When a decommissioned offshore platform is taken to shore to be dismantled there is the potential of unidentified hazardous materials. The risk that our people get exposed to such is inherently linked to this. We want to avoid exposure at all costs and our work procedures must secure that. Everyone shall go home safely also in the long term when the ill effect of exposure becomes apparent. This way we reassure our clients that their decommissioned platform is in good hands.
In most cases the Inventory of Hazardous Materials (IHM) provided by the client is indicative and not sufficient to get the level of detail required to safely dismantle the structure. The purpose of an IHM survey is to get an overall understanding of the materials used but to get the full picture you need to look beyond. This requires invasive actions that are often just not possible while the platform is still at sea. Besides, its takes a specialist to know what you are looking for and where you potentially encounter it. The IHM can be very professional but it serves a different purpose.
From the dozens of projects that HSD has processed we have learned the importance of an in-depth survey. It takes time and effort but it pays off in terms of safety and has positive spin-off in terms of waste management and efficiency.
Regardless the size and age of a structure HSD conducts the following surveys;
General survey;
Here we look for general safety aspects like safe access, stored energy, overall structural integrity, content of tanks, status of stores, housekeeping situation, etc. Any acute hazards like open floor penetrations or waste littered around will be rectified before starting with dismantling on the platform.
Asbestos survey;
An independent certified specialist will verify already known asbestos findings but we also look behind coverings and inside constructions. This requires small scale demolition to make way for the surveyor.
Paint composition survey;
Conservations systems applied on offshore structures are high grade paints that in many cases also contain hazardous materials like hexavalent chromium (Cr-6). This may complicate dismantling and waste management when not handled accordingly. The sampling and analysis of these conservation systems are performed by a certified third part specialist.
Process installation survey;
Over the years of operation NORM and mercury may have built up inside the pipework and process vessels. To get a (nearly) full understanding of this we drill holes all over the process installation and probe for indications. In this way we map the complete installation and mark-up the installation with paint, indicating contaminated and non-contaminated areas. The dismantling teams knows how to deal with each section. Where applicable, specialized teams remove the NORM and mercury contaminated parts of the installation. We try to do this in advance as much as possible.
By performing this survey we also verify if the installation is empty, free from pressure and remnants of hydrocarbons. Any liquid content will be drained using hot tapping techniques.
After completing the surveys we have much better understanding of what has arrived at our yard and how to approach it best. We can also inform our clients about the findings early in the process. This allows clients to verify “as is” and to anticipate on contractual arrangements that come in play.