Best Practice Guidelines for Safe tipping of Silo trucks/ Trailers Silo Containers and bag-in-box containers

Issue 1 November 2014

Introduction
Purpose
Scope
Risk Assessment
Requirements of the Unloading Area
Tipping Taking into Account the Product Characteristics
Technical Equipment
Tipping Trailers for Containers
Requirements for the Driver
Requirements for Inspectors/Observers
Contact List
Annex 1: Example Risk Assessment at Unloading Place
Annex 2: Example Checklist to Risk Assess Unloading Site
Annex 3: Example Checklist for Inspector/Observer

Disclaimer

This document is intended for information only and sets out best practice guidelines for the safe tipping of silo trucks/ trailers, silo containers, and Bag-In-Box containers within the chemical logistics supply chain. The information provided in these guidelines is accurate to the best of the authors' knowledge but is not warranted for completeness. It is not intended to be a comprehensive guide. Each company may apply these guidelines in full or partly, or apply any other adapted measures. No responsibility will be assumed by ECTA/Cefic in relation to the information contained in these Guidelines.

1. Introduction

In European land transport, silo trucks/ trailers, silo containers, and Bag-In-Box containers are frequently used for the transport of dry bulk chemicals, either granulates or powders.

The unloading of the above described equipment is undertaken by tipping, which places multiple requirements on the construction of the equipment, their proper maintenance, the unloading area conditions, and unloading procedures. Although serious accidents during unloading may be rare, many silo tank trailers and container trailers fall over or containers fall from the trailer while raised/tipped for unloading.

These accidents constitute a serious safety threat to personnel, drivers, and/or site operators surrounding the equipment and always cause additional important material costs. Causes for a fall over include high wind speed, mechanical failure rear support legs, unlocked twist locks, insufficient rigidity or level plane of the unloading area, incorrect way of working, and more.

2. Purpose

The requirements explained in this guideline are intended to prevent silo trucks/ trailers, silo containers, and Bag-In-Box containers from falling over or sliding off the chassis during the unloading in a raised position, causing injury to people or damage to equipment in the unloading area.

Adoption of these best practice guidelines is for each of the parties within the industry to decide how they introduce them, partly or fully, or any other adapted measures. This guideline should be part of an organisation's routine risk assessment and risk review process on how they can be implemented to meet the needs of the industry.

It is strongly recommended to implement these guidelines:

for assessing the unloading practices and driver training
for assessing the current unloading facilities and equipment
when building new facilities or taking into service new equipment

3. Scope

The aim of these guidelines is to prevent silo trucks/ trailers, silo containers, and Bag-In-Box containers from falling over.

The scope includes:

Minimum Requirements for Unloading Sites in Europe Concerning:

The unloading Area
The unloading Procedures
Driver Instructions
Checks during the unloading operations

Minimum Requirements for Hauliers Concerning

The unloading procedures
Minimum truck equipment required to allow safe tipping operations

Types of vehicles: silo trucks/ trailers, pressurized and non-pressurized aluminum containers, and "Bag in Box" 30-foot containers and "Lined" 20-foot and 40-foot containers on trailers.

These guidelines do not cover the dry bulk transport equipment that is discharged without tipping (e.g. hopper cars).

General Safety Requirements like:

Roles and Responsibilities
Site access, driver instructions, communications
PPE
Working at Height
etc.

These are described in the following ECTA guidelines:

BBS Safe Driving of Road Vehicles
Best Practice Guidelines for Safe (un)loading of Road Freight Vehicles, covering Technical, Behavioral and Organisational aspects.
Best Practice Guidelines for Safe Working at Height in the Logistics Supply Chain and Allied Sector
Best Practice Guidelines for Cleanliness of Rotary Valves and Unloading Equipment for Bulk Deliveries

More general information about the technical equipment for the transport of dry bulk cargo can be found in:

"ECTA/ CEFIC GUIDELINES FOR THE TRANSPORT OF DRY BULK CARGO TO BE DISCHARGED BY TIPPING."

More information on tipping lined Isobox containers:

ECTA "BEST PRACTICE GUIDELINES FOR THE SAFE USE OF ‘LINED’ ISO BOX CONTAINERS FOR MOVEMENT OF DRY BULK PRODUCTS"

All ECTA guidelines can be accessed via www.ecta.com and www.cefic.org.

4. Risk Assessment

4.1 General

The unloading site must perform a Risk Assessment (See Annex 1) to assess the potential impact on people and equipment like product lines, silo discharge lines, steam lines, pumps and compressors, buildings, car parks, (pedestrian) roads, and/or the site border fence, in the event a silo truck/ trailer, silo container, or Bag-In-Box container falls over or slides off the chassis during the unloading in a raised position.
The risk assessment should highlight actions that must be taken to mitigate the risk to an acceptable level. The risks assessment must take into account at least the following:

The “impacted area” also called the “danger zone”. This is the zone in which the silo truck or container can fall down when it tips over.
The unloading area (condition of the floor, other activities in the area, no overhead obstructions, etc.)
The unloading procedures
Training of drivers and operators
Degree of supervision (checks)
Equipment of the trucks
The product to be unloaded. Some products require maximum tipping at the start of the unloading process. For other products, tipping at the start is not necessary, and therefore not allowed. The risk for a trailer to fall over increases with the increase in tipping height of the silo tank/container and the weight of the product inside. Unnecessary raising must be prevented at all times.

