Calculate nozzle variables per BS EN 13445-3 9.5 in AutoPIPE Vessel report


 

To see a detailed drawing of the nozzle with indicted dimensions, generate a complete output report and open the "Isolated Opening" section. At the start of this section of the report is a number of Figures corresponding to a Figure number. Scroll further down to a particulare nozzle to see the referenced Figure number. 

Detailed information on Isolated Opening variables and how are they calculated:

Note, user should be familiar with code EN 13445, Figures 9.7-1 to 9.7-11. The equations of many variables will be based on the figure referenced above. 

Variable

General Information

 Calculation Details
ls Length of shell, from the edge of an opening or from the external diameter of a nozzle, to a shell discontinuity

From example above,

Is = 159 mm

(more to come)
lb

Length of nozzle extending outside the shell., Or, the nozzle neck length considering the nozzle external projection plus the height due to the nozzle offset that increase the real length along nozzle neck axis.

 

Notes:

Do not confuse "distance to a discontinuity" with "length available for reinforcement".

The code gives theoretical lengths for reinforcements (lbo and lso) that can be reduced by proximity to a discontinuity and/or another length of reinforcement, because one length of reinforcement cannot interfere with another length of reinforcement.
"lb" and "ls" are the remaining reinforcement lengths available taking into account all these constraints, they cannot be represented on a Figure.

From example above,

Ib = 15.53 mm

Nozzle neck (ex. B1) has Shell discontinuity (ex. nozzle B10):

Therefore, 

Notes:

The subscript "s" refers to the shell, the subscript "b" refers to the Nozzle.
But in this case, we have a Nozzle (B10) on a Nozzle (B1), so when considering B10, B1 is the shell !
You have to see the calculation of B10 to understand the calculation of B1.
The length of reinforcement on the "shell" took for B10 will reduce the available length on the Nozzle for "B1".
This is what is being shown in drawing above.

 
w

Distance between an opening and a shell discontinuity

Example:

  • W= 159 mm
eb

Effective thickness of nozzle (or mean thickness within the external length lbo or
internal length lbio) taken into account for reinforcement calculation.

Example: 

  • eb = 11.704  mm
Afs

Cross sectional area of shell (see Nozzle Figure).

Afs =  l's x ec,s  (9.5-28, -34, -43, -54, -61, -73, -79; 2021)

Example:

I's = 130.58mm

ec,s = 13.2

Afs = 138.58 x 13.2

  • Afs = 1723.69 mm^2
Afp

Cross sectional area of reinforcing plate (see Nozzle Figure).

In presence of reinforcing pads the cross sectional area Afp shall be calculated according to 9.5.2.3.1. per eq. 9.5-22; 2021

Afp = I'p x ep (9.5-22; 2021)

Where

I'p = min ( Iso; Ip ; w )   (9.5-19; 2021)

ep = min ( eap ; ecs )    (9.5-20; 2021)

Example:

I'p = min (130.582; 80 ; 159)

ep = min (15; 13.2)

  • Afp = 80 x 13.2 = 1056 mm^2
Afb

Cross sectional area of branch (see Nozzle Figure).

Afb = I'b x eb (9.5-80; 2021)

Where

I'b = min ( Ibo; Ib )   (9.5-82; 2021)

eb = refer to output report

Example:

I'b = min ( 76.21 ; 15.53)

Note: Afb is the area in the nozzle neck which is extended in the opening (Set-In) so you have to add the area in the opening (shell thickness).
Add ecs.

eb = 11.704

 

  • Afb = (15.53 + 13.2) x 11.704 = 336.26 mm^2
Afw

Cross-sectional area of fillet weld between nozzle (or plate) and shell
(see 9.5.2.3.3 and Figures 9.4-4 and 9.5-1).

When calculating nozzles reinforcement for EN13445-3, the welds area Afw is calculated as a triangle from a Sq of equal length.

See model nozzle details weld size

Example: 

Afw = L x L /2 = 10 x 10 /2

(to be fixed in AutoPIPE Vessel 47 - 1678722)

Definitions: