Hi Terry,
I have installed 1,000's of feet of buried conduit in sizes 3/4" thru 4".
I generally assemble runs on the ground and then drop them into the trench.
Regarding difficulty in making up belled ends - (1) be sure both ends are
clean as even a small amount of sand or dirt can get wedged into the
connection making it very difficult to fit up. (2) I typically have to
support the far end of larger size conduit - if the joint you are trying to
make is having to support the weight of either piece of conduit it is going
to be hard to push together because of the angular misalignment, (3) as many
have already suggested, the PVC cement does act as a lubricant, however, you
should be able to fit up the joint to about 50% insertion depth without
binding. Regarding primers - the primer softens the surface of the PVC
which increases the chemical reaction penetration of the cement. PVC cement
is not really a glue, it chemically alters the PVC so that the two pieces
actually become fused together. In any event, using a primer will generally
make it easier to make up the joint with cement. If you are working with
materials that have weathered the primer does a good job of getting you back
down to virgin material as well. Regarding your question about strength of
joints made with unions vs bell ends I don't think you have anything to
worry about. Both easily handle the bending stresses encountered when
moving the assembly around into the trench - even for very long runs.
Hope this info helps & good luck on your project.
73
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Zivney, Terry
Sent: Friday, November 03, 2017 5:03 PM
To: towertalk@contesting.com
Cc: n4tz@arrl.net
Subject: [TowerTalk] Conduit in trench
I am trying to join sections of 2 inch (nominal) PVC conduit for burial in a
trench.
This is schedule 40 electrical conduit, not water or drain pipe.
I cannot get the sections to mate. The belled portion of the conduit is too
snug on the main body. Even with the proper primer and cement, it is so
snug that I cannot manhandle two pieces together, much less dozens!
I found that the sweeps I bought would go on with some difficulty.
The short couplers, about 3 inches long will fit, but give very little
overlap, only about an inch if fully seated.
I notice that the electrical drops down the power poles around here have
the same PVC conduit, but instead of using the built-in bell ends, the crews
apparently just use the short couplers on the straight end ( I guess they
cut off the bells?).
I am worried that the short couplers may not provide adequate
strength when the conduit is stressed to drop in into the trench.
Any experience?
Terry N4TZ
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
---
This email has been checked for viruses by AVG.
http://www.avg.com
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|