U.S. patent application number 12/595167 was filed with the patent office on 2010-08-05 for seamless steel pipe for use as vertical work-over sections.
Invention is credited to Hector Manuel Quintanilla Carmona, Alfonso Izquierdo Garcia.
Application Number | 20100193085 12/595167 |
Document ID | / |
Family ID | 39673395 |
Filed Date | 2010-08-05 |
United States Patent
Application |
20100193085 |
Kind Code |
A1 |
Garcia; Alfonso Izquierdo ;
et al. |
August 5, 2010 |
SEAMLESS STEEL PIPE FOR USE AS VERTICAL WORK-OVER SECTIONS
Abstract
The present invention describes a seamless steel tube for
work-over risers comprising in weight percent, carbon 0.23-0.29,
manganese 0.45-0.65, silicon 0.15-0.35, chromium 0.90-1.20,
molybdenum 0.70-0.90, nickel 0.20 max, nitrogen 0.010 max, boron
0.0010-0.0030, aluminum 0.010-0.045, sulfur 0.005 max, phosphorus
0.015 max, titanium 0.005-0.030, niobium 0.020-0.035, copper 0.15
max, arsenic 0.020 max, calcium 0.0040 max, tin 0.020 max, hydrogen
2.4 ppm max, the rest are iron and inevitable impurities,
consisting of a geometry in which ends of the tube have an
increased wall thickness and outer diameter and having a yield
strength of at least of 620 MPa (90 ksi) throughout the whole
length of a tube body and in tube ends. The present invention also
describes methods for manufacturing a seamless steel tube for
work-over risers having a yield strength at least of 620 MPa (90
ksi) both in a tube body and in tube ends.
Inventors: |
Garcia; Alfonso Izquierdo;
(Veracruz, MX) ; Carmona; Hector Manuel Quintanilla;
(Veracruz, MX) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
39673395 |
Appl. No.: |
12/595167 |
Filed: |
April 17, 2008 |
PCT Filed: |
April 17, 2008 |
PCT NO: |
PCT/MX08/00054 |
371 Date: |
April 2, 2010 |
Current U.S.
Class: |
148/508 ;
148/332; 148/334; 148/335; 148/590 |
Current CPC
Class: |
C21D 9/085 20130101;
C22C 38/22 20130101; C22C 38/18 20130101; C21D 9/08 20130101; E21B
17/01 20130101 |
Class at
Publication: |
148/508 ;
148/332; 148/334; 148/335; 148/590 |
International
Class: |
C21D 11/00 20060101
C21D011/00; C22C 38/20 20060101 C22C038/20; C22C 38/22 20060101
C22C038/22; C22C 38/44 20060101 C22C038/44; C21D 9/08 20060101
C21D009/08; C21D 1/00 20060101 C21D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 2007 |
MX |
MX/A/2007/004600 |
Claims
1. A seamless steel tube for work-over risers comprising in weight
percent, carbon 0.25-0.28, manganese 0.48-0.58, silicon 0.20-0.30,
chromium 1.05-1.15, molybdenum 0.80-0.83, nickel 0.10 max, nitrogen
0.008 max, boron 0.0016-0.0026, aluminum 0.015-0.045, sulfur 0.0030
max, phosphorus 0.010 max, titanium 0.016-0.026, niobium
0.025-0.030, copper 0.10 max, arsenic 0.020 max, calcium 0.0040
max, tin 0.015 max, hydrogen 2.0 ppm max, the remainder being iron
and inevitable impurities; and a geometry in which ends of the tube
have an increased wall thickness and outer diameter and having a
yield strength of at least 620 MPa (90 ksi) throughout the whole
length of a tube body and in tube ends.
2. A seamless steel tube for work-over risers according to claim 1
further comprising the following mechanical properties in the
as-quench condition including 90% of martensitic transformation
when evaluated according to the following formulae:
HRCmin=(58.times.% C)+27, austenitic grain size as per ASTM minimum
5 or finer in the as-quench and temper condition, longitudinal
Tensile Test (round standard specimens when wall thickness equal or
above 1'' and longitudinal strip specimens when wall thickness
below 1''), at least Yield Strength of 620 MPa (90 ksi), Maximum
Yield Strength of 724 MPa (105 ksi), Minimum Ultimate Tensile
Strength, 690 MPa (100 ksi), Minimum Elongation (L=4D), 18%, Yield
to Tensile Ratio.ltoreq.0.92, Transverse Charpy Test, Minimum
individual Absorbed Energy: 30 Joules, Minimum Average Absorbed
Energy: 40 Joules, Maximum Hardness value, 25.4 HRC (value as per
API 5CT means average per row), Microcleanliness acceptance
criteria as per ASTM E-45 A: A, B, C, D all below 2, Passing SSC
Method A test as per NACE TM0177-2005, using test solution (A),
testing at 85% SMYS, test period 720 hours, throughout the whole
length of a tube body and in tube ends.
