Gas Plus Drill Pipe Faliure Report

Technical Report

Metallurgical Analysis of Failed 5” Drill Pipe Section

A Report To: Adrill Service – Peeraj Group

P.O.Box 8436, Dubai UAE

Document Reference: A 402373

Date: April 14th, 2014

Copy: 1

Issue No.: 1 Page 1

Document No.: A 402373 Page No.: 2 of 17

Author: Yuan Pinglin Issue Date: April 14th, 2014

Client: Adrill Service - Peeraj Issue No.: 1


Revision History

Issue No : 1 Re - Issue Date : N/A

Revised By: N/A Approved By: N/A

Reason for Revision: First issue

Issue No : Re - Issue Date :

Revised By: Approved By:

Reason for Revision:

Report Signatories and Approval

Prepared by

Yuan Pinglin Senior Metallurgist (For and on behalf of Exova (Abu Dhabi) Ltd)

Reviewed and Approved by

Pratap P Adiyodi Lab Manager (For and on behalf of Exova (Abu Dhabi) Ltd)





Contents

1.0 INTRODUCTION .............................................................................................................................4

2.0 RESULTS ......................................................................................................................................5

2.1. VISUAL EXAMINATION ....................................................................................................................5

2.2. SEM ANALYSIS.............................................................................................................................5

2.3. CHEMICAL COMPOSITION ANALYSIS ...............................................................................................6

2.4. TENSILE TEST ...............................................................................................................................6

2.5. CHARPY IMPACT TEST ...................................................................................................................6

2.6. HARDNESS SURVEY ......................................................................................................................7

2.7. METALLURGICAL EXAMINATION .....................................................................................................7

3.0 DISCUSSION & CONCLUSIONS .......................................................................................................8

Appendices ..................................................................................................................................................................................... 9 Figure 1: General views of the submitted material in as-received condition ..................................................................... 10 Figure 2: Internal view of the sample .................................................................................................................................... 11 Figure 3: Close views of the fracture surface ....................................................................................................................... 12 Figure 4: SEM fractographs @ L1 ........................................................................................................................................ 13 Figure 5: SEM fractographs @ L2 ........................................................................................................................................ 14 Figure 6: Photographs show Tensile and Charpy impact test specimens after testing .................................................. 15 Figure 7: Cross-sectional macrographs ............................................................................................................................... 15 Figure 8: Microstructure of parent material consists of temper martensite; Magnification: As scale ............................. 16 Figure 9: Combined photomicrographs at the fracture location in Met-1 showing the grain flow deformation ............ 17





1.0 INTRODUCTION

Exova Limited (Abu Dhabi) was requested by Adirll Service - Peeraj to carry out a laboratory-

based metallurgical analysis of a 5” drill pipe section. It was reported by the client that the drill

pipe was washed out during service and hence resulted in fishing. 53 singles were recovered plus

the cut joint, which is submitted to the lab for analysis. The following details were provided by the

client:

Component description: 5” Drill Pipe, G-105 19.5ppf Surface Pulled Not In Hole,

4½” IF Pin X 4½” IF Box

Material grade: Grads G105

Service life: N/A

Operating environment: drilling down hole

Others: Field name – Gas Plus Khalakan; Weld Name: Shewashan-1

The objectives of this analysis are to verify the drill pipe material grade and to determine the

failure mechanism. The following scope of work was conducted on the sample to facilitate the

investigation:

Visual examination and photographic documentation of the sample in as-received condition;

Chemical analysis of the sample to determine the elemental composition;

Fractographic examination using SEM to study the fracture surface morphology;

Mechanical test of the sample including Tensile test, Impact test and Hardness measurements

to determine the mechanical properties of the material;

Metallurgical examination including Macro cross-sectional examination and Microstructure

examination at selected locations;

Evaluation of results, assessment of probable cause(s) of the failure.





