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7.3
Maintenance instructions gland nut
According to DIN EN 1626, the leak rate must be less than 14 mm³/s (for flammable liquids less than 10
mm³/s). To achieve and maintain a lower leak rate of 0.1mm³/s, it is recommended to retighten the gland
nuts of HEROSE fittings after 50 cycles with a torque wrench and with the corresponding torque according
to table.
Torques
Nominal
size valve
DN 10
DN 15
DN 20
DN 25
DN 32
DN 40
DN 50
VA ≙ Stainless steel
7.4
Fault table
Fault
Leak at the stem
Leak between bonnet
and body
Leak in the seating
Body leaking
Globe valve does not
open / close
Operating instructions
Torque [Nm]
VA
50
Cause
Gland nut loose
Packing gland defective
Fit on the stem damaged
Bonnet loose
Seal damaged
Foreign bodies between
obturator and seating
Seating damaged
Sealing surface of obturator
damaged
Discontinuity/gas cavity open
Gland nut overtightened
Thread seized
herose.com
Remedy
Retighten the gland nut
Replace the packing gland
Replace the stem
Tighten the screws to the
specified tightening torque
Replace seal
Remove foreign body / flush
the system
Replace the body
Replace the obturator
Replace the body
Loosen the gland nut
Tightness must still be
ensured
Replace bonnet
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