NBIC Part 3 PWHT
NBIC Part 3 PWHT
(OP)
For a nozzle in an ASME Sec. VIII Div. 1 2:1 semi ellip. head:
I have a question about how "R" is defined in the Heating Band definition in section 2.5.2 of NBIC 2015 Part 3
Heating Band (HB) – this is the region that encompasses the application of heat for PWHT and is
defined in length by the equation, SB + 4*sqrt(R*t)where R is the outer radius of the spherical or
cylindrical shell in inches (mm), and t is equal to the nominal thickness of the spherical or cylindrical
shell in inches (mm).
Is R the spherical radius of the head?
I have a question about how "R" is defined in the Heating Band definition in section 2.5.2 of NBIC 2015 Part 3
Heating Band (HB) – this is the region that encompasses the application of heat for PWHT and is
defined in length by the equation, SB + 4*sqrt(R*t)where R is the outer radius of the spherical or
cylindrical shell in inches (mm), and t is equal to the nominal thickness of the spherical or cylindrical
shell in inches (mm).
Is R the spherical radius of the head?





RE: NBIC Part 3 PWHT
RE: NBIC Part 3 PWHT
RE: NBIC Part 3 PWHT
Next question in that same equation HB = SB + 4*sqrt(R*t):
Is the SB in that equation just t or 2" (whichever is less) or is it supposed to be the nozzle OD + 2 times t or 2"?
I guess the reason for this question is I'm not sure whether the equation is calculating the radius or the diameter of the HB. The figure 2.5.2-b shows all the dimensions as diameters.
Thanks
RE: NBIC Part 3 PWHT
R MUST ONLY be defined based on the OD and the thickness of the vessel, at the relevant location of the weld.
NOT the ID. Thus, you can approximate the R_calc = (0.9*ID + Twall). Alt: 0.9*(ID + Twall) which is slightly less.
Not 0.9*ID.
RE: NBIC Part 3 PWHT
from the edge of the nozzle wall, or attachment weld or repair area equally by a minimum distance as
defined by the thickness of the shell, t or 2 in. (50 mm), whichever is less. See Figure 2.5.2 b).
RE: NBIC Part 3 PWHT
2013 edition: HB = SB + 4*sqrt(R + t)
2015 edition HB = SB + 4*sqrt(R * t)
there is a huge difference between these equations. I have seen metengr posts on this section of NBIC Part 3 so would like to know his thought on this.
RE: NBIC Part 3 PWHT