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Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 1 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
ABSTRACT
For nearly a year now Quartzdyne has given extensive attention to the reported (customer feedback) problem of
Hydrogen migration through Inconel bellows. The problem resulting from hydrogen ingress, ultimately, is a
calibration shift after the gauge is removed from the well. The new hydrogen resistant bellows renders an Inconel
bellows significantly resistant to hydrogen ingress. Complete prevention of hydrogen ingress may not be realistic,
however the data presented shows these new bellows exhibited no appreciable hydrogen ingress, i.e. extension,
even after two weeks of exposure to a hydrogen rich environment. The test development to substantiate the
bellows ability to resist hydrogen ingress is also explained. Actual field testing has yet to be done and will require
the assistance of a Quartzdyne customer.
TEST DEVELOPMENT
Previous lab testing (see Quartzdyne EC2035), performed by an external vendor back in 2010, was able to
somewhat replicate the results as seen by customers, i.e. extended, squishy bellows due to hydrogen gas ingress.
This vendor had the ability to subject test units to high pressure (15 kpsi) in nearly pure hydrogen. Due to the high
cost of this testing and long lead time, it was greatly desired to develop an internal test that could be rapidly
deployed and iterated in order to develop a solution.
It was realized during early brainstorming that a pure hydrogen environment was not needed as it certainly did not
mimic downhole conditions. One paper discussed the known problem of hydrogen ingress in Inconel bellows and
diaphragms and proposed the ingress was actually hydrogen ions or protons, which, after passing through the
metal diaphragm, recombine into hydrogen gas inside the transducer (Meyer, “For hydrogen pressure applications,
go for the gold!”, Intech, July 1998, pg. 52). Once the ions have recombined into a gas, the hydrogen gas molecule
is much too large to pass back through the metal foil and remains trapped in the transducer. Through further, quite
extensive study and learnings, it was determined that simply exposing the bellows to a corrosive environment, at
elevated pressures and temperatures, was enough to generate hydrogen ions and subsequently induce hydrogen
ingress.
To validate the presence of excess hydrogen gas, two methods were used. In the first method, two test units, with
extended bellows, having been subject to the corrosive environment, were sent out for gas analysis. The bellows
were punctured, and the gasses expelled were analyzed. Both samples came back with a strong H2 presence as
seen in Figures 1 and 2 below.
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 2 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Figure 1. SN 231895 Bellows Gas Analysis Results
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 3 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Figure 2. SN 230066 Bellows Gas Analysis Results.
Despite these results, it was desired to have a secondary validation that the test environment had a hydrogen
presence and was the cause of the high levels of hydrogen measured inside the bellows. As stated earlier, it was
hypothesized the Inconel bellows could produce hydrogen gas, or was the source of the hydrogen ions, when
subjected to a corrosive liquid. It is a known chemical reaction that a corroding metal produces hydrogen ions. If
true, two pieces of bellows fragments could be used, one as an anode and one as a cathode, to create hydrogen
gas. If enough gas is generated and trapped it could be ignited, proving hydrogen is present. Wires and a power
supply, attached to each of the two bellows fragments, one positive and one negative, were used to increase the
rate of corrosion. The Inconel pieces were then submerged in the mild acid liquid in a glass tube with a sealed
stopper (see Figure 3).
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 4 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Figure 3. Generating Hydrogen Gas with an Anode and Cathode of Inconel 625
After a certain amount of time, an open flame was held above the glass tube while the stopper was removed. A
small fire ball resulted confirming the presence of a flammable gas, or most assuredly, hydrogen gas.
These tests confirmed that the corrosion of Inconel 625 was in fact a source of hydrogen. Therefore, it was
determined that the proposed test environment to stimulate hydrogen ingress was effective and could be used for
iterative tests for the purpose of finding a preventative solution. The mild liquid acid used for the test will not be
disclosed.
Hydrogen Barriers
A closed system or manifold of HiP fittings was constructed for attaching the test units (see Figure 4). The whole
system was filled with the corrosive liquid for each test conducted. One port was used to monitor pressure.
Threading the last device in, it was possible to generate upwards of 5000 psi at room temperature. Placing in an
oven, upwards of 25 kpsi was possible at 150C. High pressures were achieved simply due to fluid expansion at the
elevated temperature.
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 5 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Figure 4. Manifold of HiP Fittings for Exposing Test Units to Corrosive, HPHT Condition
Many different ideas were tested in an attempt to prevent hydrogen ingress through the bellows, which ultimately
results in a transducer being out of calibration. Various materials, coatings, hydrogen getters, plating etc. were all
candidates but none of these proved very effective. Continued research and testing led to a process that looked
extremely promising. This process was then developed and the test results are shown below. The details of this
process will not be disclosed.
RESULTS
The following results are from tests that were all conducted at 150C. Max pressure was not controlled. It was
difficult to set a prescribed pressure due to the nature of the test setup, i.e. using the temperature to generate the
pressure. Some of the variation in the results could be due to the pressure differences from test to test. Early tests
confirmed that max pressure was a variable in getting positive test results.
