Strainer Maintenance & Safe Use Instructions

Preface

BATUSAN emphasizes the importance of personal safety and the long service life of the STRAINER (FILTER) with this instruction for use, Installation and Operation Manual. This Strainer Maintenance manual will provide all necessary safety guidelines for valves, including information on handling, installation and operation of the valve. Please read it carefully before installing or maintaining the valve.

Purpose

Fluids such as liquids, gases and vapors passing through the pipe circuits carry with them even a little dirt. These contaminants are mud in old pipe circuits, rust, limestone and similar formed as a result of abrasion. Again in pipe circuits, welding slags and gasket parts. They cause destruction and damage to valves, pumps, sensitive measurement and adjustment elements connected on this circuit. In order to prevent these damages, it is necessary to use a dirt trap at the entrance of all kinds of armatures in the pipe circuits.

In order to fulfill the working principles of the STRAINER (Filter), it will be possible to ensure that it is assembled in accordance with its conditions and operated in environments suitable for its conditions. Correct assembly is also what keeps Strainer Maintenance to a minimum.

The user is responsible for the problems and consequences arising from behaviors contrary to the specified issues, including those caused by neglected Strainer Maintenance.

Considerations when selecting a strainer (filter)

The Strainer Maintenance instructions list the following selection criteria:

• The medium in which it will be used (the fluid passing through it) should be selected according to whether the fluid is liquid, gas, air or dark excess fluid containing solid particles and whether it is corrosive or not.
• Concentration and temperature of the fluid (max and min): the max temperature and min temperature of the fluid passing through the operating temperature valve must be known.
• Operating pressure (max operating pressure): max pressure of the fluid passing through the valve.
• Type of connection to the circuit: threaded, flanged, socketed, welded or unionized.
• Size or amount of fluid to be flowed per hour.
• Compliance with world standards TSE, API, DIN, EN.
• Valve passage type: full passage, reduction passage.

Considerations when installing the strainer (filter)

Correct installation is the starting point of trouble-free Strainer Maintenance; observe the requirements below.

For valve connection elements on the installation made

• It must be of suitable standard, pressure class and diameter.
• The axes of the pipes to be installed and the hole axes of the fitting to be used must be on the same axis. Example: if flange is used as connection element, bolt hole axes must be on the same axis. (Excessive stresses occurring on the STRAINER (Filter) due to such axis misalignments will jeopardize the tightness.)
• In flanged connections, bolts suitable for flange holes must be used.
• If the connection element is flange, the gaps are removed by tightening the bolts mutually, then they are tightened mutually at the given torque values.
• If needle valve space is left during installation, it should be left by calculating the length of the STRAINER (Filter) to be used and the length of the sealing elements.
• If the connection type will be threaded, the thread length on the pipe should not be less than the STRAINER (Filter) thread length.

For strainer (filter) assembly sealing element in the installation

Sealing elements are the most frequent item in Strainer Maintenance:

• Sealing element suitable for fluid type and pressure should be selected.
• The surfaces of the sealing element to be used in flange connections must be smooth.
• De-assembled, deformed sealing element should not be used, a new one should be installed.
• When installing the sealing element, care should be taken not to close the valve passage throat. (Sealing elements Klingerit, Teflon, 0-ring, rubber or rubber of suitable hardness.)

For valve installation in the installation

The Strainer Maintenance instructions require the line to be clean before the unit goes in:

• • Before STRAINER (Filter) installation, the line must be cleaned with compressed air or steam to remove any burrs, rust, foreign objects and dirt that may be present in the pipeline.

• • For the new STRAINER (Filter) to be installed, the labels / covers on both flanges must be removed.

For later Strainer Maintenance, the flange side of the STRAINER (Filter) to be installed in the installation, where the technical information is written, is mounted as the inlet. Then the other side is mounted to the installation without giving the opportunity to create tensile stress.

Points to be considered when using strainer (filter)

The following operating points are taken from the Strainer Maintenance instructions:

• • Remove the STRAINER (Filter) from its packaging when you will connect it to the installation.

• • Operating conditions are specified on the sight glass as maximum working pressure in BAR.
  • Periodic Strainer Maintenance: the filter should be cleaned periodically by removing the blind plug on the STRAINER (Filter) cover.

• • When connecting the Flow Indicator to the installation, make sure that the direction arrow is in the direction of flow.

Screen selection and open area

The screen is the working part of the unit, and choosing it correctly removes most of the later workload. Two figures describe it: the perforation or mesh size, which sets the smallest particle retained, and the open area, which is the total free area of all holes.

A finer screen catches more, but it also blocks faster and raises the pressure loss across the body. The usual approach is to select the coarsest screen that still protects the equipment downstream. A pump needs less protection than a control valve seat or a flow meter.

