Tankers

 

Tank Vehicle

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These are vehicles that have a fixed tank attached to it.  This may be one or more tanks, and the tanks may have compartments.  The tanks have one or more shells.

 

Tank Container

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These are tanks that are removable.  Tank containers carry the same substances as those in fixed tanks, though in the case of Class 2 (gases), the capacity is greater than 0.45m3 or 450l.

 

MEGC

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Multi-element gas containers comprise of several gas containers permanently connected to each other.

 

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The design and build of new tankers must be approved and certified by the competent authority within that state, where then it will be recognised by international authorities.  This certification occurred after April 2004, so tanks built before this date may still be used for UK national journeys without an approval certificate.

 

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​Tankers carrying dangerous goods are classed as either FL (flammable) or AT (anything else).

 

The tanker plate

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A metal plate will be fixed at the tank in a conspicuous place readily accessible for inspection.  The plate will show:

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the country of manufacture

the country of approval

manufacturers name and serial number

authorised body for design approval

owners registration number

year of manufacture

the pressure vessel code

test pressure

maximum allowable working pressure

external design pressure

design temperature range

the water capacity at 20°C

internal pressure test date and witness

the maximum allowable working pressure for the heating and cooling system

shell materials equivalent material in reference steel in millimetres

lining material if required

date and month of the most recent periodic test

stamp of the experts who carried out the most recent test

 

Any unloading of petrol tankers must be carried out in accordance with the approved code of practice and UK domestic regulations.  The approved code of practice explains the responsibilities of everyone involved.  This booklet includes the dangerous substances and explosive atmospheres regulations 2002.  Nominally empty tanks that are empty but not washed or purged are still subject to regulations.  The transport document entry should be preceded by the words ‘empty tank vehicle last load …’

 

Loading tankers

 

Open loading

 

This is generally gravity loading and is through the inspection hatches. The disadvantage is that the product can escape into the atmosphere, or the product can become contaminated.  Bottom loading with inspection hatches open is a form of open loading too. 

 

Closed loading

 

This is where the product is pressure after pumped in through the tank outlet or inlet valve.  This can be used for liquids and gases.  It is essential to balance the pressure in the tank container and storage tanks, so a vapour recovery line is used. 

 

 

Before the commencement of loading always check:

the right premises and the right loading point

your tank is appropriately cleaned and purged (or nominally empty / part filled, depending on operation)

hoses are cleaned and serviceable and correct for the product

correct PPE as per site rules and instructions in writing

your vehicle is immobilised during operation

the vehicle is earthed if required

with tank containers,  make sure the all twist locks are closed

no smoking

 

Earthing

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This is essential for flammable materials.  An earthing cable is connected to the tank via recognised earth point.  This reduces the build up of static which builds up when liquids or powders flow or swirl through pipes and tanks.   A scully system may be used that ensures static charges are within safe levels before loading and unloading operations can start.  

Substances such as resin or lacquer are carried in tanks and to prevent sticking to the internal surface, a solvent is used.  Ensure the tank vehicles have appropriate carriers fitted to carry the drums of solvent.

 

Discharging tankers

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Gravity discharge

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The tank vehicle is connected via a hose to the receiving tank which is at a lower level.  The tank must be vented (air allowed in) to prevent implosions.

 

Pump discharge

 

A hose, jumper hose or manifold is connected form the tank outlet valve to the cargo pump.  The product is drawn from the tank and pumped out.  The tank must either have internal pressure balanced by venting or by a vapour recovery line.

 

Pressure discharge

 

A vehicle mounted or site based compressor is connected to the tank through an air inlet system.  The compressed air (normally 30 psi or 2 Bar) forces the product out.  Usually used for corrosive substances.  Always decompress the tank before opening inspection hatches for washing or reloading.  There could be several tonnes of pressure within the tank.  For this reason, inspection hatches are fitted with safe bolts.  These prevent opening under tank pressure.  Safe bolts are secured first and opened last.

