Christmas Tree Spool Body – Aftermarket Repair


The client required a technology solution that would allow them to refurbish Christmas tree spools that had been in operation for over 20 years in the Troll Field, Norway. Due to the age of the equipment several repairs, material certification and quality assurance documentation was required as part of the overall work scope.



The overall age of the equipment was a challenge faced by the team and various procedures were required to carry out the material certification and quality assurance documentation. The collaboration between Proserv and the client was key to the success of the project which ultimately provided significant cost savings and reduced lead times by choosing a refurbishment solution of existing equipment over new component parts.


Proserv worked with the client to first understand the original material composition as this would aid in the repair process. In order to achieve this sacrificial test pieces trepanned from the base material were taken and additional outlets were machined that could later be capped off. A Positive Material Identification (PMI) was taken of the cores and results from further mechanical testing. This provided the necessary details to make revision changes to existing weld procedure specifications and procedure qualification records (WPS & PQR). These were then simulated during the 2nd and 3rd stress relieves. The repair welds were witnessed by DNV and undertaken by Proserv and NS 477 welding inspectors under strict ISO 3834 standards. Checks to the heat affected zones (HAV) and the hardness were also collected for analysis.



  • The client has further prolonged the life of their assets, while bringing the well back into full production
  • The client is to roll out the procedure for all tree spools within the field
  • Improved production

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