welding black iron pipe

[Hymodyne]

I have read quite a few threads concerning the use of a mig welder to weld black iron pipe; mostly welder websites, so not many were talking about applications that would be part of an exhaust system like the ones used on our engines. I am anticipating a clearance issue with the pipe that will come directly out of the threaded manifold flange on the engine. Instead of it coming straight out, it needs to head downward almost immediately so as not to get too close to the fiberglass underside of the cockpit floor- the part the measuring tape is pointing to in this picture:


Then the engine is in its final position (not known as of yet because the tube which will house the propeller shaft has not been set in place yet) the hot exhaust pipe will run just under the lower corner pictured. I'd like to thread a 5" piece of pipe into the exhaust flange that has a slight dip right after the threaded portion, so I can properly wrap and insulate the pipe prior to its further travels toward a riser.

Anyone welded their black iron pipe? Issues with leaks or cracking under temp?

Hmmm?? Anyone??


Many Thanks,

James

[toddster]

Well, yes, though my welds never had to hold pressure, better people can do that.
But why not just screw something like a street-45° fitting into the exhaust flange? Or even just use a close nipple if you can't find a street fitting in the angle that you need.

[ndutton]

James,

When you're done with this keep a very careful watch on the fiberglass in close proximity. When heated - and it doesn't take much - it gets really soft, like stiff butter.

[marthur]

If you are having trouble finding the fittings you need locally, try a decent industrial supply like Grainger:

http://www.grainger.com/Grainger/wwg/start.shtml

OR my favorite McMaster-Carr:

http://www.mcmaster.com/

I buy all kinds of "boat stuff" from McMaster Carr because their selection and price is better than many boat stores.

[joe_db]

My local welding shop welds my exhaust creations for me to keep them from unscrewing with a drop of weld at each junction. I think you can find a fitting to do what you want without making a welded creation.

[ndutton]

Rather than a bunch of additional fittings, I MIG weld my small water injection pipe on an angle into the last down pipe of the hot section. No problems.

Please keep in mind, the tighter that elbow and the more elbows in the system, the more inherent restriction.

[hanleyclifford]

The best source of black iron pipe is your local Plumber's Supply.

[JOHN COOKSON]

The best source of black iron pipe is your local Plumber's Supply.

Plus if you have an old hot section to take along it makes it a no brainer to match up the pieces.

TRUE GRIT

[Hymodyne]

Well, yes, though my welds never had to hold pressure, better people can do that.
But why not just screw something like a street-45° fitting into the exhaust flange? Or even just use a close nipple if you can't find a street fitting in the angle that you need.

This is the part I will most likely go with, as soon as I can find a local supplier. Thus far, it is the only problem point in this installation ( I know, its early).

The issue is that the closer I can get the manifold to the underside of the cockpit, the less of the flywheel and cover that sticks out below the ladder, and the neater the enclosure, but the closer I get the manifold to the underside of the cockpit, the greater the chance of heat being an issue from the hot exhaust portion of the pipe. It will literally be the one area of proximity; after that, the pipe will be far enough away from fiberglass that it will not present any heat related problems.

After months of searching, I finally found a picture of a Cape Dory 22D, although it had a Westerbeke, not an A4.

http://www.yachtworld.com/core/listing/photoGallery.jsp??access=Public&listing_id=63629&units=Feet&checked_boats=2129612&boat_id=2129612&imc=pg-fs&back=boatDetail.jsp&boat_id=2129612&noOfPic=4

It showed me that the way I am planning to install it will work, as there is plenty of space, but none to spare. The next decent weather day ( 55 deg yesterday and sunny, today mid 30's and snow) I will start to finalize the installation of the offset propeller shaft housing. Two sheathed fiberglass tubes, with the inner one holding the cutless bearing.

James

[JOHN COOKSON]

James
Here's another consideration. If you can get part of the riser at or across the boats midline you will be assured it will work equally well when motor sailing on either tack - assuming it is high enough of course.

TRUE GRIT

[Mo]

When I broke my hot exhaust I had the new one made up and installed as you see in 3 hours. I drilled a hole in the downward section of straight pipe, cut a small piece of pipe on a 45 degree angle and mig welded it over the hole. Didn't take long. 20 minutes maybe to drill, cut the angle and weld...not long at all. No leaks.

[toddster]

This is the part I will most likely go with, as soon as I can find a local supplier. Thus far, it is the only problem point in this installation ( I know, its early).

Yeah, I've pretty much given up on "local suppliers" unless I know for sure that they have a particular item. Grainger can often get stuff here the next day (depending on whether an item is in the nearest warehouse) and the shipping cost is less than the fuel for a trip to town.

[Hymodyne]

Well, yes, though my welds never had to hold pressure, better people can do that.
But why not just screw something like a street-45° fitting into the exhaust flange? Or even just use a close nipple if you can't find a street fitting in the angle that you need.

Took my wife up the the Berkshires to visit her family this weekend, and stopped at a Carr Hardware store up there. found the 45 street elbow, a 3 inch nipple and another 45 elbow to direct the hot exhaust down and then out from beneath the cockpit floor. When I fitted everything in place after I got home, It appears that I will still need to notch the lower portion of the cockpit floor (the corner directly below the tape measurer in the picture of the engine in place above), just to ensure proper clearance between these hot pipes and the floor. If I am able to get two cut ends threaded on the original antisiphon loop in the exhaust that came with the engine, I will use it in this installation and route the exhaust hose to the transom from there.

james

[toddster]

These things also come in 22.5 and 60 degree bends, if that helps, but you might have to order them in. FWIW, my hot section passes through a bulkhead with about 1/2" clearance around the pipe (after 1/2" insulation wrap). It hasn't caused any problems in 40 years.