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In February 2024, an important client decided to carry out the re-tubing of the critical steam transformer at the ADNOC refining crude flexibility project (CFP) Ruwais Refinery. The primary objective was to address significant operational issues, including pressure drops and leaks in the steam transformer, which compromised the plant’s efficiency and safety. The project commenced on February 24, 2024, with an anticipated completion time of one month.

Why is RETUBING Required?

Plant shutdowns, also known as “turnarounds,” are critical periods for oil and gas refineries. These shutdowns can significantly influence the financial outcomes and future commitments of the plant, either positively or negatively. Among the essential equipment in these refineries is the heat exchangers, which plays a vital role in various processes and heat transfers. The performance of heat exchangers also impacts the duration of plant turnarounds. After a turnaround, if a heat exchanger fails shortly after normal operations resume, it can lead to substantial financial losses due to reduced downtime or decreased production, despite the contractor’s warranty. During turnarounds, heat exchangers may undergo various repairs, including Partial or full Re-tubing through different methods or simple tube Plugging. Repairing heat exchangers during these periods helps minimize downtime losses and ensures the equipment’s integrity for the smooth operation of the plant.

Project Specifications
• Plant Type: Oil and Gas Refinery
• Equipment: Steam Transformer

Tube Specifications:
• Outer Diameter (OD): 16 mm
• Thickness: 0.7 mm
• Material: TP 439 Welded
• Tube to Tube Sheet Expansion: Expanded type
• Equipment Position: Horizontal, elevated at 7.3 meters
• Tube Sheet & Baffles Condition: Highly rusted and corroded

Challenges and Solutions

1. Confined Space Operations:
• Retubing was carried out in a confined space, entering through a manhole with oxygen and light deficiencies at one end and there was a 2.53 meter fixed channel cover on the other end of the transformer. Scaffolding platform erected up to 7.3-meter elevation. Retubing personnel were working inside the confined space continuously with safety harnesses & lanyards under the observation of Hole watch.
Solution:
• Technicians received specialized training for confined space operations, including safety protocols for low-oxygen environments.
• Technicians had specialized permits to work in confined spaces to carry out re-tubing operations.
• A scaffolding platform was built so that the technicians could carry out the job at a specified height.
• Appropriate PPEs & safety equipment such as H2s detector, Fire extinguisher, Air Supply, Area Gas detector, and Escape Hood were utilized to ensure the safety of the workforce.
2. Material Handling:
• These tubes were critical and sensitive materials requiring careful handling to avoid damage.
Solution:
• Use of specialized tools and equipment procured by Tritorc to handle and install the SS tubes without compromising their integrity


Using impact wrenches paired with pulling sockets facilitated the tightening of pulling mandrels into the tube ID. Tritorc-made Hydraulic tube-pulling gun TPG-30, powered by the Hydraulic Tube Pulling Power pack TPP-50, efficiently extracted the tubes. To optimize the functionality of the pulling gun, a spring-balancer was employed to suspend it, ensuring smoother operations.


Tritorc’s Impact Wrench along with Mandrel and Socket

Hydraulic Tube pulling gun driven by Master Tugger Tube Puller [ STTP 300 ]
3. Operational Efficiency:
• The re-tubing needed to be completed within a tight schedule to minimize downtime.
Solution:
• Tritorc efficiently replaced 5053 no’s tubes within 1 month with zero leak during the hydro test.
• A workforce of 14 lead technicians, including 2 supervisors and 2 site engineers ensured round-the-clock operations to adhere to the project timeline.
4. Safety and Training:
• Ensuring the safety and competency of technicians working in hazardous environments.
Solution:
• Comprehensive training programs were conducted, covering the actual scope of work, and various operational environments, such as H2S, working at heights, and confined spaces.
• Medical examinations and certifications were mandatory and approved by ADNOC, to carry out the site activity.

Project Execution

1. Inspection and Documentation:
• All visual, and dimensional inspections were completed and the dossier was handed over to the client.
2. Retubing Operations:
• Tritorc team carried out full Retubing activity including tube removal, cleaning of tube sheet holes & baffle plates, and Insertion & Expansion of tubes in the confined space.
• The operation was executed under stringent safety protocols, with continuous monitoring of oxygen levels and adherence to confined space safety regulations.
3. Project Completion:
• The project was completed within the scheduled timeframe of one month, with all 5053 no’s tubes successfully replaced and operational.
4. Adherence to Standards:
• A standardized procedure was incorporated to satisfy all the standard codes like ASME &TEMA.

Outcome

The re-tubing project at the ADNOC refining crude flexibility project (CFP) Ruwais Refinery was a critical maintenance operation that successfully addressed the issues of pressure drops and leaks in the heat exchangers. Through meticulous planning, specialized training, and the use of appropriate tools, the project was completed safely and efficiently. The plant resumed operations with enhanced efficiency and safety, meeting ADNOC’s high standards of operational excellence.

This case study exemplifies the importance of thorough preparation, skilled workforce, and adherence to safety protocols in executing complex maintenance projects in the oil and gas industry.