3. A seamless steel tube for work-over risers according to claim 1
further comprising the following mechanical properties in the
as-quench condition including at least 90% of martensitic
transformation when evaluated according to the following formulae:
HRCmin=(58.times.% C)+27, austenitic grain size as per ASTM minimum
5 or finer in the as-quench and temper condition, longitudinal
Tensile Test (round standard specimens when wall thickness equal or
above 1'' and longitudinal strip specimens when wall thickness
below 1''), at least a Yield Strength of 620 MPa (90 ksi), a
Maximum Yield Strength of 724 MPa (105 ksi), a Minimum Ultimate
Tensile Strength, 690 MPa (100 ksi), a Minimum Elongation (L=4D),
18%, Yield to Tensile Ratio.ltoreq.0.92, Transverse Charpy Test,
Minimum individual Absorbed Energy: 30 Joules, Minimum Average
Absorbed Energy: 40 Joules, Maximum Hardness value, 25.4 HRC (value
as per API 5CT means average per row), Microcleanliness acceptance
criteria as per ASTM E-45 A: A, B, C, D all below 2, Passing SSC
Method A test as per NACE TM0177-2005, using test solution (A),
testing at 85% SMYS, test period 720 hours, throughout the whole
length of a tube body and in tube ends.
4. A method for manufacturing a seamless steel tube for work-over
risers having a yield strength at least of 620 MPa (90 ksi) both in
a tube body and in tube ends comprising the following steps of: (a)
providing a steel tube comprising a composition in weight percent,
carbon 0.23-0.29, manganese 0.45-0.65, silicon 0.15-0.35, chromium
0.90-1.20, molybdenum 0.70-0.90, nickel 0.20 max, nitrogen 0.010
max, boron 0.0010-0.0030, aluminum 0.010-0.045, sulfur 0.005 max,
phosphorus 0.015 max, titanium 0.005-0.030, niobium 0.020-0.035,
copper 0.15 max, arsenic 0.020 max, calcium 0.0040 max, tin 0.020
max, hydrogen 2.4 ppm max, the rest are iron and inevitable
impurities; (b) upsetting of tube ends; (c) austenitizing between
850-930.degree. C. the full length of the tube; and (d) quenching
and tempering between 630-720.degree. C.
5. A method for manufacturing a seamless steel tube for work-over
risers according to claim 4 further comprising the following steps:
(e) destructive testing including microcleanliness, austenitic
grain size, calculate % of martensitic transformation, tensile,
hardness, toughness, sulfide stress cracking (SSC) testing; (f)
dimensional controlling of pipe body and upset ends including one
or more of outside diameter, out of roundness, eccentricity,
straightness, internal diameter, and length; (g) machining of
external and internal upset end; (h) dimensional controlling of one
or more of internal diameter, outside diameter and machined end;
(i) drift testing at the upset ends; and (j) non-destructive
testing of upset ends, weighing, measuring and marking, external
surface visual inspection, ultrasonic (UT) inspection of pipe body
and UT inspection of upset ends.
6. A method for manufacturing a seamless steel tube for work-over
risers having a yield strength at least of 620 MPa (90 ksi) both in
a tube body and in tube ends comprising the following steps of: (a)
providing a steel tube comprising a composition in weight percent,
carbon 0.23-0.29, manganese 0.45-0.65, silicon 0.15-0.35, chromium
0.90-1.20, molybdenum 0.70-0.90, nickel 0.20 max, nitrogen 0.010
max, boron 0.0010-0.0030, aluminum 0.010-0.045, sulfur 0.005 max,
phosphorus 0.015 max, titanium 0.005-0.030, niobium 0.020-0.035,
copper 0.15 max, arsenic 0.020, calcium 0.0040 max, tin 0.020 max,
hydrogen 2.4 ppm max, the rest are iron and inevitable impurities,
obtained by rolling process (MPM process); (b) heat treating the
tube comprising austenitizing between 850-930.degree. C. the full
length of the tube, and quenching and tempering between
630-720.degree. C.; (c) destructive testing including
microcleanliness, austenitic grain size, calculate % of martensitic
transformation, tensile, hardness, toughness, sulfide stress
cracking (SSC) testing; (d) dimensional controlling of pipe body
including one or more of outer diameter (OD), out of roundness,
straightness, inner diameter (ID), and length; and (e) machining
from external surface the complete length of the pipe by
programming CNC lath machine in order to achieve final dimensions
at the ends.
