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Process Piping Materials – Module 2 – M06-036 |
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Fittings |
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ASTM A105: |
Carbon Steel forged piping components, socket fittings, |
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flanges, valves for ambient and moderate temperature service |
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in pressure systems. |
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ASTM A216: |
Steel Castings for valves, flanges, fittings or other pressure- |
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containing parts for high-temperature service. Suitable for |
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fusion welding. The three grades included are WCA, WCB |
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and WCC. |
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ASTM A234: |
Pipe fittings of Wrought Carbon Steel and Alloy Steel for |
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moderate and elevated temperatures. |
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ASTM A 694: |
Forging, Carbon and Alloy Steel, for Pipe Flanges, Fitting, |
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Valves and Parts for High Pressure Transmission Service. |
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ASTM A420: |
Low Temperature Service below -18°F/-28°C - Gr. Buttweld |
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fittings. WPL6 is common. |
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ASTM A350: |
Low Temperature Service below -18°F/-28°C - Forged and |
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socket fittings. Gr. LF2 is common. |
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2.5.Killed Carbon Steel Pipes
Killed steels are defined as those, which are thoroughly deoxidized during the melting process. De-oxidation is accomplished by use of silicon, manganese and aluminum, which combine with dissolved gases, usually oxygen, during steel making. This results in cleaner, better quality steel which has fewer gas pockets and inclusions. It minimizes the possibility or extent of hydrogen blistering and hydrogen embrittlement.
•Killed carbon steel is specified:
−Where hydrogen is a major component in the process stream.
−Where hydrogen sulfide H2S is present with an aqueous phase or where liquid water containing H2S is present;
−In process streams containing any amount of Hydrofluoric acid (HF), boron tri-fluoride (BF3) or (BF) compounds; or where Monoethanolamine (MEA) and di-ethanolamine (DEA) are in solutions of greater than 5 weight percent.
−For equipment designed for temperatures greater than 900°F (482°C) since the ASME boiler and Pressure Code does not list allowable stresses for carbon steel over 900°F (482°C).
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