Saturday, December 11, 2010

DEEPWELL PUMPS ON CHEMICAL TANKERS-- CAPT AJIT VADAKAYIL




        FRAMO PUMP AND PUMPING OPERATIONS


Deepwell pumps have done away with the suction pipeline where 90% of pumping problems lie. 

It has almost eliminated cavitation for free flowing liquids. Fluids are broadly classified as Newtonian and non Newtonian depending on their obedience to the laws of classical mechanics. Newtonian fluid/ rate of flow is proportional to the force applied.. Some will not flow till the force exerted is greater than the yield point.

Deepwell pumps on our chemical tankers are mainly Norwegian Framo and Japanese Deepwell types on a few .

JD ( lets call Japanese deepwell pumps JD —for convenience ) pumps have huge disadvantages over Framo pumps .

1) The JD SS impeller is locked by a SS washer and nut which can work loose. In Framo a nylon bolt and washer ( disposable ) is used which provides  better friction coefficient.  A loose impeller can cause explosion.

2) The JD cargo seal is mechanical while for Framo it is a double lip seal teflon ring. Mechanical seal cannot run dry as it will over heat and get damaged. This overheat is not conducive to safety .

3) JD pumps do not have a jockey pump which in a Framo system runs round the clock 365 days a year to prevent cargo ingress into hydraulic system. Here the cofferdam is pressurised by air/ nitrogen from a fixed pipeline connection to prevent cargo ingress into cofferdam. This serves to cool the mechanical seal too.  While on a Framo air blow to purge the cofferdam is from an air  flexible. Fixed air connections can cause high density free flowing cargoes like Sulphuric acid to ingress the compressed air lines. Jockey pump provides continious air venting, filtration of hyd oil and prevents moisture ingress. If the JD system does not have a feed/ jockey pump, it is important to purge air from the highest point--- it could be on top of the crane.

4) Framo uses rotating impeller as a non return valve while stripping stack, while on Japanese models there could be a non return flap just on top of the impeller which is a huge disadvantage when you want to clear the suction pit off sediments by blowing air or steam.

5) In JD the hydraulic inlet valve is opened only when the cargo tank pump is run. On Framo the ball valve for high pressure inlet is closed only while servicing the pump.

6) Latest Framo pumps have stripping cones to feed impeller which reduced the rob to less than a litre.

Here we shall talk about a typical Framo system which is fitted on majority of EMS ships :---

Remember a cargo pump with a blocked cofferdam must never be used. Cofferdam separates the hydraulic system fom the cargo system. The cargo seals consists of upper single cofferdam lipseal and lower double cargo lip seal mounted on ceramic sleeve. Both must be changed together as per Framo recommendation. The wear rings need not be changed unless there is a significant reduction in pump capacity or sweeping party gets affected by cargo spray.

For 2 power packs you will have  have to start the second generator.

Main hyd system pressure must be 15 bars above the highest consumer.

The number of pumps you can use at full speed is governed by the hyd oil consumption of each as per list posted in CCR.

Remove air from hyd system always at the highest point.

Power pack has vent interlock.

Always start the Framo pump with the dischg valve shut. When starting dischg open the cargo dischg valve only when the dischg pressure is above manifold  common pressure ot you will have a backflow.

When there is high back pressure it is better to do internal stripping. If there is no possibility to do this ensure that the dischg from tank is going ashore and not to another tank. For this both the tanks dischg pressure must be higher than the manifold pressure.

It is better to run as many pumps in parallel as practicable at a reduced hyd pressure than just a few pumps at max hyd pressure. 2 pumps at 100 % capacity is same as 4 pumps at 50 % capacity. The advantage is reduced hyd system pressure on old ships where the hyd lines are corroded.

When starting screw booster pump ( molasses/ clay slurry ) without bypass ensure that the delivery side valves incl shore tank is open , or you will spring a leak.

Empty tank at reduced pressure. If required throttle delivery valve on deck. This is not reqd if you have a suction well.

When you have suction well and less back pressure like when stripping salt water , as soon as the tank  is empty close cargo valve fast and stop pump.

Pump speed depends upon backpressure, viscosity and density of cargo.

When using the CCR joystick to discharge make sure the local control STC is fully open ( fully clockwise )
Stripping cannot be done from CCR especially if there is no suction well.-- as it is important to hear the booming sound when the tank gets empty.

Stripping procedure:--

Keep some body in CCR. Reduce pump hyd pressure to 100 bars when pump loses suction as indicated by pressure fluctuation.

Go on deck and shut STC / FCV  ( turn anticlockwise to shut) till hyd pressure drop by 10 bars. You must see the movement of needle. The idea is to avoid surge while transfer of control.

Now the control is on deck.

Tell CCR to fully open the  remote flow control joystick lever by pushing it max upward.

Shut cargo delivery valve  once you hear the air rushing inside stack.

Connect compressed air to stack and strip stack.
( At 7 kg pressure. There is no need to open and shut air as the liquid always remains at bottom and air on top in stack as per the laws of Physics . Ensure air is opened slowly to avoid liquid hammer especially with dense liquids like Sulphuric acid. This can cause the ptfe gasket to creep and spray acid on the stripper. At time of stripping stack 50 bars hyd pressure is enough. Never run Framo pump less than 50 bars. It is not possible on the later models.)

Once stack is empty you can hear the pump racing. Shut the STC/ FCV ( turn anticlockwise ) to reduce pressure.

Close cargo dischg valve first.

Then put off pump from CCR by pulling down the  remote flow control  lever fully.


If the tank is aft of manifold and there is good stern trim then super strip the topline. You must have have Polypropelene super strip hoses. Basically you are transferring liquid from inboard end of shut manifold valve to outboard end.

Purge the cofferdam. Neglecting purging with high mp heated cargoes will result in a blocked cofferdam. Before purging cofferdam check that the relief valve ( lifts at 3 bars ).  First drain the compressed air line from the lowest point.  Or you get wrong measurement in container. Purge several times , not once.