7. A method for manufacturing a seamless steel tube for work-over
risers according to claim 6, further comprising the following
steps: (f) dimensional controlling one or more of ID, OD, out of
roundness, straightness and length of pipe body and machined ends;
(g) drift testing at the ends; and (h) non-destructive testing
(NDT) of ends, weighing, measuring and marking, external surface
visual inspection, ultrasonic (UT) inspection of machined pipe body
and UT inspection of machined ends in a cylindrical section.
8. A seamless steel tube for work-over riser according to claim 1,
wherein in an as quenched and tempered condition the seamless steel
tube material has a microstructure comprising tempered martensite
through the thickness, throughout the whole length of a tube body
and in tube ends.
9. A seamless steel tube for work-over riser according to claim 2,
wherein in an as quenched and tempered condition the seamless steel
tube has a microstructure comprising tempered martensite through
the thickness, throughout the whole length of a tube body and in
tube ends.
10. A seamless steel tube for work-over riser according to claim 1,
wherein the seamless steel tube has a nominal diameter from 4.5 to
10.75 inches.
11. A seamless steel tube for work-over riser according to claim 1,
wherein the seamless steel tube has a nominal diameter from 4.5 to
18 inches.
12. A seamless steel tube for work-over riser according to claim 1,
wherein the seamless steel tube has a thickness from 10 to 50
mm.
13. A seamless steel tube for work-over riser according to claim 2,
wherein austenitic grain size as per ASTM minimum 8 or finer in the
as-quench and temper condition.
14. A seamless steel tube for work-over riser according to claim 3,
wherein austenitic grain size as per ASTM minimum 8 or finer in the
as-quench and temper condition.
15. A seamless steel tube for work-over riser according to claim 2,
wherein the seamless steel tube has an absorbed energy higher than
100 Joules at specified temperature of -20.degree. C.
16. A seamless steel tube for work-over riser according to claim 3,
wherein the seamless steel tube has an absorbed energy higher than
100 Joules at specified temperature of -20.degree. C.
17. A seamless steel tube for work-over riser according to claim 3,
wherein in the as-quench condition includes at least 95% of
martensitic transformation.
18. A method for manufacturing a seamless steel tube for work-over
risers according to claim 4 wherein the upsetting of tube ends
takes place at a minimum temperature of 1000.degree. C.
19. A method for manufacturing a seamless steel tube for work-over
risers according to claim 6 wherein the upsetting of tube ends
takes place at a minimum temperature of 1000.degree. C.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a seamless steel tube for risers
used in work-over operations.
BACKGROUND OF THE INVENTION
[0002] The requirements for operating a well in the seabed involve
a plurality or systems and equipment including drilling, production
and work-over risers.
[0003] A drilling riser is a pipe between a seabed blow-out
preventer (BOP) and a floating drilling rig which is a drilling
unit not permanently fixed to the seabed such as a drillship, a
semi-submersible or jack-up unit. A drilling rig is meant to be the
derrick and its associated machinery.
[0004] A production riser is a pipeline carrying oil or gas that
joins a seabed wellhead to a deck of a production platform or a
tanker loading platform.
[0005] A work-over riser is a flowline which is used to carry on a
well work-over, which is performed on an existing well and may
involve re-evaluating the production formation, clearing sand from
producing zones, jet lifting, replacing downhole equipment,
deepening the well, acidizing or fracturing or improving the drive
mechanism.
[0006] In recent years such work-over operations have been
increasingly carried out using coiled or continuous reel tubing as
disclosed in U.S. Pat. No. 4,281,716 (Standard Oil Co.
Indiana).
[0007] However, according to WO9816715 (Kvaerner Eng, there are
several advantages using a continuous single tube when entering a
live oil or gas well. This means the well does not have to be
killed, (i.e. a heavy fluid does not have to be pumped down the
production tubing to control the oil or gas producing zone by the
effect of its greater hydrostatic pressure). Continuous tubing has
the advantage of also being able to pass through the tubing through
which the oil and/or gas is being produced, without disturbing the
tubing in place.
[0008] Taking in account that work-over risers are subjected to
fatigue and load stresses besides of corrosion attack, pipes used
in this environment are likely to have fatigue and corrosion
resistance properties to accomplish a good performance, reduce
both, the weight of the riser string and the bending loads in the
wellhead and the platform interface.
[0009] Also, these pipes need to have a good welding performance
just to be welded to weld-on-connectors to build the string.
OBJECT OF THE INVENTION
[0010] A first object of the invention is to provide a seamless
steel tube to be used as a riser in work-over operations with a
specific chemistry design and microstructure consisting of a
geometry in which ends of the tube have an increased wall thickness
and outer diameter to reduce the weight of the riser string.
