Case Study – Shell: Waterjet Cutting of Collapsed Floating, Tank Roof
Cold Cutting in Explosive Atmospheres
Task: Abrasive water jet cold cutting of a damaged floating, tank roof – Tank 201
Location: Forcados Delta, Nigeria
When: January – May 2018
Abrasive water jet cold cutting sub-contractor: RGL
• Ultra high-pressure portable diesel driven water jetting unit
• Hydraulic power packs
• Purpose built cutting tracks
• Cold cutting hoses and required accessories
• 5 man team
RGL were approached in November 2016 regarding a collapsed floating, tank roof in a refinery located in Focados Delta, Nigeria. The roof had become damaged due to flooding and was no longer
operational meaning the tank was redundant.
In order to get the tank back in service the damaged roof was required to be cut into manageable sections that could be removed, before a new roof could be installed. The tank is 72 metre diameter and due to its location within a working refinery it was decided only heat free methods of cutting could be employed. An opening into the side of the tank was also required in order to gain access to the roof and for removal of cut sections.
A site survey was arranged, in June 2017. RGL sent surveyors to undertake the survey. This visit enabled RGL to fully understand the requirements of the project, form a business relationship with other stake holders, and understand the challenges that would be faced, from location and weather through to language barriers. Upon the return to the UK, a commercial proposal, risk assessment, method statement and cutting sequence were incorporated into a safe system of work, and submitted for review.
Once the proposal was accepted, and all program and methodology were agreed, RGL’s first challenge was to ensure that all necessary machinery and consumables (including considerable contingency stock) was shipped out in compliance with Nigerian “temporary import/export” regulations so the machinery could be shipped back to the UK after successful completion of the works.
On confirmation that the shipment had arrived on site, RGL mobilised their “pre readied” team to start work with immediate effect. The client had previously erected a scaffold (to RGL design) and marked out their 5.75m x 4.5m opening (with stepped and radiused corners) so it was a matter of the RGL team setting up the site, mounting their rig(s) and cutting through the 35mm thick tank side walls to form a door opening.
When the end of the cut was near, the door sheet weight was taken by a crane and the cut completed. Once cut through, the door sheet coupon was lifted out and stored ready to be welded back in place once the tank refurbishment works were complete. With access to the roof now possible, RGL were able to move their hydraulic power packs, cutting tracks, cutting carriages and grit feeding equipment on to the roof to implement detailed plans to safely and efficiently cut the 4,070 square meter collapsed roof into 110 liftable sections.
With access to the roof now possible, RGL were able to move their hydraulic power packs, cutting tracks, cutting carriages and grit feeding equipment on to the roof to implement detailed plans to safely and efficiently cut the 4,070 square meter collapsed roof into 110 liftable sections. As the cut sections were removed this left the central section, and it took 5 days to cut this into 4 removable pieces and signified the completion of the contract.
Overview of finished project
The overall duration of the project was 17 weeks working 11 hours per day, 6 days per week. After starting the work in January 2018 it was completed in early May without any incident and actually ahead of the May scheduled deadline. RGL would like to thank all parties who assisted with the cutting work and made it possible to achieve such a result within a budget and according to programme.
In summary, we will do our utmost to deliver completesatisfaction to you by:
- responding quickly to your enquiries
- working with you to fully understand your requirements
- providing you with the benefit of our experience
- preparing detailed site safety, quality and environmental plans, including method statements and risk assessments
- providing competitive quotations
- delivering on what we promise for project start and
- deploying experienced crews and proven, correctly
- working within site safety rules and regulations
- managing the project environment including waste water
treatment and filtration
- managing each project through to completion
- COSHH Assessment and measures to avoid adverse
“What we say ….we do”
Paultons Park, Ower,
Romsey, Hampshire SO51 6AL U.K.
London – T: +44 (0)203 102 6840
RGL Company Registration Number: 01788078