×
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

Thread-seal interference

Thread-seal interference

Thread-seal interference

(OP)
Hi All,

I'm currently in the process of reading an API guide on testing casing and tubing designs (which I don't have much experience of).
I've come across the term "thread-seal interference". From researching this term I found some very vague information regarding this.

From what I can gather, I believe it has to do with the way in which the threads interact and how they form seals properly. Is this correct? I would appreciate it if someone could point me in the correct direction or provide additional info, particularly with regards to the following definitions:

thread high - seal low
thread low - seal high
thread high - seal high
thread low - seal high

Thanks,

Jevons

RE: Thread-seal interference

There's a family of threads designated NPTF.
They are also called 'dryseal'.
There's a nominal thread interference (other than the taper).

It's a cosmic joke.

Mike Halloran
Pembroke Pines, FL, USA

RE: Thread-seal interference

As MikeHalloran notes, there is a NPT standard for tapered "dryseal" pipe threads. But these thread joints still leak around the tip/roots like any other thread form will. In order to get them to seal fully, some sort of tape or compound must be used to fill the empty space at the tip/root gap.

RE: Thread-seal interference

There are hundreds of threads used on API tubulars, there are a variety of torque shoulder, seals, thread clearances, etc. Because most are proprietary, API cannot address them.

RE: Thread-seal interference

This question belongs in Pet. Production.
API does not use NPT; it uses 8 round (and 10 round, and buttress), looks a lot like NPT. It requires API dope to seal , used to be full of lead, zinc, etc, but so many children were eating it, they had to take out the lead (25yr ago). And I forgot, 20 yr ago API reverse engineered the PH6 , old proprietary thread, and adopted it. I expect Hydril is still suing API.

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