[0011] A second object is to provide a seamless steel tube for the
application as a work-over riser with a specific chemistry design
and microstructure consisting of a geometry in which ends of the
tube have an increased wall thickness and outer diameter to reduce
the bending loads in the wellhead and the platform interface.
[0012] A third object of the invention is to provide a method of
manufacturing of a seamless steel tube for the application as a
work-over riser with a specific chemistry design and microstructure
consisting of a geometry in which ends of the tube have an
increased wall thickness and outer diameter using upsetting
techniques.
[0013] A fourth object of the invention is to provide a method of
manufacturing of a seamless steel tube for the application as a
work-over riser with a specific chemistry design and microstructure
consisting of a geometry in which ends of the tube have an
increased wall thickness and outer diameter using machining
techniques.
[0014] A fifth object of the invention is to provide a method of
manufacturing of a seamless steel tube for the application as a
work-over riser with a specific chemistry design and microstructure
consisting of a geometry in which ends of the tube have an
increased wall thickness and outer diameter able to guarantee the
mechanical characteristics to have high fatigue and corrosion
resistance and a good welding performance.
[0015] Also, the tubes used as work-over risers may be reused
meaning an economical saving.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a preferred embodiment of the work over
riser of the present invention with upset ends.
[0017] FIG. 2 shows a graphical representation of the Tensile test
results (YS and UTS) from upset and pipe body sections from
material in the as-quenched and tempered condition of the different
industrial trials.
[0018] FIG. 3 shows a graphical representation of the HRC hardness
values from upset and pipe body sections showing the achievement of
the minimum % of martensitic transformation from material in the
as-quenched condition of the production of both dimensions.
[0019] FIGS. 4 and 5 show a graphical representation of the HRC
hardness values from upset and pipe body sections showing the
individual hardness readings dispersion as a function of the
location through the thickness (OD, MW & ID) from material in
the as-tempered condition of the production of 7''OD.times.17.5 mm
WT dimension and 85/8'' OD.times.15.9 mm WT dimension,
respectively.
[0020] FIG. 6 shows a graphical representation of the transverse
CVN impact testing results at -20.degree. C. from upset and pipe
body sections of the production of both dimensions showing the
individual toughness values dispersion as per specification from
material in the as-tempered condition.
[0021] FIG. 7 shows the austenitic grain size reported in 9/10 ASTM
in the pipe body and 8/9 ASTM in the upset end.
[0022] FIG. 8 shows transverse section photomicrographs showing a
microstructure constituted by martensite through the wall thickness
of the pipe body section of quenched material for Nital 2% in
300.times. magnification.
[0023] FIG. 9 shows transverse section photomicrographs showing a
microstructure constituted by martensite in the upset end of
as-quenched material for Nital 2% in 300.times. magnification.
[0024] FIG. 10 shows transverse section photomicrographs, showing a
microstructure constituted by tempered martensite in the pipe body
of quenched & tempered material for Nital 2% in 300.times.
magnification.
[0025] FIG. 11 shows transverse section photomicrographs, showing a
microstructure constituted by tempered martensite in the upset end
of quenched & tempered material for Nital 2% in 300.times.
magnification.
[0026] FIG. 12 shows microstructural observations of as quenched
material at the pipe machined body and the end zones revealing a
prior austenitic grain size of 8/9 in both zones measured by the
saturation method as per ASTM E-112.
[0027] FIG. 13 shows transverse section photomicrographs showing a
microstructure constituted by martensite through the wall thickness
of the machined pipe body section of quenched material for Nital 2%
in 300.times. magnification.
[0028] FIG. 14 shows transverse section photomicrographs showing a
microstructure constituted by martensite through the wall thickness
of the pipe end section of quenched material for Nital 2% in
300.times. magnification.
[0029] FIG. 15 shows transverse section photomicrographs showing a
microstructure constituted by tempered martensite through the
thickness of the pipe body section of quenched and tempered
material. for Nital 2% in 300.times. magnification.
[0030] FIG. 16 shows transverse section photomicrographs showing a
microstructure constituted by tempered martensite through the
thickness of the pipe end section of quenched and tempered material
for Nital 2% in 300.times. magnification.
BRIEF SUMMARY OF THE INVENTION
[0031] The present invention describes a seamless steel tube to be
used as a riser in work-over operations with a specific chemistry
design and microstructure consisting of a geometry in which ends of
the tube have an increased wall thickness and outer diameter. The
alloy design is based on high strength requirements. The main
features of the chemical composition of the tube include 0.23-0.28
wt % C, 0.45-0.65 wt % Mn, and other alloying elements such as Mo,
and Cr to achieve the required percentage of martensitic
transformation. In addition, microalloying elements such as Ti and
Nb are used as grain refiners. Low content of residual elements
such as S and residual elements such as Cu and P are used to avoid
any corrosion problem related to inclusions promotion and
segregation at grain boundaries which decrease the corrosion
performance, the hydrogen content was kept below 2.4 ppm to avoid
any problem related to hydrogen entrapment and decrease of the
corrosion performance.