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 6 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Table 1. Aug. 7 2014 Test Results Showing Extension of Various Bellows
The “Control” label is for test units with a standard bellows. “Experimental” refers to test units with the hydrogen
resistant bellows. The above results also included two units with gold plated bellows and a welded bellows, for
comparison. In a previous attempt to eradicate this problem Quartzdyne found a 65% reduction in hydrogen
ingress and bellows expansion in laboratory tests when the bellows were gold plated (see Quartzdyne EC2035).
The bellows extension results for gold plated bellows in Table 1 confirmed these findings. The test article with the
welded bellows was used on numerous tests and eventually had taken on a significant amount of hydrogen and
was not used on later tests. The labels “A” and “B” indicate two different bellows vendors.
Welded bellows were considered early on as a potential solution, but these results were later deemed inconclusive
when it was discovered we had a flaw in our test setup. Early tests used separate pressure vessels for each test
article, which is an obvious, unwelcome variable. The manifold in Figure 4 eliminated the problem by equalizing
pressure to all the test units.
0
0.02
0.04
0.06
0.08
0.1
0.12
Exte
nsi
on
(in
che
s)
Test Units @150C and 15-25 kpsi for 96 Hours
Bellows Extension Test 8/7/2014
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 7 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Table 2. Aug. 11 2014 Test Results
The welded gauge result, in Table 2, does look promising, i.e. a small amount of extension, but this is the same
welded gauge from Table 1, and therefore the .029 is additional extension beyond the already incurred extension.
0.161
0.147
0.098 0.101
0.0000.006
0.000 0.000 0.000 0.000
0.029
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
Axi
s Ti
tle
Test Units @150C and 15-25 kpsi for 96 Hours
Bellows Extension Test 8/11/2014
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 8 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Table 3. Sept. 10 2014 Test Results
The results from Table 3 were very encouraging. There was no measurable extension in the new hydrogen
resistant bellows. These bellows are still Inconel 625, just like the control units, but have been improved to greatly
reduce their susceptibility to hydrogen ingress.
0.049
0.068
0.074
0.037
0.000 0.000 0.000 0.000 0.000 0.0000.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0.080
Exte
nsi
on
(in
che
s)
Test Units @150C and 26 kpsi for 24 Hours
Bellows Extension Test 9/10/2014
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 9 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Table 4. Sept 16 2014 Test Results – Experimental Bellows Experienced 144 Hours of Exposure
Table 4 shows there was some extension, even in the improved bellows, during this 144 hour test. There is a
possible explanation for this, with supporting data; however this information will not be disclosed.
0.049
0.0680.074
0.037
0.0060.003
0.0070.004 0.006
0.009 0.011 0.009 0.0090.005
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
Exte
nsi
on
(in
che
s)
Test Units @150C and 21 kpsi for 144 Hours*Control Units were only Exposed for 24 Hours
Bellows Extension Test 9/16/2014
Preventing Hydrogen Migration In Inconel Bellows
The information contained herein is confidential and proprietary and may not be
reproduced, used, or disclosed without prior written consent by
QUARTZDYNE, Inc. Page 10 of 10
© 2014 Quartzdyne, Inc. All Rights Reserved. QUARTZDYNE, the
Crystal Logo, and DOVER are trademarks of Dover Corporation and
affiliates.
Table 5. Nov. 20 2014 Test Results – Two Week Test
In Table 5, the hydrogen resistant bellows were in the corrosive environment for 336 hours and experienced
minimal extension. It should be noted that between tests, the recipe, so to speak, for the hydrogen resistant
bellows, was tweaked a number of times to try and optimize the performance. These iterations will inherently add
some variation in test results.
One comment about the extension numbers; all measurements were taken on an optical comparator which has a
perceivable resolution of roughly +/-.001 to .002 inches. This resolution is due to the nature of this type of
instrument which uses a magnified shadow image of the profile to take measurements with. It was still the best
option available to make these measurements. For reference purposes, a .001 inch bellows extension change can
be observed simply by a small temperature change experienced by the gauge.
Conclusion
The results present a strong indication that the new hydrogen resistant bellows do inhibit or significantly slow down
hydrogen ingress. Max extension observed for a new bellows, subject to the test environment, was .011 inches.
Some final validation tests are being conducted to ensure the results continue to be repeatable and the process is
stable. Field testing still needs to be carried out. There is a question that is still outstanding and that is, is the
simulated lab environment indicative of downhole conditions? Answering this question will ultimately determine if
the hydrogen resistant bellows are going to provide the performance the customer desires.
0.057
0.021
0.001
0.0070.003 0.003
0.000 0.0000.003
0.000
0.010
0.020
0.030
0.040
0.050
0.060
Exte
nsi
on
(in
che
s)
Test Units @150C and 10-22 kpsi for 336 Hours(Note, units were pulled from test 4 times for
incremental measurements.)
Bellows Extension Test 11/20/2014