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Certain tanks (usually powder) are tipped for discharging.  Outriggers must be deployed as appropriate.  Any on board equipment must be used at the settings recommended by the manufacturer.

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Wastes are often sludgy and are usually transported in specially designed waste tanks.  These are designed to tolerate vacuums and have a large opening hatch at the rear to aid cleaning.

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Hazard Warning Panels

 

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These must be orange, except for the part where the placards are placed.  The placards must be no less than 200 x 200mm, with a line of the same colour as the relevant symbol not more than 12.5mm inside the edge and running parallel to it. If more than one placard is to be used in the panel, they are placed on the same horizontal plane (in other words, at the same level and to the side).  The panels must be clearly visible, and be kept clean.

 

If displayed on a tank constructed on or after 1st January 2005, the orange coloured plate shall be indelible and remain affixed irrespective of the condition of the vehicle.

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Dimensions:

Overall width not less than 700mm

Overall height not less than 400mm

The primary panel (containing the EAC and UN number) width is 400mm

The primary panel height is 300mm

All borders are black, 15mm

 

Interchangeable numbers and letters must remain in place during transport, irrespective of the orientation of the vehicle.

Folding placards must be designed and secured so that they do not open during transport even as a result of impact or unintentional action.

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The Specialist Advice Phone Number gives advice concerning the dangerous goods obtained in English and must be available at any time during carriage.  ‘Consult local depot’ or ‘Contact local depot’ may be displayed if the name of the carrier is clearly identifiable on the vehicle, and the fire and rescue authority (or the Scottish chief fire officer) of each area the transport unit will travel through have been notified in writing and given written satisfaction with the arrangements;

Emergency action codes are used for UK domestic loads.  ADR uses hazard identification numbers.

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The EAC is made up of two or three digits.  The number gives the type of extinguisher to be used, the letter gives the required PPE to be used in emergency and the likelihood of violent reaction, and the letter E indicates a public safety hazard.

 

The extinguishers are numbered one to four.  Any extinguisher that is the same number or higher may be used.

 

1. Course water spray

2. Fine water spray

3. Foam

4. Dry agent

 

The table below relates to the second digit of the code.

 

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When the hazard warning panel was invented in 1975, there were no requirements for subsidiary hazards to be displayed.  The class placard within a hazard warning panel is 200mm x 200mm if it is incorporated within the hazard warning panel, otherwise the placards must measure 250mm x 250mm.

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Multiload vehicles display a plain orange plate at the front of the vehicle.  Hazard warning panels are displayed on each side, with the appropriate UN number for the product in that compartment. Other compartments have the UN numbers displayed.  At the rear is a hazard warning panel with the EAC and placards, but the UN number is left blank.

 

The combined EAC is calculated using the following procedure:

The highest number of extinguisher is used

The letter is found using the combination table below

If the letter E is present, it is retained.

 

As an example, if a multi-load consists of methanol (UN1230, EAC 2WE) and isopropyl benzene (UN1918, EAC 3Y) the combined EAC is 3WE.

 

Fuel tankers that carry only petrol, kerosine or diesel are normally multicompartment.  Unlike other multi-compartment tanks, fuels show markings as if they were a single load.  The tank is marked up according to the most dangerous product, the order being petrol > kerosine > diesel.

 

IMDG requirements

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Tank containers and detached tank trailers show placards on all four sides, and the proper shipping name on two sides.  Tank vehicles show the placards on the sides and back.  For single product loads, the UN number is displayed in the lower half of the class placard, or on a rectangular orange panel alongside.  The marine pollutant environmentally hazardous substance placards are displayed where appropriate.  Any markings for IMDG must remain attached for at least 3 months in the sea.

