Elbow thickness in ASME Section 1 boilers for remaining life assessment

[DeathRay009]

Hi all,

I am currently trying to calculate the pressure design thickness of elbows in superheater section of our boiler for remaining life assessment. There's no information I have found yet on elbow thickness calculation in Section 1. So:

1. What is the standard procedure in such cases
2. Can I use the "I" factor as defined in elbow thickness calculation in ASME B31.3 and used it in the same sense for elbow of ASME Section 1

Best Regards.

 

[IdanPV]

Refer to PG-42.1.

 

[DeathRay009]

Refer to PG-42.1.

I have seen that already, as per my understanding it says that the manufacturer should design the elbow such that it has atleast the pressure resisting capacity of the straight pipe it is being used for. But it still doesnt help me, because I have to calculate the thickness at intrados and extrados for remaining life assesment.

 

[IdanPV]

PG-42.1 state that when using standard Wrought Buttwelding Fittings per B16.9, the pressure–temperature ratings shall be calculated as for straight seamless pipe in accordance with the rules of Section I, including the maximum allowable stress for the material under consideration.

For remaining life assessment, usually API 579/FFS-1 shall be use.

 

[DeathRay009]

PG-42.1 state that when using standard Wrought Buttwelding Fittings per B16.9, the pressure–temperature ratings shall be calculated as for straight seamless pipe in accordance with the rules of Section I, including the maximum allowable stress for the material under consideration.

For remaining life assessment, usually API 579/FFS-1 shall be use.

I want to use API 579 too, but as I have stated earlier, there is no design equation that links pressure to wall thickness of elbow in ASME Section 1 (a similar equation is however available in B31.3). So my original question was whether I can use the B31.3 equation with ASME Section 1 values to calculate the design thickness of elbow at intrados and extrados.

 

[IdanPV]

"there is no design equation that links pressure to wall thickness of elbow in ASME Section 1"
I think that the NOTE in PG-42.1 defines it very well.
Assuming this is standard elbow (B16.9): "When pressure ratings are established under the provisions of ASME B16.9, para. 2.1, they shall be calculated as for straight seamless pipe in accordance with this Section"

Just calculate it per PG-27.

 

[r6155]

See ASME B31.1

Regards