ISO/TS 12835:2022
(Main)Qualification of casing connections for thermal wells
Qualification of casing connections for thermal wells
This document provides procedures for assessment of casing connections for those field applications in which the operating temperatures cyclically vary between minimum values appreciably below 180 °C and maximum values that range from 180 °C to 350 °C or above, and in which the primary axial loading on the casing-connection system is strain-based and driven by constrained thermal expansion and leads to a stress state that exceeds the casing-connection system's yield envelope. NOTE This document can be considered complementary to ISO 13679 (and its core content per API Specification 5C5), which applies to classic elastic-design applications. This document contains an evaluation procedure for a candidate connection comprising of uniquely defined pin, box and interfacial components. The evaluation procedure includes: — Material property tests to assess relevant properties of the candidate connection pin and box components; — Analytical tasks to determine configuration of connection samples for physical tests, which are chosen based on worst-case combinations of the connection geometry and material properties; — Full-scale testing tasks to measure the candidate connection galling resistance, structural integrity and sealability under loading representative of connection assembly and thermal well service. This document does not address impacts of external pressure, incomplete lateral pipe support, rotational fatigue, formation-induced shear, or environmentally-induced corrosion or cracking. Clause 6 describes fundamental assumptions adopted in this document.
Qualification des raccordements de boîtiers pour les puits thermométriques
General Information
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Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 12835
First edition
2022-03
Qualification of casing connections for
thermal wells
Qualification des raccordements de boîtiers pour les puits
thermométriques
Reference number
© ISO 2022
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ii
Contents Page
Foreword .vi
Introduction .vii
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Abbreviated terms and symbols .5
4.1 Abbreviated terms . 5
4.2 Symbols . 6
5 Program overview.7
5.1 Illustrations of selected definitions . 7
5.2 Program flowchart . 7
6 Overview and fundamental assumptions .8
6.1 General . 8
6.2 Main features . 8
6.2.1 Purpose . 8
6.2.2 Applicability to service conditions . 9
6.2.3 Rationale for development. 9
6.2.4 Subject of evaluation . 9
6.2.5 Application severity levels . 9
6.3 Assessment philosophy and principles . 10
6.3.1 Fundamental principles . 10
6.3.2 Conservative evaluation procedure . 11
6.3.3 Mandatory and optional tasks . 11
6.3.4 Use of analysis and physical testing .12
6.3.5 Performance measures .12
6.3.6 Assessment criteria .12
6.3.7 Task outcomes — data categories. 13
6.3.8 Prior evaluation data . 13
6.3.9 Treatment of confidential design information .13
6.3.10 Interpretation of evaluation results . 14
6.3.11 Avoiding perception of conflict of interest . 14
6.4 Evaluation variables . 14
6.4.1 Connection loading . 14
6.4.2 Impacts of contributing variables . 14
6.4.3 Pin-box interferences and tapers . 16
6.4.4 Material yield strength . 16
6.5 Evaluation procedure . 17
6.5.1 Safety standards . 17
6.5.2 Seepage assessment — random variations . 17
6.5.3 Seepage rate thresholds . 17
6.5.4 Seal isolation . 18
6.5.5 Dope entrapment . 18
6.5.6 Thermal cycle test — bake-out and hold durations . . 18
6.5.7 Pressure and temperature loading in thermal cycle test and analysis . 19
6.5.8 Dependence of material strength on temperature . 19
6.6 Scope of reporting . 20
7 Program roles and proprietary design information .20
7.1 Program execution roles . 20
7.2 Proprietary connection design information . 20
8 Conformance requirements .21
8.1 Conformant evaluation program. 21
iii
8.2 Program non-conformances . . 21
8.3 Performance acceptance . .22
8.4 Conformance of results from previous evaluations . 22
8.5 Use of data from previous evaluations. 22
8.6 Conformance to lower ASLs . 23
9 Application severity levels .23
9.1 Thermal well load path . 23
9.2 Temperature as controlling parameter . 25
9.3 Specifications for application severity levels . 26
9.4 Selection of application severity level. 27
10 Program blocks and tasks .27
10.1 Evaluation procedure overview . 27
10.2 Critical path tasks . 31
11 Program specifications .32
11.1 Task overview. 32
11.2 Identification of program roles . 32
11.3 Identification of candidate connection . 33
11.4 Program options .34
11.5 Data from prior evaluations . 35
