Pipe Types 1

[Dymalica]

Can anyone help me understand the difference in ferrous pipe types. Most piping for HVAC, commercial use black steel or ductile iron. What is the difference and what applications does each one suit best. Is black steel more resistant to corrosion? Is cast iron pipe still used? Are these the two types of metal pipe used in America (besides galvanized steel and stainless which are rarely used)? I seriously can't find any website to explain it. They seem to use different nomenclature for pipes. Thank You

Black Steel
Applications: Hot Water, Natural Gas, Chilled Water (?)
Cost: Higher compared to ductile iron (?)
Potable water: Yes/No (?)
Corrosion: ?


Ductile Iron
Applications: Chilled Water (?)
Cost: Low compared to black steel (?)
Corrosion: ?
Potable water; Yes/No (?)

 

[JohnBreen]

http://en.wikipedia.org/wiki/Pipe_(material)

http://www.dipra.org/pdf/DIPvsPVC.pdf

http://www.dot.state.fl.us/rddesign/dr/files/Opt-Pipe-HB.pdf

http://www.calaged.org/ResourceFiles/Curriculum/advcluster/2551.txt

http://www.usace.army.mil/publications/eng-manuals/em1110-1-4008/c-3.pdf

http://www.cispi.org/pdf/2006-Handbook.pdf

http://www.dot.state.fl.us/rddesign/dr/files/Opt-Pipe-HB.pdf

Pipe material is chosen based upon many and various design requirements:

Pressure
Temperature
Corrosion Resistance
Abrasion Resistance
Weight
Electrolytic Properties
Ductility at temperature ("toughness" or impact resistance)
Weldability
etc

There are VERY MANY alloys form which metallic pipes are manufactured. Pipe materials often have "common names" (e.g. "black steel") but to specify specific piping material it is correct to use the material specification number provided by the American Society for Testing and Materials (ASTM)

Common carbon steel pipe materials"

ASTM A-53, grade B
ASTM A-106, grade B
ASTM A-333 (for use with cold temperatures

"Low alloy" steels for strength at high temperatures

e.g., ASTM A-335, grade P22

"stainless steels"

e.g., ASTM A-312, grade 340

and many hundreds more alloys that should be picked by matching the alloy to the design requirements.

John

 

[rconner]

Mr. Breen has given you links to much very good reading material (that should keep you busy for awhile). With regard to your specific questions, I think ductile iron piping (DIP, in particularly many of the sizes often used in at least such buried systems) has some notable advantages over sometimes used "black steel pipe" for water services:

1. Ductile iron piping is furnished standardly with factory applied internal cement mortar linings, that may not be readily available for the steel pipe (particularly in small sizes). Cement mortar linings have a more than 80 year, generally very successful perforamnce history in prevention of internal tuberculation and maintenance of flow properties, in even some pretty aggressive water exposures. At least some past steel pipes have been furnished either unlined or with rather thin-film, bonded coatings that have not proven suitably durable for some users/services. [For other differences between iron and steel pipe, you may also want to read some of the research and writings concerning the present "DDM" of DIPRA from dipra.org.]
2. Ductile iron piping systems can be successfully installed and repaired with common tools, and arguably even with less than highly skilled labor. The pipe, as well as a full complement of compatible valves, tapping accessories, fittings, repair materials etc., is generally also readily available.

While many large users, and some with years of experience with multiple materials, have sort of gravitated to cement mortar-lined DIP for at least for their buried services, I am aware of some of these quite large users who I understand also still use quite a bit of steel pipe e.g. within buildings. I don't know all the reasons for this, but I suspect some involve desired fabrication and also that ductile iron pipe may not be available in some smaller sizes appearing in buildings.