Figure 8A. The disk boss
(181) is
replaced with a solid disk boss (181') and when the diameter of the internal
pipe space is
greater then say, approximately 54" (greater then about 137 cm), great
pressure against
the disk boss (181') will cause it to bulge. Thus, there is required the use
of a support
disk (300) and a support base structure (301 ) featuring two orthogonally
oriented, radially
disposed cross bars (302) and (304), the distal ends of which are welded at
(310) to the
internal diameter of the pipe (32) and defined by an annular extended pipe
segment (320)
which, after use, can be cut off as will be described. Alternatively, not
shown, the cross
arms can be welded to the pipe distal end. Each cross arm (302) and (304) has
axially
oriented support elements (307), which extend to and are secured to support
disk (300),
preferably as shown in Figures 9 and 10 as being integral. The support
structure (301 )
provides support by its abutting disk (300) being flush with the obverse side
of the disk
boss (181') preventing bulging of the disk boss (181'). The test plug (190')
is assembled
and mounted into the internal space (PS) of the pipe (32), as shown, and water
is flowed
into the annular space (S) through communicating channels, not referenced buy
now to be
understood as being similar to channels (90) and (90'), shown in Figure 8.
If the pipe (32) is extremely long, say 100 metres or more, the whole pipe
(32) to the left of the test plug (190'), pipe space (PS), can be tested by
causing a high
pressure, referenced (HF) (high force) to be exerted in the direction of the
two arrows
onto the boss (181') face; bowing of the disk (181') is inhibited by the disk
(300) and the
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support structure (301). After the pipe space (PS) integrity has been
"tested", the support
structure (301) can be cut away from the pipe (32) as by an acetylene torch or
the like;
the support structure (301) is removed; then the test plug (190') can be dis-
assembled in a
manner as earlier described or if required, the pipe end that has been severed
can be now
dressed, flanged as by welding, as here and before described. The pipe-weld-
flange
interface can then be tested by relocating test plug (190') in juxtaposition
with the
interface in the fashion as earlier described.
14