12 Determination of biased test population .35
12.1 Task overview. 35
12.2 Initial material property characterization .36
12.2.1 Task description, definitions, methods .36
12.2.2 Testing conditions and scope . 37
12.2.3 Procedure for tensile tests .39
12.2.4 Interpretation and processing of tensile test results .40
12.3 Specimen configuration analysis . 45
12.3.1 Task description . 45
12.3.2 Modelling and reporting requirements .46
12.3.3 Nominal reference case . 47
12.3.4 Worst-case geometry configurations .48
12.3.5 Seal taper analysis .50
12.3.6 Impacts of material property variations . 51
12.3.7 Make-up torque for sealability tests .54
12.3.8 Test versus production specimens .56
13 Specimen procurement .56
13.1 Task overview.56
13.2 Specimen pipe procurement . 57
13.3 Material property verification . 57
13.3.1 Task description . 57
13.3.2 Specimens for tensile verification tests . 57
13.3.3 Scope of tensile verification tests.58
13.3.4 Coefficient of thermal expansion verification test . . 59
13.4 Test specimen machining and gauging .60
13.4.1 General requirements .60
13.4.2 Specimen naming convention .60
13.4.3 Specimen length and length-reference requirements . 61
13.4.4 Geometrical configurations . 62
13.4.5 Mother pipe for specimens . 62
13.4.6 Specimen machining tolerances .63
13.5 Markings .65
13.6 Specimen geometry verification .65
13.6.1 Gauging inspection scope .65
13.6.2 Inspection extent – example cases .66
13.6.3 Geometry inspection guidelines .66
13.7 Procurement and quality control of connection interfacial components . 67
iv
13.8 Specimen handling and storage . 67
13.8.1 Handling recommendations . 67
13.8.2 Treatment of damaged specimens .68
14 Full-scale physical tests and supplementary analyses .68
14.1 Task overview.68
14.2 Full-scale tests - general requirements . 69
14.2.1 Ambient temperature at test site . 69
14.2.2 Calibration of instrumentation. 69
14.2.3 Disabling of secondary seals . 70
14.2.4 Seepage measurement and rate definitions . 70
14.2.5 Load application rates .72
14.2.6 Excluded connections .72
14.3 Galling resistance test .73
14.3.1 Task description .73
14.3.2 Rationale and objectives .74
14.3.3 Make-break specimens .74
14.3.4 Scope of galling resistance test .74
14.3.5 Set-up and instrumentation . 75
14.3.6 Test procedure. 76
14.3.7 Performance assessment .77
14.3.8 Reporting . 78
14.4 Thermal cycle test .78
14.4.1 Task description . 78
14.4.2 Rationale and objectives . 78
14.4.3 Thermal cycle specimens . 79
14.4.4 Scope of thermal cycle test . 79
14.4.5 Mechanical strain compensations .82
14.4.6 Set-up and instrumentation .85
14.4.7 Test procedure. 91
14.4.8 Performance assessment .96
14.4.9 Selection of cycled specimens for bend test and limit-strain test .97
14.4.10 Reporting .97
14.5 Bending evaluation .97
14.6 Limit-strain test .98
14.6.1 Task description .98
14.6.2 Rationale and objectives .98
14.6.3 Limit-strain specimens .99
14.6.4 Mandatory test description .99
14.6.5 Set-up and instrumentation . 101
14.6.6 Mandatory test procedure .103
14.6.7 Performance assessment .108
14.6.8 Reporting .108
14.7 As-tested configuration analysis .108
15 Evaluation and inspection reports . 108
15.1 Reporting deliverables .108
15.2 Reporting scope and contents .109
15.3 Reporting templates .113
Annex A (informative) FEA modelling guidelines .114
Annex B (informative) Derivations of formulae - Strain compensation factors .124
Annex C (informative) Program role assignments and responsibilities .133
Annex D (informative) Optional program selections, tasks, and procedures . 140
Bibliography .163
v
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 5, Casing, tubing
and drill pipe.
This first edition of ISO/TS 12835 cancels and replaces ISO/PAS 12835:2013, which has been technically
revised.
The main changes are as follows:
— all optional tasks moved to Annex D;
— added option to perform thermal cycle test with cooling to intermediate temperatures;
— changed specification for to-failure portions of bend test and limit-strain test, allowing them to be
performed with water only.
A list of all parts in the ISO 12835 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
vi
Introduction
This document, also known to industry users as Thermal Well Casing Connection Evaluation Protocol
(TWCCEP), is intended to facilitate assessment and qualification of threaded casing connections for
service in intermediate or production casing strings in thermal recovery wells and in other wells
experiencing significant temperature excursions such as in geothermal applications.
The extensive effort involved in replicating thermal well field conditions in a laboratory environment
limits the extent of physical testing that can reasonably be undertaken in an evaluation program.
