WELDOLET VS COUPLING

[imagineers]

so is it better to buy a weldolet to use as an outlet branch, or a threaded half coupling? Weldolet costs almost triple the price, and requires more weld passes I assume. My other question is how would you weld a coupling to a pipe, just cut a hole in the pipe and lay the coupling on top and weld around? or do you need to cut a special size of shaped hole in the mating pipe to the coupling rests inside ?? see pic, showing two weld possibilities, I want to use the coupling becasue of cost, but is a certain way to weld other than just pressing it flat against the pipe and welding around?

 

[berkshire]

Imagineers,
this is a follow on from your post , how do I cut the parts and weld this, and really should have been posted there.
You really need to go to the shop floor and get an experienced pipe /tube welder to show you how to do this. I and Mike Halleron have tried to explain this to you. But in this case 5 minutes of hands on is worth more than a thousand words.

You are judged not by what you know, but by what you can do.

 

[imagineers]

Imagineers,
this is a follow on from your post , how do I cut the parts and weld this, and really should have been posted there.
You really need to go to the shop floor and get an experienced pipe /tube welder to show you how to do this. I and Mike Halleron have tried to explain this to you. But in this case 5 minutes of hands on is worth more than a thousand words.

I used the advice regarding the bandsaw suggestion and will weld the branches in place this way. As for the coupling its a different question. Use a weldolet on the NPT fitting or use a half coupling. If I use the half coupling, would I simply but the rounded pipe to the straight face and weld or possible cut a hole larger than the OD of the coupling, drop it inside and weld around.

 

[berkshire]

Engineers,
If you are going to use a half coupling, then normally you would just make the hole a little bigger and drop it in. The dis advantage of this in your application, is the fact that your tubes are so similar in size. The inserted tube would significantly reduce the area of the main tube/ pipe. You would also have an area where you fillet welded around without full penetration, that would leave a place for contaminants to collect inside your tubing. I notice you are using sanitary connectors , so I am presuming you want to keep the insides clean.
Your alternate method of just laying the coupler on the tube and filling the gap is also not a good one, because you will end up with a rough surface inside the tube, which would have to be dressed by grinding before the welder could go to the next stage, not to mention that having a gap there, that the welder would, have, to fill, is not a good way to make friends, and influence people.
You , or your shop, can quite easily make prepared ends on tubes/pipes, by buying a slightly longer coupler, clamping it in a vice on a milling machine, taking an end mill cutter the size of your tube, and cutting in the concave face then back milling to the desired length. You have to remember that on a joint with similar sizes the intersection will go as far as the centerline of the parent part. You then have to remember to prepare the joint for welding on both the parent tube and the stub you are fitting. the ideal is to have a Vee joint with as little material as possible at the bottom of the Vee so that the welder can put a root fillet in to seal the tube with as little weld material on the inside of the tube as possible and no gaps. You also have to remember that milling the end of the tube like this leaves an undesirable thin section at the sides of the joint farthest from the centerline of the tube which has to be removed by the Vee joint preparation. You should also remember that the hole in the tube/pipe will also not be round, but must be matched to the contour of the fitting.
B.E.

You are judged not by what you know, but by what you can do.

 

[gtaw]

The important consideration is the applicable pressure piping code you are designing and constructing this piping to. If you are using an ASME piping code, i.e., B31.1, B31.3, etc., you should look under the heading of branch connections and integrally reinforced branch fittings. Weld-o-let, Thread-o-let, etc. are trade names for an integrally reinforced branch fitting. You know, it is the old Kleenex versus facial tissue thing.

The integrally reinforced branch fitting eliminates the need to use reinforcement around the branch to replace the volume of metal removed from the run pipe to facilitate the branch. The codes typically limit the diameter of the unreinforced branch based on the diameter of the run pipe. Based on the sketch included with the post, reinforcement would be required if an integrally reinforced branch is not used.

Best regards - Al

 

[imagineers]

Thanks guys, I appreciate your time. I will go with the weldolet which is already ready and is a stronger higher pressure fiting. I found a supplier which isnt too expensiv for these, although still a little more expensive than the half coupling.