Example of a risk assessment: see Annex 1

4.2 Danger Zones and Reduced Risk Zones for Drivers

The "Impacted" area which is shown as the ‘Danger Zone’ is highlighted in RED around the trailer and can be impacted in the event of a silo trailer falling over.

The zone which provides the least risk to the driver during the unloading process is highlighted in GREEN and is called the ‘Reduced risk zone’. This is the area for the driver to operate and observe the unloading process. In this area, the driver has the opportunity to step aside into a safe position in case the trailer falls over.

4.2.1 Silo truck/ trailer

Silo truck trailer danger zones and reduced risk zone

4.2.2 Container on trailer

The area behind the trailer can also be impacted if the container slides from the trailer during tipping.

40 ft. Container on trailer with danger zone behind the trailer

4.2.3 Multiple Danger Zones

In the event of two or more trailers unloading at the same time, it is possible that the danger zones may overlap. The distance between the trailers should be at least 16 meters. (In case of container on trailer the danger zone behind the container must also be taken into account and in case of 20’and 30’ feet container other danger zone dimensions are applicable).

Both silo trailers in tipped position with an overlapping danger zone

4.2.4 Danger zones depending on tipping height

The dimensions of the danger zone are based on the maximum tipping height of the different trailers types. However, in the case of unloading very fluid products, there is no need to tip to the maximum and the danger zone would be smaller with the exception that in case of a trailer with a container, the danger zone behind the trailer remains.

If a limited tipping height is one of the measures to reduce risks, adequate procedures must be in place to manage the drivers to comply with this limited tipping height because not tipping to the maximum is unusual for most drivers, and they will always tend to tip to the maximum. Consideration should be given to the installation of physical barriers to prevent exceeding the maximum tipping height.

4.2.5 Reduction of the danger zones by installing mechanical protection

To protect silos, buildings, facilities, traffic, site road/public road, or other unloading trailers, a construction, strong enough to hold a falling trailer, can be considered.

Mechanical structure to protect people/equipment/vehicles in the event of a silo truck falling over

4.2.6 Risk of Entrapment

While tipping up or down and besides a risk of falling over, there is also a risk of entrapment because of the movement of the tipping ram and other movable parts on the trailer. Therefore the danger zone must also be considered in all cases during tipping.

5. Requirements of the Unloading Area

5.1

The unloading area must be located within the site premises and NOT on the public road unless there is a permit from the local authorities and the unloading is done under controlled conditions (e.g. marking, fencing off the unloading area, etc).

Parked on a public highway with the discharge hose trailing across the pedestrian walkway

5.2

The access road to the unloading area must be easily accessible (e.g. sufficient width, spacious curves, no obstacles (height) and rigid surface with sufficient load-bearing capacities – see 5.4 below), to have sufficient space to maneuver to and from the unloading point.

5.3

In the event that reverse driving is necessary, a competent ‘guide’ is recommended to support the driver and to avoid damaging (e.g. construction, building, facility, or trailer). At the unloading place, a “reverse stop” either through signage or a physical barrier on the ground is recommended.

5.4

The surface of the unloading area must be firm and even. When tipping the trailer, forces up to 25 tons can be exerted on each stabilizing leg. The surface should accommodate this without deformation and should preferably be constructed of concrete. Asphalt can become too soft in hot weather. The rear leg support area design/strength should be based on calculation, taking into account sewer systems or underground pipes close to the rear legs' position.

Not OK Not OK

5.5

The layout of the unloading area must allow the traction unit and trailer to be positioned in a straight line.

5.6

A slight longitudinal slope of the unloading place is acceptable, but lateral angles of slope (left to right across the chassis) are not.

Not OK Not OK

5.7

The surface of the unloading area should be made of suitable material to minimize dust and other material (e.g. gravel) to avoid contaminating the product. The working area should be adequately anti-slip, properly drained, frequently cleaned, and kept free of snow, ice, and tripping hazards.

5.8

There should be no overhead obstruction in case the trailer is tipped to the maximum height (e.g. overhead lines, gantries, or electric power cables).

Not OK Not OK

5.9

The unloading area must be adequately lit for unloading activities during hours of darkness, covering the complete area and trailer.

5.10

The unloading area must have a fit-for-purpose and properly marked earthing connection, preferably with a positive earth prove indicator.

Earthing Indicator

5.11

A spill kit must be available in case of leakage of hydraulic oil, diesel, or cooling water at the unloading location or site.

