Cast Iron Specifications

[MER3]

I am putting together a specification for a project and am not quite clear on specifications used in the 1960s. I am tying 3" DI pipe into existing Cast Iron piping using modern DI fittings. I have the old specification that these pipes were built to and it calls out cast iron piping, specifically "USAS 21.6 or 21.8, Class 22 mechanical joint to USAS 21.11 cement mortar lined to USAS 21.4, bituminous coating".

My question boils down to the class 22 nomenclature, I suspect that USAS evolved into ANSI/AWWA since the numbers line up. I do not have a copy of any of these specifications handy, but is "Class 22" called out in one of them? I've got information on thickness class 5x and pressure class XXX pipe, but nothing about class 22. I ask because I want to tie in the new DI stuff using all pressure class 350 stuff, and I want to say that pressure class 350 meets or exceeds class 22 Cast Iron.

Thanks

 

[rconner]

See page 12-5 and other Historical information at the basic portal

http://www.american-usa.com/system/..._Iron_Pipe_and_Fittings_Manual_(11-20-14).pdf

(if you can get hold of 4" x 3" reducer and don't already have the 3", 4" DIP may be same or lower price and more available now).

 

[rconner]

[and ductile iron pipe is far stronger, and more "ductile", than the former gray cast iron pipe, the latter that has not been sold in the USA since the late 1970's)

 

[dicksewerrat]

Also call the local Water utility. They may know where to get the fitting from CI to DIP. Or have the fitting and they don't need it.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[MER3]

Well this isn't public water piping. This is well water piping at a power plant. The well was built in the 70's and from what I can gather it's Cast Iron. As far as I know though, modern DI MJ fittings will fit onto old cast pipes of the same size, provided we clean everything up before installation, right?

And I am actually tying a 3" pipe DI into the 6" CI. I know that's an oddball size, but we've already picked that size pipe for the well. The 3x6 reducer isn't the most common, but they can be bought.

 

[Overbudget]

In the American Pipe Manual of the American Cast Iron Pipe Company. In Section 12, Historical Data, there are several tables that include information on class 22 pipe, including wall thicknesses, pressure ratings, etc. You can see this manual on their web site. Go to page 12-5 of the manual or page 264 of the pdf. There are several pages of information

http://www.american-usa.com/resources/technical-manuals/american-pipe-manual

 

[SteveWag]

If you are working with Gray Cast made in the 1960’s it will be the same OD as todays AWWA specified Ductile Cast. If you were working with cast pipe made in the 1920’s then you may have pipe cast in a sand mold. For this you would measure the circumference and calculate the OD. You would then purchase a compression coupling with a gasket covering that OD. I used to carry an OD tape measure that had a tape measure scaled in inches x 3.14159 on one side, just wrap and read. They were popular pipe company give-aways in the 50-60’s. Hardly used today except in certain older city’s. Anyway, 60’s and later gray cast will have been centrifugally cast and the OD was held to pretty tight standards. If not sure, expose some of the pipe and measure the circumference. The Class and all other ratings only dimensionally effect the ID.
Steve

 

[MER3]

No it's not 1920's vintage. It's a nuclear plant built in 1970. And in usual nuclear fashion we overbuilt it. Class 22 cast iron gives a wall thickness of .38, the same as thickness class 54 ductile iron. The stuff I want to put back (pressure class 350) is only .25 thick, still enough for the well pump.

It is my understanding that thickness classes are usually specified in sewer applications whereas pressure classes in water distribution applications, is that correct?

 

[rconner]

Special thickness classes of ductile iron pipe are all there was from 1965 up until 1992, when Pressure Class designations (used for decades with most other types of pipes) were then applied to ductile iron pipe design and manufacture as well.
In summary, since 1992 both water distribution and wastewater ductile iron piping has been furnished with the new Pressure Class designations. As with any new developments, some utilities stuck with old thickness class designations for some time (that are available still to the present day), but the industry overall has furnished more and more modern Pressure Class over the last now near quarter century.