The first thing that needs considering is the nature of the contents; any hardening of the residue or its viscosity and therefore if any diluents or heat are required, the atmosphere created within, and also if the contents are a product and if they are to be recovered?
Next would be questions on the tank construction; what is the tank diameter, what access to the tank internals is available, are there any obstacles inside?
Our clients have a budget and/or time scale to meet and be considered. When all these things are looked at in detail the appropriate method will be chosen, our preference is always to offer the solution which is either non entry or minimal entry cleaning.
Product tanks KHIDMAH Industrial Services have cleaned include but are not exclusive to;
|Crude Oil||Diesel/Gas Oil||HFO|
|Kerosene||Fuel Oil (Feed)||Leaded Petrol|
|Sulphur||Cat Fines||Acetic Acid|
A hydraulically driven dozer would be selected where the residual product in the tank is viscous and/or with a high proportion of solids. If the client requests no entry or if the tank is un-safe then a remote dozer is operated from the manway and can negate the need for any entry to confined spaces. For tanks containing steam coils or other internal obstacles and this is when the dozer would be need to be manned for optimum safety, the entry time is still vastly reduced as the trained operator on the dozer can do the work of many men making light work of large diameter tanks.
Whichever dozer is the most appropriate they are both an efficient manner to move and mix tank bottoms with banks of sludge. The anti-spark blade and tracks enable the top lighter layer of liquid to combine with the sludge settled on the bottom and the blade can balance any banks of sludge throughout creating a more uniform pumpable mix and efficiently drive the sludge to the suction point.
During this process, if appropriate, the thinner diluent would be added homogenising the components to create a sludge much easier to handle.
The dozers are all certified and the diesel powered hydraulic power packs required to drive the dozer and pump are fitted as standard with Chalwyn Valve and Spark Arrestor allowing this to be used in oil tanks and the operator of the manned dozer can still wear Breathing Apparatus (RPE) during the de-sludging process.
The Cannon is an alternative non-entry method of mixing a diluent in to a tank with a viscous product high in solids re-suspending the settled solids. The cannon is attached to one or more manways, depending on the tanks size and number of roof manways available, the tank is then resealed and the cannon jet is operated from a purpose built container which houses all the equipment. Due to the agitation involved certain products are not suitable for use with the cannon without a means of atmospheric control in place.
All operations are carried remotely, with no need for confined space entry, from a control room within a specially designed 20ft container which also houses the generator, pump, electrical panel, hydraulic power pack and umbilical hoses in separate compartments. The tank atmosphere can be controlled by nitrogen purging or ventilation during operations and the cannon has a gas detector to automatically shut down should unsafe atmospheric conditions arise. The cannon is capable of rotating 200o in the horizontal and in the vertical giving excellent coverage and with the integrated Zone 1 light and low-light camera for operator viewing ensures a thorough clean. With this range of movement the cannon is able to point upwards meaning underside tank roof washing is able to be began at this stage and the system is capable of being modified for roof manway applications and entry.
KHIDMAH Industrial Services can offer a sludge profiling service prior to the use of the canon system to ensure best use of the cannon and sludge quantification.
The cleaning of a tank internals using an automated spinning nozzle is a preferred option and eliminates the need for scaffolding within a confined space. This method can also enable the walls and roof to be sprayed at the same time and used along with the KHIDMAH Industrial Services A frame there is no dependency on the number of roof manways.
Dependant on the tank size and product KHIDMAH Industrial Services can provide a range of sized systems all of which have a low torque rotary jet allowing them to be used with low water supply pressures. A Frame for mounting nozzles inside the tank has been designed and manufactured in house, it is designed to be dismantled to small enough components to be passed through a manway and re-assembled inside the tank. The frame is often placed in the centre to give an overall wash but it can be moved to as many positions as necessary for full coverage of large diameter tanks. The washings can be re-circulated until the desired cleanliness is reached or until product saturation is reached and can be completed with a fresh water rinse if required.
Khidmah have sound knowledge of the chemical washing agents used and have chemists on hand to look at any difficult tank residues so the correct agent is used enduring a safe, rapid and complete clean is achieved first time.