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Installation, operation & maintenance instructions
IP152, Rev AD
April
2012
Bolting Torques
Information in this section is to the best of our knowledge correct. Since conditions of use are beyond our control users must
satisfy themselves that bolt/torques are suitable for the flange/process/conditions of the applications.
Bolting Torque details: High tensile steel bolts
IMPORTANT:-
For use with high tensile steel bolts only
Rosemount Measurement Limited use high tensile bolts/
studs as standard for pressure vessel flange applications
which allows use to full switch rating. The following
recommended torques assume the use of high tensile
bolts. If ordinary carbon steel bolts are fitted see below for
bolt tightening torques.
Min. Torques in Nm (lbf. Ft) Max. torque = Min + 10%
Flange Class 150 Class 130
3” 230 (169) 125 (169)
4” 190 (140) 220 (140)
6” 352 (260)
Flange PN16 PN40
DN65 185 (136) 80 (59)
DN80 125 (92) 95 (70)
DN100 125 (92) 150 (111)
DN125 195 (144) 225 (166)
DN150 255 (188) 280 (206)
MOBREY A 34 (25)
MOBREY G 26 (20)
Bolting torque details: Carbon steel bolts only
Min. torques in Nm (lbf. Ft) Max. Torque – Min + 10%
Flange Class 150 Class 300
3” 54 (40) 95 (70)
4” 54 (40) 95 (70)
6” 95 (70)
Flange PN16 PN40
DN65 58 (43) 58 (43)
DN80 58 (43) 58 (43)
DN100 58 (43) 113 (83)
DN125 58 (43) 194 (143)
DN150 113 (83) 194 (143)
MOBREY A 20 (15)
MOBREY G 20 (15)
IMPORTANT:-
For use with carbon steel bolts only
If ordinary carbon steel or similar lower quality bolts
are used the torques recommended are as shown
on the left.
The gasket sealing force created by the application
of these torques is not sufficient to withstand full
flange pressure rating. To achieve full rating, use
high tensile steel bolts as above.
If in doubt about your bolt/sealing application
consult your engineering department or gasket
manufacturer.
Bolt torques for SPIRAL WOUND gaskets with a
compression stop : high tensile steel bolts only.
Bolt Size Nm Lbf. ft
5/8” 122 90
3/4” 203 150
7/6” 325 240
1” 499 368
1 – 1/8” 722 533
1 – ¼” 101 750
Gasket compression for joints without compression
stops : high tensile steel bolts only.
Initial gasket
thickness
Compressed
thickness
Compression
1.6mm 1.3/1.4mm 0.2/0.3mm
2.5mm 1.9/2.0mm 0.5/0.6mm
3.2mm 2.3/2.5mm 0.7/0.9mm
4.4mm 3.2/2.5mm 1.0/1.2mm
6.4mm 4.6/5.1mm 1.3/1.8mm