Selection between LSAW and SSAW in gas pipelines 1

[Yoga Arviansyah]

Hi, I'm currently working on a project for a gas pipeline. I am confused about how to choose between LSAW and SSAW, the material used is API 5L. Both have the same longitudinal joint factor. Is there a way to calculate the safety factor between the two in the design stage?

I'm currently looking for a way to calculate it, if SSAW is safe to use then SSAW is selected. If someone can give me an idea to calculate it I appreciate it.

* I have tried to use the Distortion energy theory to calculate the safety factor but the value is the same.

Thank you

 

[LittleInch]

What "safety factor"??

What design code are you using?

Also "safe" is meaningless.

There are millions of km of spiral welded pipe in the ground so What is your concern?

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

 

[Yoga Arviansyah]

Thank you for your answer

Maybe I'm more suitable to ask it like this, If we are faced with a choice between LSAW and SSAW in gas pipelines?, how do we determine it, is there any calculation?, I've seen ASME B31.8 (longitudinal joint factor) and it turns out that there is no difference between LSAW and SSAW for API 5L. And also on several websites the information that i've obtained is only relative to one another.

In that selection what we need to pay attention to, if we choose SSAW how do we know that the SSAW will be "safe" (can run with the pressure and gas conditions we run).

by the way, this case is for horizontal directional drilling

 

[weldstan]

LittleInch is correct. While 40+ years ago spiral welded pipe was considered subpar for gas transmission lines, that is no longer true, and tens of thousands of miles of gas pipelines have been installed and operating per B31.8. There is no difference in how either is treated from the safety factors established for locations per B31.8.

 

[LittleInch]

Yoga,

There is no calculation or assessment or anything AFAIK. SSAW means spiral welded in my book.

There is usually a bit of suspicion about it as the welding and rolling process requires two variable - rotation and linear motion of the pipe to be controlled, but modern mills and / or ones with suitable levels of third party inspection produce pipe equally as good as anything else. And usually cheaper.

Traditionally you placed the weld seam at the neutral axis to avoid stresses when bending, but this can't be done for spiral welded.

I know of no impediment to using Spiral welded pipe the same as any other type of welded pipe other than ingrained fear of the unknown.

Poor quality control in any mill or poor quality testing or welding of the seam can lead to failures. Spiral welded is no better or worse.

There is no such thing as "Safe", only acceptable risk. To determine that you need data of which there is very little if any about the difference between spiral welded and straight seam in the last 20 years AFAIK.

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

 

[Yoga Arviansyah]

Thank you all, i appreciate it

 

[1503-44]

You should avoid use or reuse of spiral pipe made before 1975.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[blacksmith37]

NDE of SSAW can be more difficult ; verify that the manufacturer's NDE process is effective.