Hello everyone,

I'm being involved in a project which employ many pipelines made from thermoplastics (PP,HDPE,PVDV etc.).According to project related specification ,DVS-2205 shall be governing rule for stress analysis for piping of thermoplastics.My questions are following:

1. How to apply DVS-2205 in CII?

2. Property information of material from vendor is necessary?
3. What role creep strength play in static stress analysis for thermoplastic lines? Creep strength is very critical in DVS-2205, unlike steel piping.

Any suggestion or instruction is highly appreciated.

Rds

1. You can't use DVS-2205 for pipe stress analysis. It is for the design of tanks and vessels. You can get some info from DVS-2210-1 chapter 4. However thermoplastic piping is not incorporated in CAESAR II for some very good reasons. See my other comments on the same sort of questions.

2. Thermoplastics (well, not all) are standarized, just as steel. But there are a lot of manufacturers that do not comply to the standards. So first verify if it is standarized and if, use the standard values (DVS 2205 or EN-1778 for example). If not, use vendor values.

3. Creep in steel is only applicable at (very) high temperatures. For thermoplastics this is already applicable at room temperature (just as for wood and concrete). And it is very important too.

Ask yourself if you need to make a pipe stress analysis using CAESAR II for thermoplastic piping, taking into consideration both the code issues and the finite element limitations.

Thanks for your prompt reply.
Creep strengh shall be governing criteria since it is applicable at room temperature for thermoplastice piping?

http://www.hse.gov.uk/research/hsl_pdf/2006/hsl0621.pdf

Read this. It will give some idea about the subject.