It may be overkill, but....

[retired2]

When I decided to make my DC stationary and pipe everything to it, I knew I would be stretching the capacity of my Delta 50-760.  So, I decided I would do everything I could to minimize line loss and turbulance.

Below is a picture looking into the lateral branch of a typical HVAC wye.  As you can see, the fabrication method results in many small tabs
facing into the direction of air flow.  It seems to me these tabs are a source of unnecessary turbulance and increased friction loss, and possibly even a birds nest if you are conveying heavier shavings or stringy material.

The second photo shows a wye after I covered the tabs with "Lab Metal", and sanded it smooth.  This modification may only make a tiny improvement in the performance of my system, but it has to be better than stock wyes.

[retired2]

Chuck, I can't say if these wye's are typical or not.  All I know is I have purchased them from two different sources, and while they are fabricated slightly different, they both have tabs. 

The "flange" you noticed is an integral part of the branch pipe, and what appear to be rivets are actually tack welds.  The tabs are all from the straight run of pipe.  I think the tabs are intentionally formed to add strength, and some strategic ones are also tack welded.

I'd be curious to hear from other members who are using metal pipe whether or not their 45 degree laterals are fabricated similarly.

 

[pitbull]

The ones I purchased are not like that. They are smooth in the direction of flow and are made in the USA.

I found them to be cost efficient and very well made. The shipping was actual charge and not a flat rate. Everything came as I ordered and I felt I got a deal.
http://www.kencraftcompany.com/Dustindex.htm

[retired2]

The ones I purchased are not like that. They are smooth in the direction of flow and are made in the USA.

I found them to be cost efficient and very well made. The shipping was actual charge and not a flat rate. Everything came as I ordered and I felt I got a deal.
http://www.kencraftcompany.com/Dustindex.htm

Interesting!  I'm familiar with Kencraft, but I've never purchased from them.  I wonder how the wye's from the Lowes and Home Depot are made?  I'll have to check them out the next time I'm there.

[RCOX]

I have bought 2 wyes from Lowes and they do not have the tabs in them. The short leg is fitted into the opening and spot welded. The only thing I did not like is the crimped end is on the wrong end for dust collection. I bought a crimping tool for hvac duct years ago and now use it to crimp the other pipe on the end I want. You lose almost nothing in diameter if you are careful and it eliminates a possibility of a jam.

[retired2]

I have bought 2 wyes from Lowes and they do not have the tabs in them. The short leg is fitted into the opening and spot welded. The only thing I did not like is the crimped end is on the wrong end for dust collection. I bought a crimping tool for hvac duct years ago and now use it to crimp the other pipe on the end I want. You lose almost nothing in diameter if you are careful and it eliminates a possibility of a jam.

Rcox, I have a crimping tool that I use only when I have to.  It is a good crimper, but like most of the hand held crimpers, it produces deeper crimps and a steeper taper on the end of the pipe.  However small, that taper produces more turbulance and losses than a machine crimped pipe end.  As the title of this thread suggests, I go a bit overboard trying to keep the inside of my system as smooth as possible.