Industrial Services

​P43® sludge resuspension

The P43® rapidly desludges crude oil storage tanks, improving safety and reducing downtime.

Suitable for heavy crude blending and sludge control the P43® can be used for:
  • Gasoline blending
  • Biodiesel blending
  • Diluted bitumen blending (synthetic crude)
  • HFO (Heavy Fuel Oils)
The system uses a powerful jet of oil, which sweeps and rotates through the sludge at the base of the tank and blends soluble hydrocarbons into the total contents.

The P43® reduces the need for tank entry and achieves higher efficiency levels than any other solution on the market.  It is designed and built to exacting specifications and offers outstanding performance with minimum maintenance. 

For new, clean or gas free tanks, the P43® can be centre-mounted as a permanent installation.
3E eductors
With improved in-tank circulation and blending, our 3E eductors can be configured to suit the tank shape and application.

  • Unmanned entry
  • No electricity required
  • System contained within the tank
  • No static build up
  • Negligible maintenance required
  • Ensures a more uniform feedstock for downstream processing
  • Maximises recovery of inventory stock
  • Improves water draw off
  • Eliminates water trapping, which can contribute to corrosion of the tank floor
  • Low capital cost
  • Reduces tank outage
  • No separate power supply required; the P43® uses energy from the existing import pump
  • Maintains maximum storage capacity
​P43® flow patterns

The P43® system can be applied in a variety of ways to maximise efficiency.

Video To Demonstrate The ​P43® Sludge Resuspension Process
​P43® sludge resuspension benefits

The P43® Sludge Control System for crude oil storage tanks is more than revolutionary; it beats all previous systems hands down.

P43® sludge resuspension benefits

The P43® Sludge Control System for crude oil storage tanks is more than revolutionary; it beats all previous systems hands down.

The submerged P43® was developed specifically for sludge control in crude oil storage tanks.  Its powerful 'sweeping' action is more reliable than chemicals, more effective than side-entry mixers and far safer than manual methods.

Recovering valuable hydrocarbons

The P43® system re-suspends the hydrocarbons in the sludge into the light crude used during the de-sludging operation, leaving the total liquid content of the tank ready for processing.

In the case of one large diameter tank, this actually saved around 1000m³ in recovered product (at today's prices that’s a significant saving).

Dramatic cost savings

  • Downtime is a fraction of conventional times.
  • Recovers valuable hydrocarbons that might otherwise be wasted
  • Cuts out the need for extra storage capacity during cleaning
  • Tank contents do not require heating or chemical additions.

Enormous reductions in downtime and tank outage

Using conventional methods, a typical large diameter crude oil tank could be out of action for 8 to 12 weeks.

With the P43® system, the entire de-sludging operation can be finished in about 10 days - and that includes 2 days for emptying and re-filling the tank.  What's more, the tank can still perform a storage function during the de-sludging stage.

Improved safety

The P43® system carries out de-sludging operations without man-entry, significantly reducing hazard to operatives.  Naturally, all P43® de-sludging equipment conforms to the rigid safety requirements covering hazardous areas in the oil industry.

Permanent installations

For new, clean or gas-free tanks, the P43® can be centre-mounted as a permanent installation.  A single P43® is secured to the tank floor - together with permanent piping to the tank wall shell.

Experience has shown that about 24 hours of operation each month is all that is necessary for complete sludge control, showing dramatic savings when compared with conventional side-entry mixers.

Environmental advantages

The P43® eliminates the need to remove sludge from the tank and transfer it to temporary storage and treatment lagoons, reducing fire and associated pollution risks.

​P43® sludge resuspension service

Our dedicated technical team can design a complete sludge tank management system.

Our dedicated technical team can design a complete sludge tank management system, based on tank capacity, pump specifications, pipeline size and orientation and a crude oil analysis.

Topographic Survey

An accurate assessment of the quality and position of the sludge is fundamental when planning maintenance and scheduling for a major tank cleaning task.  We carry out a topographic survey of the sludge which will allow you to pursue your chosen method with confidence.


The P43® can be installed into the tank shell through existing manways without hot-work, or at the centre of the tank with hot-work. Feedlines can run from existing inlet lines or alternatively can be installed separately as a self-contained unit. In side entry applications, the patented design of the unit ensures that the nozzle, directed away from the tank side, is operational.

In a typical test, P43®s were used to resuspend approximately 2600m³ of sludge in a tank. After 15 hours operation, 2300 of these had been re-suspended. After a further 15 hours the total increased to 2500m³ – exceeding 90% efficiency.

After removal of the P43® de-sludging equipment, residues can be handled by conventional methods. Alternatively, the tank can be put straight back into operation for storing crude.

