Microstructural and Mechanical Properties Characterization of the 9% Ni Steels Welds Using Nickel Alloys for LNG Tanks.

SoldOza has led a Technological Research Project, financed by Lincoln Electric, the ThermalSpray Center of the University of Barcelona, and BOSE (Bureau of Organization, Welding and Testing, S.L.) and SoldOza. In this project, the Microstructural and Mechanical Properties Characterization of the LNG tanks welds were done to know the effect of the direct and indirect welding variables on the mechanical properties of the deposited weld metal. To carry out the study were used tested samples from PQRs of several projects since 2003 and, tested samples from several benchmarking studies done for the selection of consumables. All these tested samples had been carefully preserved and keep traceable even up to 10 years, for a later, and more in-depth study. With this study, I obtained the title of Ph.D. Eng. in Materials Technology from the University of Barcelona in July 2017.

In the stage prior to the creation of SoldOza, I participated and developed several Metallurgical, Technical Studies and Benchmarking of Products, of Welding Machines, and Nickel-based Welding Consumables.

Analysis of Nickel Alloys Weld Metal Cracking Phenomena.

In late 2008 I finished out a work to identify and characterize the cracks in the 9% Ni steels welds using high Nickel filler metal. This job was entitled “Analysis of Nickel Alloys Weld Metal Cracking Phenomena”. with which I obtained the Diploma of Advanced Studies in Materials Technology, University of Barcelona.

During the time I was working at Lincoln Electric, in addition to my standard duties, I did several projects or activities directly related to LNG tank welding, these activities were:

Developed Activities for LNG Projects in Lincoln Electric France, Rouen. 2008 – 2010.

  • Technical Assistance Support for Welding Submerged Arc Welding Procedures, Meeting with the Design requirements.
  • Commissioning and start-up of the new generation equipment acquired by Felguera IHI for welding the horizontal joints with SAW process of the LNG TK-3002 and TK-3003 Tanks in Barcelona.
  • Optimization of welding parameters and redesign of welding joints for the TK-3003 Tank.
  • Welding samples for the Certification of the Submerged Arc Consumables in accordance with ASME II, for Tecnicas Reunidas and Felguera IHI for their respective Projects.
  • Qualification of the Welding Procedures with Submerged Arc Welding process of Felguera IHI for its Tanks TK-3002 and TK-3003 in Barcelona and for Tecnicas Reunidas for the FB-242 LNG Tank in Escombreras, Cartagena.

Developed Activities for LNG Projects in Lincoln KD, Spain. 2006 – 2008.

  • Development of the Procedure with SAW to guarantee 400 / 690MPa in the horizontal seams of the LNG Tanks, thus maximizing the allowable design efforts according to API 620 10th edition.
  • Technical Cooperation Project with ENAGAS, Welding of test pieces for evaluation of the Automatic Ultrasound Process. Specimens were welded without Defects, with Natural Defects and with Induced Defects with the SMAW and SAW processes.
  • Comparison of performances of AC Machines for welding with Nickel Base Coated Electrode for LNG Tanks.

Work Done for LNG Applications in Lincoln Cleveland, July - September 2008.

  • Analysis wire feedability and welding parameters to solve the problems presented happened during the welding of Tanks TK-3001 and FB-241.
  • Benchmarking of different configurations of submerged arc welding equipment in order to improve the stability of the process by minimizing defects in welding metal and improving the operability of the process.
  • Evaluation of Fluxes and welding parameters effects on mechanical properties of the 9% Ni Steel welds with nickel alloys using Submerged Arc process. Developed at Lincoln Cleveland, July to September 2008.


Technical Research Trials: Testing and selection of Welding Consumables for Cryogenic Application. 2003.

  • To Weld Austenitic Stainless Steel by SMAW: Benchmarking between both Stainless Steel electrodes for SMAW developed for Cryogenics Applications: The ferrite controlled rutile stick electrodes and Basic covered stick electrodes.
  • To Weld 9%Ni Steels by SAW and SMAW, (Supported by Dr. Norihico Katayama, from IHI, Japan). A benchmarking study of four electrodes manufacture branches and four wire-flux combinations were performed for the welding consumables selection. The evaluation criteria were cracking sensitivity, weldability and mechanical strength. Also, this study allow us to determine the optimal welding parameters to be used for WPS and production welding.

Implementation of the Phase Array Technique to Examine the Weld Joints of LNG Tanks.

Production of Blind Test Plate for Phase Array Technique Validation.
In 2007, Enagas performed a Validation of the Registrable computer supported Ultrasonic Examination Techniques Project, in which different NDE laboratories to participated to determine, the resolution capacity and detection capacity of the different registrable computerized supported Ultrasonic Techniques to reveal flaws in horizontal and vertical dissimilar welds between 9%Ni Steel plates and full Austenitic high Nickel alloys weld metal. Also, the performance of these NDE laboratories were evaluated in this project. In that time Enagas propose me to weld samples with artificially induced reflectors and natural flaws typically produced in horizontal joints welded by Submerged Arc Welding Process and on vertical joints welded by Shield Metal Arc Welding Process. A total of 12 samples were welded by me, in 3G by SMAW and in 2G SAW, 12mm and 21mm, with natural flaws and artificially induced reflectors, plus several preliminary samples welded to develop the production techniques of each type of flaw/reflector.

Implementation of the Registrable UT Technique.

2011. Supported the implementation of the Phase Array Technique in liu of the X-ray examination during the construction of the Mejillones LNG Tank in Chile.

2018. Responsibles of the review and acceptance the examination procedure proposed by NDE subcontractor for the Ultrasonic Examination during the construction of the LNG Panama LNG Tank.

2018. As Renaissance HI, Advisor we presented the Technical Query requesting the authorization to use the Registrable Ultrasonic Examination in Tonopah LNG Tank, Russia, this implementation was supported by a comparative study between X-ray and UT resolution capacity. This request was accepted by Linde Engineering as Project EPC and by Pethon as whole Project EPC and Gazprom as Project Owner.

2021. Implementation of the Ultrasonic Examination Instead of X-ray examination of the 347H high Carbon Stainless Steel welds, in accordance of API 650 Annex U, during the Reparation of 1 Hot Salt Tank in Tonopah, Nevada USA.