Many people have been replacing various parts of the plumbing around their holding tanks. Age has a way of catching up with all of us. Several boats I have seen have have replaced the bronze valve under the holding tank with a plastic valve.  It seems like a good idea at first blush, but there are complications. 

It’s true that the plastic valve does not need to be connected to the bonding circuit, but the thru-hull fitting itself is bronze, and it does need to be connected to the bonding system. The problem is if a valve with the correct threads (BSPP) is used, there is no exposed metal left to connect the bonding system to the bronze thru-hull.  

Since this fitting is glassed into the hull, replacing it would be a challenge that should be avoided as much as possible, and that means connecting it to the bonding system. From what I have seen, that means sticking to a quality bronze (not brass!!!) valve that allows a good connection to the bonding system.

Bill Kinney
SM160, Harmonie
Daytona, Florida
http://www.cruisingconsulting.com

The Groco IBV Series with BSPP threads is constructed of C83600 bronze.  1 ¼” valves and above include a grease zerk for lubrication to help prevent freezing of the ball followed by breaking of the valve stem.

 

For those with an A54 replacing the aft head valve is a task best left to an Amel service center if you value your well being, time, and marriage.  Removing the engine with two paint sticks and a small pair of pliers is slightly easier than changing this valve.

 

https://www.groco.net/products/valves-seacocks/inline-valves/ibv-series-bspp-thread

 

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Mark Mueller
former Brass Ring  A54

Mark,

I completely agree that the Groco valves are a great choice.  Nice that they also have a terminal for a bonding connection.

Bill Kinney
SM160, Harmonie
Daytona, FL
http://www.cruisingconsulting.com

On Tue, Mar 21, 2023 at 01:10 PM, Mark & Debbie Mueller wrote:

The Groco IBV Series with BSPP threads is constructed of C83600 bronze.  1 ¼” valves and above include a grease zerk for lubrication to help prevent freezing of the ball followed by breaking of the valve stem.

 

For those with an A54 replacing the aft head valve is a task best left to an Amel service center if you value your well being, time, and marriage.  Removing the engine with two paint sticks and a small pair of pliers is slightly easier than changing this valve.

 

https://www.groco.net/products/valves-seacocks/inline-valves/ibv-series-bspp-thread

 

--
Mark Mueller
former Brass Ring  A54

You clearly have not done the front one yet! It took me more then a week for all the bruises to heal….

Arno Luijten
SV Luna,
A54-121
Rotterdam