Reducing stress on hose reel

Summary

This Paper considers the issues and variables involved with stress on Hoses and Marine Breakaway Couplings when wound onto Hose Reels.

Introduction

Hose Reels
In recent years there has been a trend towards transfer operations adopting Hose Reels as a method for deploying, recovering and storing Hoses in offshore transfer operations.There are several benefits in using this method; including increased storage capacity, a neater and therefore safer working environment, lower risk of random damage and reduced fatigue on Hoses and more efficient Hose application during transfer operations.

Marine Breakaway Couplings
With the aid of connectors at each end, the Marine Breakaway Coupling is fitted within the Hose string and is designed to close off both the upstream and downstream flow of media and then separate when an event causes an Activation. There are typically two events that can provoke an Activation.
The first is when the Hose is stressed beyond its safe envelop – usually due to the drift of a vessel beyond predetermined parameters.
The second is due to a pressure surge. In either case, the Marine Breakaway Coupling will reduce the risk of spill, help protect assets from damage and limit the potential of injury to the workforce. Risk of extended downtime and extensive clean-up costs due to damage to the environment are also reduced.

Application of Marine Breakaway Couplings to Hose Reels
Marine Breakaway Couplings have been protecting Hose transfer operations for decades; including when Hoses tended to be wrapped or left on vessel deck rather than wound on a Hose Reel. When Hose Reels increasingly became part of Hose transfer operations, the Marine Breakaway Coupling simply wound on the Hose Reel as part of the Coil. This method is adequate; however, outstanding issues remained regarding Hose and Coupling stress and therefore the potential risk of asset damage and increased depreciation of operational equipment.

Variables to consider when Marine Breakaway Couplings are part of the Hose Reel Coil
Marine Breakaway Couplings that are maintained within manufacturer recommendations do not present any particular issues within a Hose String. However, when wound to a Hose Reel, there is an unavoidable and distinct interruption in the otherwise natural radius of the Coil.
This profile interruption or Coil Discrepancy presents resistant variables that causes stress on the Hose and on the Marine Breakaway Coupling. The consequence of this stress can be fatigue on both the Hoses and Marine Breakaway Coupling Breakstuds.
The level of Coil Discrepancy determines the Contact Angle of the Hose in relation to the inner wound Hose. Where there is no Marine Breakaway Coupling fitted to this section of Hose then the Coil Discrepancy is zero and the correct Contact Angle is maintained.
Where a Marine Breakaway Coupling is fitted then a Coil Discrepancy will exist and the Contact Angle will be imperfect; there is then a value that is determined by the extent to which the Marine Breakaway Section of Hose is raised above the Inner Hose.
The length of a Marine Breakaway Coupling determines this value and therefore the value assigned to each stress factor.  This can be mitigated by the radius of the Hose Reel. A greater radius reduces Coil Discrepancy. A shorter Marine Breakaway Coupling may also reduce Coil Discrepancy and therefore reduce stress.