Title

CHARACTERIZATION OF A LOW MANGANESE-HIGH NIOBIUM STEEL FOR OIL AND GAS TRANSPORTATION SYSTEM PIPES WITH SOUR SERVICE REQUIREMENTS

CHARACTERIZATION OF A LOW MANGANESE-HIGH NIOBIUM STEEL FOR OIL AND GAS TRANSPORTATION SYSTEM PIPES WITH SOUR SERVICE REQUIREMENTS

Authorship

PORTO, RICARDO; SOUZA, MARDEN VALENTE DE; OLIVEIRA, BÁRBARA FERREIRA DE; BARBOSA, FABIANO ALMIR

PORTO, RICARDO

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SOUZA, MARDEN VALENTE DE

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OLIVEIRA, BÁRBARA FERREIRA DE

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BARBOSA, FABIANO ALMIR

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DOI

10.5151/2594-5297-42594

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Abstract

ERW pipes were produced to meet API 5L X65 requirements for sour service, using heats with varied Mn and S contents, with and without calcium treatment. The slabs were thermo-mechanically rolled to 6–12 mm thickness. Microstructure analysis showed quasi-polygonal ferrite and grain size 13. Inclusion analysis revealed more oxides and sulfides in calcium-treated heats. All samples met tensile strength requirements, with higher values in the transverse direction. Charpy impact tests at -20°C showed 100% ductile fracture, with no brittle-ductile transition down to -100°C, confirming excellent toughness even in heats without calcium treatment.

ERW PIPES WERE PRODUCED TO MEET API 5L X65 REQUIREMENTS FOR SOUR SERVICE, USING HEATS WITH VARIED MN AND S CONTENTS, WITH AND WITHOUT CALCIUM TREATMENT. THE SLABS WERE THERMO-MECHANICALLY ROLLED TO 6–12 MM THICKNESS. MICROSTRUCTURE ANALYSIS SHOWED QUASI-POLYGONAL FERRITE AND GRAIN SIZE 13. INCLUSION ANALYSIS REVEALED MORE OXIDES AND SULFIDES IN CALCIUM-TREATED HEATS. ALL SAMPLES MET TENSILE STRENGTH REQUIREMENTS, WITH HIGHER VALUES IN THE TRANSVERSE DIRECTION. CHARPY IMPACT TESTS AT -20°C SHOWED 100% DUCTILE FRACTURE, WITH NO BRITTLE-DUCTILE TRANSITION DOWN TO -100°C, CONFIRMING EXCELLENT TOUGHNESS EVEN IN HEATS WITHOUT CALCIUM TREATMENT.

Keywords

Sour Service, Low Manganese HTP Process, toughness, Inclusion

Sour Service, Low Manganese HTP Process, toughness, Inclusion