×
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!
  • Students Click Here

*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.

Students Click Here

Jobs

Pipe, API 5L X42 or X65 which one is better for H2S containing Service

Pipe, API 5L X42 or X65 which one is better for H2S containing Service

Pipe, API 5L X42 or X65 which one is better for H2S containing Service

(OP)
Hi All,

We want planning for our client's sour service natural gas pipeline system. You know API 5L X42-X65 all satisfy the requirements of the NACE MR0175. But, I wonder if you can introduce me an any recommendation/document which compares X42 vs. X65. I want to know which one is much better for our application. We normally do our PWHT for thicknesses higher than 12.5mm for sour services; then, using X42 implies higher thickness and hence can bring the costly PWHT requirement.
On the other hand, X42 for a specific MAWP has a higher thickness and then it can be more resistive to corrosive environment.
There are many advantageous and disadvantageous for using both of them. But, some practice can be helpful, if their is any.

Best Regards
Mehdi Eskandarzade

RE: Pipe, API 5L X42 or X65 which one is better for H2S containing Service

High hardness at the welds will be the principal issue with either. If you limit the maximum carbon equivalent of the X-42, it will more likely meet NACE hardness requirements in the welds.

Many years ago a major gas supplier specified X-42 for a similar application without specifying a max. CE. They were compelled to PWHT the welds to comply with hardness. The X-42 was equivalent to X-60 and had a CE to match.

RE: Pipe, API 5L X42 or X65 which one is better for H2S containing Service

Quote (Iskanderzade)

....higher thickness and then it can be more resistive to corrosive environment

Taking the failure point as loss of corrosion allowance, time to failure will be mostly governed by the amount of corrosion allowance. The same corrosion allowance is likely to be applied to both grades of pipe once the pressure and stress calculations have been completed. Thus, the target would be to achieve a thickness that wouldn't need PWHT by your company's philosophy, and one which minimises costs of transport and other installation activities, whilst still maintaining weldability. Sour service X65 from major pipe mills is a reasonably straightforward weldability proposition these days but its cost per tonne will probably be higher.

It's a typical pipeline engineering/materials selection exercise that tends to go through a few iterations before landing on a choice.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

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