Structural analysis at high temperatures 2

[Christian_S]

Hey

I'm not a structural engineer, so excuse my ignorance on the topic. We have some pipe support shoes that are to be attached to pipes that are 300 degrees Celsius. We had a material engineer who said it was okay to use 316L Stainless steel at these temperatures, but the person doing the structural analysis of these shoes was a bit unsure how to proceed as there were no guidelines in Eurocode 3 about analyzing at high temperatures. I wonder if the exclusion of this topic might mean that it's not relevant as long as you use the material properties for the temperature in your environment.
Would it be okay to proceed with the material as long as we consider the yield and tensile strength at the temperature given?

Tensile table for some 316L alloys attached, as you can see they have defined properties up to at least 350 deg Celsius.

 

[ThomasH]

You can find guidelines in the Eurocode for analyzing steel at high temperatures, EN 1993-1-2. The standard is for fire design but I believe that it should be applicable.

 

[Christian_S]

Thanks, I’ll look into EC 1-2

 

[dvd]

one other area for consideration with high temperature analysis is the change in elastic modulus - see file attachment for more information

 

[Christian_S]

Yes, seems to be about a 10% drop in elastin modulus at my temperature case. Thanks!

 

[JStephen]

The pressure vessel and boiler codes have some properties for materials at elevated temperatures as well.

 

[HTURKAK]

If the design temperature of the pipe 300 degrees Celsius (so, elevated temperature ) , It is not a good idea to use welded attachments directly to the pipe and you should consider using hot insulated supports .When you search ( Pipe shoe elevated temperature insulated pipe support ),

Some of the probable outcomes ;

-

https://www.pipeshields.com/products/base-mounted/

-

http://www.cmt-engineering.co.uk/spartan-clamps-floats/technical-information/

-

https://pipingtech.com/products/pipe-shoes-pipe-guides/supports-with-no-field-welding/

If the only solution is the use of pipe support shoes attached to pipes;

You may look Pressure and vessel codes , EN 1993-1-2 ( as previously suggested ) .

My suggestion will be to look ( Design Guide for Steel at Elevated Temperatures
and High Strain Rates , Technical Note 6 , FABIG )






Not to know is bad;
not to wish to know is worse.

NIGERIAN PROVERB

 

[Christian_S]

If the design temperature of the pipe 300 degrees Celsius (so, elevated temperature ) , It is not a good idea to use welded attachments directly to the pipe and you should consider using hot insulated supports .When you search ( Pipe shoe elevated temperature insulated pipe support ),

I've looked into using hot insulated supports, but they seem to be too weak for my load cases. What exactly is the downside of using welded shoes at this temperature? I thought the weld might be the weak link, but that as long as you followed B31.3 you'd be okay. I might be wrong here though.

 

[HTURKAK]

You did not supply alot of information here.. At least two concerns using welded shoes at this temperature;

- Personnel safety ( if it is not a remote location) ..

- Heat loss at welded shoes ..

I would consider the use of spacer ( to avoid metallic contact ) and load distribution plate ..


My opinion..


EDIT: hot surfaces defined as those greater than 60 C ( by OHSA ) and it is a requirement to protect against burns ( with insulation, protection cake etc).






Not to know is bad;
not to wish to know is worse.

NIGERIAN PROVERB

 

[Christian_S]

- Personnel safety ( if it is not a remote location) ..

- Heat loss at welded shoes ..

I've considered the heat loss aspect, and that could be an important factor in switching to shoes with insulation barriers between the clamps and pipe.
When you say personal safety, are you referring to the surface temperature of the supports?

 

[JLNJ]

Make the shoes out of the same material as the pipe.

 

[Christian_S]

Make the shoes out of the same material as the pipe.

I wish and hoped to do that, but unfortunately the client have some requirements that prevent us from using other materials than 316L or lean duplex.