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Fri04182014

Last updateThu, 17 Apr 2014 1pm

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Materials Q&A

Do I need to be concerned about galvanic corrosion when selecting valve materials?

materials q and a 300x300A: This is a good question, and the answer should begin with discussing exactly what is meant by galvanic corrosion.

Have PMI testing limitations changed with the advances in technology?

materials q and a 300x300A: The short answer is that the situation has changed in some ways, but that PMI still has limitations. The long answer is a bit more complicated. First, let’s clarify what is meant by the term PMI (which stands for positive material identification).

Titanium Valve Grades

materials q and a 300x300Q: Why are cast titanium valves commonly offered in grades different than my wrought pipe?

 

Nickel-Copper Alloys

materials_q_and_a_graphicQ: Are the nickel-copper alloys (such as UNS N04400) acceptable for use in accordance with the NACE sour service standards?

NACE MR0103 Material Compliance

materials_q_and_a_graphicQ: I have a material certified to be compliant with NACE MR0175. Is that material also compliant with NACE MR0103?

Which Valve for Nitric Acid Service?

materials_q_and_a_graphicQ: I requested CF8 valves but the supplier is offering CF8M valves at less cost. However, I am not sure this alternative is a good choice for my nitric acid service. Are my concerns warranted?

 

Addressing Welding Procedures Not Covered by ASME Section IX

materials_q_and_a_graphicQ: My customer has rejected my welding procedure specification (WPS) and has asked me to address items that are not required by ASME Section IX. Is this reasonable?

HIC Testing

materials_q_and_a_graphicQ: I’m working on an order in which the customer’s material specification imposes HIC testing. What is HIC testing?

Cobalt-base Alloy 6

materials_q_and_a_graphicQ: Is there a problem using cobalt-base Alloy 6 material in amine applications in refineries and gas treatment plants?

Cast or Forged?

materials_q_and_a_graphicQ: Should I be concerned whether my valve is cast or forged?

 

ASTM A182

materials_q_and_a_graphicQ: In the last Materials Q&A column, you discussed using forged bar to make hubbed-flange components such as bonnets. I noticed that ASTM A182 specifically states that forged bar cannot be used for flanges. Was your original statement in error?

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