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The internal pressures are calculated by using the following formula:

Temperature < 120°C

german1.png

Temperature > 120°C

OD/ID <= 1.67:

german2.png

1.67 < OD/ID <= 2.0:

german3.png

Where:

P Internal pressure (MPa) (*10 => bar)
tmin Minimum wall thickness (mm)
S Allowable stress (S = Rp0.2/1.5*) (MPa)
OD Nominal outside diameter (mm)
ID Inside diameter (ID = OD-2×tmin) (mm)

*Safety factor 1.5 require delivery with certificate according to DIN / EN 10204.

For austenitic steels when Rp0.2/Rm <= 0.5 at 20°C the allowable stress can be calculated using Rp1.0 instead of Rp0.2.

For steels with less ductility than 25% (A) higher safety factors are required.

The allowable stress has been calculated according to following:

S = Rp1.0/1.5 for austenitic steels (3R12, 3R60, 6R35, 8R40, 5R75, 2RK65and Sanicro 28)
S = Rp0.2/1.5 for 3RE60 and SAF 2304
S = Rp0.2/1.56 for SAF 2205
S = Rp0.2/1.6 for SAF 2507

Attention: The pressures on these pages are given only as guidance. Dimensioning of piping systems also depend 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. For tubes in pressure vessels and boilers it is important to consider AD Merkblätter and TRD (Technische Regeln Für Dampfkessel).

Allowed wall thickness and outer diameter:
2RK65™ t <= 20.0 mm OD <= 220 mm
Sanicro® 28  1.0 <= t <= 20.0 mm OD <= 250 mm
3RE60™ 1.0 <= t <= 7.0 mm 10 <= OD <= 76 mm
SAF 2304® 1.0 <= t <= 24.0 mm 5 <= OD <= 260 mm
SAF 2205™ t <= 24.0 mm OD <= 260 mm
SAF 2507® 1.0 <= t <= 10.0 mm OD <= 220 mm*

*Cold finish only!

Proof strength Rp1.0 (MPa)

Sandvik W-Nr 20°C 100°C 150°C 200°C 250°C 300°C 350°C 400°C
3R12*1) 1.4306 215 181 162 147 137 127 121 116
3R60™*2) 1.4435 225 199 181 167 157 145 139 135
6R35 CF*3) 1.4541 CF 235 208 195 185 175 167 161 156
6R35 HF*4) 1.4541 HF 215 181 162 147 137 127 121 116
8R40*5) 1.4550 240 211 196 186 177 167 161 156
5R75 CF*6) 1.4571 CF 245 218 206 196 186 175 169 164
5R75 HF*7) 1.4571 HF 225 199 181 167 157 145 139 135
2RK65*8) 1.4539 250 205 195 185 175 165 160 155
Sanicro® 28*9) 1.4563 250 220 205 190 185 180 175 165

(1 MPa = 10 bar)
*1) DIN 17458, Juli 1985
*2) DIN 17458, Juli 1985
*3) DIN 17458, Juli 1985, cold finish
*4) DIN 17458, Juli 1985, hot finish
*5) DIN 17458, Juli 1985
*6) DIN 17458, Juli 1985, cold finish
*7) DIN 17458, Juli 1985, hot finish
*8) Vd-TÜV-Blatt 421, 06.2005. OD<=200mm, t<=20mm.
*9) Vd-TÜV-Blatt 483, 06.96. OD<=250mm, 1.0<=t<=20.0mm

PROOF STRENGTH Rp0.2 (MPa)
Sandvik W-Nr 20°C 100°C 150°C 200°C 250°C 300°C
3RE60™*10) 1.4417 450 370 (350) 330 (325) 320
SAF 2304®*11) 1.4362 400 330 310 290 280
SAF 2205™*12) 1.4462 450 360 335 310 295
SAF 2507®*13) (1.4410) 550 480 445 420 405

(1 MPa = 10 bar)
*10) Vd-TÜV-Blatt 385, 06.88. 10<=OD<=76mm, 1<=t<=7mm. Tmax 300°C (1<=t<=4mm allows Rp0.2 20°C 480 MPa) Values at 150°C and 250°C are interpolated.
*11) Vd-TÜV-Blatt 496, 09.2001. Tmax 280°C Beiblatt 12.2001 5<=OD<=273mm, 1.0<=t<=24.0mm.
*12) Vd-TÜV-Blatt 418, 06.2004. OD<=260mm,t<=24.0mm. Tmax 280°C
*13) Vd-TÜV-Blatt 508, 09.2001. OD<=220mm, 1<=t<=10mm; cold finish only! Tmax 250°C