THE IMPACT OF HEAVY HYDROCARBON PERMEATION ON PE PIPE · 2015-05-29 · Test Matrix for Saturation and Desaturation Testing The Impact of Heavy Hydrocarbon Permeation on PE Pipe Parameter

THE IMPACT OF HEAVY HYDROCARBON

PERMEATION ON PE PIPE

Karen Crippen, Gas Technology Institute

Ernest Lever, Gas Technology Institute

AGA Operations Conference and Biennial Exhibition May 19 - 22, 2015 2

The Impact of Heavy Hydrocarbon Permeation on PE Pipe

Project Objective

To develop a validated method to be used by any plastic testing laboratory to quantify the effects of hydrocarbon permeation on:

• The fusibility of plastic pipe. • The life expectancy of existing fused joints that may have been

subjected to hydrocarbon permeation.• The Hydrostatic Design Basis (strength) of plastic pipe. • The impact on slow crack growth.

The results of this study may lead to new or revised consensus standards and increase our understanding of hydrocarbon permeation effects on plastic pipe and the possible effects on pipeline safety.


Research is sponsored by the US Department of Transportation Pipeline and Hazardous Materials Safety Administration, Contract Number: DTPH56-14-H-00001

This project is relevant to PHMSA’s mission of enhancing pipeline safety as it will address the third identified gap by the Design/Materials/Welding-Joining and Valves working group:“Investigate the effects of hydrocarbon permeation on plastic pipe strength and fusion performance.”

The research being conducted seeks to further understand how the presence of heavy hydrocarbons in a plastic matrix can change the performance characteristics of PE plastic pipe used in the transportation of natural gas in local distribution systems.



Need for the Research

There is an increasing visibility in certain geographic regions of North America where heavy hydrocarbon permeation is a factor that needs to be addressed in plastic pipeline operations.

The phenomenon is being openly discussed by regulators and utility staff.

Industry is seeking guidance as to how to rate modern polyethylene pipe that has been subjected to heavy hydrocarbon permeation.



Approach:

a) Survey LDCs for their experiences in dealing with hydrocarbon permeated pipe and use this information to validate butt fusion procedures and make fusion technique recommendations

b) Use laboratory testing to look at the impact of hydrocarbon permeation on pipe strength, fusibility, and slow crack growth.

c) Use the results of the study to create a practical guidance for the industry on how to mitigate the effects of hydrocarbon permeation in gas distribution pipe.



This project kicked off in January of 2014.

Work to date has focused on:

1. The detailed design and commissioning of the overall test plan,

2. Establishing the technical advisory panel for the project.

3. Establishing the correct mixture of heavy hydrocarbons for use in this project,

4. Developing the analytical procedure to monitor saturation levels,

5. Executing the test plan with appropriate data-logging



A Technical Advisory Panel was formed comprising of three pipeline/utility operator representatives having assets relevant to the project scope, plus two technical experts. They will provide technical review comments on all aspects.

Panel members include:

Dr. Tom Walsh (President, Walsh Consulting Services Company)

Dr. Aaron Foster (Materials Research Engineer at NIST)

Mr. Michael Zandaroski (Manager, Materials Engineer, CenterPoint Energy)

Mr. Ed Newton (Pipeline Integrity Manager, Sempra Energy)

Mr. Reid Hess (Operations Supervisor, Questar Gas)



Material to be Studied

Based on feedback from the Advisory Panel, the following PE material was selected:

• PE2406/PE2708 unimodal MDPE (TR 418 )

• PE2708 bimodal MDPE

• PE4710 bimodal HDPE

These resins were selected to show applicability of the developed test protocols to different resins.



Rationale For The Heavy Hydrocarbon Cocktail

GTI has a small database of analyzed hydrocarbon pipeline condensate analyses. This data was mined to determine a “typical” hydrocarbon condensate composition.


