Process Piping Materials – Module 2 – M06-036

CHAPTER – 4

MATERIALS – UNDERGROUND PIPING

4. BURIED PIPING

Two common buried pipe materials are:

1.Cast Iron and Ductile Iron Pipe

2.Plastic Pipes

4.1.Ductile Iron Pipe

Ductile iron pipe (DIP) is an outgrowth of the cast iron pipe industry. While both ductile and cast iron are created by introducing carbon, ductile iron differs in that it is made by adding magnesium, phosphorous and sulfur into the hot molten iron bath. The process gives DIP an ability to slightly deform (bent) without cracking. This is a major advantage of ductile iron pipe. Ductile pipe is used mainly in domestic water distribution service in sizes ranging from 8 inches to 42 inches in diameter.

x Characteristics

Advantage - Good corrosion resistance when coated. High strength

Drawbacks - Heavy

Standards - AWWA C151 and the Cement lined DIP: AWWA standard C104.

Installation - ANSI/AWWA C600, C105/A21.5

4.2.Plastic Pipes

Plastics are solid materials that contain one or more polymeric substances which can be shaped by flow. Polymers, the basic ingredient of plastics, compose a broad class of materials that include natural and synthetic polymers. Nearly all plastics are made from the latter. In commercial practice, polymers are frequently designated as resins. For example, a polyethylene (PE) pipe compound consists of PE resin combined with colorants, stabilizers, anti-oxidants or other ingredients required to protect and enhance properties during fabrication and service.

Common pipe materials include Polyethylene (PE or HDPE for HighDensity PE), polypropylene (PP), Polyvinyl Chloride (PVC), Acrylonitrile-butadiene-styrene (ABS), and Polybutylene (PB).

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