Purging the cofferdam must be done as a ritual—
1) Immediately after loading
2) 12 hrs after loading
3) If leaking purge every day, other wise every 7 days
4) If doing recirc like clay , then before after start/ stop.
5) Before / after dischg.
Fill up the Framo purging log , chief officer must ensure.

No air coming out means a blocked cofferdam. Use steam/ solvent to clear the block.

To fill up cofferdam with water ( while dischg Molasses etc ) use the same system of purging cofferdam in reverse.  This means that the air purging connection must be opened out to vent air out which is displaced by water. For cargoes like clay slurry the water must be recirculated or the cargo seals will get damaged.

Filling up cofferdam with ( to avoid cargo ingress and improve seal life , always ensure hyd return pressure converted to head is higher)---
Phenol / caustic recirc hot water.
TDI/ MDI and polymerising cargo fill up with DOP (VD is 13.5)
Crystallising cargo like Molasses fill up with FW
Phosphoric acid/ recirc with FW to remove residue
Clay slurry/ Kaolin flush cofferdam 3 times daily . Don’t use deepwell pump to strip tank.
Flushing of cofferdam during dischg of viscous cargoes has cooling effect on friction heat between cargo sleeve and ceramic sleeve.

Hyd oil leakage into cofferdam upto 200 ml a day is nothing to worry about.
For this you have to stand the sample for oil to separate out from mixture.
For Hyd oil in cofferdam, pressurise the hyd return side. Change mech oil seal or shaft seal.
If cargo leaks into the cofferdam don’t just change the seal. First find out where the leak is from. To pressure test cofferdam blank by rubber gasket the relief valve and test for pressure drop at 3 kg and soap water. 400ml of cargo in cofferdam when pump is running the full day is ok.

It is better to superstrip the topline before stripping the pumpstack when you are dealing with viscous Luboils, Molasses etc. This way you are able to strip against the lowest backpressure. For your info Molasses is NEVER loaded through framo pump if there is no filter at ships manifold—there might be the odd old shoe or cane piece coming along. High brix Molasses ( Columbian is 93 ) is usually pumped out by Framo portable screw pump MP125, of head 100 m. The pump can be reversed to dispose off fibres of Molasses in the screws.

During tankwash ensure the bottom is always dry. Water in must be equal to water out. In the end allow 10 cm of wash water build up by stopping the pump. Then run pump full speed for 3 minutes to flush internal parts. At this time open and shut stripping valve to flush the stripping line.

Never allow saltwater to remain in pump stack. Always flush with FW.

Every 6 months Framo pump wear test should be carried out. This can be done by running Framo with dischg valve shut as good speed and FW as medium. Wear rings get worn out by running a pump dry. Dry running happens during stripping and tankcleaning. The Framo pumps can be run against a closed cargo valve without an risk of eventual overheating as the wear ring loss comes back into the tank.

The bearings in the Framo cargo pump is lubricated and cooled by hyd return oil and so the pump can run dry without any damage.  This means that the hyd return oil temperature is also a bearing monitoring system. An alarm will be activated if the temp is greater than 60 deg C. If temp exceeds 65 deg C all powerpacks are automatically unloaded except one. When temp drops <60 deg C they will be automatically reloaded. System reset button must be activated before any pump can be restarted. The temp is automatically maintained between 30 and 50 deg C by cooling water.

When picking up anchor and for stations keep system pressure sufficiently high.  Max main Hyd pressure allowed is around 240 bars. The return to tank is 4 kg.  Joint leaks on old ships always happen while starting, due to air bubbles smashing in pressure line, and expansion in return line.

Cargo in cofferdam means—cargo seal, ceramic sleeve, pumphead seal leaks.

Ceramic sleeves can be polished. Worn seals can be reconditioned by Framo shore service.

Oil in cofferdam means---mech or lip shaft seal, pumphead seals leaks.

If hyd oil /cargo leakage is too much close hyd valves and use portable Framo.

Cofferdam seperates cargo section from hyd section.

Cargo seal is exposed only to static head from cargo.

Avoid dry running of Framo pumps or steaming stack for more than 10 min.

To replace a worn shaft bearing the complete pump needs to be withdawn by the shore crane.

The following passage is for better technical understanding of swivel angle/ swash plate and is available in the technical manuals—

Framo power pack load sharing is by ammeter or swash plate angle.

FCV has been replaced by STC on new Framo systems. STC or speed torque control valve prevent overspeed of pumps. STC regulated hyd pressure and limits the flow of hyd oil to pump motors . The max outflow is adjusted by Framo manufacturer and the adj screw is sealed. If the seal is broken the warrantly claims will not be honoured. The construction of a hyd motor is exactly the same as the hyd pump.

Pilot pressure controller:
To keep a balance between oil delivery and consumption a PCV is needed. This valve is a stepless remote control from CCR. When system pressure reached the set value of the PCV , the valve will open for oil to the pump angle control cylinder. The swivel angle will now balance out. If the oil consumption from the cargo pump is increased, system pressure will drop slightly and oil flow through the PCV will drop. The swivel angle will now increase until a new balance is achieved between oil delivery and consumption. By means of this system , oil delivery will always remain same as oil consumption.

The coarse filter on the suction side of the powerpack pump is 100 microns while the fine filter on the delivery side of pump is 10 microns.

The flow into the cargo pump hydraulic motor is regulated by FCV. The control signal into this valve can be adjusted locally ( deck ) or remotely ( CCR ) with the motor rpm depending upon hyd delivery pressure. Varying hyd pressure varies motor rpm. In closed system the level of hyd pressure is fed back to the control side of pump. This signal adjusts the swash plate of the pump adjusting the delivered hyd oil quantity. The pilot pump supplies the desired hyd pressure signal to the swash plate control and thus signal is adjustable. The feed pump maintains a slight positive pressure on the suction side of the pump and should only deliver fluid when the main system has some leakage or the hyd oil contracts due to lowering temp.

