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Formula

The internal pressures are calculated by using the following formula:

Do/Di ≤ 1.7:

euro1.png

Do/Di > 1.7:

euro2.png

Symbol Description
P Internal pressure (MPa) (*10 => bar)
eord Ordered wall thickness (mm)
c1 Manufacturing tolerance, absolute value (mm)
Do Nominal outside diameter (mm)
Di Nominal inside diameter (mm) (Di =Do-2×eord)
z Welding factor, 1.0 for seamless tubes
f Maximum allowed stress (MPa), see also below:
At Minimum ductility, transverse (%)

Austenitic steels

At >= 35%
f = Rp1.0t / 1.5 ( or min. ( Rp1.0t / 1.2 ; Rmt / 3 ), if Rmt is available)* ( t = here at temp.)

30% <= At < 35%
f = min (Rp1.0t/1.5 or Rm/2.4)*

*The programme always calculates with Rp1.0t/1.5 for austenitic grades, but if Rmt or Rm is known for the specific grade and size, and at temp. for Rmt, this may give a more favorable result in case of At > 35% or respectively > 30% as above.

Austenitic steels with At < 30 % and steels other than austenitic (here used for the austenitic - ferritic steels, i.e. duplex stainless steels)

f = min. ( ( ReHt / 1.5) or Rp0.2t / 1.5 ; Rm / 2.4 )

Attention: Allowed maximum wall thickness
Austenitic corrosion resisting steels 60 mm
Austenitic - ferritic steels 30 mm

Attention: The pressures on these pages are given only as guidance. Dimensioning of piping systems also depends on other factors like external forces, thermal stresses, dead weight etc. Furthermore, the design must be made according to regulations from local authorities and approved accordingly.

Proof strength Rp1.0 (MPa) for austenitic grades (EN 10216-5: 2004)
Sandvik EN No 20°C 50°C 100°C 150°C 200°C 250°C 300°C 350°C 400°C At%
3R12 1.4306 215 200 180 160 145 135 127 121 116 35
3R60™ 1.4435 225 217 200 180 165 153 145 139 135 30
3R65 1.4404 225 217 200 180 165 153 145 139 135 30
6R35 cf 1.4541 235 222 208 195 185 175 167 161 156 30
6R35 hf 1.4541 215 201 181 162 147 137 127 121 116 30
8R40 1.4550 240 232 210 195 185 175 167 161 156 30
5R75 cf * 1.4571 245 232 218 206 196 186 175 169 164 30
5R75 hf * 1.4571 225 217 199 181 167 157 145 139 135 30
2RK65™ 1.4539 250 244 235 220 205 190 175 165 155 30
Sanicro® 28 1.4563 245 240 220 205 190 185 180 175 165 35
2RE10 1.4335 210 200 180 170 160 150 140 135 130 (40)
2RE69 1.4466 295 262 225 205 190 180 170 165 - 30
254 SMO 1.4547 340 306 270 245 225 212 200 195 190 30
Sanicro® 30 1.4558 210 198 185 175 170 165 160 155 150 30

(1 MPa= 10 bar)

* SS-EN 10216-5: 2004/ AC: 2008 (E)

Proof strength Rp0.2  (MPa) for austenitic - ferritic grades (EN 10216-5: 2004)
Sandvik En-No 20°C 50°C 100°C 150°C 200°C 250°C At% Rm
SAF 2205™ 1.4462 450 415 360 335 310 295 22 640
SAF 2304® 1.4362 400 370 330 310 290 280 25 600
SAF 2507® 1.4410 550 530 480 445 420 405 20 800
3RE60 1.4424 4801) 430 370 350 330 325 30 700

(1 MPa = 10 bar)

1) Wall thickness e below 4mm. (e > 4mm 450 MPa)