--- On Mon, 12/1/08, Jack Burgess <jack@yosemitevalleyrr.com> wrote:
From: Jack Burgess <jack@yosemitevalleyrr.com>
Subject: RE: [STMFC] Re: Pipe loads on the cheap
To: STMFC@yahoogroups.com
Date: Monday, December 1, 2008, 7:54 PM











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.yosemitevalleyr r.com


























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