Session: 09-04-01 fracture and toughness for H2 pipelines

Paper Number: 132612

132612 - Fracture Toughness Evaluation of JCOE Pipe Under High Pressure H2 Gaseous 

Abstract: 

Demand for pipeline that transports low carbon hydrogen gas such as green, blue hydrogen have been increasing to create a decarbonization energy system all over the world for the reduction of CO2 emissions.

Currently, material requirements for hydrogen pipeline are frequently referred to ASME B31.12 “Hydrogen Piping and Pipelines”. The key requirement in it is considered to have adequate resistance to fracture in hydrogen gas, since hydrogen has a negative impact on fracture toughness due to hydrogen embrittlement. And this is specified by the threshold intensity values K_IH, which shall be above K_IA (the applied stress intensity factor obtained at a project design pressure for the assumed elliptical surface crack) or 55 (MPa・√m), whichever is greater. Therefore, it is important to know the fracture toughness value of materials under hydrogen gaseous properly to maintain integrity of hydrogen pipeline.

In this research, longitudinal submerged arc welded(LSAW) pipe X65MS 24”x23.8mm manufactured by JCO + Expander(JCOE) process which has been widely used for onshore & offshore pipelines in oil and gas transportation, was selected to evaluate the fracture toughness of base metal, weld metal and HAZ in the pipe. The base material of the pipe was Nb-TMCP with fine homogenous bainite microstructure. The heat affected zone of SAW was controlled by Nb micro-allying to prevent grain growth. The longitudinal weld seam had fine acicular ferrite microstructure. The fracture toughness test was conducted under 100% H2 gaseous with testing pressure 21MPa, using compact specimens in compliance with ASTM 1820 which enable us to obtain quantitative fracture toughness value of the materials and meet validity of plain strain fracture toughness. The K-rate in a linear-elastic stage was set to 6.0 (MPa・√m/hr) which would be low enough to represent high effectiveness in hydrogen embrittlement. The crack extension was monitored by alternative current potential drop method (ACPD). The plain-strain fracture toughness J_IQ was obtained from J-R curve, then it was converted to K_JQ.  In the HAZ specimen, the notch position was located just on the intercritically reheated coarse grain (ICCG) HAZ where is considered as the most brittle zone in the pipe. However, the HAZ exhibited K_JQ more than 100 (MPa・√m), which met the criteria of ASME B31.12. Microscopic fracture behaviors are also discussed in this paper.

Presenting Author: Kota Nakashima Al Gharbia Pipe company

Presenting Author Biography: Product Design & Quality Control Manager, Al Gharbia Pipe Company LLC

Academic Experiences
2004, Bachelor’s Degree from Saga Univ., Science and Engineering
2006, Master’s Degree from Kyushu Univ., Advance Energy Engineering Science

Industrial Experiences
2006, Joined JFE Steel
2006-2010, Operation engineers of HSAW pipe mill
2010-2014, Product design & production control of UOE pipe
2014-2017, Houston office, JFE America as a technical engineer
2018-2020, Deputy plant manager of UOE pipe mill
2020-present, moved to Al Gharbia Pipe Company LLC as a product design & quality control manager

Authors:

Kota Nakashima Al Gharbia Pipe company
Nobuyuki Ishikawa JFE Steel
Hikaru Imayama JFE Steel