Keep the special Framo tools like—
Antirotating tool for impeller hub
Extractors for impeller/ hub/ sleeve / hyd motor
Assembling cylinder
Mech seal assembler
Drain tool
Drain pump
Jack
Lifting bolts
Mirror
Plastic strips
Etc in a safe place and not mixed up with other tools

When loading through the Framo pump must the manufacturers rates be NEVER be exceeded. When planning the loading rate the density of the cargo must be considered to avoid possible irreparable damage to the submerged pump.
In case a cofferdam is blocked—no air returned while purging—inform the chemical operator.
NEVER use abrupt and sudden movements of the Framo joystick in the CCR. When starting discharge, keep pump at slow speed until all checks have been completed, before increasing pump speed. When discharging against high back pressure—do internal stripping.
     
When tankcleaning , the cargo pump stripping capacity should be balanced against the volume of washing water being introduced to the tank. NEVER OPERATE THE CARGO PUMP DRY

Simple rules for the correct operation of the Framo Pumps

1 Purge cofferdam, before during and after use.
2 Check back pressure in return filters and in oil cooler.
3 Refill the oil tank through the filter box.
4 Drain off any water or sediment in the oil tank.
5 Slow down pump when tank cleaning.



                   PORTABLE FRAMO PUMP



If a vessel is fitted with individual deepwell pumps, then she will also be required to carry at least one portable pump.

The pumps should be tested at least 4 times a year and hydraulic couplings on deck should be identified, kept operational and covered with denso-tape.

The use of the portable pump occurs when a main tank pump fails and the tank can only be discharged using the emergency procedures.

The use of the portable pump is a labour intensive and high risk operation, which can be further compounded by the nature of the chemical to be discharged.

If the emergency pump is to be used, then the terminal and owners should be advised.

The terminal should also be aware of any problems anticipated and co-operation and communication is vital for the safe and efficient discharge of the cargo.

The pump described below is a FRAMO TK4. If another type of pump is on board, then the particular operation of that pump is to be used.

There are basically three main components which make up the portable pump.
1 The pump unit.
2 The starter head with hoses between pump and head.
3 Pressure and return hoses between the starter head and the snap on coupling stations on deck.

Flexible hoses of sufficient length are coupled to the pump to effect the discharge. The length of flexible hose should be kept to the minimum to reach the installed pipework.

               The portable pump is lowered into the cargo tank by a sling and not by the hydraulic hoses.

PORTABLE FRAMO TRY OUT


As soon as a new Chief officer/ Pumpman joins he should at the earliest rig up the portable Framo pump and try it out.

Never hook up without a flow control valve for speed control and stop/ start.

A) Fill up a empty 200 litre drum with SW and keep a couple of fire hoses standby to fill it up.

B) Use tripod the same way you will use in a tank.

C) Before connecting hyd hoses close flow control valve.

D) Check for cleanliness on snap on couplings.

E) Always connect return hyd hose first--- ‘and open valve’.

F) Connect pressure hyd hose and open valve.

G) Open flow control valve till the required rpm is reached, don’t let the drum go dry. If so then put dischg back into the drum.

H) Probable  specs of a portable framo will be 180 bars/ 70 cum  per hour/ 140 ltrs hyd oil per min

I) After you are satisfied , rinse with FW.  Then  first shut flow control valve.  Make system pressure zero.

J) Close pressure line valve first and then return.

K) Always disconnect pressure hyd hose first and then return.

L) Before keeping back in store release the oil pressure inside hyd hoses by removing about 20 CC of oil, by pushing with fingers.  Otherwise in an actual emergency you will have difficulty in connecting the snap on couplings.

M) Don’t kink the hoses in the store.

Portable Framo pump is not used to pump ashore. Rather it is used to pump from one tank whose pump does not work to another tank of the same grade or empty tank whose pump works.

If the emergency pump is to be used, then the terminal and chemical operator should be advised. The terminal should also be aware of any problems anticipated and mutual co-operation is vital for the safe and efficient discharge of the cargo.

Ensure that only the lower half of the pump is submerged and is lowered as the cargo level falls .


                          FRAMO DEEPWELL PUMP OVERHAULING

MODELS: SD125  AND SD150 ( design number 5 )

Shut inlet valve of main hydraulic inlet pressure line.
Purge the cofferdam.
Take the Framo tool box down.


To dismantle impeller and wear rings:

Remove 8 nos bolts to dismantle pump support ring.
Lift up the support ring and tie it up with a rope about one metre high.
Loosen 8 nos bolts of upper wear ring support.
Then loosen 2 turns only 6 nos allen bolts for impeller hub (inner ).
Turn impeller clockwise for easy access.
Press down the bolts and impeller.
When impeller is loose remove the bolts.
Remove 4 nos bolts between volute casing and cargo leg.
Replace 2 of the bolts with long lifting bolts---one bolt on each leg.
Remove remaining bolts between volute casing and bearing housing of cargo flange.
Now all volute casing , impeller and suction cover is hanging on lifting bolts diagonally positioned on each cargo leg.
Lower unit on plastic strips.
Slide the unit out of the well.
Remove upper wear ring and inspect it ( white large ring ).
Remove black o ring and small white seal element between impeller and impeller hub.
Put unit upside down
Remove nuts between suction cover and impeller.
Inspect white wear ring. Normal radial clearance is 0.2 mm. if clearance becomes greater than 1mm renew.
Loosen locking bracket and remove locking ring.
Fit back the suction bellmouth to lift up the suction cone
Finally lift up the impeller.
Note; wear rings usually last 10 years for clean oils. For sediment cargoes like clay slurry you will have to renew often.

To dismantle double cargo lip seal and cofferdam seal:

First dismantle 4 bolts on the lower part of thin cofferdam check pipe.
Put a mirror.
Dismantle impeller hub from the pump shaft.
Loosen lock washer.
Remove bolt and pull out impeller hub.
Use extractor to remove impeller hub.
Don’t damage or ring and ceramic sleeve.
Put on the assembling cylinder to keep the ceramic sleeve in place and protect seal lips.
Pull down seal ring housing with cargos seal.
Remove the thin white Teflon seal ring.
Remove (thick small with spring) double cargo lip seal.
Remove single lip cargo seal.
Note : always change single and double cargo lip seal together as they come as one spare part.
Remove ceramic sleeve after removing the assembling cylinder.

