The Marflex Deepwell Pump

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					The
Marflex
Deepwell
Pump


      • • • • •
                                       Headoffice:
                                      Marflex b.v.
                   Oud-Beijerland, The Netherlands




Introduction                          • • • • •
     Marflex Holding b.v., which is based near Rotterdam, The Netherlands,
     is the parent company of the Marflex group of companies world-wide.
     Founded in 1980, the company has specialised itself in many fields
     related to the maritime branch.
     Beginning 80’s, Marflex specialised itself in producing hydraulic driven
     portable submersible pumps and generator sets for sales and rental.
     Apart from the production of above mentioned equipment Marflex also
     established a repair service center in the field of repairing a wide range of
     cargo pumps and hydraulic systems. Due to these activities Marflex built up
     during the 80’s a high level of know how concerning cargo pumps/hydraulic
     systems and its problems onboard of tanker ships world-wide.
     This expertise was the basis for starting to create a complete new and
     unique Deepwell pump design during 1986/1987.
     In 1988 Marflex sold the first complete Deepwell pumping system to a
     major Dutch tanker operator.
     With subsidiaries in Singapore and Houston and a world-wide network of
     sales representatives, Marflex is today in the position to offer her
     customers a professional and reliable service world-wide.




 2
From the start Marflex has always pro-     The new pump design is based upon
moted and applied the hydraulic-drive      the modern technologies available
principle for her cargo pumps thanks       nowadays and the presence of existing
to the advantage of variable-speed         knowledge and experience of todays
control and the non-overload charac-       used cargo pumping systems.
teristics of a hydraulic motor.            As a result of the great demand for
                                           double-hull stainless steel chemical
However, the availability of sophistica-   tankers on the Dutch market Marflex
ted and class-approved ‘explosion          introduced the new designed Marflex
proof’ electric motors and ‘static         Deepwell pump in 1987.
frequency converters’ and also the fact    In close cooperation with the local
that shipowners in Europe became           tanker operators, Marflex introduced a
more and more reluctant to install         Deepwell pump with a unique oil-
hydraulic systems onboard their new-       lubricated drive shaft.
buildings, changed this philosophy.        Marflex sells her cargo pumping
For the above-mentioned reasons            systems all over the world ever since.
Marflex started the development of a
total new pump design in 1986.




                                                                                    3
        The
     Marflex
    Deepwell
       Pump                              • • • • •
       Already for many years various well-known pump manufacturers have
       produced Deepwell pumps for chemical and product tankers with a so-
       called cargo lubricated drive shaft.
       The operational disadvantages of such a design are well-known in the
       shipping industry.

       As the new Marflex Deepwell pump               The service life of an ‘oil lubricated shaft
       needed to be driven by an electric motor       arrangement’ is more than 10.000
       we first had to develop a ‘non cargo           running hours and is based upon the
       lubricated drive shaft’.                       service life of the bearings in the electric
       The development has resulted in a unique       motor.
       ‘oil lubricated shaft’ running in a separate   The 10.000 running hours are normally
       supporting pipe.                               sufficient to last the service life
                                                      (20-25 years) of a sea-going vessel.

                                                      To explain the Marflex Deepwell pump in
                                                      details we like to divide the total pump
                                                      in three sections:
                                                      • Deck arrangement
                                                      • Pipe stack
                                                      • Pumphead



4
Deck arrangement




Pipe stack




Pumphead




             5
       Deck
arrangement                           • • • • •
     The Marflex Deepwell pump can be driven by an explosion-proof and
     class-approved electric motor or a hydraulic motor.
     However, since the introduction of this new design in 1987, 95% of all,
     by Marflex installed, Deepwell pumps are electrically driven for the
     following reasons:

     Advantages of electrically-driven Deepwell    The speed of the electrically driven
     pumps compared to hydraulically-driven        Marflex Deepwell pumps can be control-
     Deepwell or submerged pumps:                  led in several ways:
     • Total system efficiency approximately
       20% higher;                                 One-speed electric motor
     • Low noise level;                            • Suitable for tankers which carry
     • Easy to install thanks to the electrical      products with a small specific gravity
       wiring instead of a complicated hydrau-       range, like the so-called product
       lic piping system (commissioning will         tankers.
       be reduced to a real minimum);
     • Simple and robust AC motor;                 Two-speed electric motors
     • Clean system (no hydraulic oil leakages);   • This is not really practical due to the
     • Reduced maintenance.                          fact that the Marflex Deepwell pump
                                                     is single-stage pump;
                                                   • Can be considered only for tank clea-
                                                     ning or cargo circulation purposes.

