HomeMy WebLinkAbout5Examination of 2".RED THdEAD@ pipe Removed
from Gulf 0i1 Service Station #G86,
San Luis 0bispo, California
Report No. 189
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REPORT NO. I89
Examination of 2" RED THREAD@ Pipe Removed from
Gulf 0il Service Station #686, San Luis Obispo, California
TITLE:
Examination af 2" RED THREAD@ Pipe Removed from Gulf Oil Service S'lation #686'
San Luis Obispo, Caiifornia
STATEMENT OF PROBLEM:
Pipe samples were removed after noticeable product loss occured and there
wai an accumulation of gasoijne in a nearby telephone conduit. Gulf is inter-
ested in the cause of the leaks in this p'ipe because they may be asked to pay
for the cost of repairs to the telephone cable.
SUMMARY:
Four of the six spec'imens show obvious signs of physical damage and each of
these specimens leaked during an B0 ps'i pressure test.
CONC LUS I ONS :
Examination of the pipe indicates that all leaks are the result of physical
damage. Specimens i and 4 vrere the most severe'ly. damaged. All of these Pip9.
were-eithei mishandled or improperly buried. The damage is obvious and should
have been detected during instaliation or repair work.
PROCEDURES:
All spec'imens were visually inspected and photographed. Each specimen was
then hydlostaticall-v tested to city water prcssure, BO-B+i-. _Lefrki'ng'areas-
were marl(ed.
One failure area in specimen 4 was cut out, sectionedo and photographed to
show the extent of wal'l damage.
DiSCUSS]ON:
Specimens 1,2,3, and 4 leaked during pressure testing. Figures 1 - 19 show
views of these specimens. Circles in the overall vjews indicate the ieaking
areas in spec'imens l, 2, and 3. Specimen 4 leaked in the damaged area adjacent
to the labbled collar in Figures 14 and 15. The close up views show areas of
physical damage which leaked during pressure testing.
The leak areas in specimens 2 and 3 are clean which indicate that these speci-
lnens were probably iamaged after or during removal. Stains in the damaged
areas of specimeni I and 4 indicate that these areas leaked in service. The
most severb Aiscolorat'ion js in spec'imen l. The damage in both of these
specimens'is very severe and obvious. These pipe have been subjected to
rather severe point loading or impact.
The damaged area in specimen 4 is particularly interesting because it appears
t,hat in making a repair the contractor cut through a damaged area, taperedthe ends, and then joined them with a sleeve coufling. ll is difficuit to
imagine a situation'in which those making a repair would not see the damage
shown externally in Figure 16 and internally in Figure ,l7, lB' and .l9.
How-
ever, the red tracer threads at the ends of the two spigots match as if the
pipe had been cut through the damaged area. The damaged areq.s aiso match in
w'iatn and frayed ends of the damaged pipe are covered with adhesive indicating
that the danrage existed prior to bonding'into the coupling. l"hese features
can be seen in Figures 17, 18, and .l9.
Figure 20 shows permanent bending in specimens 3 and 5. This is not unusual
foi pipe which has been installed under a bending stress, The wall faiiures
are not related to the bending and the performance of this piping system
wou'ldnotbeaffectedbythjsamountofbending.
Specimens 5 and 6 were stained in localized areas on the exterior by what
airpears to be an asphaltic residle. There are no leaks in either of these
specimens.
I
Ken th J. 0s d
Technical Service Supervisor
Research & Development
KJ0/dk
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Fi gure
0verall View of Specimen l.
Figure 2
Physicai damage in specimen i.
1
. Figure 3
Physical dama5le in spectmen i.
Figure 4
Physicai damage in specimen l.
Fi gure
Physical damage 'in specimen l.
Figure 6
Physical damage in specinren l.
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1
Figure 7
Overall view of specimen 2.
Figure B
Overall view of specimen 2.
Figure 9
Physical damage in specimen 2.
Figure 10
Physical damage in spec'imen 2.
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Figure 1 1
Physical damage in specimen 2.
Figure 1 2
Ovbral'l view of specimen 3.
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Figure 1 3
Physical damage in spec'imen 3.
Fi gure '14
0verall view of specimen 4.
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i gure '15
Physi cal damage i n spec'imen 4.
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Figure i6
Physical damage in specimen 4.
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Figure 17
Inside view of physical damage 'in specimeh 4 showing
alignment of red tracing threads and width of damage.
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Figure 1B
Inside view of physical damage in specinien 4.
Fi gure
Inside view of physical
19
damage in specimen 4.
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Figure 20
Overal I vi etv of specinlens 3 , 5, and 6.
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