×
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

Fiitings fabrication (internal threads)

Fiitings fabrication (internal threads)

Fiitings fabrication (internal threads)

(OP)
My question is regarding ANSI B1.20.1, article 4 ''SPECIFICATIONS FOR INTERNAL STRAIGHT THREADS IN PIPE COUPLING' NPSC.''

- Does that means coupling internal threads are straight threads (NPSC)?

- Or that means it can be possible for some applications?

- If it is used on some applications I would appreciate to have some examples and the pros & cons about it.

- Does coupling stands for all fittings (el, tee,couplings etc...)?

- When internal NPT taper threads are used if so ?

Thanks

Marc

RE: Fiitings fabrication (internal threads)

Taper pipe threads are self sealing where straight pipe threads are not.  Straight pipe threads are much stronger than taper pipe threads.  This has it's advantages in cases where added strength and fatigue resistance is needed.  Unless the joint is carefully designed it will usually require a secondary seal.

We started using straight pipe threads to repair a connection between two components in our manufacturing process after the original all welded connection failed.  We could use 1" Sch 160 or XX pipe to handle 2500 psi at 600°F.  This application required the pipe to go through one piece and screw into the other. We would thread the pipe and feed it through on piece and screw it into the second piece. Then a single pass seal weld was applied.

You can have straight pipe threads on any fitting though some are not readily available as standards.

When I worked at a fitting company we made a lot of malleable iron straight pipe fittings of a major oil company. No idea of the end use.

Taper pipe threads are standards for nearly  all use in domestic and industrial water, oil, and gas. This also means any other thing that is compatible with material of construct and pressure temperature ratings.

Some electrical conduit use to have straight pipe threads. I don't know if that's still true.    

RE: Fiitings fabrication (internal threads)

Taper threads can also have different thread tooth shapes.  One type (I think it is called 'dryseal') is more resistant to weeping leakage.

RE: Fiitings fabrication (internal threads)

Dryseal has a more complete thread contact (and is  identified by adding the letter 'F' as in: 1/4 NPTF). Even within the dryseal type there are two grades. Grade 2 requires gage-type inspection.

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! Already a Member? Login


Resources

White Paper - The New World of Thermoplastic Manufacturing
Digital-direct thermoplastic manufacturing offers exceptional quality, opens the door to novel design parameters not possible with injection molding while also bypassing the long lead time and up-front investment in injection molding tooling, offering a better total value proposition. Download Now
White Paper - Strategies to Secure Connected Cars with Firewalls
White-hat hackers have demonstrated gaining remote access to dashboard functions and transmissions of connected vehicles. That makes a firewall a vital component of a multilayered approach to vehicle security as well as overall vehicle safety and reliability. Learn strategies to secure with firewalls. Download Now
White Paper - Model Based Engineering for Wire Harness Manufacturing
As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency. Download Now
White Paper - What is Generative Design and Why Do You Need It?
Engineers are being asked to produce more sophisticated designs under a perfect storm of complexity, cost, and change management pressures. Generative design empowers automotive design teams to navigate this storm by employing automation, data re-use and synchronization, and framing design in the context of a full vehicle platform. Download Now

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