Single Buoy Mooring (SBM), also known as Single Point Mooring, is the recommended infrastructure for large marine mooring nearshore, as it offers more flexibility than Multiple Buoy Mooring, allowing tankers to move freely while moored, so as not to be affected by wind and wave direction. When taking a holistic approach, however, an SBM setup is not a one-size-fits-all solution.
Some time ago in 2016, MARSOL International performed Single Buoy Mooring maintenance for a client in the Middle East who was experiencing regularly required hose changeouts that were consuming their OpEx budget faster than the norm.
Onsite, we replaced the buoy in use and assembled new hoses into hose strings for installation onto the SBM offshore. Upon inspection of their marine hoses, we noted a number of seemingly minor issues that as a whole could contribute to massive hose failure. For readiness of all such cases, we recommend that an emergency plan is in place.
One of the hoses had a small cosmetic crack on the hose taper section, and many of the steel flange nipples suffered chafing damage on the galvanising. We also noted that most of the hoses had minor bulges on their outer surface.
These bulges disappeared throughout the day when temperatures rise above 40 degrees centigrade, but they would return in the evening when temperatures dropped below thirty. While hoses are designed to cater for fluctuation in temperature, the infrastructure around the hose may not be so forgiving.
Through holistic analysis, we concluded that this temperature fluctuation combined with their standard support cradles (that did not cater to this unique environment) lead to constant hose damage that cost the company thousands of dollars in premature hose changeout.
We also found that their transportation straps used to secure hoses to their cradles were the main contributor to chaffing damage.
To kick off analysis, we provided a supervisor and testing equipment to perform leak testing offshore, according to the SBM testing protocols, for varying SBM Installations.
Cosmetic cracks were repaired to ensure that the hoses did not deteriorate in service prematurely.
Chaffed locations were repaired with a “cold- galv” paint application, as agreed with SBM, prior to load out of the hoses into the water.
To combat the recurring bulges caused by temperature fluctuation, we redesigned their hose assembly process, not only ensuring a safe installation and changeout for this project, but also for a sustainable result.
The process: Assembly of Hoses
All Materials delivered to the site were visually inspected and any anomalies identified to the SBM site representatives and logged on record sheets.
All hoses delivered to the site had their plastic transportation wrappers removed once the cradles were removed from the trucks. Each hose had its inner and outer surfaces studied, along with the condition of the nipple on each end and the leak indicators.
The Floating Hose String (Inner Hose A and Outer Hose B) assemblies were performed onshore on the quayside in the port. All hoses were assembled including the tanker rail, butterfly valve, camlock spool piece and blind flange.
All hoses were installed with the leak indicators at the 12 O’Clock position.
After a thorough inspection and proper assembly, the risk of failure and defects before towage and during service were largely minimised. With long-term sustainability in mind, MARSOL increased the client’s hose reliability and lifespan, while minimising operational and production interruptions.
The goal of this project was to enhance protection for this client across the following areas:
We are proud to say that this project was a success, with results still visible today.
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