[0032] The production route for manufacturing the upset seamless
pipe for the application of as Work Over Riser, includes the
following steps: steel casting (Continuous Cast Bar), seamless pipe
rolling (MPM process), pipe ends upsetting, heat treatment,
destructive testing (including microcleanliness, austenitic grain
size, calculate % of martensitic transformation, tensile, hardness,
toughness, SSC testing), dimensional control of pipe body and upset
ends (outside diameter, out of roundness, excentricity,
straightness, internal diameter, length), machining of external and
internal upset end, dimensional control (internal diameter, outside
diameter and machined length), drift testing at the upset ends,
non-destructive testing (NDT) of upset ends, weighing, measuring
and marking, external surface visual inspection, UT inspection of
pipe body and UT inspection of upset ends (cylindrical section
only).
[0033] The production route for manufacturing the machining
seamless pipe for the application of as Work Over Riser includes
the following steps: steel casting (Continuous Cast Bar), seamless
pipe rolling (MPM process), heat treatment, destructive testing
(including microcleanliness, austenitic grain size, calculate % of
martensitic transformation, tensile, hardness, toughness, SSC
testing), dimensional control of pipe body (outside diameter, out
of roundness, straightness, internal diameter, length), machining
from external surface the complete length of the pipe by
programming CNC lath machine in order to achieve final dimensions
at the ends, dimensional control (internal diameter, outside
diameter, out of roundness, straightness, and length) of pipe body
and machined ends, drift testing at the ends, non-destructive
testing (NDT) of ends, weighing, measuring and marking, external
surface visual inspection, UT inspection of machined pipe body and
UT inspection of ends (cylindrical section only).
[0034] The combination of chemical composition and tight control of
heat treatment parameters allows achieving the adequate
microstructure after quench and temper in order to achieve the
mechanical properties and pass the SSC Method A tests requirements
described above.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0035] The chemical composition of the seamless steel tube of the
present invention comprises in weight percent: carbon 0.23-0.29,
manganese 0.45-0.65, silicon 0.15-0.35, chromium 0.90-1.20,
molybdenum 0.70-0.90, nickel 0.20 max, nitrogen 0.010 max, boron
0.0010-0.0030, aluminum 0.010-0.045, sulfur 0.005 max, phosphorus
0.015 max, titanium 0.005-0.030, niobium 0.020-0.035, copper 0.15
max, arsenic 0.020 max, calcium 0.0040 max, tin 0.020 max, hydrogen
2.4 ppm max, the rest are iron and inevitable impurities.
[0036] A more preferred composition comprises: carbon 0.25-0.28,
manganese 0.48-0.58, silicon 0.20-0.30, chromium 1.05-1.15,
molybdenum 0.80-0.83, nickel 0.10 max, nitrogen 0.008 max, boron
0.0016-0.0026, aluminum 0.015-0.045, sulfur 0.0030 max, phosphorus
0.010 max, titanium 0.016-0.026, niobium 0.025-0.030, copper 0.10
max, arsenic 0.020 max, calcium 0.0040 max, tin 0.015 max, hydrogen
2.0 ppm max, the rest are iron and inevitable impurities.
[0037] The seamless steel tubes have a geometry, in which ends of
tubes have an increased wall thickness and outer diameter, and
following mechanical properties:
[0038] In the as-quench Condition
[0039] 90% of martensitic transformation when evaluated according
to the following formulae: HRCmin=(58.times.% C)+27
[0040] Austenitic grain size as per ASTM minimum 5 or finer
[0041] In the as-quench and Temper Condition
[0042] Longitudinal Tensile Test (round standard specimens when
wall thickness equal or above 1'' and longitudinal strip specimens
when wall thickness below 1'').
[0043] Minimum Yield Strength: 90 ksi (620 MPa)
[0044] Maximum Yield Strength: 105 ksi (724 MPa)
[0045] Minimum Ultimate Tensile Strength: 100 ksi (690 MPa)
[0046] Minimum Elongation (L=4D): 18%
[0047] Yield to Tensile Ratio.ltoreq.0.92
[0048] Transverse Charpy Test (using 10.times.10 mm specimen)
[0049] Minimum individual Absorbed Energy: 30 Joules
[0050] Minimum Average Absorbed Energy: 40 Joules
[0051] Maximum Hardness value: 25.4 Hrc (value as per API 5CT means
average per row)
[0052] Microcleanliness acceptance criteria as per ASTM E-45 A: A,
B, C, D all below 2
[0053] Compliance with NACE, acceptance criteria: Passing SSC
Method A test as per NACE TM0177-2005, using test solution (A),
testing at 85% SMYS, test period 720 hours.