To dismantle Mech oil seal :

Mech seal can be dismantled without draining oil from the hyd pump stack.
Remove bearing housing from pump casing.
Put upside down and remove upper seal ring housing.
Use 2 lifting bolts and remove mech seal stationary part ( black ) and Teflon seal element.
Use special tool for rotating part of mech sealnever use grease on oring of stationary seal---use soap water.
Dismantle pumpshaft, ball bearing and back stop unit ( after reading the manual ).
For hyd motor you must drain out hyd oil from pump stack.
Use air driven drain pump given by Framo.
Lower hyd motor by using Framo jack.

Assembling

Assembling is done the reverse way the things came off.
However turn ceramic sleeve by 180 degrees.
Groove from double lip cargo seal must be facing towards the impeller.
Fit retainer ring on geared shaft correctly at end of ceramic sleeve.

Running test:

Pressure test cofferdam at 3 bars pressure.
Blank cofferdam vent pipe.
Unscrew the complete air relief valve and connect pressure guage.
Check for pressure drop . Pressure must be stable for 30 minutes.


FRAMO HARDWARE


When a new delivery Master or Chief Engineer goes to the yard to take over a ship , they must know the following minimum essentials.

They must know which hardware is yard supply and what is Framo supply. The Framo supply is usually perfect, the yard supply and the interfacing needs to be checked in great detail—this is why they are sent by company to the yard well in advance. The new building superintendent is of course there much before, and he need to read this chapter too.  Sometimes for yard’s convenience they do not fit Framo supply hardware, and this must be rectified.

For example, recently when one of our Masters pointed out to the yard, that the Framo air purge couplings for stripping the stack do not have non return ball valves ( but wrongly fitted with yard supply shut off cocks ) as is usual for Framo fitted ships as a Framo supply  , the yard initially stonewalled—but since this was done in writing with copy to Framo and company, the yard was forced to recify it free of cost before delivery. Imagine Sulphuric acid spraying on the Pumpmans face, after he finished stripping the stack!!.

Look for alien voltage from interfaced equipment prior to working. There must be sufficient service space and lifting hook pad eyes. Hydraulic oil used must be mineral based and must have FP between 180 and 230 C.  This was another mistake recently noticed---the yard had to drain out the cheap quality yard supply hydraulic oil , flush the system and then fill up again with the correct viscocity/ FP hydraulic oil ,as specified by Framo.

Any hyd leak spray must not come in contact with heated surfaces. Check hyd oil connections, valves and flanges—if necessary put splash tapes on flanges. If the power pack is in the ER—an oil mist detector is desirable. This is bound to be a regulation very soon.

Welding on framo equipment in not to be done without permission.

There must be no paint on flexible hoses and rubber dampers—as it will crack very soon.

It is important to know the hyd oil conspumption of all cargo pumps—big and small , ballast pumps,  portable pump,  tankcleaning pump etc in litres/ minute.  This must be posted at the remore panel in the CCR.

Any consumer hooked on to the central hydraulic ring , main system can be run ( like crane ) as long as the oil delivery is sufficient. To control the speed of the hyd motor a FCV ( old ships ) / STC ( all  new ships )  is fitted. Framo does not make FCV any more—they make it only for the portable pumps.

Check the hydraulic oil storage tank and clean oil drain tank. Both must have sloping bottoms away from the suction and towards the bottom drain for efficient water draining. These tanks are usually yard supply—the rest are Framo supply.

In case the power pack is situated outside the ER, the ventilation must be sufficient—without ingress of salt spray. The advantage of having the power pack in the higher level FP store is the natural head of hydraulic oil afforded , to the mechanical hydraulic oil seal at cofferdam of submerged cargo pump,  in case the Jockey pump fails.

There must be an obstruction free arrangement in case the whole pipe stack and pump head has to be removed from the tank with a tall crane.

The pipestack must be parallel to the bulkhead, where the bracket for the intermediate support is welded.

From Framo CCR control—you should be able to see manifold—the console is made by yard.

Look for dents on framo pump risers –due to incorrect handling by slings or forklift marks under power pack units ( they must be lifted by 4 hooks ). The risers have concentric pipes inside inlet/ return/ cofferdam.

Framo pumps must be installed only after the welding causing spatter, grinding, pickling in the tanks are over in SS tanks -- or for the matter ,painting in coated tanks.

Note—Framo recommends hyd drums to be stored horizontally when it is kept out door—so that the bungs are covered by oil—oil can leak out—but water cannot come in.
Water has a negative effect on hyd oil additives , which have been primarily put to improve oil quality.

Framo drops must not lead to pump suction—it must not hit steam coils—must slip underneath and hit the forward bulkhead for tsunami recirculation.

Flexible hoses for stack stripping will have SS snap on couplings, with a NR  ball valve at each end. The hose will not be > 2 metres long, will be SS braided, will be heavy duty and hard to bend at 180 deg angles. There will be NO jubilee clips—if you notice Jubilee clips it is a deliberate yard mistake. They have fitted a compressed air outlet valve far away from the pump, and instead of relocating the air valve they did the next best in a clandestine manner—that is, give the ship a longer hose with couplings fixed by jubilee clamps. After stripping the stack there must be no need to shut a cock before disconnecting. Cargo must not ingress the air flexible even if air pressure drops from 7 kg.

Exhaust traps must have 50 cms clearance to keep a collecting bucket . Cofferdam blow is done into a compatible bucket and not into the clear sample glass bottle. There must be different buckets for different grades of cargo.

The intermediate riser supports must no be welded in corners or slope of corrugated solid steel –or on 2 different bulkheads at corners of tank. Framo have certain calculations on which they decide whether to put one or two intermediate riser supports. Be aware in tanks without sloshing considerations and less load density,  carriage of free flowing high density cargoes like sulphuric acid of SG-1.85 can cause cracks. Master must prevent ship from rolling excessively and not trust the Framo calculations to deliver his tanks from cracking danger . Framo calculations have not taken into account the ships tanks’ load density—if a heavy cargo of 2.0 SG can be loaded 98% or partially full.

