Re: Pipe loads on the cheap

Jack Burgess
 

In discussing pipe types and modeling them, we need to keep a couple of
things in mind. First, which types of pipe were not manufactured locally and
thus might be shipped by rail? Iron pipe might be one type but concrete and
clay pipe might not. Second, we need to remember that we are talking about
pipe types from 60 years ago, not what is currently being used.

When I started working in a municipal engineering department in the
mid-1960s, vitrified clay pipe (VCP) was used for sanitary sewers and
probably had been for decades since it is resistant to acids and sewage. Now
days, in our area, VCP has been replaced for new installations by plastic
pipe since it is faster to install. VCP has a bell on one end with a rubber
gasket but I wonder if it was ever shipped by rail. If so, it is generally
in smaller diameters (12" is a very big sanitary sewer with 8" more typical)
and is red in color since it is made from clay. Interestingly, the Yosemite
Valley Railroad (built in 1906) had a lot of VCP storm water culverts, some
of which are still in place (but out of service <g>). These latter pipes
would have diameters from 12" to 24".

Storm water pipes are typically reinforced concrete pipe (RCP) but I'm not
sure how long RCP has been available...probably a long time. Again, I'm not
sure if it was shipped by rail. This pipe is still used and is joined via
"T&G" joints (meaning that there was no bell and one end has a female joint
with a reduced diameter on the outside of the joint area and the other end a
male joint) rather than a bell joint since leakage isn't a serious problem.
As the pipe is laid, these joints are mortared to minimize leakage. These
pipes are heavy and thus not that long. Larger diameter pipes are shorter
than smaller diameter pipes.

When I started working, water lines were laid in our area with
asbestos-cement pipe (ACP) but plastic is now used for obvious reasons. As I
recall, ACP is joined with via a "T&G" joint supplemented with a rubber
gasket. ACP was popular in areas where metallic pipes were subject to
external corrosion such as our Bay Area with salt water intrusion. Use of AC
pipe ceased due to health concerns associated with the mining, installation,
removal, and disposal of asbestos products. I guess that, due to the
location of asbestos mines vs. manufacturing plants, ACP might be shipped
via rail. ACP is typically smaller, 6-12" in diameter and white in color
with an asbestos texture. But ACP would have been widely used in the era
that we are modeling.

Natural gas lines in our area have been long been steel which is
field-welded together; there is no bell on these pipes since they were
welded together. Long distance transmission lines may be 30" or more in
diameter. There is no question that this pipe was transported by rail. We
also have a gasoline transmission line through our city which is also steel
(8" in diameter). It was originally used to transport jet fuel from a Shell
refinery to the San Jose Airport but was later used by transport gases used
in the high-tech industry but that was built outside our era.

In California, long-distance transportation of water is typical all over the
state. The early lines, such as the line from near Yosemite to serve San
Francisco, was riveted steel (60" and 76" in diameter) and without rereading
Ted Wurm's book on this construction project and its railroad, I'm not sure
that it was transported by rail but I can imagine that it was.

Ductile iron pipe is rarely used in our area due to salt intrusion below
grade. But it is extremely strong and has its advantages. It would have been
logically shipped via rail. This pipe has uses a bell joint.

One pipe type that hasn't been mentioned is galvanized corrugated metal pipe
(CMP) which is still used for storm water culverts. Because of the
specialized manufacturing processes required, these might have been shipped
by rail. Culverts range from 12" in diameter to 48" or more. Again, because
they are used for storm drain systems and water leakage isn't a problem, the
sections are joined with a collar as I recall.

In general, water line joints need to be pressure-proof and thus must have
strong joints requiring both a physical connection and a gasket. Sanitary
sewers also must not leak but aren't under pressure and bell joints work
okay. Storm drain systems don't need to be completely leak proof.

Jack Burgess
www.yosemitevalleyrr.com

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