API 5CT tubing as pipeline

[Jkaen]

Hi all,

We have been asked by a client to use existing API 5CT tubing (5", L80 GRE lined, threaded ends) as pipeline material for a water injection network.

I can't see anything in ASME B31.4 stopping us from using this material, but we are a bit stuck on how to handle branches off the main line, and connections to valves, instruments etc which will be standard 6" items.

We are trying to do the system to standards and stress the complete system (Caesar II)

Has anybody done the above, or can they recommend how to handle the fittings and transitions to standard pipe sizes?

Regards
Stephen

 

[LittleInch]

Using drill pipe for pipelines is not common, so there are few good examples.

Presumably you will need custom connections to go from a 5" drill pipe to a 6" standard pipe? Just model that in Caesar.

I'm a little surprised that a company that is willing to use screwed drill pipe is actually concerned about stress issues.... The stress concentrations around the screwed ends are complex enough.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Jkaen]

Yes, we are not completely happy about it, but are trying to be flexible and helpful to the client etc.

The stress guys are complaining that as it would be a custom joint in Caesar they don't have any details regarding the performance of the joint which invalidates the whole model. Will try to convince them to come up with something that will get us through

Thanks
Stephen

 

[LittleInch]

Why are you doing a stress analysis?

Using stress analysis for screwed drill pipe is just a joke.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Jkaen]

We are doing stress because the client requests it. I think their head office has said they can only use the drill pipe if they get full stress analysis on the line first

 

[LittleInch]

Ah, that makes more sense. The "system" is catching up with the field guys who are just trying to use what they have lying around. There is often a disconnect between drilling guys and piping / pipeline people on the use of drill pipe as pipe / pipeline.

I'm a little surprised your stress guys aren't worried about the complexity of the screwed ends. Are they using screwed couplers for this?

Why don't you use a screwed reducer to get to a 6" pipe and then use standard components from there. A reducer with a coupler should model the same as a piece of pipe to pipe coupling, or just weld a 5 x 6 reducer onto your pipe? a 6 x 5 reducer is a standard component, if quite rarely used to B16.9 so I'm having difficulty understanding what the issue is here?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.