the marflex deepwell pump

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The Marflex Deepwell Pump •••••

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Page 1: The Marflex Deepwell Pump

The Marflex Deepwell Pump

• • • • •

Page 2: The Marflex Deepwell Pump

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• • • • •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 fieldsrelated to the maritime branch.Beginning 80’s, Marflex specialised itself in producing hydraulic drivenportable submersible pumps and generator sets for sales and rental.Apart from the production of above mentioned equipment Marflex alsoestablished a repair service center in the field of repairing a wide range ofcargo pumps and hydraulic systems. Due to these activities Marflex built upduring the 80’s a high level of know how concerning cargo pumps/hydraulicsystems and its problems onboard of tanker ships world-wide.This expertise was the basis for starting to create a complete new andunique Deepwell pump design during 1986/1987.In 1988 Marflex sold the first complete Deepwell pumping system to amajor Dutch tanker operator.With subsidiaries in Singapore and Houston and a world-wide network ofsales representatives, Marflex is today in the position to offer hercustomers a professional and reliable service world-wide.

Headoffice:Marflex b.v.

Oud-Beijerland, The Netherlands

Page 3: The Marflex Deepwell Pump

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The new pump design is based uponthe modern technologies availablenowadays and the presence of existingknowledge and experience of todaysused cargo pumping systems.As a result of the great demand fordouble-hull stainless steel chemicaltankers on the Dutch market Marflexintroduced the new designed MarflexDeepwell pump in 1987.In close cooperation with the localtanker operators, Marflex introduced aDeepwell pump with a unique oil-lubricated drive shaft.Marflex sells her cargo pumpingsystems all over the world ever since.

From the start Marflex has always pro-moted and applied the hydraulic-driveprinciple for her cargo pumps thanksto the advantage of variable-speedcontrol and the non-overload charac-teristics of a hydraulic motor.

However, the availability of sophistica-ted and class-approved ‘explosionproof’ electric motors and ‘staticfrequency converters’ and also the factthat shipowners in Europe becamemore and more reluctant to installhydraulic systems onboard their new-buildings, changed this philosophy.For the above-mentioned reasonsMarflex started the development of atotal new pump design in 1986.

Page 4: The Marflex Deepwell Pump

44

Already for many years various well-known pump manufacturers haveproduced 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 theshipping industry.

As the new Marflex Deepwell pump needed to be driven by an electric motorwe first had to develop a ‘non cargolubricated drive shaft’.The development has resulted in a unique‘oil lubricated shaft’ running in a separatesupporting pipe.

The service life of an ‘oil lubricated shaftarrangement’ is more than 10.000running hours and is based upon theservice life of the bearings in the electricmotor.The 10.000 running hours are normallysufficient to last the service life (20-25 years) of a sea-going vessel.

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

• • • • •

The Marflex

Deepwell Pump

Page 5: The Marflex Deepwell Pump

Deck arrangement

Pipe stack

Pumphead

5

Page 6: The Marflex Deepwell Pump

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• • • • •

Deck arrangement

The Marflex Deepwell pump can be driven by an explosion-proof andclass-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 thefollowing reasons:

Advantages of electrically-driven Deepwellpumps compared to hydraulically-drivenDeepwell or submerged pumps:• Total system efficiency approximately

20% higher; • Low noise level;• Easy to install thanks to the electrical

wiring instead of a complicated hydrau-lic piping system (commissioning will be reduced to a real minimum);

• Simple and robust AC motor; • Clean system (no hydraulic oil leakages);• Reduced maintenance.

The speed of the electrically drivenMarflex Deepwell pumps can be control-led in several ways:

One-speed electric motor• Suitable for tankers which carry

products with a small specific gravityrange, like the so-called producttankers.

Two-speed electric motors• This is not really practical due to the

fact that the Marflex Deepwell pump is single-stage pump;

• Can be considered only for tank clea-ning or cargo circulation purposes.

Page 7: The Marflex Deepwell Pump

Variable speed control by meansof a ‘static frequency converter’We like to mention the followingadvantages of a ‘static frequencyconverter’ system:

1. Power• High efficiency;• Energy consumption according to

actual need;• E-motors and consequently genera-

tors do not need to be over-dimen-sioned for products with a highviscosity and/or specific gravity;

• Soft start (no inrush peaks): less frequent start-up of generators.

2. Control• Independent control of each

Deepwell pump;• Accurate, variable control;• Low mechanical wear;• Low cavitation;• Programmable for specific pumping

requirements:- minimized discharging time;- minimum cavitation;- liquid level;- specific gravity;

• Connection to cargo-monitoring ormachinery automation system.

7

Page 8: The Marflex Deepwell Pump

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Pipe stack

The design of the Marflex Deepwell Pump is based upon a drive shaftwhich 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 cargothe following advantages are obvious:• The material of the intermediate drive

shaft is 42CrMo4V which is a heattreatable steel. If the shaft should beexposed to the cargo, AISI 316L steelis required which is not the idealmaterial for a Deepwell Pump.

• As the shaft is oil lubricated the pumpnever runs ‘dry’ during stripping andtank cleaning operations.- No explosion danger resulting from

overheating of intermediate shaft bearings.

- Extended life time of the shaft bearings (approx. 10.000 running hours).

• Because the intermediate pump shaftand bearings are oil-lubricated, the pump can run on relative highspeeds. This results in a single stageDeepwell Pump.

The shaft bearings of the Marflex Deep-well pump are made of Railko® material,held within a Viton® or Kalrez® flexiblemember.

• • • • •

Page 9: The Marflex Deepwell Pump

Advantages of the Marflex inter-mediate shaft design:• No shaft-alignment problems;• Fixed coupling between the shaft of

the drive motor on deck and theintermediate drive shaft;

• Thanks to the oil-lubricated inter-mediate shaft bearings the service-life of the intermediate shaftbearings will be quite extensive.