2.0 RESULTS

2.1. VISUAL EXAMINATION

A cut pipe section including the fracture location was provided by the client. Figure 1 shows the

general views of the submitted material in “as-received” condition. Length of the sample is

measured 28 inch. Fracture occurred at straight pipe portion, approximately 14 inch away from

the reducing section. Evident diameter reduction (necking) and plastic deformation can be seen

at the fracture region, while no significant corrosion such localized pitting or metal loss was

observed on external surface.

As shown in Figure 2, the sample was partially bisected (close to the fracture) along the

longitudinal axis to reveal the internal surface condition. Cross-sectional thickness reduction can

be clearly seen. Internal surface of the pipe exhibited beige colour coating; localized corrosion

was observed at the ID changing region/geometrical change area, however showed no concern

with the fracture.

Figure 4 shows the close views of the fracture surface after proper cleaning. It can be seen that

the fracture is at a 45 degree angle to the cross section of the sample, appearing to be due to

ductile overload.

2.2. SEM ANALYSIS

The fracture surface was analysed using the Scanning Electron Microscope (SEM) to study the

features of fracture surface (locations indicated in Figure 3, L1 & L2). Low magnification SEM

fractographs showed extensive post fracture rubbing marks. Elongated dimples appearance was

observed when examined at high magnification, which suggest a ductile fracture mode due to

tension overload (Figures 4-5).





2.3. CHEMICAL COMPOSITION ANALYSIS

Chemical analysis was carried out on the failed sample using Optical Emission Method to

determine the chemical composition of the material. Results are given in Table 1. Chemical

composition of the tested material meets the requirement of API 5D Grade G105.

Table 1 Chemical Analysis Results

Elements Test Results, % Wt API 5D Grade G105

Requirements

C 0.24 ---

Si 0.26 ---

Mn 1.06 ---

P 0.013 0.030 max

S <0.005 0.030 max

Cr 0.84 ---

Mo 0.17 ---

Ni 0.04 ---

Cu 0.11 ---

V <0.01 ---

2.4. TENSILE TEST

One longitudinal tensile specimen was machined from the sample and tested in accordance with

standard ASTM A370. The fracture surface of the specimens (Figure 6) after testing showed a

typical ductile fracture appearance. The test results are given in Table 2, which are in line with

the tensile requirements of API 5D Grade G105.

Table 2 Tensile Test Results

Longitudinal Direction Yield Strength Tensile Strength Elongation Reduction

of area

Test results 812 Mpa 891 Mpa 16% 65%

API 5D Grade G 105 Requirements

724 -931 Mpa 793 Mpa min 13% min -

2.5. CHARPY IMPACT TEST

A set of three Charpy impact test specimens were longitudinally extracted from the sample and

tested in accordance with ASTM A370. The fracture surface of the specimens (Figure 6) after

testing showed a typical ductile fracture appearance. Table 3 gives the test results, which meet

the requirement of API 5D Grade G 105.

Table 3 Charpy Impact Test Results

Specimen Dimension : 10 х 10 х 55 mm Test Temperature: 23°C

Charpy Impact Energy, J 150 142 152 Average: 148

API 5D Grade G105 Requirements Minimum average 54 J, single specimen 47J @ 21ºC ± 2.8ºC

for specimen size 10 X 10 X55 mm





2.6. HARDNESS SURVEY

Vickers hardness survey using 10kg load was carried out on the sample. Results are given in

Table 4. Hardness readings of the sample are found generally uniform indicating homogeneity of

the material. Hardness at the fracture locations gave slightly higher readings, which is likely due

to the work hardening effect introduced by the plastic deformation.

Table 4 Vickers Hardness Test Results

Test location Sample 1 Sample 2

Close to fracture 319, 317, 314 314, 316, 312

Away from fracture 294, 302, 301 300, 296, 299

2.7. METALLURGICAL EXAMINATION

Two metallurgical specimens were longitudinally removed from the sample across the fracture

region (locations see Figure 3). The specimens were prepared using standard metallographic

techniques and examined visually. The cross-sectional macrographs, as shown in Figure 7,

revealed evident plastic deformation and thickness reduction adjacent to the fracture location.

