6
9. Service and Repair
For safety assurance, each valve should be surveyed and maintenance
carried out regularly especially for those which are used rarely. The
frequency of these activities should be determined by the user on the basis
of working (operating) conditions, nevertheless they should be done at least
once a month. The stem thread must also be lubricated periodically.
All service and repair jobs should be carried out by authorized staff using suitable tools
and original spare parts. Before removing the valve from the pipeline, or before service,
the pipeline should be out of operation. During service and repair jobs it is necessary to
decrease pressure to 0 bars, valve temperature to ambient temperature and to use
appropriate personal protective gear at all times. After valve removal it is necessary to
replace the flange connection gaskets between the valve and pipeline.
Precautions should be taken when touching the gasket between the body and
the valve bonnet. The gasket contains a metal core which may cause injury,
Every time the valve bonnet is disassembled the sealing surfaces should be cleaned.
During assembly a new gasket of the same type as previously used should be applied.
Body-bonnet bolt connections should be tightened when the valve is in the open
position. The bolts should be tightened evenly and crosswise using a torque wrench.
1
3
4
2
・
Tightening torques
Screw M8
M10
M12
M16
Torque (N
⋅
m)
15 – 20
35 – 40
65 – 70
140 – 150
・
Before re-installing the valves in the pipeline it is necessary to check valve
operation, and tightness of all connections. A tightness test should be carried out
with a water pressure of 1.5 times the nominal pressure of the valve.
10. Troubleshooting
When troubleshooting the valve, all safety rules should be strictly obeyed
Fault
Possible reason
Remedy
Valve closed
Open the valve
No flow
Flange dust caps were not removed Remove dust caps on the flanges
Valve is not open enough
Open the valve
Dirty filter
Clean or replace the screen
Poor flow
Clogged pipeline
Check the pipeline
Dry stem
Grease the stem
Difficulty operating
the handwheel
Gland overtightened
Slightly slacken gland nut. Pay
attention to maintaining gland
tightness
Stem leakage
Bellows damage
Tighten the gland until leakage
stops and replace the upper part of
the valve as soon as possible.
Seat leakage
Incorrect shut off
Tighten the handwheel without
using any auxiliary tools
The table continues on next page
TEG-BE8H-M-00 20 August 2013