Prior pump installation the deck trunk and brackets for intermediate and bottom support have to be welded into the tank. A good yard will use a Framo provided dummy with laser beam holes to avoid templating misalignment. Good alignment means no cracks. While the Japanese yards are experts in this—newly mushroomed yards who have jumped into the fray with the chemical Type 2 tanker veg oil shipping boom ( after 1.1.2007 ) may not be so. In such yards the Owners yard new building superintendent must carry his own laser pencil beam—available in the market.

Welding seams of deck trunks must not be facing the ship side where they can get pounded by a incompressible green water wave.

Ammeters must be be provided for motors > 7.5 KW. A good chief engineer who knows about swash plate angles of variable displacement Framo power pack pumps will hardly need this Ammeter.  The ratio of current transformer must be told to Framo by yard if an ampere meter is required on the hydraulic system control panel.

Cables for motor heating elements and thermistors must not be interchanged as voltage >2.5V will damage the thermistors.  Motor heating elements must be powered up immediately after installation.

Hydraulic oil tanks must be vented indoors repeat indoors -and that too with an air filter, not to outer decks. The storage volume must be min 50% of the total oil volume in the hydraulic system—the recommended is 70%.

The storage and clean oil drain tank must be SS to prevent coating—if not grit blast to SA2.5 and give two coats of hyd oil resistant epoxy 100 microns each. Only SS pipes are used, copper or galvanized pipes must never be used.

Manometer test connections must be provided by the yard at both supply and return lines, to do trouble shooting and to test for pressure peaks.

Venting plugs must be at the highest point—at both pressure and return pipes.

Framo does not accept hydraulic  cylinders connected to the system. If  a crane has to be used they recommend a separate hyd system with hyd motor driven from Framo system. But as long as the CCR OOW is aware that a crane is being operated , he can be vigilant.

Pipelines must not have too much of pressure drop ( smooth internal surface ) or air pockets. Framo pressure drop calculations are based on minimum ID .

Unnecessary flanges must be avoided by yard. All pipeline spool welds must be possible to be inspected from a flange—say using a video scope, at the yard.

The resilient pipeline clamps must have 4 rubber pads at all 4 quadrants—equally compressed to absorb vibrations and prevent transmission to deck structures. These clamps must be welded to rigid structure.

Pipeline bulkhead penetrations must be resilient Framo supply. The inner bulkhead must have a protection cup,, lined with glass wool.—both yard supply.

Expansion loops on hyd pipelines must be always horizontal—never vertical.  These are for thermal expansion and axial forces/ deflection of ship’s structure.

Water ballast pumps must be connected to different RCV blocks—to ensure operation of ballast system if one valve block is out of service.

Pilot pipes on open decks must be made of SS.  Pilot pipes min distance between expansion loops is 25 metres. If attached to the catwalk—expansion loop must correspond with the expansion joint. If there are 2 tiers there must be no contact between any pipe and adjacent flange—flanges can be turned to avoid contact. Only cold bending is permitted.—free of wrinkles on inner side and 7%  ovalty. Pipes must be degreased before bending and pickled after bending. Low pressure pipes have Teflon mandril inside the pipes.

TIG welding with Argon gas is recommended for SS. Carbon steel pipes must be coated with zinc rich epoxy. Neutralization of carbon steel pipes after pickling—2% phosphoric acid at 85 deg C for 5 min, the Framo way is wrong—Nitric acid would have been the best.  Neutralization of SS ( passivation ) 14% Nitric acid at ambient temp for 45 min.

Pipe clamps must be welded only AFTER alignment and assembly of pipes. Adjusting spools are min 2 to 3 metres long—the pipes must be pulled apart before inserting to prevent damage to spool O ring. Use Molebnenum Sulphide grease on screw connections.

As soon as you join the ship –check the manifold—if the manifold athwartship pipes are  above the fore and aft cargo deck lines it simplifies the loading. If it is below—it simplifies the stripping. This  knowledge is vital with high MP cargoes loaded from barges in freezing weather—like Phenol loading / dischg in winter. If pipelines get frozen with toxic cargo and you have to put you crew in danger to unfreeze the lines—it is a disgrace.

If the manifolds are above deck lines—then separate drain lines have to be installed for all deck pipelines.  If the manifold common collector is above the manifold pipelines—then 2 drain tanks at the manifold.

Hyd oil pour point should be around -26 deg C, with viscosity ISO VG46—the trade name whether it is TELLUS--Shell/ RANDO--Texaco or BARTRAN—BP  will have the number 46. The hyd oil must always be filtered by using the Framo hyd oil transfer unit when the oil is filled into the system from the storage tank. Water content must be below 300 ppm or 0.03%

Air in the system is indicated by –
Back flow into the system when at standstill
Great difference in tank level at low and high system pressure
Foaming
Discoloured oil

Cooling water pipelines are fitted with flexible bellows to prevent vibrations. Piping at the outlet side must be routed above the oil cooler and a vacuum breaker must be installed.

The tank risers have concentric hyd pipes for max safety. Framo cofferdam is at atmospheric pressure, unlike the Japanese deepwell pumps who use air pressurized cofferdams to make up for the lack of Jockey pump—and that too with a fixed air connection!

Remember Framo cargo double lip seal faces only static pressure. Framo pump design permits dry running during stripping and tankcleaning. It facilitates in tank replacement of wear and tear parts without interfering with hydraulic section.

By purging only the condition of the double seal cargo seal is known, hence replace both single lip and double lip cargo seals together always.

After fixing the snap on  hydraulic couplings of portable framo, secure it with locking ring—only then the arrangement is safe.

Portable Framo TK80 usually provided on board EMS ships have a capacity of 90 cum/ hr. Portable  Framo inlet pressure is usually 180 bars and the  return line pressure 16 bars.

Before purging cofferdam drain the compressed air supply line off water. When purging cofferdam the cofferdam relief valve operates at 3.5 bars. If not, then you get air into the hydraulic system with once the air pressure is greater than the jockey pump pressure, due to a blocked cofferdam.

