4
PENBERTHY
SERIES U FLAT GLASS GAGES
INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
6 OPERATION
Before initializing liquid level gage operation,
check that all installation procedures
have been completed. Use only qualified,
experienced personnel who are familiar with
liquid level gage equipment and thoroughly
understand the implications of the tables and
all the instructions. Check to determine that
all connections are pressure tight. Assure
that nuts have been retorqued to their proper
values as specified in Table 2. Remove self stick
caution tape from the glass and inspect to be
sure that glass is clean and free of any damage
such as cracks, scratches, pits and chips.
6.1 Hydrostatic test
DANGER
Liquid level gage installations should be brought
into service slowly to avoid excessive shock or
stress on the glass. Rapid pressurization or
sudden changes in temperature may cause glass
breakage. To avoid excessive thermal shock
or mechanical stress on glass, the connecting
gagecocks should be opened slightly and the gage
temperature and pressure allowed to equalize
slowly. If the gagecocks are equipped with ball
checks, the gagecocks must be opened all the
way after the pressure and temperature have
equalized to permit operation of the automatic
ball checks in the event of failure. Failure to
follow the recommended operating procedures
can result in death, severe personal injury and/or
property damage.
Take all precautions necessary to handle
the possibility of leakage during the test.
Hydrostatically pressure test all installations
to at least 100 psig (690 kPa) but less than the
design pressure and correct any leakage before
proceeding.
5.2 Differential thermal expansion
High mechanical loads may be imposed on a
gage by expanding and contracting pipes due
to hot or cold service. Such mechanical loads
on the gage must be minimized by the use of
expansion loops in the system. Failure to allow
for expansion or contraction can result in leaks
or glass breakage.
5.3 Mirror viewing
For added safety, a system of indirect viewing
by means of mirrors should be installed to
protect personnel from the hazards of possible
gage failure.
5.4 Nut retorquing
Nut retorque is vital to the operation of a liquid
level gage because gaskets take permanent
set under initial bolt loading at assembly.
Tightening of nuts before installation to values
specified in Table 2 is necessary to insure
pressure retaining capabilities of a liquid
level gage to specific design ratings. The user
must refer to the liquid level gage model and
assembly number and to the purchase order or
tag to determine materials of construction.
SAFETY INSTRUCTIONS
Before placing liquid level gage into initial
operation, torque values must be verified. From
factory testing to installation, gasketing may take
'set' reducing closure force. Retorquing before
operation reduces the chance of leakage or
gasket 'blow out'.
Using a torque wrench, tighten cap screws
and nuts in 5 ft·lb (7 Nm) increments following
the 'Z' pattern sequence in Figure 1, until the
torque values shown in Table 2 for the specific
liquid level gage are reached. For multiple
section gages, torque the center section(s) and
progressively work toward the ends of the gage.
If bolting, gasketing or glass on any repaired
section of a multi-section gage is disturbed,
all sections must be checked for integrity and
retorqued as necessary.
WARNING
Failure to comply with the proper torquing
sequence or force value can lead to leakage,
gasket blow-out or glass breakage resulting in
gage failure, serious personal injury or property
damage.
Note:
depending on gage size there may be
less bolting than shown in Figure 1. Start at
the center and follow 'Z' pattern outward to the
limit of bolting on a specific gage.
TABLE 2 - BOLT TORQUE VALUES
Gasket material
ft·lb (Nm)
NBR (Buna-N) w/302 STS retainer (standard)
FKM (Viton
®
) w/302 STS retainer (optional)
PTFE (Teflon
®
) (optional)
60 to 65 (81 to 88)
FIGURE 1
Nut tightening sequence
