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LESSONS & TOPICS

Stainless Steel Pipe

Stainless Steel Pipe

Stainless Steel pipe normally used whenever corrosion resistance is needed. Adding Chromium will provide good corrosion resistance to the material. However, it is very rare to see stainless steel pipe to be used for underground application due to economic reason. There are three types of stainless-steel pipe, as shown below:

1. AUSTENITIC STAINLESS STEEL
This type of pipe can be identified by 300 series and having maximum content of 0.15 percent carbon and minimum of 16 percent chromium, as well as other elements such as Nickel and or Manganese. Austenitic Stainless Steel poses an excellent combination of strength, ductility and corrosion resistance.

 

2. FERRITIC STAINLESS STEEL
usually identify with 400 series, and having chromium content between 14 to 27 percent, while Martensitic Stainless Steel contain 11.5% up to 18% Chromium and they both are magnetic. However, the most stainless-steel piping comes from the Austenitic variety, with the common grade is 304 and 316. There are also Austenitic Stainless Steel with lower carbon content and designated by the suffix “L”.

 

2. APPLICATION
Stainless steel piping is used for foods, beverages, and also at pharmaceutical, where iron dissolution cannot be allowed. This pipe never be installed underground and also no painting needed.

 

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Some of Specification for Stainless Steel Pipe
ASTM A312 Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes
ASTM A358 Electric-Fusion-Welded Austenitic Chromium-Nickel Alloy Steel Pipe for High-Temperature Service
ASTM A409 Welded Large Diameter Austenitic Steel Pipe for Corrosive or High-Temperature Service
ASTM A790 Seamless and Welded Ferritic /Austenitic Stainless-Steel Pipe
ASTM A999 General Requirements for Alloy and Stainless Steel Pipe
ASTM C220 Stainless-Steel Pipe, 1/2 in (13 mm) and Larger

 

Carbide Precipitation
It is a phenomenon that occurs when austenitic (300 series) stainless steels are heated, as for example during welding, that the carbides attract chromium atoms. The surrounding region of the stainless contains less chromium since it is bound with the carbides, which make that regions, where the corrosion resistant properties are deficient, and prone to corrosion attack.
There are two ways to prevent carbide precipitation during welding. One is to use a LOW-CARBON GRADE of Stainless-Steel, identified by the suffix “L” (for “low-carbon”). The other option is to stabilize the stainless steel with the addition of columbium or titanium. However, in practice, it is more common to use the low-carbon grades of stainless

 

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