The macro specimens were further prepared for micro examination under optical microscope

with different magnifications. General microstructure of the pipe material consists of homogenous

tempered martensite with no inherent metallurgical anomalies such as microfissuring (see Figure

8). Figure 9 shows the microstructure at the fracture location, evident grain flow deformation was

observed adjacent to the fracture location, which is indicative of the plastic deformation due to

tension load. No inherent metallurgical anomalies with regards to the fracture were found.





3.0 DISCUSSION & CONCLUSIONS

The chemical composition of the drill pipe material was in accordance with the requirements of

API 5D Grade G105.

The tensile test and charpy impact test results both meet the requirements of API 5D Grade

G105.

Hardness survey gave generally uniform readings indicating homogeneity of the material.

Hardness at the fracture locations gave slightly higher readings, which is likely due to the work

hardening effect introduced by the plastic deformation during fracture.

Metallurgical examination of the material revealed no inherent metallurgical abnormalities

such as micro fissures which could have contributed to the failure. General microstructure of

the material consists of homogenous tempered martensite, which indicates a quenched and

tempered condition of the material.

Visual examination of the sample showed no significant corrosion attack on the outside

surface of the sample. Internal surface of the pipe showed localized corrosion at the ID

changing region/geometrical change area, however no due concern with the failure of the

sample. The fracture occurred at the straight pipe portion, with evident diameter reduction

(necking) and plastic deformation at the fracture region. The fracture is at a 45 degree angle

to the cross section of the sample, and appeared due to ductile overload.

Fractography examination of the fracture surface exhibited extensive and rubbing marks and

elongated dimples, which are typical characteristic in ductile fracture.

Macro cross-sectional examination showed evident plastic deformation and thickness

reduction adjacent to the fracture location. Microstructure at the fracture showed evident grain

flow deformation was observed adjacent to the fracture location, which is indicative of the

plastic deformation due to tension load.

Based on the laboratory results conducted, our investigation revealed no inherent abnormalities

or deficiencies of the drill pipe material which could have caused the failure of the sample; the

overall characteristics of the analyzed sample indicate a ductile overload fracture mechanism. It

was reported by the client that the drill pipe was washed out in downhole, which resulted in

fishing. The original washed out / failed pipe portion was not able to be found out, therefore, the

original failure mechanism of the drill pipe cannot be found out based on the submitted sample.

Failure of the submitted pipe portion is likely a subsequent overload fracture (after the original

wash out failure of the sample) during the fishing.

The results contained within this report have been reported in an abbreviated format. The test data and result sheets containing more detailed information in accordance with the technical works procedures or standards used are held at Exova as part of the accredited quality assurance

system. Opinions and interpretations expressed herein are outside the scope of the UKAS accreditation of this laboratory.

END OF TEXT





Appendices





Figure 1: General views of the submitted material in as-received condition

14 inch

28 inch





Figure 2: Internal view of the sample showed localized corrosion but no concern with the fracture; cross-sectional

thickness reduction can be clearly seen





Figure 3: Close views of the fracture surface

L2

L1

Met 1

Met 2





Figure 4: SEM fractographs @ L1





Figure 5: SEM fractographs @ L2





Figure 6: Photographs show Tensile and Charpy impact test specimens after testing

Figure 7: Cross-sectional macrographs showed evident plastic deformation and thickness reduction adjacent to the fracture location

OD

ID

Fracture

surface

ID

OD

Fracture surface

Met 1

Met 2





Figure 8: Microstructure of parent material consists of temper martensite; Magnification: As scale





Figure 9: Combined photomicrographs at the fracture location in Met-1 showing the grain flow deformation

OD

ID

Fracture

surface

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Gas Plus Drill Pipe Faliure Report