×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• 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.

J tube

J tube

(OP)
I hope someone can explain more clearly about J tube, and how to estimate it.

regards,
Ron

RE: J tube

A J tube is exactly that: a tube shaped like a J, extending from the top of a jacket to the mudline (or close to the mudline), with a bell mouth on the end, to provide a conduit to pull risers up.  The radius of the J is a function of whether the risers to be pulled up the J tube are flexible or (more normally) rigid pipe- on the platform I'm on at the moment, the 3 J tubes' radius is about 100ft, and they are each 16" OD.

RE: J tube

To expand on the description. In submarine pipelaying, the normal method in shallower water is to S lay the pipe, where the pipe is welded horizontally (or near horizontally) on a lay barge and runs off a stinger in an S (reverse) curve.

In deeper water the J lay method can be used where the pipe is welded in the vertical and there is a single curve near the seabed.

RE: J tube

On the platforms that I work with, a J tube houses an umbilical or flexible flowline from the bottom part of our hull up to the topsides.  In my case the platform is a Tension Leg Platform in deep water.  For installation, the umbilical or flowline is connected to a "pull head" that is used to pull the umbilical through the J tube up to the topsides.  The J tube is curved at the bottom so that it follows the curve of the umbilical as it leaves the platform.

The OD of the tube and the bend radius need to be large enough to allow the pull head to be pulled all the way through the tube.  The wall thickness should be such that the pipe can resist wave/current loads and any loads applied by the umbilical or flowline.  The length of the tube in my case is around 170'. Typical sizes in my application are 16" to 22" OD and approximately 3/4" thick. You may also need flanges on the tube and supports to hold it to the platform.

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.

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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!