Welding baseplates?

[Yamanx]

It doesn't need to be welded both sides IMO.

 

Handling is a major issue when plating, and unless you have unlimited access to a crane then you need to do things in a way that all your steel can be handled with jacks, ratchet straps etc. A full length bottom to be turned over and put in place wouldn't be an option without heavy lifting kit.

 

There are loads of methods, however the one I employed was to have the boat on four trestles, which I made, about 1200 off the ground so you can get under it to weld it. Prep each plate, jack the boat up, a normal car bottle jack will lift it enough, at the point you want to slide in the plates, and then weld each individual plate to the existing bottom, clean the weld back, offer the next plate up and weld. This way the new bottom is securely welded to the existing boat at the seams. In addition we plug welded in various places. This involved drilling a hole in the bottom and welding up from both sides.

 

Leave the plates big whilst welding around the sides. We actually welded new sides on afterwards as well up to 500 high. Then trim off with cutting gear the excess, I actually left about 40mm of chine.

 

Easy

[blackrose]

Easy

 

To all the non-welders amongst us it sounds like a nightmare...

[talisman]

Im still trying to find a method of having my baseplate overplated. My thoughts are .......my hull is in 5 sections, bow 6ft, then 4x 8ft sections,total 38ft. The first 6ft and last 8ft sections of hull are ok. Its really the middle 24ft section. Here there is pitting to the chine area which is formed to a curve.I thought to overplate the hull to include the chine. My method is to lay out 6 sheets of 8x4 steel and weld together. Possibly both sides if it can be done. Lower the boat on top and weld bracing between the old and new steel. Sit new steel sides onto the new baseplate and weld, then weld at the waterline. My boat has a flat bar rubbing strake 3 inches above the waterline. It is only welded along the top edge. I thought to stitch the bottom every foot or so and then weld the new steel sides directly to the rubbing strake. Im hoping that this way i will not have to remove the tongue and groove lining.I know its not perfect but im sure it would work,cash is, as always the limiting factor.Comments please.

[talisman]

Just an update if anyone is interested lol.I jumped to the wrong conclusion. The surveyor was actually referring to the keel and not the baseplate,whew what a relief. My springer has a centre keelson and pitting is apparent at the weld to the baseplate. Therefore i may have to have a new keel ,say 500mm to 1mt wide welded underneath. Nowhere near as expensive as another baseplate. Its a relief as it was beginning to become expensive. So next year i will have new chines and a new keel fitted,that i can handle.

[Myself]

Still in dry dock? Hope the work is going well. Joy x

[talisman]

Hi Joy.Im back on my mooring. It was a change of scenery at least. Just got a bit more welding, not much really, could be worse.

[onionbargee]

Be handy if it could be magnetised

would cut down on shopping trolleys in the cut !

 

 

The original post is really a misunderstanding of welding. The weld will be full penetration right back into the old plate, unless you've got a gap toothed Gypsie doing it.

Edited September 11, 2012 by onionbargee

[talisman]

I think you should read my post again onion. I was referring to several plates being welded together ,before welding to the baseplate.

[Justme]

A weld applied from one side can penetrate the full thickness of the plate if its prepared & welded correctly.

 

Even very very thick (think inches) plates can be done one sided.

[talisman]

Im sure that good welds from one side are quite possible. However i think that for a hull ,welding both sides has to be preferred method.I worked at a yard a few years ago and they refused to work on the hull of a widebeam because it was only welded on one side.

[Timleech]

Im sure that good welds from one side are quite possible. However i think that for a hull ,welding both sides has to be preferred method.I worked at a yard a few years ago and they refused to work on the hull of a widebeam because it was only welded on one side.

 

How do you think pipelines are welded, much more critical than canal boat hulls? Does a little gnome go in to weld the inside?

 

Tim

[Ex- Member]

How do you think pipelines are welded, much more critical than canal boat hulls? Does a little gnome go in to weld the inside?

