Horizontal Directional Drilling (HDD), Longitudinal Stress during operation

[Yoga Arviansyah]

Hello everyone, I'm currently working on a HDD design project. But I'm stuck in adjusting to the given specification document. The specification states that the longitudinal stress should not be less than 60% SMYS.

The case I'm working on is a 20 in pipeline with a thickness of 12.7 mm. This pipeline has a design temperature of 150 F and a design pressure of 150 Psig. Pipeline has material API 5L X52.

I've tried varying the thickness, radius of curvature of the HDD, design temperature, and pipe material. but still does not meet the criteria.

Do you have any suggestions or insights on this matter?
Is this criteria incorrectly stated?, maybe under 60% SMYS?

Thank you

 

[LittleInch]

Can't recall any project where a minimum stress was required.

Looks like a typo to me at the moment.

So either the word not shouldn't be there or replace less with more.

In the first instance I would check with whoever gave you that specification. Doesn't seem right but maybe they have a reason. I can't think what that is but it doesn't mean there isn't one.

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

 

[Yoga Arviansyah]

Thank you for your respond

 

[LittleInch]

No problem. That's quite a thick pipeline for only 150 psi so not surprising you're getting fairly low stresses.

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