Working pressure calculation for Tees
Type of Tee
Standard
Grade
Temp C°
JointFactor
Diameter (D) mm
Diameter (D1) mm
Length (F) mm
Branch height (G) mm
Radius (R)* mm
Thickness req. (T) mm
Thickness req.(T1) mm
Result:
lblResult
1. Standard
Calculation is performed according to regulated formulas and stress values. The Standards defines the grades and their required Design stress.
2. Grade
Different grades have different design stress, selection of grades have impact on the dimensioning of the pipe system. Basis for the selection of grade should be corrosive environment, strength, durability, high temp requirements and cost.
3. Temperature
Select the maximum design temperature for the application.
4. Joint factor
The joint factor (z or Ej) for the longitudinal weld is regulated in the design standards. Z/Ej=1.0 is achieved with 100% Eddy Current or 100% Radiographic testing. This means that the strength of the weld is equal to that of the base material. Welded pipes delivered to EN 10217-7 have a weld factor of 1.0. ASTM-pipes must be 100% X-rayed to get Ej=1.0.
5. Diameter
The outer diameter of the tee
6. Radius
For fabricated tees with a welded branch to the run R=1,5x T1 is automatically calculated
7. Pressure requirement
Set the maximum design pressure for your application.
7. Thickness requirement
Set the maximum design thickness for your application.
Calculation basis
*) For fabricated tees with a welded branch to the run, (R) is automatically calculated using R=1,5x T1
The calculation is made using Annex B in EN 10253--3/4 based on formula (8.4.3-3) ; (6.1-1) ; (8.4.1-2) and (8.4.3-1) in EN 13480-3:2002
For standard EN10253-3 the following applies:
for equipment not subject to non-destructive testing other than visual inspection : 0,7
for equipment subject to random non-destructive testing : 0,85
For standard EN10253-4 the following applies:
Following methods of examination can be used for fittings according to EN10253-4 (Z=1,0)
  • "radiographic examination"
  • "eddy current examination for fittings with wall thickness not greater than 6 mm"
  • "ultrasonic examination"
If you have any questions, please contact soren.nytomt@outokumpu.com
Disclaimers
This calculation tool is intended as a useful guide in calculating the sizes for OSTP welded elbows of certain grades and sizes.
However results obtained should be regarded as rough indications only. Dimensioning of pipe systems is also dependant on external forces, thermal stress, static weight etc.