The evaluation procedure adopted in this document balances technical rigor and practicality to
provide a baseline level of confidence in the candidate connection’s performance. Connection users
should consider the scope of this evaluation and appropriate additions to address operation-specific
conditions. Successful field use of a connection meeting the requirements of this protocol does not
preclude an operator’s need to employ appropriate product quality assurance measures and field
operating practices.
Only outcomes of the performed full-scale tests are compared with assessment criteria to determine
suitability of the candidate connection for the intended field service. While this document aims to
enable a statistically significant full-scale test, it does not demand a rigorous check of a true statistical
placement of the tested sample responses relative to field connection performance, and thus inherently
assumes that the test specimens are representative of subsequent field connections. For this reason,
only connections with the same design parameters as the candidate connection should be considered
representative of the connection assessed under this protocol.
This document is the culmination of a thorough review of factors contributing to performance of casing
connections in thermal well applications. The evaluation procedure adopted in this document has
been developed using input from operators’ descriptions of field practices, manufacturers’ feedback
on connection design and production, available literature, knowledge of past connection qualification
programs, and additional analytical and experimental work performed in support of the protocol
development.
vii
TECHNICAL SPECIFICATION ISO/TS 12835:2022(E)
Qualification of casing connections for thermal wells
1 Scope
This document provides procedures for assessment of casing connections for those field applications in
which the operating temperatures cyclically vary between minimum values appreciably below 180 °C
and maximum values that range from 180 °C to 350 °C or above, and in which the primary axial loading
on the casing-connection system is strain-based and driven by constrained thermal expansion and
leads to a stress state that exceeds the casing-connection system's yield envelope.
NOTE This document can be considered complementary to ISO 13679 (and its core content per API
Specification 5C5), which applies to classic elastic-design applications.
This document contains an evaluation procedure for a candidate connection comprising of uniquely
defined pin, box and interfacial components. The evaluation procedure includes:
— Material property tests to assess relevant properties of the candidate connection pin and box
components;
— Analytical tasks to determine configuration of connection samples for physical tests, which are
chosen based on worst-case combinations of the connection geometry and material properties;
— Full-scale testing tasks to measure the candidate connection galling resistance, structural integrity
and sealability under loading representative of connection assembly and thermal well service.
This document does not address impacts of external pressure, incomplete lateral pipe support,
rotational fatigue, formation-induced shear, or environmentally-induced corrosion or cracking.
Clause 6 describes fundamental assumptions adopted in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products
ASTM E8, Standard Test Methods for Tension Testing of Metallic Materials
ASTM E21, Standard Test Methods for Elevated-Temperature Tension Tests of Metallic Materials
ASTM E831-06, Linear Thermal Expansion of Solid Materials by Thermomechanical Analysis
ISO 11960, Petroleum and natural gas industries — Steel pipes for use as casing or tubing for wells
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
ambient temperature
ambient temperature in the facility where a physical testing task is executed
3.2
application severity level
connection loading specifications assumed to be representative for a range of operational conditions,
which determine the scope of analysis and testing required by the evaluation procedure (3.13) for those
operational conditions
3.3
assigner
party that commissions an evaluation program (3.14), controls its execution, and owns the rights to that
evaluation program’s data and results
3.4
average string strain
average axial strain along the controlled elongation interval (3.11) of a specimen string (3.36)
3.5
bend test specimens
subset of candidate connection specimens (3.8) subjected to the optional bending evaluation (3.6) per the
evaluation procedure (3.13)
3.6
bending evaluation
analysis and physical testing conducted to determine sensitivity of a candidate connection (3.7) to
casing curvature
3.7
candidate connection
casing connection product that is being evaluated, and is uniquely defined by its design features and
production specifications with respect to size, weight, and component materials including pin, box, and
interfacial components
3.8
candidate connection specimens
set of connection specimens that is representative of design and features of the candidate connection
(3.7), and is provided for an evaluation program (3.14) of that candidate connection
3.9
casing pup
short piece of casing pipe cut from a mother joint
3.10
connection
single design-specific assembly of pin and box and interfacial component(s)
3.11
controlled elongation interval
portion of a specimen string (3.36), along which the elongation is measured and controlled
