Continued from last Blog posting.
Polymer composite seacocks
Polymer composite is another reliable material for the manufacture of seacocks, such as those produced by New Zealand-owned Tru-Design Plastics (TDP). These are sometimes referred to as “Maralon”, which is just a brand name of one polymer composite.
TDP’s glass-fibre reinforced polymer ball valves are fully compliant with all standards including the demanding ISO 9093-2 standard requiring that the ball valve and skin fitting continue to operate while a 1,500N (155kg) weight is suspended from the end of the fitting. TDP are also believed to be the world’s only producer of polymer composite fittings to gain the prestigious Bureau Veritas approval for through hull fittings and ball valves (Certificate Nbr 27801/ AO BV).
Polymer composite seacocks are about one sixth the weight of bronze (which can be particularly important in some sailing yachts and planing power vessels), corrosion free without the need for bonding wires, and price-competitive.
But just as there are seacocks produced from inappropriate metals there are low quality seacocks produced from polymer composites offered by some manufacturers, so in all cases be sure to select seacocks with parallel threads, the necessary approvals for marine use, and never use standard domestic water supply plumbing fittings in below-the-waterline seawater applications.
What should the boat owner do?
Firstly locate and document the internal and external location and function of every seacock and through-hull on the vessel. Check they are supplied from reputable manufacturers whose products meet the necessary marine standards and not subject to corrosion in sea water.
All seacocks should be accessible and operable, and if they are not able to be closed they should be serviced at the earliest opportunity, particularly if they are below the waterline. Don’t be concerned if bronze seacocks have a greenish tinge, this is normally only non-harmful verdigris, formed when copper alloys are exposed to air or seawater.
The owner should also check that the correct quality of hoses for below waterline use are installed, that two marine grade 316 stainless steel hose clamps have been used on all fittings, that these clamps are tight and in good condition, that there are no water leaks, and that the electrical bonding wires are connected and not corroded. Some stainless steel hose clamps have worm screws produced from inferior grades of stainless steel, and these need to be checked and treated with anti-corrosion grease. Seacocks should also be operated occasionally, for example monthly, to ensure they are working correctly, and this also keeps the owner familiar with their location and operation.
A selection of tapered soft wooden plugs should be kept in a handy location to stop the flow of water through any seacocks which do fail.
Should I close my seacocks when leaving the vessel?
This depends on how long the vessel is being left unattended, and on the personal choice of the skipper. Most skippers would not close their seacocks if leaving their vessel unattended for a day, while many would close their below waterline seacocks if leaving the vessel for more than a day. In my opinion it would be foolhardy not to close all below waterline seacocks when leaving the vessel unattended for more than a few days. Regularly closing and opening the seacocks is good for them, as well as constantly reminding the skipper of their location. However there is a danger of inadvertently leaving one or more seacocks closed when next using the vessel, leading to possible damage of the equipment they supply water to. To easily reduce this risk the skipper can place a sign on the ignition key as a reminder of closed seacocks.
Another solution is to install seacocks which are able to be remotely monitored, such as the polymer composite seacocks produced by TDP. These can be wired directly to equipment, for example an engine, to prevent it from being started if the seacock is in the closed position.
Selection of seacocks produced only by reputable manufacturers to recognised standards using correct materials such as bronze or polymer composites, together with their regular inspection, operation and maintenance will greatly reduce the risk of problems in this vital area.
Polymer composite seacocks
Polymer composite is another reliable material for the manufacture of seacocks, such as those produced by New Zealand-owned Tru-Design Plastics (TDP). These are sometimes referred to as “Maralon”, which is just a brand name of one polymer composite.
TDP’s glass-fibre reinforced polymer ball valves are fully compliant with all standards including the demanding ISO 9093-2 standard requiring that the ball valve and skin fitting continue to operate while a 1,500N (155kg) weight is suspended from the end of the fitting. TDP are also believed to be the world’s only producer of polymer composite fittings to gain the prestigious Bureau Veritas approval for through hull fittings and ball valves (Certificate Nbr 27801/ AO BV).
Polymer composite seacocks are about one sixth the weight of bronze (which can be particularly important in some sailing yachts and planing power vessels), corrosion free without the need for bonding wires, and price-competitive.
But just as there are seacocks produced from inappropriate metals there are low quality seacocks produced from polymer composites offered by some manufacturers, so in all cases be sure to select seacocks with parallel threads, the necessary approvals for marine use, and never use standard domestic water supply plumbing fittings in below-the-waterline seawater applications.
What should the boat owner do?
Firstly locate and document the internal and external location and function of every seacock and through-hull on the vessel. Check they are supplied from reputable manufacturers whose products meet the necessary marine standards and not subject to corrosion in sea water.
All seacocks should be accessible and operable, and if they are not able to be closed they should be serviced at the earliest opportunity, particularly if they are below the waterline. Don’t be concerned if bronze seacocks have a greenish tinge, this is normally only non-harmful verdigris, formed when copper alloys are exposed to air or seawater.
The owner should also check that the correct quality of hoses for below waterline use are installed, that two marine grade 316 stainless steel hose clamps have been used on all fittings, that these clamps are tight and in good condition, that there are no water leaks, and that the electrical bonding wires are connected and not corroded. Some stainless steel hose clamps have worm screws produced from inferior grades of stainless steel, and these need to be checked and treated with anti-corrosion grease. Seacocks should also be operated occasionally, for example monthly, to ensure they are working correctly, and this also keeps the owner familiar with their location and operation.
A selection of tapered soft wooden plugs should be kept in a handy location to stop the flow of water through any seacocks which do fail.
Should I close my seacocks when leaving the vessel?
This depends on how long the vessel is being left unattended, and on the personal choice of the skipper. Most skippers would not close their seacocks if leaving their vessel unattended for a day, while many would close their below waterline seacocks if leaving the vessel for more than a day. In my opinion it would be foolhardy not to close all below waterline seacocks when leaving the vessel unattended for more than a few days. Regularly closing and opening the seacocks is good for them, as well as constantly reminding the skipper of their location. However there is a danger of inadvertently leaving one or more seacocks closed when next using the vessel, leading to possible damage of the equipment they supply water to. To easily reduce this risk the skipper can place a sign on the ignition key as a reminder of closed seacocks.
Another solution is to install seacocks which are able to be remotely monitored, such as the polymer composite seacocks produced by TDP. These can be wired directly to equipment, for example an engine, to prevent it from being started if the seacock is in the closed position.
Selection of seacocks produced only by reputable manufacturers to recognised standards using correct materials such as bronze or polymer composites, together with their regular inspection, operation and maintenance will greatly reduce the risk of problems in this vital area.
No comments:
Post a Comment