Light cargoes like Methanol/ Naphtha bypass cargo seals and penetrate cofferdams more easily than viscous ones like Lub oils/ Veg oils.  Cofferdam ingress of cargo volume means nothing, if the type of cargo purged is not mentioned.

Non viscous cargo leakage 0.5 litres/ day is normal. Oil leakage 0.25 litres / day is normal.
Cargo leakage in cofferdam can be—
Wear on ceramic sleeve
Leaking pump stack/ pumphead seals

To fill up a cofferdam prior dischg, for cargoes like Caustic soda—
Disconnect exhaust trap piping from pump top plate—use a suitable adaptor and fill up.—allow air to escape from snap on air coupling –in other words this is reverse of purging

For continious circulation of water while discharging ,for cargoes like Clay slurries:--
Same way as you blow the cofferdam. Ensure the hyd return oil pressure is higher than the cofferdam  pressure.

If the hyd oil temp is <20C circulate the oil for heating at max 100 bars prior to raising the pressure to 150 bars.

When using deck mounted heaters –make sure the cargo is circulating though the heater before opening steam inlet valve. Never heat without necessary cargo flow through the heater to avoid carbonizing. Shut off heating medium before the pump is stopped. For deck mounted heaters do NOT heat while discharging—or cargo will come back into the tank.

Jockey pump also prevents water entry into hydraulic oil from leaking cooler.

If oil temp is <20C, circulate the oil though the heating/ venting valve –with one power pack running.

Manual override:--
Mode one--1)Sensor on oil tank is indicating shut down level, and it has been determined that level is OK
2)A limit switch is indicating closed valve and it has been verified that the valve is fully open.

Mode 2—for PLC failure

Cooling water valven for power pack is automatic , 50C open—30C shut

The Framo pumps can be run against a closed cargo valve without any risk of eventual overheating as the wear ring loss is led directly back into the tank.

PCV is a proportional valve for precise and fast control of pressure. This valve is primarily used for remote control of pilot pressure to a Framo hyd control valve. PCV is a compact unit with integrated electronics and a pressure transducer for controlling the pressure on port A. when the current to PCV is zero the spool is in spring return position.

When the actual pressure at port A is lower than the set pressure, the spool will more so that port P and port A are connected, while port T ( to tank ) will close. The valve is then in supply mode.
A limitation is built into the electronics so that the PCV will not open unless the command signal exceeds a pressure of 10-12 bars. The valve closes when the command signal gets lower than 10 bars. When using remote control PCV, the local control valve must be set in max position and vice versa.  Everybody on the ship must know this—when a tank is being discharged in bulk or at sea , the local control valve STC must be fully open or fully clockwise. The command signal to the valve is usually set by a potentiometer at the control panel.

Emergency over ride—
This procedure must be known to Chief engineer. Read the Framo manual as soon as you join, and familiarize how to do it, where the allen key has to be inserted and how it has to be turned after loosening the check nut.   If you do this simple procedure fast, the chief officer need not rig up the labour intensive portable Framo and end up with ROB and a mandatory and costly pre-wash.

If the valve has an electrical fault you can mechanically connect port P to port A, and run the cargo pump from local control. Remember to unload local control valve before changing to manual override. Use an allen key—clockwise. After operations connect port A to port T ( tank ) by screwing counter clockwise. Fasten the locknut—don’t use force with allen key.



CAPT AJIT VADAKAYIL ( 28 YEARS IN COMMAND )
..

38 comments:

  1. Dear Capt. Ajit ,
    Can you provide some description on the drawing and function of superstrip system .

    rgrds
    Shishir

    ReplyDelete
  2. sishir,

    Superstrip of cargo pipelines , must be done on a chemical tanker after dischg to comply with Marpol ROB min quantity.

    Also -- in case of inconvenient cargoes like Sulphuric acid , Luboils and high MP cargoes, after completion of loading.

    Basically you shove cargo from inboard side of the shut manifold valve , to outboard shore side.

    You cant blow cargo in a large dia pipeline uphill against gravity , ( aft of manifold with trim by stern ) from tank till manifold, as air will skim on top of cargo inside the pipeline.

    So air is blown inboard of a shut manifold valve , to force the cargo to flow downhill, to the aft tank stack, and then the cargo is ushered into a small diameter superstip pipeline ( this could be portable --if fixed piggy back superstrip pipelines are not fitted for all aft tanks ) , which takes the cargo outboard of the shut manifold valve, ashore. Air cannot skim on top of cargo in a very small diameter pipeline.

    On modern Chemical tankers, superstrip piping is avoided by raising the aft tank delivery pipes upwards , so that cargo flows towards manifold by gravity --due to a sloping pipeline.

    This makes sure that after dischg all your cargo goes ashore by gravity. But on the other hand after completion of loading your manifold cross pipes of aft tanks will be full of cargo. Sulphuric aacid sloshing in rolling during loaded passage , can destroy all the butterfly valves at the manifold, on both sides.

    CAPT AJIT VADAKAYIL
    ..

    ReplyDelete
  3. dear captain ,
    we faced with one remark in veetting inspection ..could you pls advise brand of oil mist dedector for power pack room as used for framo system...
    thanks in advance,
    sehyuc@yahoo.com

    ReplyDelete
  4. hi,

    you can go for any of the three OMD --

    DAIHATSU
    GREEN INSTRUMENTS AS
    QMI MULTIPLEX

    capt ajit vadakayil
    ..

    ReplyDelete
  5. Pipelines must not have too much of pressure drop ( smooth internal surface ) or air pockets. Framo pressure drop calculations are based on minimum ID.

    Automated Feed Pump for Grease Traps

    ReplyDelete
  6. Thanks Capt. Ajit Vadakayil for information

    i'm student in naval architect and marine engineering dep. , Port-Said university , Egypt
    and i'm doing a research on differences between chemical and oil tankers.

    i need to ask about something pls

    1 - is there any protection for deep well pumps in case of tank loaded with aggressive acids ?
    2 - can you tell me what is the main differences between chemical and oil tankers in pumping system?

    thanks in advance

    ReplyDelete
  7. hi mahmoud,

    1) acids are loaded in stainless steel tanks, with stainless steel deepwell pumps, with teflon inserts. epoxy and zinc silicate paints cannot handle acids. framo deepwell pumps have a cofferdam to prevent acid cargo entering the hydraulic oil impeller motor drive.

