Corrrosion allowance for Stud on Flanged Connections (ANSI B16.5)

[Leo_IWI_EWI_MSc_BSc]

Hi Sirs,

What is the Corrosion Allowance considered by ANSI B16.5/31.3 to determine the bolt size for flanged join?. This is because when you use ANSI standard flanged joins, the bolt size is predefined by own standard, no matter what the design corrosion allowance you have for the design conditions under consideration.

Thanks for your help on this point.

lmg.

lmg(IWI,EWE,BSc,TBOSIET)

 

[XL83NL]

I dont fully understand your question, but if your question is if corrosion allowance needs to be applied to the studs or bolts, then no, this is not a requirement by B16.5/B31.3. The obvious reason is that corrosion allowance is (usually) applied to the inside due to a present medium that can initiate corrosion, which normally isnt present on the outside.
This doesnt mean that stud and bolts/nuts dopnt rust, and that your design should take this into acocunt.

 

[Leo_IWI_EWI_MSc_BSc]

Hi,
Thaks for the clarification.

The core of my issue is to know whether ANSI standard considers any corrosion allowance, not if I have to be considered it to determine the sutd bolt size to be used.

This is because I have a Company that it is requiring to determine us what the corrosion allowance on bolts, since before starting up the plant, they found pitting corrosion over them. What we told them was, it was not important since with brushing and touching-up after, it will be fine. They accepted it. But I still keep in mind the doubt what ANSI's consideration on this?

TIA.

lmg.

lmg(IWI,EWE,BSc,TBOSIET)

 

[LittleInch]

Basically section 5.1.1. is all you get, i.e. "The possibility of material deterioration in service should be considered by the user."

Not really very helpful!

Basically B 16.5 gives you bolt diameters to use and that's it. Clearly sometimes bolts suffer corrosion - how much is too much?? No guidance given as far as I can see.

Just grease them....



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

Or coat them. Which bolt grade suffered? And suffered from what? Can you either take the corrosive medium away, or protect the vulnerable (corroded) grade with a coating? We apply Xylan 1070 PTFE coating to all our bolts.

 

[Leo_IWI_EWI_MSc_BSc]

thanks for your support... done.
Very useful.
Best Regards.
lmg.

lmg(IWI,EWE,BSc,TBOSIET)