Hey Fed Express,
All comments are welcome, my apologies for not getting back to this earlier, I have been OS
as for what drugs they are on, I have submitted a TQ to the committee to find out ;o)

I tend to agree with some of your comments regarding AS but this is what we (I am) are stuck with
As for AS2980, my understanding this is largely based on ISO 9606 (with the acceptance criteria of 5817), this explains why are standards are messy
An example of what is in ISO5817, it uses a 'really smart' (in theory and said with a degree of sarcasim) allowance for weld reinforcement 1mm = 0.1m x w with w being the width of the weld
in theory this is a sound idea the wider the cap the greater the allowable reinforcement to control toe angle, but try inspecting this on a job when the cap vary from 6mm to 10mm wide, its fun, I have been there

The current trend is if we (no SAI Global) adopt an ISO rather than develop new or amend existing standards, which from my experience only confuses the situation

Anyway back to your current issue of LoCSA
To be perfectly honest very few people apply this as it is so cumbersome to apply

But this is my take

Porosity - (that is grouped not GP, elongated cavities, worm hole, piping porosity whatever you want to call it) refer to porosity charts out of AS4037 which are the same as ASME, as you point out it states 'Internal - see loss of cross sectional area', but it also states for RT use Porosity charts from AS4037, I would be opting for the later every time

As we are For GP, worm holes, elongated cavities, piping porosity  you have to use LoCSA, Do not refer to the porosity section as this is just for Porosity and not individual pores

I know, I know clear as mud

LoCSA (is listed in the AS2812 glossary of terms - effective loss of weld cross-sectional area due to imperfections) - so I can not categorically say if they mean transverse of longitudinal to the weld or both, to me it makes sense to do it on the shear area of the weld which is longitudinal but knowing the AS system, they are referring to transverse

but here is a worked example based on my humble opinion

a Single Vee butt on 20mm plate, 1 meter long weld the cross sectional area is

Transverse area = Area of triangle 1/2 b x h = 13 x 20 =260 mm2 therefore you are allowed 13mm2 of discontinuity (defect of say 6mm wide x 2mm height = 12mm2) (if you are working on transverse area only)

Longitudinal Area = 20mm x 1000mm = 20000mm2 therefore you are allowed 1000 mm2 of combined defects but none exceeding transverse allowance (defect of say 400mm long x 2mm height = 800mm2)

as I am typing this it is reinforcing that if anything it should be volume (mm3) not area (mm2) so it takes into account both length, width and height

back to your example

Using only the transverse area

Single Vee in 18.26WT
= A (of a triangle) mm2 =1/2bxh
= using Trig to calculate = 1/2b=10.5mm
= 10.5 x 18.26mm
=191.7mm2 cross section area of weld

allowance of 5% = 9.58mm2

a GP of 2.5mm diameter has an area of 4.9mm2 therefore it complies to this example

and yes I agree this is a long winded way of doing it but you did ask

I trust this is some help

R
Flash