    2)oil tankers have pumprooms with pumps and all tanks are connected at the bottom level of tank. you can prevent an overflow while loading by opening an empty tank.

    chemical tankers do NOT have pumproom as all pumps are situated inside the tanks- to prevent having a suction pipe, where all pumping problems lie. this way all tanks are connected above tank level at the manifold. here overflow is prevented while loading by shutting the full tank.

    capt ajit vadakayil
    ..

    ReplyDelete
  8. thanks for provided a nice information
    We Manufacturers and Suppliers of Single Spring Mechanical Seal, Dry Mechanical Seals, Reactor Mechanical Seal ,Cartridge Mechanical Seals, Mechanical Shafts Seal Manufacturers.

    ReplyDelete
  9. Capt Vadakayil,

    I was surfing the net and found very helpful info of chemical tankers on your blog. Excellent details.
    Have a question today on carriage of Furnace oil with 2% sediments in it for a long voyage on a IMO-II chemical tanker with Framo deep well pumos. How do you see this as a problem cargo and any risk associated.

    Appreciate your input.

    Many thanks.

    S Modak.

    ReplyDelete
  10. hi modak,

    it is very difficult to clean FO tanks after discharge.

    the next cargo CANNOT be a clean one. the best next cargo will be LDO ( NOT the golden gas oil ).

    if the charterers push you--take your own sweet time for tankcleaning and ask for enough degreaser tankcleaning chemicals --

    dont ever get rushed, for nobody will give you a gold medal for being an eager-beaver -- but you will get hung if your ship fails the next first foot.

    extensive flushing of pipelines with degreaser will be required. the black oil tends to get behind even a valve seat ring.

    the first pre-wash cannot be hot -- as the lighter solvent fractions will evaporate, and the balance sediments will involve nightmare cleaning. .

    remove cold interface while HOT washing.

    capt ajit vadakayil
    ..

    ReplyDelete
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    > Single Spring Mechanical Seal</a>.

    ReplyDelete
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    ReplyDelete
  13. Dear Capt. Vadakayil
    Regarding framo pumps cofferdams, what could be the reason to fill the cofferdams with water?, different from the reason of avoiding clogging (molasses, etc). Many thanks in advance! JBracho

    ReplyDelete
  14. hi jesus,

    cofferdam prevents cargo from entering the hydraulic system-- and also hydraulic oil from entering the cargo tank.

    conversely both hyd oil and cargo are expected to ingress in the cofferdam in small quantities--as this space is also a INDICATOR which tells you if the cargo or oil seal requires renewal, due to wear.

    hence cofferdam must always be clear. you must NOT load cargo in a tank whose pump's cofferdam is clogged.

    there are certain cargoes which will harden inside the cofferdam and hence cannot be purged with air, before loading the next cargo.

    also some of these cargoes may be "ABRASIVE" ( like clay slurry ) and destroy the ceramic sleeve on which the cargo seal abuts. and since clay slurry is INSOLUBLE in water and HEAVY , just filling up the cofferdam will NOT do.

    crystallizing cargoes like phosphoric acid and caustic soda are also abrasive.

    when the pump runs, water has to be continiously filled and ejected out on deck.

    TO AVOID INGRESS OF WATER INTO HYD OIL (WHILE RECIRC OF WATER) -- DO NOT TRUST THE SMALL PRESSURE EXERTED BY THE JOCKEY PUMP -- RUN THE FRAMO SYSTEM, WHEN WATER IS FILLED IN THE COFFERDAM.

    capt ajit vadakayil
    ..

    ReplyDelete
  15. Dear Capt. Vadakayil
    Many thanks for your prompt answer and help!
    Very best regards,
    JBracho

    ReplyDelete
  16. dear captain,
    Greetings.i have sailed in bulk carrier for two years and i have done single contract as 4/e in bulk carrier.now i am getting a offer from a maritime agency to do chemco and join a chemical carrier as 4/e but the wages they give is 1800$,kindly advice on this.in bulk carrier they pay me 3400$

    ReplyDelete
  17. dear captain,i have sailed in bulk as 4/e and now i get 3400$ monthly and i got a offer from a maritime agency to do chemco and join their chemical tanker for 1800$ monthly.is chemical tanker safe to work with and also i heard life is hectic at chemical tankers...kindly advise

    ReplyDelete
    Replies
    1. hi vijay,

      it is good to do chemco and get experience on a chemical tanker.

      negotiate your wages and go for a short contract.

      life on chemical tankers is safer than on a old bulk carrier.

      capt ajit vadakayil
      ..

      Delete
    2. DEAR CAPTAIN...
      I HAVE ONE QUISTION AND IAM LOOKING FOR THE ANSWER FROM LONG TIME CAN U PLZ ANSWER THIS....

      What is the precaution to be followed when replacing the mechanical seals in a cargo pump of an tanker?

      PLZ SIR,,

      Delete
    3. hi harshal,

      The lapped seal faces are brittle and may crack if dropped or scratched against other parts.

      -Never touch seal faces with bare hands; use clean gloves.

      -Never use any lubricant on seal faces, -they must be assembled completely dry, clean and
      dust-free. Clean the seal faces using denatured alcohol.

      -Check that o-rings for rotating and stationary seat, and rubber bellows, are undamaged prior to installation.

      Dynamic O ring and static O ring have different surface roughness—check value in manula drawing

      -To reduce frictional forces when installing rotating seat on shaft or sleeve, thinly lubricate the dynamic o-ring, or shaft/sleeve area for o-ring with silicone grease. Never use grease incompatible with o-ring material.

      -Use approved assembly tools when installing rotating seat on shaft.

      -Use Loctite 243 or equivalent on set screws. Set screws must be renewed after every
      dismounting.