[0054] The geometry of seamless steel tube of the present invention
and the mechanical characteristics are obtained by two methods of
manufacturing: upsetting and machining.
[0055] The upsetting manufacturing method comprises the following
steps: [0056] (a) providing a steel tube containing a composition
in weight percent, carbon 0.23-0.29, manganese 0.45-0.65, silicon
0.15-0.35, chromium 0.90-1.20, molybdenum 0.70-0.90, nickel 0.20
max, nitrogen 0.010 max, boron 0.0010-0.0030, aluminum 0.010-0.045,
sulfur 0.005 max, phosphorus 0.015 max, titanium 0.005-0.030,
niobium 0.020-0.035, copper 0.15 max, arsenic 0.020, calcium 0.0040
max, tin 0.020 max, hydrogen 2.4 ppm max, the rest are iron and
inevitable impurities, obtained by rolling process (MPM process)
[0057] (b) upsetting of tube ends; [0058] (c) austenitizing between
850-930.degree. C. the full length of the tube; and [0059] (d)
quenching and tempering between 630-720.degree. C. [0060] (e)
destructive testing (including microcleanliness, austenitic grain
size, calculate % of martensitic transformation, according to the
formulae HRCmin=(58.times.% C)+27, tensile, hardness, toughness,
SSC testing) [0061] (f) dimensional control of pipe body and upset
ends (outside diameter, out of roundness, eccentricity,
straightness, internal diameter, length) [0062] (g) machining of
external and internal upset end [0063] (h) dimensional control
(internal diameter, outside diameter and machined end) [0064] (i)
drift testing at the upset ends [0065] (j) non-destructive testing
of upset ends, weighing, measuring and marking, external surface
visual inspection, UT inspection of pipe body and UT inspection of
upset ends.
[0066] The machining manufacturing method comprises the following
steps: [0067] (a) providing a steel tube containing a composition
in weight percent, carbon 0.23-0.29, manganese 0.45-0.65, silicon
0.15-0.35, chromium 0.90-1.20, molybdenum 0.70-0.90, nickel 0.20
max, nitrogen 0.010 max, boron 0.0010-0.0030, aluminum 0.010-0.045,
sulfur 0.005 max, phosphorus 0.015 max, titanium 0.005-0.030,
niobium 0.020-0.035, copper 0.15 max, arsenic 0.020, calcium 0.0040
max, tin 0.020 max, hydrogen 2.4 ppm max, the rest are iron and
inevitable impurities, obtained by rolling process (MPM process
[0068] (b) heat treatment o pipes (austenitizing between
850-930.degree. C. the full length of the tube; and quenching and
tempering between 630-720.degree. C.) [0069] (c) destructive
testing (including microcleanliness, austenitic grain size,
calculate % of martensitic transformation according to the
formulae, tensile, hardness, toughness, SSC testing) [0070] (d)
dimensional control of pipe body (OD, out of roundness,
straightness, ID, length) [0071] (e) machining from external
surface the complete length of the pipe by programming CNC lath
machine in order to achieve final dimensions at the ends, [0072]
(f) dimensional control (ID, OD, out of roundness, straightness and
length) of pipe body and machined ends [0073] (g) drift testing at
the ends, [0074] (h) non destructive testing (NDT) of ends,
weighing, measuring and marking, external surface visual
inspection, UT inspection of machined pipe body and UT inspection
of machined ends (cylindrical section only).
[0075] Both methods are also performed providing a seamless steel
pipe with the preferred composition, as disclosed above.
[0076] The seamless steel tube of the present invention may be
divided into two zones. As shown in FIG. 1, there is an increased
wall thickness and diameter end with internal and external length
(upsetting or machined zone) and the tube body. Due to a
combination of the manufacturing methods and the chemistry design,
both the whole tube body and the ends have the same yield strength
of at least 620 MPa (90 ksi) (YS) and at most 724 MPa (105 ksi), a
Yield to Tensile Ratio not greater than 0.92, also, the same
ultimate tensile strength (UTS) of at least 690 MPa (100 ksi),
elongation of at least 18%, hardness Rockwell of at most 25.4 HRC
(value as per API 5CT means average per row) and corrosion
resistance (Compliance with NACE, acceptance criteria: Passing SSC
Method A test as per NACE TM0177-2005, using test solution (a),
testing at 85% SMYS, test period 720 hours). Prior Austenitic Grain
Size is 5 or less. The product after the quench heat treatment
process shall comply with Prior Austenitic Grain Size (PAGS) is 5
or less a microstructure of at least 90% martensite in the
as-quench condition.
