Hi all,
I would like to know if it is possible I use in the same equipment, full radiography only in longitudinal joint and use E = 1 for efficiency of the longitudinal seam (Joint Category A) and E = 0.85 for efficiency of the circumferential seam (Joint Category B)?

Thank you

Pedro

Pedro,

That would be a user defined efficiency in PVElite. Data Plate marking would show RT-4 (others don't apply) and have the details shown in the remarks section of the data report.

EJL

Tanks EJL,

But, according RT-4, I must use E = 0.85 for efficiency of the longitudinal seam in my case, correctly?
According RT-2, if I full radiography the longitudinal joint and spot radiography the circumferential joint, I can use E = 1 for efficiency of the longitudinal seam and E = 1 for efficiency of the circumferential seam too, correctly?
And then, when I can use different efficiency for longitudinal and circumferential joint?

Pedro

Pedro,

This item has always caused confusion. If you fully radiograph per UW-11 (a) the long seam then you will have an efficiency of 1 (for type 1 joint). Without performing any other radiography your circumferential seam efficiency will be 0.7. This is the value to be used in calculating the required shell thickness per UW-27 equation 2. This thickness will seldom govern but is needed for the data report. This will need an RT-4 marking as none of the other markings are applicable. The efficiency of the head (this is really a quality factor) would be 0.85 in accordance with UW-12(d) as you did not do a spot on the circuferential seam to satisfy UW-11(a)5(b).

If you add an extra spot (essentially to achieve a better quality factor for the heads) on the circuferential seam then you would in fact have RT-2. Your circumferential seam efficiency to be marked on the data report would still be 0.7 but then the head efficiency (quality factor) would be 1 in accordance with UW-12(d).

UG-116(e)(4) states that RT-4 is to be used when only part of the vessel satisfies UW-11(a) i.e. the long seam, and when the other markings do not apply.

I hope this makes things a bit clearer.

Regards,
EJL