Preventing Hydrogen Migration in Inconel Bellows Migration In Inconel Bellowspdf.pdf · Preventing...

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. 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.







affiliates.

Figure 1. SN 231895 Bellows Gas Analysis Results







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).







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.







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.







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







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








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








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








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.)


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