Sewer pipe engineering?

[surfer46us]

I have been doing some extensive research about ABS sewer pipe.
(I know...I need to get a life!). What I learned is that ABS pipe
contracts/expands 5 inches per 100 feet for each 10 degrees F.
change in temperature. Applying this to the approximately 6.5 feet
of pipe connecting the black and gray tanks, there is nearly 3/8 ths
inch of expansion with 100 degrees change of temperature. It appears
to me that this puts excessive strain on the tanks that could cause
cracking. I am going to saw the pipes in too on each side between
the dump valves and the 90 degree bend and reconnect them with
flexible
hose clamp type unions. I would appreciate some opinions pro and con
if this idea is sensible? Also did all Wanderlodges come with the
tanks plumbed together with no provision for pipe expansion or does
mine have a non standard repair? Thanks

Jim Keefauver/Jonesborough, Tn./1985 PT36

[Jeff Miller]

The tanks were connected around '79 or '80. It has always been a
rigid connection, one run of ABS. The tanks are not that tightly
mounted either, often can be moved a little when empty. I don't see a
concern with the original setup. The 3/8" means that each end has to
flex 3/16" maximum over that temp. range, doesn't sound like a
problem for ABS. If you replaced the solid-body (DuPree) valves with
a 4-bolt type like the Valterra I would expect that the strain could
cause a leak, but solid-body valves and ABS should be fine with the
original setup IMO.

Putting flexible couplings on both ends as you're suggestion could
allow the main pipe to droop. Putting a flexible coupling in the
middle shouldn't cause it to droop in the same way, but would in
theory increase the stress on the tank fittings and valves.

- Jeff Miller
http://www.wanderlodge.net


--- In WanderlodgeForum@yahoogroups.com, "surfer46us"
wrote:
>
> I have been doing some extensive research about ABS sewer pipe.
> (I know...I need to get a life!). What I learned is that ABS pipe
> contracts/expands 5 inches per 100 feet for each 10 degrees F.
> change in temperature. Applying this to the approximately 6.5 feet
> of pipe connecting the black and gray tanks, there is nearly 3/8 ths
> inch of expansion with 100 degrees change of temperature. It
appears
> to me that this puts excessive strain on the tanks that could cause
> cracking. I am going to saw the pipes in too on each side between
> the dump valves and the 90 degree bend and reconnect them with
> flexible
> hose clamp type unions. I would appreciate some opinions pro and
con
> if this idea is sensible? Also did all Wanderlodges come with the
> tanks plumbed together with no provision for pipe expansion or does
> mine have a non standard repair? Thanks
>
> Jim Keefauver/Jonesborough, Tn./1985 PT36

[Tom]

Jim I am looking at the same thing, but dont believe the
expansion/contraction is a big deal and nothing to worry about. I am going
to remove the present ABS pipes and install all new ABS pipes with electric
Drain Master valves. There is a slight expansion and contraction as you
noted but as Jeff Miller noted the tank is made of fiberglass , and I
believe it will flex a little itself. My present system is over 20 years
old and does not leak with one Dupree valve on the black tank and a Ventura
valve on the grey tank.

Tom Warner
1982 FC35
Vernon Center,NY
In the beautiful Mohawk Valley

At 12:10 AM 4/18/2005 +0000, you wrote:

>I have been doing some extensive research about ABS sewer pipe.
>(I know...I need to get a life!). What I learned is that ABS pipe
>contracts/expands 5 inches per 100 feet for each 10 degrees F.
>change in temperature. Applying this to the approximately 6.5 feet
>of pipe connecting the black and gray tanks, there is nearly 3/8 ths
>inch of expansion with 100 degrees change of temperature. It appears
>to me that this puts excessive strain on the tanks that could cause
>cracking. I am going to saw the pipes in too on each side between
>the dump valves and the 90 degree bend and reconnect them with
>flexible
>hose clamp type unions. I would appreciate some opinions pro and con
>if this idea is sensible? Also did all Wanderlodges come with the
>tanks plumbed together with no provision for pipe expansion or does
>mine have a non standard repair? Thanks
>
>Jim Keefauver/Jonesborough, Tn./1985 PT36
>
>