Painting A335 P11 (1.25Cr 0.5Mo STEEL)

[pipeneer]

Hi to all
A simple question which I do not know the answer to,Does a fabricated spool in A335 P11 grade material which is subjested to Op.Temp.120 Deg C (DP for what it's worth is 132 bar)needs to be painted? and yes what would be it(Aluminium......etc).Thanks in advance.

 

[SJones]

In a humid coastal/offshore environment, corrosion rates could exceed 0.1 mm/year and be anything up to 1 mm/year if water can be retained against the hot pipe for periods. It could get to look pretty ugly. An inorganic zinc coating as per Process Industry Practice CTSE1000 System No1 would be a starting consideration for uninsulated pipe.

Steve Jones
Materials & Corrosion Engineer

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