The length of the pipestack has no res-trictions. However, after every 6 metersof pipestack an intermediate shaftsupport will be installed (see drawing page 8). This support consists of a ballbearing which takes the axial load ofeach shaft length of 6 meters only.Axial thrust/load from the impeller willbe taken only by the pump shaftbearings and not transmitted to theintermediate shaft (bearings) due to thespline connection between the pumpshaft and intermediate pump shaft. 9

Page 10: The Marflex Deepwell Pump

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Pumphead

A so-called ‘spline’ connection betweenthe intermediate drive shaft and thepump shaft in the pumphead makes itpossible to disconnect the pumpheadfrom the pipe stack by lowering thepumphead by approximately 30 mm.The maximum space between thesuction side of the pumphead and thebottom of the pump well is 40 mm.

1. The pump shaftThis shaft is made of 32CrNiMo6V steelwhich can be considered as a very high-grade material and excellent to serve asa pump shaft.Like the intermediate drive shaft, thematerial of the pump shaft is not made ofAISI 316L because the pump shaft is notexposed to the cargo but oil-lubricated.

The Marflex Deepwell pump is designed in such a way that the total pumphead can be disconnected from the pipestack, which makes maintenancevery easy.

2. Seal arrangementThe Marflex Deepwell pump is standarddelivered with a special-seal arrangementto segregate the cargo from the lubrica-ting oil and vice-versa.This seal design exists already for morethan 20 years and has proven to be asimple and reliable seal for all chemicalsand mineral-oil products.

The seal arrangement is built up as follows:a. Primary oil seal: this is a Viton® lipseal

running on a hard-chromium SS sleeve.b. Secondary cargo seal: this is a Teflon®

lipseal running on a silicon carbide sleeve.c. Secondary oil seal: this is a Teflon® lip-

seal running on a silicon carbide sleeve.d. Primary cargo seal: this is a Teflon® lip-

seal running on a silicon carbide sleeve.

• • • • •

Page 11: The Marflex Deepwell Pump

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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.

On request, the Marflex

Deepwell pump can be

also produced of higher-

grade materials such as

‘duplex’ to fulfil the

customer’s requirements.

Between the two secondary seals is anatmospheric drainage chamber. This chamber is called the ‘cofferdam’,which is acting as a safety barrierbetween the oil seals and the cargoseals.Any leakage that might occur will becollected in the cofferdam. The coffer-dam is connected to the main deck bymeans of two purge lines.By purging the cofferdam with air ornitrogen the contents of the cofferdamcan be blown out and collected ondeck.By following a regular purging routinethe condition of the seals is constantlymonitored.

The advantages of such a sealarrangement are:• Double protection with an atmos-

pheric drainage chamber betweenthe cargo and lubrication-oil side.

• Proven to be reliable and simple.• Easy replacement by ship’s crew

(low cost).• Seal condition can be monitored

from main deck side.

Note:Especially for abrasive, solidifying orpolymerising cargoes or cargoes witha temperature above 100 °C, Marflexhas developed in close cooperationwith Nippon Pillar Japan a special‘knife’ seal.

Page 12: The Marflex Deepwell Pump

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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.

INERT GAS / AIR

UNDER PRESSURE

OUTLET

STRIPPING CARGO PIPE

MAIN CARGO PIPE STRIPPING CARGO PIPE

FLEXIBLE HOSE

Stripping procedure

Page 13: The Marflex Deepwell Pump

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INERT GAS / AIR

UNDER PRESSURE

MAIN CARGO PIPE

STRIPPING CARGO PIPE

SNAP-ON-COUPLING

SNAP-ON-COUPLING

NON-RETURN VALVE

CARGO STRIPPING VALVE

OPEN

OPTIONAL:

DIRECTLY TO MANIFOLD

FLEXIBLE HOSE OPEN

MAIN CARGO VALVE

CLOSED

OPEN

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 designand minimum clearance between pump and pump well bottom.

Page 14: The Marflex Deepwell Pump

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3

2000

Q(m/h)

1000

MD

P-2

50

MD

P-3

00

500 200 300 400

MD

P-1

50

MD

P-1

25

MD

P-2

00

100 50 30 40

MD

P-1

00

20

30

40

50

100

200

H(m

)

Pump performance curves

Page 15: The Marflex Deepwell Pump

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Marflex b.v.

Postal / visit address:Louis Pasteurstraat 123261 LZ Oud-BeijerlandThe Netherlands

Tel.: +31 186 89 02 00Fax: +31 186 89 02 99E-mail: [email protected]: www.marflex.com

SUBSIDIARIES:

Marflex repair

Postal / visit address:Langeweg 13214 LJ ZuidlandThe Netherlands

Tel.: +31 181 45 88 00Fax: +31 181 45 88 09E-mail: [email protected]: www.marflex.com

Marflex Tanker Services b.v.

Postal / visit address:Langeweg 13214 LJ ZuidlandThe Netherlands

Tel.: +31 181 45 88 10Fax: +31 181 45 88 19E-mail: [email protected]: www.marflex.com

Marflex Asia Pte. Ltd.

Postal / visit address:No. 50 Raffles PlaceLevel 37, Singapore Land TowerSingapore 048623

Tel.: +65 861 55 53Fax: +65 861 41 98E-mail: [email protected]: www.marflex.com

Marflex Moscow

Postal / visit address:Building 1, Nikoloyamskaya 49Flat no. 414109004 MoscowRussia

Tel. / fax: +007 095 912 35 01Website: www.marflex.com

= subsidiaries

= representatives

Page 16: The Marflex Deepwell Pump