INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Pipeline wall thickness for full vacuum

Pipeline wall thickness for full vacuum

(OP)
Hello,

There is a 36" 6km long crude oil pipeline. Thickness is 9.5mm with 3mm corrosion allowance.

How do I verify if this thickness is sufficient for full vacuum condition?

Thanks,

Never forget what you are. The rest of the world won't. Wear it like an armor and it can never hurt you.

RE: Pipeline wall thickness for full vacuum

As per your applicable design code.

RE: Pipeline wall thickness for full vacuum

Do an extrenal 1 bar pressure calc. Look at any subsea design code.

It will be ok.

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

RE: Pipeline wall thickness for full vacuum

See what your piping code refers to. it maybe ASME BPV VIII Div 1 UG-28 to 30

RE: Pipeline wall thickness for full vacuum

(OP)
Thank you LittleInch.

XL83NL and KevinNZ,

Design code is ASME B31.4. It does not lead me to ASME BPV VIII Div1 UG 28. Only ASME B31.3 does. But my pipeline is not as per ASME B31.3. Even if I follow ASME VIII Div1 UG 28, what will be the value of L in L/D?

Thanks for your responses.

Never forget what you are. The rest of the world won't. Wear it like an armor and it can never hurt you.

RE: Pipeline wall thickness for full vacuum

L is the length between stiffeners. In your case L = 6000m

RE: Pipeline wall thickness for full vacuum

(OP)
Yes I tried with L = 6000m. It's failing.

But should I really follow Section VIII here?

Thanks.

Never forget what you are. The rest of the world won't. Wear it like an armor and it can never hurt you.

RE: Pipeline wall thickness for full vacuum

Try DNV OS F-101 - it's free to download from DNV, section 5 D400.

you need to calculate a fair number of items, but it's a recognized pipeline code.

If you're taking the min wt as 6.5mm, that's a D/t of 150 - pretty thin.

I think that's a bit excessive though, both as a CA and to remove the entire wt from the pipe calc.

You may well be in trouble at that sort of thickness.

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

RE: Pipeline wall thickness for full vacuum

Why not refer to para 402.4 of B31.4 as it seems the appropriate section for your design code?

RE: Pipeline wall thickness for full vacuum

The issue isn't circumferential stress, it's buckling which is different.

31.4 states in a number of places that the pipe shall be designed with a margin of safety over buckling, but doesn't tell you how to do it....

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

RE: Pipeline wall thickness for full vacuum

(OP)
@LittleInch, Yes sir exactly. I will try DNV OS-F-101. Though the pipeline thickness is 9.5mm, it's inclusive of 3mm corrosion allowance and a negative mill tolerance of 12.5%. So, I think the check has to be done for 5.3mm

Never forget what you are. The rest of the world won't. Wear it like an armor and it can never hurt you.

RE: Pipeline wall thickness for full vacuum

This little table http://lss.fnal.gov/archive/test-tm/1000/fermilab-...

multiplied to 36" gives a value of around 7mm.

Also this doesn't take into account any other forces, moments or axial stress, all of which could impact the final number.

apparently API RP 1111 has a formulae as well. Tried that and got a collapse pressure for 6mm pipe of 18 psi, but allowable is 0.7 of that so 13.2 psi.

http://fianagusta.blogspot.co.uk/2012/02/pipe-wall...

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

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close