Stress Corrosion Cracking by Hydrophosphines

Question

Stress Corrosion Cracking by Hydrophosphines

GetAtMeWolf (Mechanical)

(OP)

17 Apr 20 12:36

I have three pressure vessels, constructed of 304SS and 316SS which operate at 50psig and contain hydrophosphine product with a Nitrogen blanket. As this is a highly flammable & toxic product, our client is looking to propose non-intrusive NDE in lieu of internal inspections.

I'm wondering if anyone here has experience operating with Hydrophosphines and any potential degradation or cracking mechanisms that are typically associated with them and stainless steels.

Thanks!

Dhurjati Sen (Materials) · Answer 1 · 2020-04-21 04:24:27

Check ASME Corrosion Handbook Volume 13

DHURJATI SEN
Kolkata, India

EdStainless (Materials) · Answer 2 · 2020-04-21 14:36:39

How old are they? How much does the pressure very or cycle? What is the current condition?
The risk analysis on something this hazardous is tricky.
Why do you suspect cracking? Any Cl of Fl in the system (even ppb levels)?
What wall thickness are you dealing with are what are the calculated critical crack sizes?
Unless you know that you can detect a crack smaller than the critical size it is a no-go from the start.

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P.E. Metallurgy

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Stress Corrosion Cracking by Hydrophosphines