2" thru hull fitting removal

[kennyh]

Hi

I need to replace a 2" thru hull / skin fitting used for holding tank discharge; due to a seeping seacock I am going to remove the seacock and the skin fitting at the same time (as I'm not confident as to it's solidity).

Anyway, the skin fitting is 2" diam. And the retaining nut is recessed in a well and in a confined space making it impossible to get a set of grips or spanner on to it.

My plan is to remove the entire skin fitting & seacock (& valve) assembly by cutting/removing the skin fitting dome head from the outside and pulling the whole assembly on the inside.

For fitting the new DZR Brass components I will ideally I need a 68mm box spanner to tighten the nut on the skin fitting (as it is in a recessed well ). But I can't track one down!

I have considered fabricating/welding my own tool to do this, but that is a lot of design/work in its own right.

So, the question is, what could I use to tighten a retaining nut on a 2" skin fitting in a very confined space?

Any ideas will be gratefully received.

Thanks
Kenny.

 

[captainboo]

Would this work even if you had to add some thin packing pieces (not that I think you would need them as it is only 2mm larger)

http://www.toolfinder.co.uk/hand-to...x-200mm-8in/?gclid=CP6Vhsr85b0CFWUOwwodaikAZw

Even cheaper on Amazon:

http://www.amazon.co.uk/Melco-Tim12-Metric-Spanner-70mm/dp/B0001P0EC8

 

[cimo]

68mm or 86mm?

http://www.ebay.co.uk/itm/NEW-HEAVY...ATER-BOX-SPANNER-/380876851661#ht_1597wt_1077

 

[GrahamM376]

If you install TruDesign skin fitting and seacock, the skin fitting can be epoxied into the hull, it's one of their suggested fitting methods. Doing it that way, no need for a tight backing nut and you can pre-fit the seacock so the handle is where you want it.

http://www.trudesignplastics.com/products/20-skin-fittings-threaded#guides

 

[oldbilbo]

I wish I'd known about this little item a while ago....

 

[Norman_E]

Does the nut have to be sunk into the recess, or could you put a spacer under it? You can use a holesaw to drill through some thick plastic (like a kitchen chopping board) to make thick "washers" to occupy the recess.

 

[SHUG]

To remove/destroy a skin fitting .
Drive a wooden plug into the outer end and saw off flush. Get a HSS hole cutter where the internal diameter is the same as the outside diameter of the screwed part of the skin fitting. Carefully start the hole cutter at the centre of the plug and press on until the flange is cut off and the whole assembly comes away.
I have succesfully done this a couple of times and the new fitting slides in with a little marine epoxy to help the seal.
To tighten the nut, a plumbers or monkey wrench usually opens far enough.

 

[kennyh]

Thanks all for your comments / ideas.

Cimo, it's definitely 68mm face to face on the nut, thus an immersion spanner won't work.

Getting the original fitting out shouldn't be a big problem; I'll remove the some head with a dremel cutting disk.

I don't think a big fat washer under it will work either; the replacement fittings will be large/ heavy 2" valve and elbow, so I'd rather have the skin fitting snug/tight down onto the hull to ensure a good tight fit. I'd be concerned that a fat washer would compress too much. And the recess is probable around 5cm.

So I'll just need to come up with another idea or find a box spanner to suit

I did see one for sale in eBay, but the sale closed a few weeks ago - bummer!

Cheers Kenny.

 

[David2452]

I will ideally I need a 68mm box spanner to tighten the nut on the skin fitting (as it is in a recessed well ). But I can't track one down! I have considered fabricating/welding my own tool to do this, but that is a lot of design/work in its own right. So, the question is, what could I use to tighten a retaining nut on a 2" skin fitting in a very onfined space?

Any ideas will be gratefully received.

Thanks
Kenny.

I get my very large or unusual box spanners from Thomas Meldrum, I have a 65mm x 70mm, I doubt the extra 2mm would make any difference tightening a 68mm nut, it's 8" long.

you can buy one retail (Melco branded) here http://www.toolbank.com/0/p/MELTIM12

 

[kennyh]

Thanks all for your comments and suggestions.

Well I got the job done as follows:

Firstly I removed most of the internal fittings after heating with a heat gun and melting the thread sealant.
It was then clear that I could not remove the thru hull from the inside due to access to the original nut.
I then used a electric drill and 2" hole saw to remove the thru hull exterior dome.
I then used a hammer to carefully knock through the rest of the through hull.
I got my hands on a 68mm deep socket by asking my local garage if they had any van axle nut sockets that could fit (and they had one that nearly fitted - a little filing of the thru hull nut and it fitted perfectly).
I then cut the thru hull shorter (than original 110mm) to accommodate the deep socket being able to tighten the nut taking account if the hull thickness.
After cleaning and preparing the area I test fitted the new thru hull, seacock and elbow (checking for orientation) and marked the direction of fit, and then fitted using 3M 4200FC for the thru hull sealant and Loctite 577 for the thread sealant.

Job done and no leaks!

It did take a couple of days to complete in a very cramped "crawl hole" to get to the fittings, but at least now I have a watertight, working seacock to my holding tank.

Thanks
Kenny.

 

[Talulah]

When I've removed a skin fitting I've just found it easier to use an angle grinder. Working outside use the angle grinder around the opening of the skin fitting. Reduce the thickness where the lip edge meets the central part. The lip then drops off like a ring and the seacock can be knocked through.

 

[garvellachs]

When I've removed a skin fitting I've just found it easier to use an angle grinder. Working outside use the angle grinder around the opening of the skin fitting. Reduce the thickness where the lip edge meets the central part. The lip then drops off like a ring and the seacock can be knocked through.

Yup, that's the easy way.

 

[nigelmercier]

Yup, that's the easy way.

The easy way to accidentally cut into the hull, yes.

 

[pvb]

The easy way to accidentally cut into the hull, yes.

Not unless you're incredibly clumsy! Simply grinding off the corner of the opening is the easiest way, and is what most boatyards do.

 

[nigelmercier]

Not unless you're incredibly clumsy!

You are speaking to someone who got his fingers caught in an electric plane.

 

[pvb]

You are speaking to someone who got his fingers caught in an electric plane.

Enough said! Pay people to do your repairs.

 

[ghostlymoron]

How about a plumbers 'basin spanner' for tightening the nut?