[0077] The tubes may be utilized in sour and non-sour service.
[0078] The tubes' nominal diameter to be upsetted ends may be from
41/2'' to 103/4''.
[0079] The tubes' nominal diameter which ends will to be machined
may be from 41/2'' to 18'' due to the manufacturing facilities.
[0080] The tubes' thickness ranges from 10 mm to 50 mm.
EXAMPLES
Example 1
[0081] Two industrial development trials for two dimensions of
tubes (85/8'' OD.times.15.9 mm WT and 7'' OD.times.17.5 mm WT) were
carried on. The chemistry design is shown in Table 1 and the
desired ranges of mechanical properties are shown in Table 2.
TABLE-US-00001 TABLE 1 Element Minimum Maximum C 0.25 0.28 Mn 0.48
0.58 Si 0.20 0.30 P 0 0.010 S 0 0.0030 Mo 0.80 0.83 Cr 1.05 1.15 Nb
0.025 0.030 Ni 0 0.10 Cu 0 0.10 Sn 0 0.015 Al 0.015 0.045 Ti 0.016
0.026 As 0 0.020 Ca 0 0.0040 B 0.0016 0.0026 N 0 0.008 H 0 2.0
TABLE-US-00002 TABLE 2 Property Min Max Yield Strength EUL 0.5%
(MPa) 620 724 Ultimate Tensile Strength (MPa) 690 n/a Yield to
Tensile Ratio (Y/T) 0.92 Elongation (%) (L = 4D) 18 -- Individual
Absorbed Energy At -20.degree. C. (J) 30 -- Average Absorbed Energy
At -20.degree. C. (J) 40 -- Hardness Rockwell HRC-value (tempered
n/a 25.4* condition) Microcleanliness (acceptance criteria as -- 2
per ASTM E-45A: A, B, C, D) Test Corrosion period Solution NACE
TM0177-2005 SSC Method A-85% 720 hrs. A SMYS *API 5CT: value =
average per row
[0082] The upsetting manufacturing operation was performed
following the steps of: [0083] a) The pipe ends in the as-rolled
condition were heated up to the appropriate forging temperature
heating the calculated pipe length. The upsetting operation takes
place at a minimum temperature of 1000.degree. C. [0084] b) Once
the heating cycle was accomplished, pipe ends were upset with the
appropriate die and tooling design for each particular dimension.
[0085] c) Inspection was then made on pipes' external and internal
surfaces after each strike/punch in order to find any possible
defect generated by the upsetting operation.
[0086] Special care was taken into consideration when designing the
heating curve to be use during the heat treatment process in the
austenitizing furnace (860-940.degree. C.) and the tempering
furnace (640-720.degree. C.) for the upset ends of the 85/8''OD
product. After austenitizing heat treatment process, the pipe must
enter the quenching process above AC3 to guaranteed through-wall
transformation. Then, for the 7''OD product, a few heat treatment
adjustments were made on the heating curves based on the results
obtained from the other dimension 85/8'' OD pipe.
[0087] The actual temperatures from the pipe body and upset ends
outer surface were carefully measured throughout the trial stages
right at the entrance of the pipes into the quenching head by using
a manual pyrometer in addition to the furnace pyrometers.
[0088] After the heat treatments, a mechanical characterization was
performed. From the as-quenched material, the % of martensitic
transformation was calculated. Tensile, hardness, and toughness
tests were performed on the quenched and tempered material on both
upset and pipe body sections. Specifications were met; good
hardenability, yield strength values of over 92 ksi as-tempered HRC
values below the maximum allowed (25.4 HRC) and absorbed energy
higher than 100 Joules at the specified temperature of -20.degree.
C.
[0089] Extensive destructive characterization and corrosion SSC
Method A (NACE Standard Tensile Test, TM0177-96) were also
conducted.
[0090] Homogeneity in tensile properties, hardness and toughness
test results are a consequence of a very homogenous microstructure
through the wall on both upset end and pipe body in the as quenched
and tempered condition. FIGS. 2 through 5 illustrate several
graphical representations of the mechanical properties including
hardness.
[0091] The austenitic grain size was measured on as-quenched
material by the saturation method as per ASTM E-112. As shown in
FIG. 6, the grain size reported on the samples were 9/10 in the
pipe body which was above the required size since the minimum
required was 5. The upset samples showed a grain size of 8/9 and
9/10 complying with the specifications as illustrated in FIG.
6.
[0092] The transversal face to the rolling axis was
metallographically prepared and etched with Nital 2% to perform
microstructural observations with an optical microscope. (Nital:
Solution of 2% of Nitric acid in Ethyl Alcohol).