The P43® installation can remain in situ on a sale or rental basis for future two day ON LINE sludge re-suspension operations.

When permanently installed, the P43® controls sludge efficiently even while operating intermittently, depending on the conditions and characteristics of the crude oils.

Key Parameters & Materials

Height: 548mm (21.6 in)
Weight: 205kg (353lbs)
Nozzle Tip to Tip: 738mm (29.1 in)
Pressure Rated: 20.6 bar (300psi)
Temperature Rating: -10°C to 93°C (14°F to 200°F)

Main Body: Aluminium Bronze. 
Nozzle Body: Ni Resist S.G. Iron. 
Nozzle Tip: Aluminium Bronze. 
Gearcase Components: Phosphor Bronze, Aluminium Bronze, Stainless Steel. 
Fastenings: Stainless Steel
‘O’ Rings: Viton


P43® sludge resuspension FAQs


P43® sludge resuspension FAQs


For Shell mounted P43®s, what prevents the crude from discharging against the tank shell?

The shell mounted P43® is designed with an internal baffle that only permits discharge of crude through the nozzle which is facing away from the tank shell.

Does the P43® cause rotation of the tank roof and/or does the jet impinge on the roof?

Based on all operating experience to date, the pressure of the roof seal against the tank shell coupled with the anti-rotational device already installed in the tank, have been sufficient to prevent any rotation of the floating roof. This was true even in the case of the 500,000 barrel crude oil storage tank with only 12 feet of oil in which three shell mounted P43®s were installed and all three machines lined up resulting in a measurable rotational movement of fluid in the tank. Because the P43® directs the jets of crude across the tank bottom, there is no direct impingement of the jet on the tank roof. The observed level of activity on the tank roof during P43® operation is no greater than one would see from the operation of side entering propeller mixers.

What is the effect of the P43® on tank internals such as heating coils, roof drains and water drawoff lines?

Care should be taken in the installation of the P43® to ensure that the centre line of the jet does not directly impact tank internals in the vicinity of the P43®, as this would reduce the penetration of the jet. For purposes of a detailed structural analysis on the impact of the jet on tank internals, the following equation may be used to determine the centre-line velocity of the jet at any distance from the P43®:

U = 0.1776 x Q/KD

Where U = Jet Centre Line Velocity (Ft/Sec)
Q = Flow per Nozzle (USGPM)
K = Distance from Nozzle (Feet)
D = Nozzle Diameter (Inches)

Based upon our operating experience to date, no damage has occurred to roof drains or water drawoff lines resulting from the P43®. Tank internals should be secured from drifting off supports, in most cases this has already been done with U-Bolts.

Can you use cargo hose and temporary piping for installing a P43®?

Yes. In fact, in the initial tests that were conducted at the Gulf Terminal in Ireland and the Gulf Refinery in Milford substantially reduced the capital cost of the P43® installation and made it an economically attractive alternative to conventional desludging methods.

How much clearance must be provided between the bottom of the P43® and the tank floor, and the tank shell and the P43®?

The only requirement is that the P43® must not rest on the tank bottom and that enough clearance is provided between the nozzles and the tank shell to permit free rotation of the P43®. As a general rule of thumb, the bottom of the P43® should be 75mm from the tank bottom and the centre line of the flange to which the P43® is attached should be 500mm from the inside of the tank wall.

How can you tell the shell mounted machine is installed correctly?

Look down through the inlet of the machine past the impeller and you will see the baffle that prevents discharge against the tank shell. The P43® should be installed such that the open area symmetrically faces to the centre of the tank and the baffle symmetrically faces the tank shell. There is also a notch on the edge of the casting below the inlet flange.

How far are the nozzles from the tank floor and is this dimension critical for the installation?

The P43® nozzles are approximately 20-30 inches above the tank floor. As the P43® resuspends sludge through a combination of direct jet impact and jet entrainment, this dimension is not critical. As a general rule of the thumb, the P43® should be mounted with the nozzles as close to the tank floor as possible, while minimising the impact of the jet centre line with tank internals.

Does the P43® fit through 20 and 24 inch manways?

Yes. However, installation often requires the removal of one or both of the nozzles from the P43®. The machine is then installed through the manway door and the nozzles reattached by reaching in through the manway and bolting them on to the P43®.

What is the service interval on the P43®?

The P43® has been designed with the service interval of seven to ten years. The service programme for the P43® requires the customer to contact Veolia Environmental Services when service is needed on the machines.

Are there any problems with static electricity during the operation of the P43®?