Typical Liquid HC Ranges

Carbon #

Condensate ID Number

1 2 3 4 5 6 7 8 9 10

Wt% Wt% Wt% Wt% Wt% Wt% Wt% Wt% Wt% Wt%

C1 BDL BDL BDL BDL BDL BDL BDL

C2 0.02 0.02 0.02 BDL BDL 0.02 BDL

C3 0.2 0.1 0.1 0.01 0.04 0.1 BDL

Ga

so

lin

e R

an

ge

C4 0.6 0.1 0.2 0.2 0.1 0.4 BDL

Na

ph

tha

Ran

ge

C5 1.4 0.5 0.6 0.03 0.6 1.9 1.0 1.1 0.4 0.8

Ke

ros

en

e R

an

ge

C6 3.5 1.9 1.3 0.2 1.2 3.5 1.2 14.8 2.0 1.9

C7 10.7 6.2 3.4 1.4 3.8 8.0 0.8 26.6 6.4 3.7

C8 16.5 12.4 7.9 5.4 8.3 10.0 9.7 25.7 10.8 6.7

C9 17.2 14.3 12.2 13.7 14.1 11.3 5.5 18.1 20.8 10.2

C10 12.2 16.6 15.1 19.1 17.1 9.3 11.5 8.4 23.9 12.0

C11 8.8 17.0 15.6 18.9 19.8 12.2 8.1 1.6 17.6 13.7

C12 6.3 12.7 11.5 15.0 15.8 12.6 19.1 0.4 8.4 13.3

C13 5.2 8.4 8.4 11.1 10.0 10.6 17.1 0.4 3.5 11.6

C14 3.8 4.7 6.3 8.4 4.4 8.7 12.9 0.4 3.5 11.6

C15 2.6 3.1 7.1 4.5 1.9 6.1 7.8 0.2 1.5 10.0

C16 2.0 1.3 5.4 1.7 0.7 3.1 2.4 0.3 0.1 1.0

C17 1.7 0.5 3.2 0.5 0.2 1.4 1.2 0.1 0.04 0.1

C18 1.5 0.2 1.4 BDL 0.1 0.4 0.7 0.2 0.03 0.1

C19 1.2 0.1 0.4 BDL BDL 0.1 0.2 0.1 0.03 0.2

C20+ 4.6 0.04 0.2 BDL BDL BDL 0.03 1.6 1.0 3.1


The combined data was used to generate the hydrocarbon cocktail.


Carbon # Compound Weight % Carbon # Compound Weight %

Mixed IRM 901 10 7 heptane 5

7 toluene 2 8 octane 16

8 xylenes 1.5 10 decane 26

5 cyclopentane 1 12 dodecane 21

6 cyclohexane 0.5 14 tetradecane 12

6 hexane 3 16 hexadecane 2

Included in the mixture is IRM-901, a reference immersion oil that is used in testing polymers for the auto industry.

This will allow a closer approximation to industrial solvent compositions.

The suggested hydrocarbon mixture is a blend of approximately 4% aromatics, 2% cycloalkanes, 92% paraffins, and 3% naphthenics.


Test Plan For Examining The Impact Of Heavy Hydrocarbon Permeation On Pipe Strength

• Plastic pipe specimens were exposed to the hydrocarbon cocktail.

• Exposure temperatures are set at 23°C (73°F) 60°C (140°F) 80°C (176°F)

• Pipe strength will be examined using DTMA,tensile, and compression testing over the same range of temperatures using strain rates reflective of typical

industry operating conditions.



Correlating Absorption of Heavy Hydrocarbons with Time

• The saturation level was correlated with time using headspace gas chromatography with a flame ionization detector (HS-GC-FID).

• Microtomed coupon specimens will enable the determination of the depth of penetration.

• In order to determine the impact of any outgassing, a selected subset of test coupons wasallowed to desorb prior to microtoming and analysis.

• Percent weight gain and dimensional measurements were also determined as corollary data.



Optimizing the HS-GC-FID Analysis: What Temperature to Desorb At?


m in17.9 18 18.1 18.2 18.3 18.4

pA

0

250

500

750

1000

1250

1500

1750

F ID 1 A , (07152014-000001.D )

n-O ctane a t 140C

n-O ctane a t 175C

n-O ctane a t 200C

n-O ctane a t 225C

F ID 1 A , (07152014-000003.D )

F ID 1 A , (07182014-000001.D )

F ID 1 A , (08012014-000003.D )

Octane

m in26.4 26.5 26.6 26.7 26.8 26.9

pA

0

1000

2000

3000

4000

F ID 1 A , (07152014-000001.D )

n-D ecane a t 140C

n-D ecane a t 175C

n-D ecane a t 200C

n-D ecane a t 225C

F ID 1 A , (07152014-000003.D )

F ID 1 A , (07182014-000001.D )

F ID 1 A , (08012014-000003.D )

Decane

m in39.9 40 40.1 40.2 40.3 40.4

pA

0

250

500

750

1000

1250

1500

1750

F ID 1 A , (07152014-000001.D )

n-T etradecane a t 140C




F ID 1 A , (07152014-000003.D )

F ID 1 A , (07182014-000001.D )

F ID 1 A , (08012014-000003.D )

Tetradecane

140°C Best Response

175°C

200°C

225°C


Saturation Test Vessels


Pressure Tested to 150 psi with no leaks


Saturation Test Specimens


• 95% Convergence is defined as the time required to reach 95% of the maximum (saturation) or minimum (desorption) concentration

• Compression disk coupons (≈ 6.4 mm in diameter and ≈4.1mm in thickness) were prepared from each of the twelve lots of material

• A cage was used to separate the various lots of materials in the heavy hydrocarbon cocktail.

• After exposure, and prior to HS-GC-FID analysis, half of each coupon was microtomed into four 500 µm slices to look at HHC presence at different depths.