 6
Variable speed control by means            2. Control
of a ‘static frequency converter’          • Independent control of each
We like to mention the following              Deepwell pump;
advantages of a ‘static frequency          • Accurate, variable control;
converter’ system:                         • Low mechanical wear;
                                           • Low cavitation;
1. Power                                   • Programmable for specific pumping
• High efficiency;                            requirements:
• Energy consumption according to             - minimized discharging time;
   actual need;                               - minimum cavitation;
• E-motors and consequently genera-           - liquid level;
   tors do not need to be over-dimen-         - specific gravity;
   sioned for products with a high         • Connection to cargo-monitoring or
   viscosity and/or specific gravity;         machinery automation system.
• Soft start (no inrush peaks):
   less frequent start-up of generators.




                                                                                 7
    Pipe stack                           • • • • •
        The design of the Marflex Deepwell Pump is based upon a drive shaft
        which is separated from the cargo. The pump stack consists of two pipes;
        one is the discharge pipe and the other is the enclosure for the inter-
        mediate drive shaft, the shaft bearings and lubricating oil.

        As the shaft is not exposed to the cargo    • Because the intermediate pump shaft
        the following advantages are obvious:         and bearings are oil-lubricated,
        • The material of the intermediate drive      the pump can run on relative high
          shaft is 42CrMo4V which is a heat           speeds. This results in a single stage
          treatable steel. If the shaft should be     Deepwell Pump.
          exposed to the cargo, AISI 316L steel
          is required which is not the ideal        The shaft bearings of the Marflex Deep-
          material for a Deepwell Pump.             well pump are made of Railko® material,
        • As the shaft is oil lubricated the pump   held within a Viton® or Kalrez® flexible
          never runs ‘dry’ during stripping and     member.
          tank cleaning operations.
          - No explosion danger resulting from
             overheating of intermediate shaft
             bearings.
          - Extended life time of the shaft
             bearings (approx. 10.000 running
             hours).

8
Advantages of the Marflex inter-
mediate shaft design:
• No shaft-alignment problems;
• Fixed coupling between the shaft of
  the drive motor on deck and the
  intermediate drive shaft;
• Thanks to the oil-lubricated inter-
  mediate shaft bearings the service-
  life of the intermediate shaft
  bearings will be quite extensive.

The length of the pipestack has no res-
trictions. However, after every 6 meters
of pipestack an intermediate shaft
support will be installed (see drawing
page 8). This support consists of a ball
bearing which takes the axial load of
each shaft length of 6 meters only.
Axial thrust/load from the impeller will
be taken only by the pump shaft
bearings and not transmitted to the
intermediate shaft (bearings) due to the
spline connection between the pump
shaft and intermediate pump shaft.         9
 Pumphead                             • • • • •
     The Marflex Deepwell pump is designed in such a way that the total pump
     head can be disconnected from the pipestack, which makes maintenance
     very easy.

     A so-called ‘spline’ connection between     2. Seal arrangement
     the intermediate drive shaft and the        The Marflex Deepwell pump is standard
     pump shaft in the pumphead makes it         delivered with a special-seal arrangement
     possible to disconnect the pumphead         to segregate the cargo from the lubrica-
     from the pipe stack by lowering the         ting oil and vice-versa.
     pumphead by approximately 30 mm.            This seal design exists already for more
     The maximum space between the               than 20 years and has proven to be a
     suction side of the pumphead and the        simple and reliable seal for all chemicals
     bottom of the pump well is 40 mm.           and mineral-oil products.

     1. The pump shaft                           The seal arrangement is built up as follows:
     This shaft is made of 32CrNiMo6V steel      a. Primary oil seal: this is a Viton® lipseal
     which can be considered as a very high-        running on a hard-chromium SS sleeve.
     grade material and excellent to serve as    b. Secondary cargo seal: this is a Teflon®
     a pump shaft.                                  lipseal running on a silicon carbide sleeve.
     Like the intermediate drive shaft, the      c. Secondary oil seal: this is a Teflon® lip-
     material of the pump shaft is not made of      seal running on a silicon carbide sleeve.
     AISI 316L because the pump shaft is not     d. Primary cargo seal: this is a Teflon® lip-
     exposed to the cargo but oil-lubricated.       seal running on a silicon carbide sleeve.
10
                                                                                     Pump materials