No. Crude oil is not an accumulator of static electricity. Therefore, as the jet is submerged and there is no misting of the hydrocarbon, static build-up and subsequent discharge is not a factor in P43® use. For non-crude service, such factors as conradsen carbon number, electrical conductivity and vapour pressure of the liquid to be circulated with the P43® must be examined on a case by case basis to determine the potential hazard from static electricity.

How much oil must be in the tank to operate the P43®?

In general, the recommended minimum level of oil is such that the tank roof is floating with the roof legs in the high position. The roof legs should then be raised to the low position during the operation of the P43®, so as not to impede the jet penetration. The P43® is equally effective with the tank completely filled with oil. The greater amount of overhead oil the better the solubility.

Would you expect an increase in hydrocarbon loss due to the turbulence resulting from operation of the P43®?

No more than you would expect from the operation of side entering propeller mixers. In fact, as the integrated amount of energy inputted by the P43® is less than that inputted from the operation of side-entering propeller mixers in any given month, the hydrocarbon emissions resulting from mixing will probably be less.

With the nozzles of the P43® being between 20 and 30 inches off the tank floor, how is the P43® capable of picking up sludge underneath the nozzles before the jet has impacted the sludge?

The P43® resuspends tank sludge by two mechanisms. The first, in the region immediately adjacent to the P43®, is by way of jet entrainment. The effectiveness of this mechanism for sludge resuspension has been demonstrated in all cases. The second mechanism is direct jet impact on the tank sludge which occurs within 15 or 20 feet of the P43® due to the expansion of the jet at approximately a 14° angle.

How effective is the P43® at mixing tanks?

A centre mount P43® was permanently installed in tank number C3 at the Irish Refining Companies, Whitegate Refinery. The tank, which is 150 feet in diameter, was filled with approximately 24 feet of water. The P43® system was connected to the refinery fire water which was used to run the P43® during the test. Due to limitation of the fire water system, the P43® would only be operated at 57% of its rated flow. This corresponded to a mixing horse power input of .3 horse power per thousand barrels.

As the P43® was running, a dye, Rhodamine WT, was injected in the P43® feed line. Water samples were taken at 2 minute intervals from dip hatches located 90° apart on the tank roof and analysed for dye concentration. A steady state concentration of dye, signifying complete mixing of the tank contents, was reached in approximately 30 minutes. The concentration profile followed the classic pattern for tank mixing and demonstrated the ability of the P43® to rapidly turn over the tank volume.

The results of analyses of BS and W on oil samples taken at 2 metre intervals in a 500,000 barrel crude oil storage tank following the operation of the P43®, showed that the P43® not only resuspended the 3 feet of sludge uniformly deposited across the tank bottom, but could yield an almost uniform concentration of BS and W throughout the entire depth of the tank.

Once mixed, how long does the sludge remain in suspension?

Only 3 inches of the approximately 3 feet of sludge that was resuspended in a 500,000 barrel crude oil storage tank, at the Gulf Trans-shipping Terminal in Bantry Bay, redeposited in one month’s time. In addition, oil samples taken every 2 metres, one month following the operation of the P43®, indicated that there was virtually no restratification of the tank contents based on BS and W analyses of these oil samples.

What are the downstream impacts from processing sludge following a tank cleaning with a P43®?

A centre mounted P43® was permanently installed in tank number C3 at the Irish Refining Companies, Whitegate Refinery. The tank remained unmixed for five months. During this period, approximately two cargos per month were transferred in and out of the 150,000 barrel tank for processing in the refinery. Because the tank was unmixed, approximately 3 feet of sludge accumulated in the tank bottom. During the fifth month of operation as the tank was being filled, flow from the tank inlet was diverted to the P43®, thereby utilising the tanker cargo pumps to operate the P43®. In the nine hours during which the tanker was discharging to the tank, the sludge was completely resuspended in the overhead oil. As expected, the crude in the tank was off specification in BS and W and could not be directly processed. To circumvent this problem, crude from the tank with the P43® was blended with crude from another tank in a one-to-one ratio, so that composite crude was within specifications for processing. If the P43® had been operated, as recommended during this five month period, one day per tank per month, the crude would have been suitable for direct processing.

The concentration of salt in this composite crude was reduced to acceptable levels by the desalter. Effective removal of this salt should minimise the thermal fouling tendencies of the crude. Operators were instructed to be on the lookout for evidence of fouling while processing this crude and no problems were reported. In addition, all products resulting from the processing of this crude were on specification. The only operating problem that was encountered was an overcurrent in the desalter due to the abnormally high BS and W in the feed crude. This problem could have been avoided by adjusting the ratio of the crude blend. Alternatively, a chemical demulsifier could have been injected into the crude tank as the P43® was being operated. This would have resulted in a crude sludge mixture with substantially lower BS and W and possibly would have rendered the crude suitable for direct processing.