Hi Ajmat,

I have found this definition thru google.

"Polybutene and polyisobutylene are liquid oligomers widely used as plasticizers for high-molecular weight polymers, such as polyethylene, and as carriers and lubricants. They are not to be confused with the high molecular weight polymer polybutene-1."

Seems like it is not considered FRP or GRP. So I think ISO 14692 is not applicable in this case.

My experience with HDPE piping (not sure if it is the same) is we ask some vendor guidelines regarding support spanning and loop sizing. We have done some crude calcs using beam analysis software but I think the result will not be so accurate due to large displacement. This is just to estimate nozzle loads on pumps (using Elastic modulus and other physical properties to be inputted in software).

I'm not sure, but I think there is no solid "Code" regarding tackling stress analysis of "Polyethelene Plastic Piping".

In your case, the job seems like a trouble shooting work on how to eliminate the leak.

Not sure how to prove it analytically. I'm interested to know also from other fellows how to prove this.

From my point of view, I would handle it this way. (If the leak is on the metallic T- connection). I would do this steps.

1) Visit the site and see if the leak is due to cracks in the tee body itself or in the joints?

2) Check for possible fatigue sources such as pressure cycling. Maybe you can ask operation guys regarding it's operation history.

3) Is there over pressurization of the line?

At the end, maybe your suggestion to the client is to add more material on that leaking point. To quantify how much material is needed you need to identify what's causing the leak and maybe perform some crude calcs.

But in the end, it's hard to guarantee it unless you really have a solid backup on how to eliminate the leak.

Anyway, I'm interested to know the solution to this problem.

Just correct me in case I've made some wrong statements.

Any other opinion is highly appreciated.

Cheers,