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.

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×% 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≦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×% 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≦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° C. the full length of the tube; and   (d) quenching and tempering between 630-720° 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° C. the full length of the tube, and quenching and tempering between 630-720° 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° 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° 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° 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° C.