      Use torque On screws according to table.

      -To reduce friction during assembly, wet the stationary o-ring and all sliding surfaces for the o-ring with water. If the stationary seat is impossible to install using water, add some soap to the water. Use as little soap as possible.

      The stationary o-ring must never be lubricated with grease.

      -When pressing in the stationary seat with o-ring, make sure that the pressure distribution is uniform and that the o-ring is not damaged.

      -Do not use any assembly tools against seal face. Press seat into seal housing by hand using clean gloves .

      -On stationary seats where no lock-ring is installed, - make sure that a possible twisted o-ring during assembly is not forcing the stationary seat out of seal housing after assembly.

      When looking at the sliding surface of the rotating seat, a right handed shaft
      requires a right handed spring and vice-versa.

      -When mounting mechanical seals with conical
      springs, the spring must be pushed onto the
      shaft with a screwing movement identical to the winding direction of the spring; this causes the spring to open.

      If a provision has been made for a stationary, as well as a rotating pumping screw the spiral direction of the
      stationary member must oppose that of the rotating pumping screw.

      After installation is finished a pressure test of the mechanical seal should be performed if possible.

      . For detailed procedures, refer to the pumps service manual or assembly instructions.
      Pressure test with clean dry air.

      If the mechanical seal is used as oil seal, the return chamber,-where this is possible,- should be pressure tested to 6 bar for 15 minutes. Monitor pressure in cofferdam during test.

      Install right side up-- rotating and stationary seats.

      capt ajit vadakayil
      ..

      Delete
    4. Dear Capt. Vadakayil
      Many many thanks for your prompt answer and help!
      Appreciate your input
      Many thanx..AGAIN

      Delete
  18. Captain Vadakayil,
    Sir what are the reasons for stopping overflow on oil tanker by opening an empty tank but shutting a full tank on a chem tanker/

    ReplyDelete
    Replies
    1. hi ka,

      punch into google search-

      INSTRUCTIONS FOR OVERFLOW PREVENTION ON CHEMICAL TANKERS VADAKAYIL

      oil tankers tanks are connected to each other at the bottom of the tanks.

      chemical tanker tanks are connected to each other about 2 metres above main deck level at the manifold ( if they are connected by spools or internal looping hoses ).

      capt ajit vadakayil
      ..

      Delete
  19. hello sir
    read your extremely helpful blogs.. thanks for sharing your knowledge with us.
    my query is what are the risk and hazards associated with framo pumps on a chemical tanker..

    ReplyDelete
    Replies
    1. hi vs,

      do NOT allow the impeller to work loose . sometimes after changing the cargo seals the engineers so a poor job in boxing back.

      leaky wear rings can spray cargo.

      high MP cargoes -- the pump and dischg column can freeze . no not allow cold ballast interface.

      capt ajit vadakayil
      ..

      Delete
  20. hello sir,
    i just would like to ask what checks to be carried out before discharging the cargo on fixed framo system
    1. by deck side
    2. by engine side
    if you can then please e-mail me on
    marinepush@gmail.com
    thanks n brgds
    pushkar

    ReplyDelete
    Replies
    1. hi pk,

      i do NOT take such comprehensive academic questions -- meant for orals and exams, due to obvious reasons.

      there is more than enough info in my blog posts on this subject.

      and i do NOT come on email.

      punch into google search-

      CHEMICAL TANKERS , DISCHARGE OPERATIONS VADAKAYIL

      it goes without saying that engineers have to check the hyd oil level , ensure jockey pump is running, start cooling water system , check oil filters , start requisite number of generators and vent air from system if there is sound.

      and deck officers have to purge pump cofferdams, check for leaks and tell engineers how many power packs they will use.

      If the hydraulic oil temperature is below 20 °C, circulate the oil for heating at
      maximum 100 bar prior to raising the hydraulic system pressure to max.

      capt ajit vadakayil
      ..

      Delete
  21. Dear sir
    can you explain what is the reason for starting additional feed pump before starting power pack

    ReplyDelete
    Replies
    1. hi vsk,

      in the framo systemthe feed pump is called jockey pump-

      it runs 24 hrs a day-- 365 days a year -- NON STOP.

      read item no 3 --right on top of the post.

      capt ajit vadakayil
      ..

      Delete
  22. Dear sir
    It is understood that jockey/feed pump runs all the time in framo system. my doubt is why it is required to start second feed pump while starting powerpack. two feed pumps will be running when powerpack runs and only one feed pump when powerpack is not running. it is inbuilt system and additional feed pump starts automatically when powerpack is started.Can you explain the reason sir.
    Best regards

    ReplyDelete
    Replies
    1. hi vs,

      this depends on the operation manual--

      maybe the hydraulic circuit is designed that way.

      capt ajit vadakayil
      ..

      Delete
  23. Dear Sir

    Thanks for this informative article. Could you please enumerate on how to go about during change over of tanks during cargo discharge. Discharging from 1W,5 W and 6 W. I will like to keep 1W and 6W running but need to change 5W to 4 W ? Thanks in advance

    ReplyDelete
    Replies
    1. hi ta,

      i do NOT take such questions-- due to obvious reasons.

      however you can read another post-

      punch into google search-
      CHEMICAL TANKERS , DISCHARGE OPERATIONS VADAKAYIL

      when you do the job practically on the ship-by assisting in cargo work , you will come to know.

      capt ajit vadakayil
      ..

      Delete
  24. Can you please advise me the external inspection of the deepwell pumps inside the tanks to be carried out during tank inspections.

    Thanks,

    ReplyDelete
    Replies
    1. hi np,

      read the post properly.

      punch into google search-
      CHEMICAL TANKERS , DISCHARGE OPERATIONS VADAKAYIL

      capt ajit vadakayil
      ..

      Delete
  25. Nice blog!
    It gives some good and useful information about oil equipment and it's uses. The equipment shown in this blog is really good and high quality.
    Air Operated Pumps

    ReplyDelete
  26. I went across your blog it is really good. It has very important and useful information.
    Workshop Equipment

    ReplyDelete