                                                                                     The Marflex Deepwell
                                                                                     pump is completely built
                                                                                     from hot-rolled and forged
                                                                                     materials except the pump
                                                                                     impeller.
                                                                                     The standard material
                                                                                     specification is DIN 1.4435
                                                                                     which is a 316L quality
                                                                                     with a minimum molybde-
                                                                                     num content of 2,5%.
                                                                                     All seals and O-rings in
                                                                                     contact with the cargo are
                                                                                     Teflon® or Kalrez®. Thanks
                                                                                     to the applie materials the
                                                                                     Marflex Deepwell pump is
                                                                                     fully chemical-resistant
                                                                                     and suitable to handle
                                                                                     cargoes with a temperature
                                                                                     up to 180 °C.
Between the two secondary seals is an      The advantages of such a seal             On request, the Marflex
atmospheric drainage chamber.              arrangement are:                          Deepwell pump can be
This chamber is called the ‘cofferdam’,    • Double protection with an atmos-        also produced of higher-
which is acting as a safety barrier           pheric drainage chamber between        grade materials such as
between the oil seals and the cargo           the cargo and lubrication-oil side.    ‘duplex’ to fulfil the
seals.                                     • Proven to be reliable and simple.       customer’s requirements.
Any leakage that might occur will be       • Easy replacement by ship’s crew
collected in the cofferdam. The coffer-       (low cost).
dam is connected to the main deck by       • Seal condition can be monitored
means of two purge lines.                     from main deck side.
By purging the cofferdam with air or
nitrogen the contents of the cofferdam     Note:
can be blown out and collected on          Especially for abrasive, solidifying or
deck.                                      polymerising cargoes or cargoes with
By following a regular purging routine     a temperature above 100 °C, Marflex
the condition of the seals is constantly   has developed in close cooperation
monitored.                                 with Nippon Pillar Japan a special
                                           ‘knife’ seal.




                                                                                                      11
                                           INERT GAS / AIR                     OUTLET
                                         UNDER PRESSURE                        STRIPPING CARGO PIPE


                                              FLEXIBLE HOSE




Stripping procedure

                                                      MAIN CARGO PIPE       STRIPPING CARGO PIPE




     When the cargo tank is empty the cargo stripping valve has to be
     opened and the main cargo valve to be closed.
     The remaining cargo left in the main cargo pipe is purged by
     means of inert gas or air via the stripping pipe into the cargo line
     on deck. During the purging/stripping procedure the pump should
     be kept running (the impeller acts as a dynamic footvalve) until the
     cargo pipe has been purged empty.
     This procedure will guarantee an absolute minimum of remaining
     cargo in the pump well. Present and future IMO rules are achieved.




12
         NON-RETURN VALVE                                                                   STRIPPING CARGO PIPE



                                                                                            CARGO STRIPPING VALVE
                            OPEN                                                            OPEN
FLEXIBLE HOSE
                         SNAP-ON-COUPLING

                              MAIN CARGO VALVE
                                        CLOSED




                             MAIN CARGO PIPE
                                                                             OPTIONAL:
                                                                             DIRECTLY TO MANIFOLD




                SNAP-ON-COUPLING
                                                    OPEN




                               INERT GAS / AIR
                               UNDER PRESSURE




                                   Type of Pump               Remaining quantity
                                                            of cargo after stripping
                                     MDP- 100                            12 ltr.
                                     MDP- 125                            20 ltr.
                                     MDP- 150                            30 ltr.
                                     MDP- 200                            30 ltr.
                                     MDP- 250                            50 ltr.
                                     MDP- 300                            50 ltr.
                               These stripping results are based upon a proper pump well design
                               and minimum clearance between pump and pump well bottom.




                                                                                                                    13
            Pump performance curves
H(m)




200




100
                                  00




                                              25



                                                         50




                                                                           00



                                                                                 50




                                                                                         00
                                 P-1




                                             P-1



                                                     P-1




                                                                          P-2



                                                                                P-2




                                                                                        P-3
                             MD




                                        MD



                                                    MD




                                                                          MD



                                                                                MD




                                                                                        MD
50



40




30
       20   30   40   50   100         200         300        400   500          1000         2000

                                                                                                  3
                                                                                               Q(m/h)




 14
                             = subsidiaries
                             = representatives




Marflex b.v.               SUBSIDIARIES:                    Marflex Asia Pte. Ltd.

Postal / visit address:    Marflex repair                   Postal / visit address:
Louis Pasteurstraat 12                                      No. 50 Raffles Place
3261 LZ Oud-Beijerland     Postal / visit address:          Level 37, Singapore Land Tower
The Netherlands            Langeweg 1                       Singapore 048623
                           3214 LJ Zuidland
Tel.: +31 186 89 02 00     The Netherlands                  Tel.: +65 861 55 53
Fax: +31 186 89 02 99                                       Fax: +65 861 41 98
E-mail: info@marflex.com   Tel.: +31 181 45 88 00           E-mail: marflex@pacific.net.sg
Website: www.marflex.com   Fax: +31 181 45 88 09            Website: www.marflex.com
                           E-mail: inforepair@marflex.com
                           Website: www.marflex.com
                                                            Marflex Moscow

                           Marflex Tanker Services b.v.     Postal / visit address:
                                                            Building 1, Nikoloyamskaya 49
                           Postal / visit address:          Flat no. 414
                           Langeweg 1                       109004 Moscow
                           3214 LJ Zuidland                 Russia
                           The Netherlands
                                                            Tel. / fax: +007 095 912 35 01
                           Tel.: +31 181 45 88 10           Website: www.marflex.com
                           Fax: +31 181 45 88 19
                           E-mail: infomts@marflex.com
                           Website: www.marflex.com




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