Open area is compared with the pipe bore rather than judged on its own. A screen whose open area is several times the pipe cross section keeps the pressure loss low even when partly loaded, so the line does not lose performance between two cleaning intervals. Screens with too little open area make Strainer Maintenance a weekly task instead of a scheduled one.

Installation orientation and blowdown connection

The pocket that holds the screen must be positioned according to the fluid. In horizontal liquid lines the pocket points downward, so that separated dirt collects at the bottom and leaves the flow path. In steam and gas lines the pocket is turned to the side, because a downward pocket fills with condensate and the screen then works under water.

In vertical lines the flow must run downward through the unit. An upward flow lifts the collected dirt back into the line every time the flow stops and starts.

Fitting a small valve to the drain plug is strongly recommended. With a blowdown valve in place, routine Strainer Maintenance can be carried out by opening the valve briefly under line pressure, and the cover only has to be removed for a full clean. On lines that cannot be shut down, this single fitting is the difference between a two-minute task and a shutdown.

When to clean: differential pressure

Strainer Maintenance intervals should not be guessed. The reliable indicator is the pressure difference between the inlet and the outlet, read from two gauges or from a single differential gauge fitted across the body.

Record the pressure difference when the unit is new and clean; this is the reference value. As the screen loads, the difference rises. A widely used rule is to clean when the difference reaches roughly twice the clean value, and never to let the line run at the maximum figure given by the manufacturer, because a heavily loaded screen can collapse.

The first weeks after commissioning are the heaviest. New pipework releases scale, welding slag and gasket fragments, so Strainer Maintenance is frequent at first and then settles into a longer interval once the line is clean.

Strainer Maintenance cleaning procedure

The full Strainer Maintenance clean follows a fixed order.

• Isolate the unit using the upstream and downstream valves, and confirm that both are closed.
• Depressurize the section and let the fluid cool to a temperature that can be handled safely.
• Drain the body through the blowdown valve or the drain plug, collecting the fluid where required.
• Remove the cover bolts evenly, in the reverse of the tightening sequence, and lift the cover clear.
• Withdraw the screen, wash it in a suitable solvent or with clean water, and blow it through from the inside outwards so that the dirt leaves the way it entered.
• Clean the body seat and the cover face, and check that no debris remains in the pocket.
• Fit a new gasket, refit the screen with its seating face in the correct position, and tighten the cover bolts evenly to the specified torque.
• Restore pressure slowly and check the cover joint for leaks before returning the line to service.

Reusing the cover gasket is the most common shortcut and the most common source of leaks afterwards. Treat the gasket as a consumable item of every Strainer Maintenance operation.

Screen inspection and replacement

During Strainer Maintenance the screen is inspected while it is out, not only cleaned. Look for tears, flattened areas, split seams and any deformation of the mesh, all of which let unfiltered fluid pass without any visible change in the line.

A screen that has collapsed inward has been run far past its allowed pressure difference. Cleaning it does not restore it, and a repaired or patched screen does not return to its original open area. Replace it and shorten the cleaning interval until the cause is understood.

Corrosion is checked at the same time. A screen material that is not compatible with the fluid thins gradually and fails without warning, so the material of the replacement should be confirmed against the service rather than assumed from the part in hand.

Safety precautions before opening

Every Strainer Maintenance operation begins with isolation. Confirm that the line is depressurized at the unit itself and not only at a remote gauge, and that no valve can be reopened while work is in progress.

Hot fluid is the main hazard. Let the body cool before loosening the cover, because a trapped pocket of hot liquid can flash to vapour as soon as the joint is broken. Loosen the last bolts carefully and allow any remaining pressure to release in a controlled way.

Use protective equipment appropriate to the fluid, and treat the collected dirt as contaminated with whatever the line carries. Where the medium is hazardous, the drained content is handled under the plant procedure for that fluid.

Maintenance records and intervals

A short record makes the interval self-correcting. Note the date, the pressure difference before cleaning, the condition of the screen and the gasket that was fitted.

After a few entries the pattern becomes visible: an interval that is always too short points to a screen that is too fine or to a problem upstream, while a screen that is still clean at every visit allows the interval to be extended. Planned Strainer Maintenance based on recorded values costs less than an unplanned stop caused by a blocked or collapsed screen.

Keep the record with the line documentation rather than with the unit itself. When a strainer is replaced or moved, the history of the position is more useful than the history of the part, because the dirt load belongs to the line. A Strainer Maintenance file held per position also shows whether an upstream repair has changed the loading, and the interval can then be set from evidence instead of habit.

Tools and materials to be used

Strainer Maintenance requires only a simple tool set: a double-ended wrench, suitable for connecting bolts and nuts.

Conclusion

If you want your existing installation to work properly, placing a strainer (filter) in the main circuits will reduce operating costs.

The sight glass connected to the installation should be operated within the size and working pressure specified on the needle valve to prevent possible leaks and operating costs.

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