3.12
effective string length
portion of the total length of a specimen string (3.36) that is assumed to deform appreciably under
mechanical forces in the thermal cycle test (3.42)
3.13
evaluation procedure
set of analytical and testing tasks performed to assess performance of the candidate connection
specimens (3.8)
3.14
evaluation program
evaluation of a candidate connection (3.7) by means of the evaluation procedure (3.13)
3.15
evaluation report
collectively, all documents prepared by an evaluator (3.16), according to applicable reporting
requirements, that describe execution history and results of an evaluation program (3.14)
3.16
evaluator
party that performs analytical and testing tasks required by an evaluation procedure (3.13)
3.17
excluded connection
connection (3.10) that has been evaluated in a full-scale test but whose performance has been excluded
from comparison with threshold performance requirements (3.44)
3.18
galling
cold welding of contacting material surfaces followed by tearing of metal during subsequent sliding
3.19
high cycle temperature
highest temperature targeted in the thermal cycle test (3.42)
3.20
inspection report
collectively, all documents prepared by an inspector (3.21) that describe conformance of the executed
evaluation program (3.14) with applicable specifications
3.21
inspector
party that verifies conformance of the executed evaluation program (3.14) with applicable specifications
3.22
integral specimen
single connection consisting of one casing pup (3.9) with a box end and one casing pup with a pin end
3.23
interfacial component
design-specific component of a connection (3.10) applied to the pin and box either during their
manufacturing (e.g. coating) or during the connection assembly (e.g. thread compound)
3.24
limit-strain specimens
subset of candidate connection specimens (3.8) subjected to the limit-strain test (3.25) per the evaluation
procedure (3.13)
3.25
limit-strain test
tension test, to structural failure, of the limit-strain specimens (3.24)
3.26
low cycle temperature
lowest temperature targeted in the thermal cycle test (3.42)
3.27
lower-bound temperature
lowest temperature expected in thermal cycles in field applications
3.28
make-break specimens
subset of candidate connection specimens (3.8) subjected to multiple make-ups and break-outs per the
evaluation procedure (3.13)
3.29
make-up support pin
pin component of candidate connection (3.7) with seal removed, used to support a coupling’s open end
during make-up and break-out of that coupling’s opposite end
3.30
material coupon
cylindrical section of pipe from which material strip specimens (3.31) are cut
3.31
material strip specimen
longitudinal steel strip cut from a material coupon (3.30) and machined for use in mechanical property
characterization tests
3.32
prior evaluation data
set of data acquired in a connection performance assessment carried out by analysis and/or physical
tests prior to issuance of this protocol and/or according to a procedure/protocol different than the
evaluation procedure (3.13)
3.33
program roles
collective reference to the roles of assigner (3.3), supplier (3.38), evaluator (3.16) and inspector (3.21)
3.34
repairable galling
galling (3.18) that can be repaired according to a supplier’s (3.38) field-repair procedure for a candidate
connection (3.7)
3.35
severe galling
galling (3.18) that cannot be repaired according to a supplier’s (3.38) field-repair procedure for a
candidate connection (3.7)
3.36
specimen string
collective reference to a single connection specimen and/or an in-series assembly of two or more
connection specimens in a thermal cycle test (3.42)
3.37
substantially qualified party
person/company possessing technical skills and experience necessary to perform a task, as designated
by the assigner (3.3) and the supplier (3.38)
3.38
supplier
party that manufactures candidate connection (3.7)
3.39
tensile strain threshold
tensile strain value that a connection specimen is expected to survive during a limit-strain test (3.25)
3.40
test specimen
connection specimen that is provided for a full-scale test
3.41
thermal cycle specimens
subset of candidate connection specimens (3.8) subjected to the thermal cycle test (3.42) per the
evaluation procedure (3.13)
3.42
thermal cycle test
thermo-mechanical test of connection specimens, in which several thermal cycles are applied between
the low cycle temperature (3.26) and the high cycle temperature (3.19)
3.43
threaded-and-coupled specimen
two connections consisting of a single coupling and two casing pups (3.9) with pin ends joined by that
coupling
3.44
threshold performance requirements
set of connection performance criteria for a candidate connection (3.7) considered as having met
applicable minimum performance requirements
3.45
upper-bound temperature
highest temperature expected in thermal cycles in field applications
4 Abbreviated terms and symbols
4.1 Abbreviated terms
ASL application severity level
BF fast box taper
BS slow box taper
CSS cyclic steam stimulation
CTE coefficient of thermal expansion
FEA finite element analysis
IC integral connection
max. maximum
min. minimum
PF fast pin taper
PS slow pin taper
SAGD steam assisted gravity drainage
TC threaded-and-coupled connection
TWCCEP thermal well casing connection evaluation protocol
TF(WGS) final make-up torque for specimen with WGS configuration
TF(WGT) final make-up torque for specimen with WGT config
...
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