Seismic assessment - pipework

[bkal]

I am not sure if this is the right forum - so my apologies if it is not.

I might get involved in assesseing an existing pipework in a power stations for seismic loads. The pipework is made of plastic. I would like to get some ipnut in what aspects do you think are the mosst important / vulnerable. My initial gut feeling is that ductility / flexibility might be an issue for differential support motions and that glued connections might also be susceptible. I am not sure what type of joints do they have. In case we go ahead with that we will get site visit done - any ideas on what to pay special attention to (in addition to usual surveys).

Thanks

 

[JAE]

What sort of seismic hazard area are you in?

 

[bkal]

Some clarifications: the area corresponds to 0.2g peak ground accelaration. The pipework is overground, and some of it is elevated to platforms.

 

[rd78]

Does the piping system has an existing stress analysis for the original design? To what code was it designed? What sizes and operating conditions?

You can add seismic accelerations to the operating loads in Caesar II/ Caepipe, etc. You ought to make sure the correct properties for the pipe are used in the stress analysis. This might be a moving target because properties are sometimes hard to get. Glued joints, if done properly, probably aren't any worse than other areas, except when the pipe wall is shaved down to fit into the socket.

Also remember if this is filament wound fiberglass plastic pipe, the axial strength is not the same as the hoop strength (far lower).

Best of luck with the evaluation.

 

[bkal]

Thanks to the reply so far. I forgot to mention that I have experience in assessing steel pipework - however I have never dealt with the plastic one. My main concern is different material behaviour (ductility issues) and joints flexibility and any other issues I am not aware at this stage and hope that the forum can draw my attention to.