"Darts" in pipe 1

[TangoCleveland]

We want to weld a 36" OD weld cap on a 36" ID standard pipe. Some of our older piping uses "darts" to align similar configurations. The larger pipe has 4 to 6 axial slits, about 6" long, which are full-pen welded to draw in the OD of the pipe. Is this an acceptable configuration?

I'm more familiar with "dart" as a sewing term......

Larry

 

[saxon]

NewBPEng?, Before I would say yea or nay, I always like to know the press., temp., and process medium. Your old sytle connection sounds like the fab. crew used an old common welders technique to neck down the pipe od to fit the cap od. This allows the crew to then properly set up the butt weld. Depending on press., temp., and medium; I don't see a problem. BTW, does the pipe spec. call for full radiography of all welds?

saxon

 

[TangoCleveland]

No, I moved on from Sohio in 1986. I'm with a NASA Contractor in Cleveland now.

We're working with 165 psig dry air at 100°F. We usually use 5% random radiography. If we go with the darts, we're doing an in-process exam with our Level III NDE guy. I'm comfortable with the darts, I just hadn't seen them before and wondered how common they are. We're talking 1940's vintage piping.

Larry

 

[saxon]

OldSohioEng., In old piping this is common. I've seen some stuff put in the teens and twenties, before the advent of forged fittings, that used mitered tee's, ell's and reducers. At the temp., press, and medium, you shouldn't have a problem. Provided you've got a good welder. These days, their more scarce than mitered fittings.

saxon

 

[TangoCleveland]

Thanks for the observation. We have big pipe around here, most ranges from 24" up to 96", so even some new construction has mitered fittings. Ever see an 11 foot butterfly valve?

Larry

 

[unclesyd]

Damn, I must be getting old as I've actually laid out "Darts and Orange Peel End Caps and Segmented Heads". You had me looking for my black handbook.

 

[tblaser]

Yes, I have. It was on the Lewis vacuum piping header. We were running a 30" compressed air header piggybacked onto the 72" vacuum piping. The piping and equipment out at Plumbrook is much more interesting.

 

[TangoCleveland]

I can see the 30" header on the vacuum line from the back of my building. Nice job!

That replacement was part of my then-company's tasks. We replaced the WWII vintage butt-end brittle pipe with beveled end pipe good to -20°F. Yep, I've been through Plumbrook too.


Larry