 

ADR requirements

 

Vehicles carrying a single substance will have an orange plate at the front and rear of the vehicle with the hazard identification number in the top and the UN number in the lower half.  Class placards (both main and subsidiary) are displayed on both sides and rear.  Multiload tankers show plain orange plates front and rear.  Main and subsidiary hazard placards are displayed at the rear.  Orange plates displaying the HIN and UN number, along with placards show in line with each compartment.

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Hazard Identification number (HIN)

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This was previously known as the Kemler Code.  The code is as follows:

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1. Emission of gas due to pressure or chemical reaction

2. Flammability of liquids (vapours) and gases, or self-heating liquids

3. Flammability of solids or self-heating solids

4. Oxidising (fire intensifying) effect

5. Toxicity or risk of infection

6. Radioactivity

7. Corrosivity

8. Risk of spontaneous or violent reaction

 

Where the hazard can be adequately indicated by a single figure, this is followed by a zero, and doubling of the figure intensifies the hazard.  Some HINs have a special meaning such as 22 being a refrigerated asphyxiant gas.  If an X is present at the end of the HIN, it indicates a violent reaction with water.

 

UK Single Compartment Tanker

 

 

 

 

 

 

 

 

A plain orange plate is displayed at the front of the vehicle.  Hazard panels are on both sides and the rear.

 

UK Multiload Tanker

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A plain orange plate is displayed at the front of the vehicle.  Hazard panels are on both sides and the rear.  The UN numbers are displayed in line with each compartment.

 

ADR Single Compartment Tanker

 

 

 

 

 

 

 

 

Orange plates front and back (optionally on sides) displaying the HIN in the top half and the UN number in the lower half.  Class placards are displayed both sides and rear of the vehicle.

ADR Multiload Tanker

 

 

 

 

 

 

 

 

Plain orange plates on the front and rear.  Orange plates in line with each compartment displaying the HIN UN number for each product.  Class placards are displayed as appropriate on each compartment on the sides.  If they all share the same class, one placard may be used.  All relevant placards are displayed at the rear of the vehicle.

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There are many different types of tanks, these are designed and constructed in accordance with their intended purpose.  LPGs are carried under pressure, in steel tanks with thick shells.  Some gases need to be refrigerated, so cryogenic tanks are insulated.  Flammable liquids are generally transported in lightweight tanks such as aluminium in order to maximise the payload; discharge is either by pump or gravity.  Powders and granules are transported in tanks that generally tip and discharge by pressure, and sometimes a vibrating plate is used to fluidise the product.  Some substances (such as bitumen and phenol) are transported hot.  These tanks are insulated and may also have steam heating under the tank.  Tanks used for the carriage of dangerous goods may not be used for foodstuffs.  Corrosive substances are generally transported in stainless steel or rubber lined tanks and are discharged by pressure.  Tanks that don’t use pressure to discharge are atmospheric tanks.

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Most tanks may not be offered for carriage if:

The degree of filling is more than 20% but less than 80% unless the tank has separate compartments or surge plates in sections no larger than 7500l;

Residues adhere to the outside of tanks.

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Inspection lids (a.k.a. man lids or filling hatches) seal using a ring under them.  The seal must be able to withstand the product carried.  The hatch or lid is usually fastened down with winged bolts.  Safe bolts are used on pressure tanks and prevent the lid opening under pressure.  They are closed first and opened last.  

Dipsticks may be used to measure the level of liquid inside the tank.  The correct dipstick must be used that resists the substance carried.

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Pressure relief valves are spring operated safety devices that open when the pressure increases to a set amount, and allows venting into the atmosphere.  Vacuum relief valves, like the above pressure relief valves, these operate at a set low pressure to prevent implosions.  Pressure vacuum relief valves do both the above at the same time.  Bursting disks are fitted below the above valves to prevent products contacting and potentially damaging the valves themselves.  A tell tale pressure gauge is fitted between the bursting disk and the valve.  If this reads anything other than zero, the bursting disk needs to be replaced.