 

Tim

 

Sort of, Robot Gnomes

 

An_internal_welding_robot_system_for_600_mm_steel_pipelines.PDF

 

 

https://docs.google.com/viewer?a=v&q=cache:_NH-2KeyMGgJ:www.iaarc.org/publications/fulltext/An_internal_welding_robot_system_for_600_mm_steel_pipelines.PDF+internal+welding+of+steel+pipe+pipes&hl=en&gl=uk&pid=bl&srcid=ADGEESj5eQgjhgUQ3ND7ZyJh9WqdsT25UzjEgLCWHNYvV45TCKYuwmYeyKhKzm8mXkVyJgQJ3k7sP01vmFYIxmElZ0S2ci33Eq1MCVJynmd2criyZVvxioEOfosyYgjYdlhD2pacm6Z3&sig=AHIEtbQuONRZ8m93QbGnochuHWF1DHhzJw

 

 

[Timleech]

Sort of, Robot Gnomes

 

An_internal_welding_robot_system_for_600_mm_steel_pipelines.PDF

 

 

https://docs.google.com/viewer?a=v&q=cache:_NH-2KeyMGgJ:www.iaarc.org/publications/fulltext/An_internal_welding_robot_system_for_600_mm_steel_pipelines.PDF+internal+welding+of+steel+pipe+pipes&hl=en&gl=uk&pid=bl&srcid=ADGEESj5eQgjhgUQ3ND7ZyJh9WqdsT25UzjEgLCWHNYvV45TCKYuwmYeyKhKzm8mXkVyJgQJ3k7sP01vmFYIxmElZ0S2ci33Eq1MCVJynmd2criyZVvxioEOfosyYgjYdlhD2pacm6Z3&sig=AHIEtbQuONRZ8m93QbGnochuHWF1DHhzJw

 

Link doesn't work for me. So far as I know, they are usually done from outside only. Not really my field, though.

 

Tim

[onionbargee]

I think you should read my post again onion. I was referring to several plates being welded together ,before welding to the baseplate.

ok, then the welder will vee the edges of the plates 60 degrees , and the first weld run will be at the bottom of the vee, this " root" run will completely fuse the underside, other runs on top of this will fill the rest of the vee.

[Yamanx]

A weld applied from one side can penetrate the full thickness of the plate if its prepared & welded correctly.

 

Even very very thick (think inches) plates can be done one sided.

 

This is correct, we weld even 80mm thick (No kidding) from one side.

 

Tight diameter tube or rollings, for instance, have to be welded from one side as you cant get in to weld the inside. These are full pen welds with 100% NDT.

 

It is not necessary to turn the plates, full pen welds are straight forward from one side, particularly at that thickness.

[Gibbo]

This is correct, we weld even 80mm thick (No kidding) from one side.

 

Tight diameter tube or rollings, for instance, have to be welded from one side as you cant get in to weld the inside. These are full pen welds with 100% NDT.

 

It is not necessary to turn the plates, full pen welds are straight forward from one side, particularly at that thickness.

 

And how do you grind the ends of a plate to form a V when they're on the floor?

[RLWP]

And how do you grind the ends of a plate to form a V when they're on the floor?

 

Move them apart and slip a bit of wood underneath

 

Richard

[gazza]

Or alternatively, set root gap, 1.6mm is about right for 6mm plate using MMA, 2mm for MAGS, tack plates, then run down the length of the joint with a 9" grinding disc, this will give a u preperation of about the right width, the depth of cut should leave around 2mm of plate at the bottom of the groove.

U prep is preferable to single v butt joint in terms of controlling distortion.

Multi run passes to complete the joint, bobs your uncle etc

Crude but effective.

Edited September 12, 2012 by gazza

[Yamanx]

Or alternatively, set root gap, 1.6mm is about right for 6mm plate using MMA, 2mm for MAGS, tack plates, then run down the length of the joint with a 9" grinding disc, this will give a u preperation of about the right width, the depth of cut should leave around 2mm of plate at the bottom of the groove.

U prep is preferable to single v butt joint in terms of controlling distortion.

Multi run passes to complete the joint, bobs your uncle etc

Crude but effective.

 

Yes, and I would use flux core MAG as well, its a better job than MMA, less chance of slag inclusion IMO, easier and if done correctly would pass any NDT. Normal MIG/MAG can be porous.

 

Easy to lift up the edge of even a 4000 x 2000 x 10mm plate with a bar, sling a bit of wood under, if you want to put a Vee on. But the root gap method is better.