Contact US

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.

Students Click Here

ASME VIII 1943 Sections U-68 and U-69

ASME VIII 1943 Sections U-68 and U-69

ASME VIII 1943 Sections U-68 and U-69

Hi All,

In the 1943 year of ASME VIII they list two different joint efficiencies to use for non-seamless components in U-68 and U-69.

It's not clear which one I should use. I tried reading U-68 and U-69 and it doesn't make sense.

Any help is appreciated.

RE: ASME VIII 1943 Sections U-68 and U-69

The U-1 Data Report should list the joint efficiency on Line 8. If you don't have a U-1 it's possible that the joint efficiency was listed somewhere on the original drawing, or if the MAWP was listed it may be possible to back-calculate the joint efficiency.

Otherwise if you have documentation to back up that all of testing outlined in U-68 was performed, the efficiency E = 0.90. Otherwise, E = 0.80 as long as the requirements of U-69 are met.


RE: ASME VIII 1943 Sections U-68 and U-69


Thank you for the guidance.

Do you know why the joint efficiencies were relatively high in the 40s but were lowered starting in the 50s?

I find that concerning because many of these old vessels were built with very little corrosion allowance so if today's joint efficiencies were applied to these 1940s vessels they would most likely be below Tmin.

RE: ASME VIII 1943 Sections U-68 and U-69

Design allowables were
lower in the '40s.

RE: ASME VIII 1943 Sections U-68 and U-69


True and rightfully so due to the technology back then

However, the S.F. was increased to 4 temporarily due to WWII in the early 40s to save metal for the military. Is it safe to assume that any vessel built during this time period should be heavily questioned if they are still in operation today?

RE: ASME VIII 1943 Sections U-68 and U-69

The 4:1 design margin in the API-ASME Code was first introduced in 1934 so it pre-dates WWII. If I remember correctly ASME Section VIII maintained a 5:1 design margin until 1950.

Many such vessels have been in continuous operation since that era without any problems.


RE: ASME VIII 1943 Sections U-68 and U-69

Why were there two separate codes back then? How did one know which one to use back then?

From what I read, if a vessel was built to API-ASME it didn't have a U stamp correct?

RE: ASME VIII 1943 Sections U-68 and U-69

Some information about the history of the API-ASME code is discussed the Forward of earlier editions of API 510:


"In December 1931, API and the American Society of Mechanical Engineers (ASME) created the Joint APIIASME Committee on Unfired Pressure Vessels. This committee was created to formulate and prepare for publication a code for safe practices in the design, construction, inspection, and repair of pressure vessels to be used in the petroleum industry. Entitled APIIASME Code for Unfired Pressure Vessels for Petroleum Liquids and Gases (commonly called the API/ASME Code for Unfired Pressure Vessels or API/ASME Code), the first edition of the code was approved for publication in 1934."


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


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