Comparing of pipe thikness in ASME B31.3 and 31.1 1

[Pavis1968]

Hello,

In our piping spec for refinery is written
"As a minimum requirement, piping shall be designed in accordance with ASME B31.3, Process Piping. Steam, boiler feed-water and blow down piping, associated with steam generating equipment shall be designed in accordance with ASME B31.1"

I cheked the thickness calculation for above services (steam, blow down, ...) but they also calculated as per ASME B31.3.
My question is this:
1- Is it required the thickness for steam lines in refinery to be calculated as per ASME B31.3 or not?
2- What is the difference between thickness as per B31.1 and 31.3? which code has more safety factor? which thickness is bigger and why?

Thanks and Regards,

 

[MJCronin]

Suggest that you re-post in the Piping & fluid mechanics engineering forum.

You will get a more lively discussion

-MJC

 

[ClemPipe]

The diference is in the Allowable Stress Values of the table A-1 from B31.1 and B.31.3. When you calculate the minimun required thickiness of pipes the equation depends from this value and it changes.
The pipe used for Steam, boiler feed-water services normaly has a corrosion allowance of 0.125 while there are other services where is 0.0625.
These a pair of reasons of the diference

 

[stanweld]

Process steam lines (Non-boiler External Piping) in Refineries are often designed and constructed per ASME B31.3. That piping specific to the boiler or steam generator (boiler feed blowdown, Boiler Extenal piping is normally per B31.1.