ASME VIII 1943 Sections U-68 and U-69 1

[Rubje]

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.

 

[Christine74]

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.


-Christine

 

[Rubje]

@Christine74

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.

 

[weldstan]

Design allowables were[pre][/pre] lower in the '40s.

 

[Rubje]

@weldstan

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?

 

[Christine74]

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.


-Christine

 

[Rubje]

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?

 

[Christine74]

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

https://law.resource.org/pub/us/cfr/ibr/002/api.510.2006.pdf

"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."


-Christine