NPT & NPS Mismatch continued

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Manny

Manny

.
Oct 5, 2006
983
Hunter 82? 37 Cutter Wherever the wind takes me
Okay, we all know we aren't supposed thread thru-hulls, valves, etc with mismatched threads. But I am curious, have any of you had any sort of failure, under regular use, directly caused by the mismatching of thread types? I'm not talking about circumstances like heavy items falling on or hitting a valve or thru-hull. Maybe something like someone turning the handle on a valve and the whole assembly popped right of the thru-hull, or a capped thru- hull let go? Manny
 
Manny

Manny

.
Oct 5, 2006
983
Hunter 82? 37 Cutter Wherever the wind takes me
Okay, we all know we aren't supposed thread thru-hulls, valves, etc with mismatched threads. But I am curious, have any of you had any sort of failure, under regular use, directly caused by the mismatching of thread types? I'm not talking about circumstances like heavy items falling on or hitting a valve or thru-hull. Maybe something like someone turning the handle on a valve and the whole assembly popped right of the thru-hull, or a capped thru- hull let go? Manny
 
sailaway78

sailaway78

.
May 11, 2005
3,431
Seidelman S37 Slidell, La.
I don't think

I don't think that mis matched threads are going to just come apart or break with out some considerable pressure or being hit with something. I do not know how much weaker these are than a proper threaded connection. But this will be the weakest link. I am sure many people have gotten away with this for years with no problem.
 
sailaway78

sailaway78

.
May 11, 2005
3,431
Seidelman S37 Slidell, La.
I don't think

I don't think that mis matched threads are going to just come apart or break with out some considerable pressure or being hit with something. I do not know how much weaker these are than a proper threaded connection. But this will be the weakest link. I am sure many people have gotten away with this for years with no problem.
 
Roger (Ninette Manitoba)

Roger (Ninette Manitoba)

.
Jan 22, 2008
519
Sundance Sundance 20 Weekender Ninette, Manitoba, Canada
original equipment

I had such a failure. Thank goodness I had opted to repair after haulout, because as soon as I put any kind of pressure on the in hull hoses to remove them, the through hull snapped off level with the inside hull surface. It had been attached to a mismatched valve. Had that happened at sea, I could have managed it with the plug that was conveneintly placed nearby, but it would have necessitated an emergency haulout. Do not trust an 'other than standard' installation of a through hull.
 
Roger (Ninette Manitoba)

Roger (Ninette Manitoba)

.
Jan 22, 2008
519
Sundance Sundance 20 Weekender Ninette, Manitoba, Canada
original equipment

I had such a failure. Thank goodness I had opted to repair after haulout, because as soon as I put any kind of pressure on the in hull hoses to remove them, the through hull snapped off level with the inside hull surface. It had been attached to a mismatched valve. Had that happened at sea, I could have managed it with the plug that was conveneintly placed nearby, but it would have necessitated an emergency haulout. Do not trust an 'other than standard' installation of a through hull.
 
Ross

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Having the shank of the thru hull break can happen

for several reasons but that doesn't constitute a failure of the mismatched threads betwixt the valve and the thru hull. Had the thru hull been supported by the proper flange then no radial force could have been applied to the threads.
 
Ross

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Having the shank of the thru hull break can happen

for several reasons but that doesn't constitute a failure of the mismatched threads betwixt the valve and the thru hull. Had the thru hull been supported by the proper flange then no radial force could have been applied to the threads.
 
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