[0093] In the as-quenched samples, a martensitic microstructure was
observed on OD, ID and MW sections through the thickness achieving
a martensitic transformation of over 90% measured from the HRC
hardness values as shown in FIGS. 8 and 9.
[0094] In the as-quench and tempered material, a microstructure
constituted by tempered martensite was observed through the
thickness as shown in FIGS. 10 and 11.
[0095] The microstructures observed in as-quenched material were
mainly martensitic with over 95% of martensitic transformation
through the entire thickness of the pipe on both pipe body and
upset which indicates that the temperature at which the pipe
entered the quenching stage and the quenching itself were
homogeneous. On the other hand, the microstructures observed in
tempered material, tempered martensite was present through the
thickness.
[0096] The material passed the SSC Method A test at 85% SMYS as per
NACE TM0177-96 accomplishing the 720 hours.
Corrosion Testing Results as per NACE Method A
TABLE-US-00003 [0097] NACE TM-0177-96 Method A Stress Initial Final
Applied Sample Location Heat Specimen Diameter Initial PH Diameter
Final PH SMYS % Result 98449 Upset 19874 A 6.39 2.69 6.21 3.64 85
NF* 98449 Upset 19874 B 6.42 2.69 6.33 3.62 85 NF* 98449 Upset
19874 C 6.4 2.69 6.29 3.69 85 NF* 8448 Pipe Body 19874 A 6.36 2.66
6.24 3.53 85 NF* 8448 Pipe Body 19874 B 6.41 2.66 6.31 3.51 85 NF*
8448 Pipe Body 19874 C 6.4 2.66 6.29 3.52 85 NF* 98448 Upset 19874
A 6.37 2.66 6.22 3.5 85 NF* 98448 Upset 19874 B 6.37 2.66 6.2 3.5
85 NF* 98448 Upset 19874 C 6.4 2.66 6.33 3.49 85 NF* *NF: Not
failed
Example 2
[0098] An industrial development trial for a dimension of tube
(8.26'' OD.times.44 mm WT and 9.97'' OD.times.41 mm WT) were
carried on. The chemistry design is shown in Table 1 and the
desired ranges of mechanical properties are shown in Table 2 of
Example 1.
[0099] The pipe was rolled in a heavy wall condition. The wall
thickness was about 44 mm.
[0100] After rolling, heat treatment is performed. Similar
considerations about this step were made such as in Example 1 to
obtain through wall transformation.
[0101] After heat treatment of pipes, detail mechanical
characterization was performed such as in Example 1. Dimensional
control of the outside diameter (OD), out of roundness, inside
diameter (ID) and length of pipes was carried on followed by the UT
inspection.
[0102] In order to achieve final dimensions, the complete length of
pipe body was machined from external surface by programming CNC
lath machine.
[0103] Once again, a dimensional control of pipes after machining
was carried out.
[0104] For quality purposes, non destructive inspection of straight
pipe body section using automatic UT and manual for the cylindrical
ends.
[0105] As in Example 1, a mechanical characterization was
performed, calculating the % of martensitic transformation from the
as-quenched material. On the quenched and tempered material,
tensile, hardness, and toughness tests were performed on both
machined ends and pipe body sections. Specifications were met; good
hardenability, yield strength values of over 94 ksi as-tempered HRC
values below the maximum allowed (25.4 HRC) and absorbed energy
higher than 100 Joules at the specified temperature of -20.degree.
C.
[0106] Extensive destructive characterization and corrosion SSC
Method A (NACE Standard Tensile Test, TM0177-96) were also
conducted.
[0107] Homogeneity in tensile properties, hardness and toughness
test results are a consequence of a very homogenous microstructure
through the wall on both machined ends and pipe body in the as
quenched and tempered condition.
[0108] Microstructural observations of as-quenched material at the
pipe machined body and the ends zones reveal a prior austenitic
grain size of 8/9 in both zones measured by the saturation method
as per ASTM E-112. The modified end on the analyzed sample showed a
grain size of 8/9 complying with the specifications as shown in
FIG. 12.
[0109] The transversal face to the rolling axis was
metallographically prepared and etched with Nital 2% to perform
microstructural observations with an optical microscope. (Nital:
Solution of 2% of Nitric acid in Ethyl Alcohol).
[0110] In the as-quenched sample, a martensitic microstructure was
observed on OD, ID and MW sections through the thickness achieving
a martensitic transformation of over 90% measured from the HRC
hardness values as shown in FIGS. 13 and 14.
[0111] In the as-quench and tempered material, a microstructure
constituted by tempered martensite was observed through the
thickness as shown in FIGS. 15 and 16.
[0112] The material passed the SSC method A test at 85% SMYS as per
NACE TM0177-2005 accomplishing the 720 hours.
* * * * *