4.1 mm


Test Matrix for Saturation and Desaturation Testing


Parameter Permeation Testing Desaturation Testing

Elapsed TimeHourly, Daily, Weekly as

necessary to capture gradients

Hourly, Daily, Weekly as necessary to capture

gradients

Replicates 2 2

Exposure Temp. (°C) 23, 60, 80 ---

Materials

MDPEbmMDPEbmHDPEAldyl A

MDPEbmMDPEbmHDPEAldyl A

Total # Specimens 120 40


Saturation Test Results for MDPE at 23°C (left) and 80°C (right)


Physical Measurements – Mass and Dimension (Disc Thickness)

• 80°C data (right) converges quicker than 23°C data (left)

• Mass gain (red) is quicker than dimensional change(purple) – steeper initial rise

Physical Measurement

Approximate Time to 95% Convergence,

hours

Difference Between 23°C and

80°C23°C 80°C

Mass 625 56 11 xThickness 925 63 15 x


Saturation Test Results for MDPE at 23°C (left) and 80°C (right)


GC Headspace Data

• 80°C data (right) converges quicker than 23°C data (left)

• Outer surface (blue) equilibrates quicker than the interior

• Physical change data equilibrates quicker than the absorption into the test disk interior (2000 micron depth) suggesting that the initial swelling takes place more rapidly than the time to full material saturation

Depth, microns


hours

Difference Between 23°C and

80°C23°C 80°C

500 225 20 11 x1000 600 70 9 x1500 925 105 9 x2000 1100 103 11 xMass 625 56 11 x

Thickness 925 63 15 x


Desaturation Test Results for biMDPE exposed at 80°C


• Desorption temperature = 23°C

• Outer surface (blue) equilibrates slower than the interior – expected since the HHC will desorb from the interior to the exterior

• Desorption times appear much longer than absorption using the 95% convergence criteria

Depth, microns


hours500 2225

1000 21501500 21502000 2125

• No physical change data was collected for this sample set

• Additional data sets are on-going



Non-Saturated Saturated

Reduction

[%]

UCL Mean LCL UCL Mean LCL Mean

Horizontal Activation Energy [kJ] 113.2 104.4 95.5 92.2 86.3 80.4 17.3

Vertical Activation Energy [kJ] 10.6 10.0 9.3 8.2 7.6 7.0 23.9

Activation Energy RMS [kJ] 114 105 96 93 87 81 17.4







23⁰ C Data



23⁰ C Data





bp b se dof tst sigma2 r2 (R^2)R2adj

(AdjR^2)

1.30E-01 -18.3184 12.5932 5447.945 -3993437 737000.1 4 2.776445 0.02911 0.609864 0.414796

7.69E-02 17552.86 9329.353 -3993437 2.99E+09 -5.6E+08

6.14E-02 -3635.69 1763.994 737000.1 -5.6E+08 1.07E+08

sigmalpl 10223 23°C 97.5% LPL LCL 477

sigmalcl 10271 23°C 97.5% LCL HDB 536

HDB 848 23°C 50% LPL LCL Ratio 12.11 LCL Ratio 0.89100000 [h]

3 Coeff ISO 9080 Model - Limited data as of 5/15/2015 indicating 23°C strength of saturated material approximately 70% of

reference model strength

ASTM D2837 60°C HDB 80% of reference model - LCL Ratio of 0.89 vs requirement of 0.9 for 2708 materials (0.85 foer 2406

CM (Cov)

D2837

100000 [h]

100000 [h]

bp b se dof tst sigma2 r2 (R^2)R2adj

(AdjR^2)

7.46E-14 -35.59 3.6 28.242386 -22695.76 4437.466 60 2.000297822 0.463085996 0.65 0.64

4.91E-15 31125 2948 -22695.76 18768624 -3739735

5.58E-15 -6219.6 591 4437.466 -3739735 754349.58

sigmalpl 985 23°C 97.5% LPL LCL 1124

sigmalcl 1084 23°C 97.5% LCL HDB 1153

HDB 1180 23°C 50% LPL LCL Ratio 0.92 LCL Ratio 0.97

3 Coeff

CM (Cov)

D2837

100000 [h]

100000 [h]

100000 [h]





Test Plan For Examining The Impact Of Heavy Hydrocarbon Permeation On Pipe Fusibility

• A total of 600 controlled fusions have been made• -10⁰F – 120⁰F Ambient• 375⁰F – 525⁰F Heater Plate• 10 psi – 110 psi Interfacial Pressure• 10 s – 30 s Soak Time• 0%, 50%, 100% Saturation• Three material types





• Visual observations,

• Bendback testing for percent ductility,

• High strain rate-low temperature tensile, and

• Long-term creep testing

• Ultrasonic scans




Thanks to the Project Team

Russell Bora

Abby Castillo

Nick Daniels

Tony Kosari

Oren Lever

Jim Louis

Brian Miller

Peter Mulligan

Sooho Pyo

Nicole Reiff

Documents

THE IMPACT OF HEAVY HYDROCARBON PERMEATION ON PE PIPE · 2015-05-29 · Test Matrix for Saturation and Desaturation Testing The Impact of Heavy Hydrocarbon Permeation on PE Pipe Parameter