Vacuum Toilet Pipe descaling System

The Problem

Waste water pipe DE-SCALING.

With time, the pipework of a marine sewage system becomes progressively lined with a build-up of calcium, magnesium hard water scale and struvite deposits.


The subsequent reduction in the cross sectional area of the pipe leads to reduced flow rates and eventual blockages in the system.


The Benefits of the Marinevac System

All toilets remain in working order and cleaning can be conducted with a full complement of crew during normal operations.

  • No flushing hoses around the ship
  • Unit is small, mobile and easy to set up
  • Reduced risk of leaks or spillages due to pipe work being under vacuum
  • Not detrimental to biological process of STP
  • No dismantling of pipe work

This method of cleaning is currently the preferred procedure on many Superyachts, large Cruise Ships, Oil Rigs the British Navy & Royal Australian Navy.

We believe that this is by far the best available technology and method for pipe cleaning available today, and eliminates all OHS&E issues that usually arise while using any other conventional method.

Contact us to discuss your Vacuum de-Scaling requirements >>>

The Problem

Imagine the nightmare scenario;
…it is the middle of the season with a full compliment of guests and crew and your toilet system blocks up!
This would not only be an embarrassing issue for the Captain, crew and guests on board but could be extremely costly and difficult to rectify at short notice.

Scale build up in vacuum pipework is a result of calcium and magnesium hard water scale and struvite deposits. Struvite is deposited in a variety of forms dependant of the pH of surrounding media, either as rhomboid, platelet or needle shaped crystals, these provide a larger surface area which traps and encourages the deposition of Magnesium and Calcium hard water scale. The scale can build up rapidly and consequently reduce the bore until nearly or completely closed. Such a restriction will cause blockages in the vacuum line and can result in major issues within the system and even flooding.

The blockages are always difficult to locate and even more difficult to access and remedy, usually involving disruption of surrounding furniture and carpentry work and certainly downtime in the sewage system itself; major inconvenience to guests and crew alike.

An annual cleaning of the vessels’ sewage system is the only way of avoiding this problem. And unfortunately, current cleaning solutions are inconvenient and, as many yacht’s engineers will testify, may cause more problems than those their purpose is to avoid!

Current Cleaning Methods

The common current methods of cleaning of vacuum cleaning toilet discharge pipe work all have their disadvantages and problems:

Periodical dosing from in line automatic dosing units

These units can be fitted to vacuum pipe work but can prove to be expensive and ineffective due to the following:

  • Units are fitted to the horizontal sections of pipe work leaving the risers untreated which in time will result in blockages.
  • Units positioned incorrectly along pipe runs resulting in inconsistent cleaning.
  • Continuous dosing of clean lines is unnecessary and expensive.
  • Increased man hours to maintain and monitor the chemical.
  • Dosing bottles require storage space for easy access.
  • Increased possibility of vacuum leaks from additional equipment.

Periodical dosing from the WC / Toilet

Small quantities of either naturally formulated or chemical products are flushed down the toilet at the end of each line. Unfortunately this remains ineffective over long pipe runs, as the products quickly dissapate and dilute within small sections of the pipeiline having little or no effect on the removal of large scale build up. This method is very time consuming, expensive and can also cause blockages further down the line by removing chunks of scale from one particular area.

Pour and soak method

Certain lines/toilets are taken out of operation whilst the lines are saturated in a mixture of acid and water. All toilet discharges must be plugged to ensure the acid does not get into the operating mechanisms. The lines must also be monitored regularly for leaks and be proved with water prior to administering acid. This method can cause damage and and will cause disruption of services on board the vessel. It is also important that the acid solution is not dropped to the tank too soon; otherwise blockages will occur (particularly with PVC pipe work).

Closed loop recirculation

Certain lines/toilets are taken out of operation whilst the lines are being cleaned. The line is broken into via a flange or valve and a return line connected to an acid recirculation bath and pump unit. The supply line is then connected to the vacuum central incoming flange and the acid/water solution plumped round the pipe work in a “close loop” system. More effective than the above methods, a better cleaning is ensured by removing air pockets. Again, all of the toilet discharges must be plugged to ensure that the acid does not get into the operation mechanisms. The lines must also be monitored regularly for leaks and mst be proved with water prior to administering acid. This method can cause damage and will cause disruption of services on board the vessel.

The Marinevac Solution

Our System is unobtrusive, safe and reduces the possibility of leaks. The self contained unit is compact and mobile.

The method is non-damaging to pipework, toilet mechanisms and biological sewage treatment plants. Single or multiple lines can by cleaned as required.

The cleaning technique can be performed without any effect or disruption to the vessel’s normal operation.

Our cleaning method is the only system available on the market which effectively cleans the vacuum toilet system whilst all of the toilets remain in operation.

The effectiveness and safe action of the Marinevac dosing unit cleaning method is due to:

Spiral Action

Previous experience has proved that the slug of sewage moves down the vacuum pipe work in a spiral action. Consequently, the chemical will move in the same manner, thereby ensuring that the complete wall of calcinate will eventually be coated with the chemical dilutant.

Little and Often

With the inherent spiral action the Marinevac dosing unit method only requires a small amount of chemical on a “Little and Often” basis, which would not be considered detrimental to the sewage treatment plant biological process, toilet mechanisms or pipe work.


The quantity and strength of chemical injected into the system in a normal cleaning cycle can be considered minimal and is usually discharged into the vacuum collection plant before disposal either directly overboard or to an STP. The solution eventually becomes diluted within the pipe work and tank contents.

The Result

As you will see from the before and after pictures below, the Marinevac treatment will remove scale build up of upto 90%, leaving the pipe completely clean.

At the time of cleaning it is important that the pipe work and the vacuum generation plant on board the vessel is in a good working condition.

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