5.12

The average unloading time is between 1 and 2 hours. During unloading, the driver must stay in the vicinity of the trailer in the reduced risk zone to observe the process. A shelter should be provided outside the danger zone behind the trailer with a free view to the rear of the trailer for the driver to protect against adverse weather conditions. Moreover, a restroom within walking distance should be made available.

5.13

The unloading site must have a wind speed meter (anemometer) and alarm system/procedure to stop and/or adjust the unloading activity in case of strong wind. Average wind speeds above 4 on the Beaufort scale (6.5 m/sec) increase the risk of tipping over. The risk assessment needs to consider wind speeds, wind directions, and the physical layout of the unloading place.

5.14

If the unloading site requires a sample from the top of the silo tank or container, provisions to work safely at height must be implemented (e.g. stairs, fall arrest systems in combination with safety harness). More guidance is available from ECTA/Cefic in the guidelines for Safe Working at Height in the Logistics Supply Chain and Allied Sectors.

6. Tipping Taking into Account the Product Characteristics

6.1 Different Types of Products

The flow characteristics of the product to be loaded, transported, and unloaded significantly impact the selection of the transport solution. The producer of the product, along with the haulier, needs to determine the fluidity of the product and the way of discharging.

The driver must be informed/trained, understand the differences between products, and account for risks like avalanching during discharge.

6.2 Tipping Free Flowing Products

Products like Polypropylene, Polyethylene, PVC granules, or other free-flowing products do not require tipping at the start of unloading. Tipping can be done step-by-step as needed during unloading. Products vary, with some requiring tipping only to the first ram and others to a higher level for full emptying. Tipping higher than necessary should be avoided.

6.3 Tipping Products with Avalanche Risk

Powders like chalk that can cause product 'bridging' require maximum tipping before unloading starts to ensure smooth flow. Such products cause mass falls that can result in tipping incidents, making specialized equipment or fluidizing equipment necessary to mitigate this risk.

6.4 30’ BIB Containers

For products with avalanche risk, particular attention must be given to fluidizing and tipping processes. Under specific conditions and a risk assessment, tipping without stabilizing legs can be justified. The use of rear stabilizing legs under any conditions is encouraged.

7. Technical Equipment

7.1 Minimum Equipment Requirements

7.1.1 Introduction

Tipping equipment on a trailer is considered machinery under EC Machine Directive, requiring CE marks asserting that the equipment meets health and safety standards. For trailers without a CE mark, a CE Risk Assessment and potential retro-fitting are mandated.

7.1.2 Tipping Mechanism

The tipping mechanism must have a Dead Man’s Switch that requires constant pressure to operate, halting tipping if the operator ceases engagement. Placement at the rear corner is critical for safe operator egress.

7.1.3 Remote Control on Silo Trucks

While not advisable for containers, remote controls help keep operators out of danger zones.

7.1.4 Twist Locks

Twist locks made for tipping applications must be used, equipped with indicators for open/closed statuses visible to the driver.

Front Indicator Back Indicator

7.1.5 Level Indicator

Trailers should feature level indicators, especially at the rear, to confirm proper leveling before tipping.

7.1.6 Rear Stabilizing Legs

Rear stabilizing legs should be mechanically reliable and robust, used to support the trailer and ensure stable tipping. Proper maintenance and in-use checks are crucial.

7.1.7 Safety Clamps/Locking Pins

Various connection systems should be employed to ensure hoses do not disconnect during unloading, such as Guillemin coupling and others as shown.

7.2 Additional Safety Equipment

Incorporate evolving technology and safety features on trailers as they become available, including sensors for detecting stabilizing leg positions and twist-lock statuses.

7.2.1. Sensors on Stabilizing Legs

Sensors may be installed to ensure rear stabilizing legs are correctly positioned before tipping begins.

7.2.2 Interlocked Sensors for Twist Locks

Twist-lock interlock sensors prevent the trailer from tipping if locks are not secure, ensuring safe operations.

7.2.3 De-pressure Valve at Working Height

Devices should be installed to allow for safe de-pressurization from the ground level.

8. Tipping Trailers for Containers

8.1 Chassis Body

Chassis bodies must undergo regular inspection and maintenance to ensure structural integrity, particularly when used for lifting operations. Materials used should be type-approved for the intended design.

8.2 Heel Plates

Primarily used for container positioning, heel plates do not significantly contribute to safety in case twist locks fail.

Heel Plates

8.3 Toe Plates

Toe plates, which have short horizontal beams running under the container, help ensure proper positioning and aid in keeping twist locks correctly oriented.

Toe Plates

8.4 Front Bolster Bar

A front bolster bar spreads load evenly across the container bottom rail, while tipping.

Front Bolster Bar

8.5 Rear Bolster Bar

Regular maintenance of the rear bolster bar, which serves as the pivot point for tipping, is crucial.

Rear Bolster Bar

8.6 Side Beams

Side beams linked to front and rear bolsters provide additional safety by ensuring a rigid and stable bed for containers during tipping. Though they add weight, they improve overall safety.