Hi,

We are running ASME B31.3 std CAESARII pipe stress analysis. The stress team is using and adding an SIF=4 at pipe anchors, 3-ways or a single axial support, to reserve enough capacity at the attachment point to qualify a lug at Y-3000 (ASME III Div 1).

Worked on multiple projects and this SIF has never been used. Is this too conservative and is it required? Could I ignore it or avoid using it? Could I justify not using it?

Thanks,

I do not think there is a SIF requirement for the supports. But the support and connected pipe should comply with the allowable stress requirements given by ASME under the loads and load combinations. Support design engineer should check this as required.

This part unfortunately is ignored by many since they use standard support drawings which are not supported by calculations for applicability. Stress engineers do not even know that the supporting calculations do not exist.
Some companies are aware of the problem and they use several trick that show they considered the support effect by using SIFs or other methods. But they are suppose to verify this application by proper calculations.

If the pipe stress person and the support design engineer are the same person this may be evaluated adequately since the same person is responsible for both actions. In case the company leave support selection actions to the designers they can only manage the selection against the standard drawings which most of the case are not supported by calculations.

In your case, whatever they do or you do, you still need to verify support by adequate calculation. Primary and secondary stresses should be identified and allowables considered.

Please consider that these are my observations from my experience, I do not blame anyone.

You can't actually prove by this that support is safe. for instant, if the CAESAR II output shows failure at these SIF locations, what will be the approach? are you going to reduce the reactions by adding flexibilities? In my personal view your piping system to be designed for optimized support load with the required level of flexibility only. and support calculation shall be performed for its strength and local stresses in the parent pipe for generated loads if the support standard doesn't provide the allowable values.

also this is interesting to know the basis of these SIF value of 4.