Installation
40
236 Series Twin-Screw Pump -
Installation, Operation & Maintenance Manual
Do not connect the piping to the
pump until:
• The grout for the baseplate
or sub-base becomes hard.
• The hold-down bolts for the
pump are tightened.
Connecting the piping without adequate pump support
increases the risk of pipe strain
Piping strain on the pump may cause distortion resulting
in misalignment or vibration
Check
Explanation/comment
Checked
Piping, subject to high
temperatures, must be fitted with
a means of absorbing expansion.
Piping strain on the pump (due to thermal expansion),
may cause distortion resulting in misalignment or
vibration
Make sure that all piping
components, valves and fittings,
and pump branches are clean
prior to assembly.
Twin-Screw rotors incorporate very close running
clearances, it is very important that suction side piping be
thoroughly cleaned before connecting piping to the pump
to prevent the introduction of small hard damaging
particles such as weld spatter or grit
Make sure that the isolation and
check valves are installed in the
discharge line.
Locate the check valve between the isolation valve and
the pump. This will permit inspection of the check valve.
The isolation valve is required for inspection and
maintenance of the pump.
The check valve will prevent
hydraulic shock acting upon the pump and will also
prevent reverse rotation of the pump when stopping the
unit.
Fit suitable pressure relief valve
to the pump discharge
Pressure relief valves must be installed between the
discharge valve and the casing discharge flange of 2-
Screw pumps to protect both the pump and piping
system. The valve and piping system must be solidly
constructed of proper material with ample opening for
passage of full discharge capacity, because positive
displacement pumps can build up pressure rapidly, if the
discharge is restricted or shut off. This type of relief valve
must lead back to the source of supply or other suitable
collecting point to prevent product loss and an excessive
temperature rise of the re-circulated fluid in pump that
operate unattended.
Alignment criteria for pump flanges
To check piping alignment of pumps having bolted flanges, insert flange bolts through pipe and
pump flange. If bolts are easily moved within the bolt holes and if flange faces are parallel with
each other, piping is properly aligned.
Maintain sufficient gap between flange faces for inserting the gasket. Flanges must not butt
tightly before being secured. The criteria below apply to acceptable alignment for the
flanges.
