[ End User Feature ]
low oxygen content at the root . High-purity shielding and purging gas ( 99.997 %) were also applied . To ensure maximum efficiency , most of the joints were welded with an internal clamp with an integrated purge dam , including bends and tie-ins through a modified internal clamp . It ’ s worth noting that 24 ” pipe production has inside welding , which differs from 16 ” production with coil methodology , where the root pass is welded with autogenous welding . These best practices ensure the success of the welding process , making the project a resounding success .
Technical challenges The construction of large-scale projects often comes with various challenges , some of which include the first-time implementation of new ISO 17781 requirements along with new company specification requirements on hot tensile tests and SCC tests on field girth welds . One of the main challenges that arise when dealing with larger diameters is maintaining oxygen content below 500ppm to avoid oxidation at the root . Stress corrosion cracking test ( SCC ): Strict technical requirements were specified , including four-point bend test as per NACME TM0316 for autogenous welding . SCC tests were conducted on the 16 ” line pipe production weldment in a third-party lab accredited by ISO 17025 . The same SCC test requirements were subjected on the girth welding produced in the field , even though all passes were welded with filler metal , to evaluate the heat affected zone ( HAZ ) of the line pipe with autogenous weld . As the girth weld is not subjected to solution annealing , the welding parameters were tuned to ensure the girth weld and its HAZ meets the SCC test criteria of no pits . Elevated tensile test : Performed at the design temperature , this is an important property for this line and shall meet room temperature mechanical strength requirements . Charpy impact test : Was conducted to meet ISO 17781 Quality Level 1 requirements even though Quality level 2 is accepted for oil and gas environments . Also test temperature applied in line with ISO 17781 -46deg C , in spite of the minimum design temperature being warmer than 5deg C . Pitting corrosion test : ASTM G48 test was conducted on the weldment in the as-welded condition without altering
Figure 3 . Aerial view of the duplex pipeline construction site .
the root condition . No pickling was performed to simulate the production weld , and the entire thickness was subjected to test method A . The test was successful and weight loss was lesser than 4gm / m 2 .
“ Remote inspections and frequent communication with suppliers and manufacturers helped maintain manufacturing quality .”
Overcoming project schedule challenges The project faced technical challenges in meeting yield strength , hot tensile , corrosion , and impact tests . COVID-19 restrictions affected raw material and product shipments , but effective remote inspections and frequent communication with suppliers and manufacturers helped maintain manufacturing quality . Deviations from specification requirements were managed through technical authority approvals . Qualifying submerged arc welding posed challenges , but optimising welding parameters improved toughness and corrosion test requirements . Double welding before transferring to the site improved productivity and helped meet project schedules . To ensure manufacturing quality , technical alignment and pre-inspection meetings were held in the mill , and close monitoring and collaboration with vendors were established to mitigate COVID-19 restrictions . A third-party inspector was mobilised to the mill for effective monitoring and quick resolution .
Construction of this larger diameter DSS pipeline required special equipment including internal clamps , purge monitors , flow meters , boroscope inspection equipment and highly-skilled welders . The COVID-19 pandemic posed significant challenges in mobilising highskilled welders , equipment , and tools to the construction site .
Summary In conclusion , the successful fabrication and installation of a large diameter DSS pipeline underlines the resilience of the oil and gas industry in the face of unexpected challenges like the COVID-19 pandemic . Despite disruptions and logistical hurdles , the project was completed before the deadline , meeting all requirements , and demonstrating the benefits of innovative practices and effective collaboration between pipe mills , contractors , and end users . The use of digital tools for remote inspections and close monitoring of vendors helped ensure compliance with project requirements , while technical authority approvals managed any deviations . The project ’ s success is a testament to the dedication and technical expertise of the team involved , who overcame all odds and obstacles to deliver a high-quality and reliable pipeline . This project serves as an excellent example of how best practices , technical alignment , and innovation can help organisations overcome challenges and achieve their goals .
Acknowledgements The authors would like to express their gratitude to Petroleum Development Oman , as well as the individuals , contractors , and suppliers , associated with this project . Their contributions and support have been invaluable in making this project a success .
16 Stainless Steel World April 2023 www . stainless-steel-world . net