ASME II-D, subpart 3 - definition of P.L.

[XL83NL]

I was programming an Excel file to calculate to verify external pressure, and Im using the mehtod of VIII-1 para UG-28. Upon further review of ASME II-D subpart D, table HA-5 and table NFN-15 show "P.L." at certain values of B. What does P.L. mean? I did not dick through the complete code to find any leads but as far as I know havent seen this in the code.

 

[Jano6924]

I went into a similar situation recently, and could not find anything in Secc. II-D to define “P.L.”.

However take a look into Figure HA-5, you will notice that each curve has two segments, the left side segment is a straight line, and then it reaches what I call the “inflection point” meaning that when, for the 20°C curve, A=0.00134 and B=131 the straight line ends and then a curved segment starts. A lot of curves in II-D have this characteristic.

I have no idea on what “P.L.” means but to my eyes that is the “inflection point”. And for my calculations I have had no problems.

Hope this helps.

 

[XL83NL]

The only thing I noticed on HA-5, but not on NFN-15, is the knick it has after the first straight line from left-under to upper-right. This is a deviation of HA-5 to all other figures.

On the other, I dont foresee any future need for figure HA-5 nor NFN-15, we usually deal with other materials, but I'm still curious to know what it means.

/edt; the oldest copy I have for II-D is 2004, and it's in that one too, so I guess it's not something new/from the recent past

 

[CLFletch]

Just a guess but I believe it is referring to proportional limit. I base this assumption off of Sect II D Appendix 3

 

[XL83NL]

Upon review of 3-700(c)(2):

(2) Chart Construction.​

The external pressure charts​

are plotted in log–log coordinates, with A as the abscissa
and B as the ordinate. Section II, Part D, Subpart 3 limits B
to one-half of σ[sub]y min[/sub]. Thus, the curves can generally be
plotted in two or three segments, which may be more convenient
for curve fitting. The first segment is linear, representing
the linear portion of the σ–ε curve up to the
proportional limit, if there is a proportional limit

So I guess this proportional limit only exists for HA-5 and NFN-15.