 

Tank implosions occur when the pressure in the tank reduces to the point the atmosphere crushes it.  This occurs during delivery, when the vapour line isn’t opened in all but pressure discharges.  It also occurs following a hot wash out, when the inspection lids have been closed immediately.  Pressure gauges show internal tank pressures and delivery hoses in PSI or bar.  There may also be thermometer gauges to show internal tank temperatures.  Flame traps or spark arrestors are used to prevent ignition of flammable gases.  Fusible element is fitted as an aid to the pressure relief valve in the event of a fire.  These are made of a low melting point metal alloy that melts when hot enough allowing significantly more venting of vapour from the tank.  The internal valve or foot valve is fitted inside the tank or compartment.  These effectively seal the tank or compartment from the inside, so in the event of damage to the external valves there is no loss of substance.  These valves are manually operated on some tanks and pneumatically operated from ground on newer ones.  The external outlet valve, otherwise known as the faucet or API (American Petroleum Industry standard) is operated by the driver.  On some tanks a break interlock system is attached to this outlet.

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All seals such as washers in loose ring connectors, flange gaskets or man lid seals must in be good working order and resist the action of the goods being carried.  Connections must no be allowed to leak.  Hoses vary according to the substance below delivered. It is essential to use the correct hose for a particular substance.  Elevated temperature liquids for example will require a hose suitable for high temperatures.  Any damaged or defective hoses must be reported.

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Flange connections are generally used for corrosive substances.  These use bolts to connect to the opposite face.  It is essential to ensure that the bolts required are used and have a suitable gasket or packing in place and correctly fitted. Flanges are normally measured in tables. Table D is the most common size used.

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Emergency shutoff valves may be fitted to some tanks the driver should know where they're located, what they shut down and how to isolate them.  Most are pneumatic and close the foot valve.

 

Excess flow valves may be fitted between the tank outlets and the delivery hose.  This is normally used for deliveries into the bottom of a stock tank where the delivery hose is likely to be under great pressure.  The valve automatically slows the flow rate down should it be too high, and also automatically closes the hose off should a rupture occur.

 

For tank deliveries:

• Report to the person in charge

• Follow the site rules

• Use the correct PPE

• If required, provide a sample

• Make any connections leak proof

• Check that you have vented the tank or used a vapour recovery line

• Check the load is discharge into the right tank

• Check ullages

• Ensure the vehicle cannot move – brakes and / or chocks

• Follow the correct procedure for driver controlled deliveries as well as for attended deliveries

 

If your delivery note contains a pre-delivery signature request, GET IT SIGNED BEFORE COMMENCING A DELIVERY.

 

Static electricity can cause flammable atmospheres (gas, vapour or dusts) to ignite.  Static is caused by friction as the product flows through pipes and swirls in tanks.  Operations must be earthed prior to product movement.  Clothing should not be made of a material that is likely to cause a spark.  Where appropriate, anti-static and flame retardant PPE is used, however these require specialist cleaning.

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For deliveries of flammable products, non-ferrous tools and fittings should be used to prevent sparking when dropped.

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Tanks are cleaned out at special stations when necessary to prevent product contamination.  The driver is responsible for providing information on the last load carried.  Liquid tanks are washed out and dried, gas tanks are purged.  All the ancillary equipment such as hoses and pumps also require cleaning.  The clean certificate issued after cleaning is usually valid for 24 hours, and is required before the tank is loaded with another product.  In some circumstances, manual cleaning is required – someone goes in the tank, however this is a specialist operation.  It is very important not to close the inspection lids after cleaning to allow the pressure to equalise, or tank implosion is a possibility.

 

Liquids and powders may surge as the vehicle accelerates, brakes or turns which then affect vehicle stability.  Tanks are fitted with baffles to prevent excess product movement.  Drivers must be aware of how to perform an emergency stop whilst keeping the vehicle under control.  Rollovers can occur at low speeds if the vehicle is turned too quickly.

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