Seacock failure

I am following this thread with interest as I recently had two 3/4" valves fail in this manner after two seasons afloat (circa 13 or 14 months). In my case the handles came away completely and the drive on the end of the spindles had disintegrated through, what to my untrained eye, looked like dezincification. According to the datasheet the spindles, ball and body were all DZR. I returned them to the supplier who sent them onto the manufacturer (although I was informed the actual manufacture is outsourced to a 3rd party) but was told there was not enough material for testing the composition. Just to be clear I do not know why the valves failed and cannot rule out environmental factors. I installed two other 3/4" valves from the same supplier at the same time in different locations and these appear to be fine, whereas the two that failed (one for a deck drain, and one for a combined sink/shower drain) developed excess play in the handles in the first season afloat. None of the valves are bonded.
 
Ammonite said:
I am following this thread with interest as I recently had two 3/4" valves fail in this manner after two seasons afloat (circa 13 or 14 months). In my case the handles came away completely and the drive on the end of the spindles had disintegrated through, what to my untrained eye, looked like dezincification. According to the datasheet the spindles, ball and body were all DZR. I returned them to the supplier who sent them onto the manufacturer (although I was informed the actual manufacture is outsourced to a 3rd party) but was told there was not enough material for testing the composition. Just to be clear I do not know why the valves failed and cannot rule out environmental factors. I installed two other 3/4" valves from the same supplier at the same time in different locations and these appear to be fine, whereas the two that failed (one for a deck drain, and one for a combined sink/shower drain) developed excess play in the handles in the first season afloat. None of the valves are bonded.
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They are wriggling! Composition is obtainable from amounts too small to see in a scanning electron microscope. Not an expensive instrument these days. A ball from a 3/4 inch valve would be plenty for more conventional methods, e.g. XRF as used by scrapyards. The Vanta Series - Handheld X-ray Fluorescence (XRF) Analyzer
 
I thought that gate valves were recognised as crap by all on this forum by now! Quite apart from the poor choice of material from which they are made, their mode of operation is such that I wouldn't use in any situation. Nor am I that keen on ball valves.

Gate valves operate in a similar way to sluices in lock gates, and we all know how leaky they become. The sealing faces wear away with use but with gate valves they tend to leak even when new. When I was a student I had a regular summer job with a heating installer and learned that to close a gate valve one turned the handle fully clockwise then backed it off a bit and hoped that pressure off the fluid in the pipe pushed the gate against the seal. It often didn't fully seal, even when new.
 
I have replaced my heads outlet ball valve with a Trudesign and am pleased. The ball valve had become almost impossible to close. The pipework had been blocked the previous year, fitted the Trudesign over winter, which is much better and the loo works fine now. It's a Lavac so also refurbished the hand pump. One reason the outlet pipe blocked was the contorted long pipe route from the loo to outlet(nearly 4 metres)and a horizontal portion which obviously held contents over time. I now have a note in the heads to say "pump 19-20 times" which is twice the recommended time. I also rerouted the the pipe so shorter and no horizontal sections.
 
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