HDPE Transitions
HDPE Transitions
(OP)
I'm laying out the gathering system for a new field development, the client likes SDR-7 HDPE and I've modeled the trunks, laterals, and individual well flow lines and have settled on 10-inch SDR-7 on all the trunks, 6-inch SDR-7 on the laterals, and the well flow-lines are 4-inch SDR-7.
The pressure drops and velocities all make good sense, but now I'm looking at how to tie the pipes together. My first look said that I didn't want a bunch of weight stacked above a plastic pipe so I was going to transition to steel a joint either side the tie-in risers. As I read about this stuff I'm thinking that maybe I'm being excessively conservative. If I use a 10X6 reducing tee in SDR-7, transition to steel and immediately swedge down to 4-inch S-40 steel for 3 ft, and then set about 700 lbs of valves, fittings, piping, and flanges on top of it will I break the 10-inch? If it is a problem, I can come off with the tee on the horizontal and 90 up with a thrust block under the 90, but I wanted to avoid the potential water trap.
David
The pressure drops and velocities all make good sense, but now I'm looking at how to tie the pipes together. My first look said that I didn't want a bunch of weight stacked above a plastic pipe so I was going to transition to steel a joint either side the tie-in risers. As I read about this stuff I'm thinking that maybe I'm being excessively conservative. If I use a 10X6 reducing tee in SDR-7, transition to steel and immediately swedge down to 4-inch S-40 steel for 3 ft, and then set about 700 lbs of valves, fittings, piping, and flanges on top of it will I break the 10-inch? If it is a problem, I can come off with the tee on the horizontal and 90 up with a thrust block under the 90, but I wanted to avoid the potential water trap.
David





RE: HDPE Transitions
http://virtualpipeline.spaces.msn.com
RE: HDPE Transitions
I'm trying to determine the "best" way to connect the flow lines to the laterals and the laterals to the trunks.
David
RE: HDPE Transitions
http://virtualpipeline.spaces.msn.com
RE: HDPE Transitions
WWW->WWWWWLWWW<-WWW
WWW->WWWLWWW<-WWWWW L
L L
L LWWW<-WWW
L L
L L
TTTTTTTTTTTTTTTTT->TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT Comp
L
L
WWW->WWWLWWW<-WWW
The "W" are 4-inch SDR-7 well ties, the "L" are 6-inch laterals, and the "T" are 10-inch trunks.
David
RE: HDPE Transitions
Is it save to assume that the 10X6 reducing tee has been reinforced to allow the 10-inch leg to resist buckling when the branch is a max load?
David
RE: HDPE Transitions
I would put some flexibility into the tie-ins and the laterals as they approach the laterals and trunklines, respectively, to avoid large axial loads from dumping into the connection. I think large axial loads from the lateral would tend to displace the 10" first, rather than buckle the T. There will probably be some thermal movements and I think allowing for those movements might be good, as it will aleviate any punching and bending into the 10", so I
don't think I would use thrust blocks either.
Actually I'd just do it like this and not look back.
use valve pads or sand-cement bags under the valves and their fittings.
http://virtualpipeline.spaces.msn.com
RE: HDPE Transitions
I've decided to transition to steel about 1/2 joint either side of the tee for the valve set and then all the problems just vanish and I can build my valve sets the way they need to be.
Thanks for looking into this.
David