drag boxes mgf technical file
TRANSCRIPT
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2.3.1Issue 4
DescriptionSimple to assemble, two sided mechanical shield system designed to be installed by an excavator utilising the excavate and drag technique.
Normally selected for installing utility pipes in non-urban enviroments where high laying rates are required and where large ground movements are not critical. Size of system specified is dependant upon max depth requirements and size of individual pipe sections and bedding. The system works by using a raised back strut system at rear of panel to allow the box to be dragged over and above the installed section of pipe. Generally suitable for trench depths of up to 3.25m and trench widths of up to 3.0m, pipe lengths of up to 6.6m and a pipe OD of up to 2.2m.
Fabricated from fully welded Grade S355 120x60mm or 200x100mm steel box sections to form 60mm or 100mm thick panels, the system comprises drag panels in a variety of lengths and heights. The panels are propped off each other by robust telescopic struts available in a variety of lengths to suit the required width. All components in the system are connected together via simple pin and clip assemblies.
MGF can supply the systems with a full range of suitable lifting and extraction chains, Edgesafe edge protection panels, Laddersafe access platforms and pole ladders, Davitsafe retrieval / fall arrest systems, Endsafe protection panels, trench road plates and confined spaces regime equipment.
Manufactured and designed in accordance with BS EN 13331 : 2002 Parts 1 and 2 Trench Lining Systems and BS 5975 (2008) Code of Practice for Temporary Works Procedures and the Permissible Stress Design of Falsework.
Product Notes1. Boxes should only be used in the configurations shown in ground assessed as self supporting by competent
persons following MGF installation guidelines. 2. Drag Boxes should not be used in weak ground (especially soft clays, running sand, silts or peats) or where
significant groundwater is present. They should only be used in ground that will stand to the excavated depth for the anticipated duration of the works.
3. Boxes are not suitable for usage in trenches with multiple service crossings. 4. Flying of the box above the base of the excavation is strictly prohibited.5. Drag Box systems are extremely heavy and great care must be taken in selecting a suitable excavator for
handling, installing and extracting these systems. As a general guide excavators should be sized to be at least 5 x weight of assembled drag box. If stacking panels on site, timber packers must be used to separate the panels.
6. The Box must only be moved by pre-digging ahead of the box and then carefully lifting and dragging the unit via the front struts using the bucket of the excavator. Care must be taken to ensure that the outside faces of the box are not side loaded by the ground.
7. Always use MGF specified extraction chains to release a stuck drag box from the ground prior to any attempt to lift the box out of the trench. Always use MGF specified lifting chains when lifting and handling the boxes or components. NB If a drag box becomes stuck extraction / drag forces of up to 300kN (30t) can be required to release the box.
8. Always enter box via a ladder located within the box and never, from an unsupported edge.
9. Prior to every lifting operation all lifting points must be carefully inspected by a competent person for evidence of damage.
10. During lifting or extraction operations ensure personnel are well clear of the equipment.
Tel. 0808 1153 122
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2.3.2Issue 4
MGF Davitsafe (S) - See Section 6
MGF Edgesafe - See Section 6
MGF Drag Box
MGF GRP Ladder - See
Section 7
MGF Laddersafe - See Section 6
For Safe System of Works Guidance for MGF Drag Boxes please see the MGF website & YouTube channel.
youtube.com/mgfltdmgf.ltd.uk
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2.3.3Issue 4
Strut Pocket Pin DetailTelescopic struts are
connected to the panel pockets using a pin and
R-clip detail.
Telescopic Strut DetailTelescopic strut inners and
outers are connected using a pin and R-clip detail.
Handling PointAll Drag Boxes are lifted and handled by attaching MGF lifting chains to the handling
points as shown.
Tel. 0808 1153 122
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2.3.4Issue 4
Product ID 4.701 4.702 4.703* 4.704 4.705 4.706* 4.707
Description L × H
3220 x 1460
Drag Box
4000 x 2060 Drag
Box
5100 x 1824
Drag Box
5100 x 2424
Drag Box
5100 x 3260
Drag Box
7500 x 2048
Drag Box
7500 x 2460
Drag Box
Panel Resistance
SWL (kN/m2)
40 30 30 40 30 20 20
Panel Thick/Weight
T(mm)/(kg)
60/ 452 60/ 854 100/ 1146 100/ 1433 100/ 2200 100/ 2400 100/ 2800
Approx Assembled
Weight (kg)
1004 2028 2612 3186 4720 5120 5920
Internal Trench Width** Wi(mm)
600-3000 600-3000 600-3000 600-3000 600-3000 600-3000 600-3000
Trench Width** We(mm)
720-3120 720-3120 800-3200 800-3200 800-3200 800-3200 800-3200
Clearance Below Bottom Strut*** Cv(mm)
790 1150 1072 1372 2258 1496 1500
Clearance Between
Struts Li(mm)
2590 2970 4220 4220 4220 6620 6620
Telescopic Strut Type 100 150 150 150 150 150 150
* These boxes can be used as top units to achieve depths of up to 5.10m in conjunction with a design issued by our technical department. ** Greater widths (up to 5m) possible utilising Telescopic Strut Adaptors *** Based on rear strut - additional clearance possible utilising Strut Adaptors
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2.3.6Issue 4
100 Telescopic Struts
150 Telescopic Struts
Component150 Telescopic Struts
Strut Inner Strut OuterSpecification 150x150x12.5 SHS 180x180x10 SHS
Material Grade S355 S355Axial SWL 492kN 492kN
Moment SWL 38.9kNm 38.9kNmHole Details Φ48mm holes Φ48mm holesUnit Mass 52.7kg/m 50.7kg/m
Component100 Telescopic Struts
Strut Inner Strut OuterSpecification 100x100x10 SHS 120x120x8 SHS
Material Grade S355 S355Axial SWL 228kN 228kN
Moment SWL 9.9kNm 9.9 kNmHole Details Φ30mm holes Φ30mm holesUnit Mass 27.4kg/m 26.4kg/m
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2.3.7Issue 4
Rigid Struts
Telescopic Strut Pins and Retaining Clips
Component Strut ValueSpecification 150x150x12.5
Material Grade S355Axial SWL 492kN
Moment SWL 38.9kNmHole Details Ø48mm holesUnit Mass 52.7kg/m
Component 100 Strut Pin 150 Strut Pin
Specification Ø28mm round bar, 160mm long
Ø45mm round bar, 220mm long
Material Grade 080M40 (EN8) 080M40 (EN8)Shear SWL 228kN 492kN
Weight 1kg 3kg
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2.3.8Issue 4
100 Telescopic Strut Combinations
100 Telescopic Strut Adaptors
Range (mm) Inner Type Outer Type Strut Weight (kg)650 - 835 4.602 4.611 27.1
870 - 1220 4.603 4.612 41.81275 - 1725 4.604 4.613 59.11775 - 2725 4.605 4.614 87.32175 - 3000 4.605 4.615 98.4
200 x 200 SHS - Trench Box Strut Adaptor (500mm long)
This adaptor will allow MGF 200 Series strut extensions to be used as 3220 x 1460
Drag Box struts.
Range (mm) 3000 - 5000Product ID 9.200Weight (kg) 27
Section 100x100x10 SHSMaterial Grade S355
If the above 100 telescopic strut combinations cannot be achieved a minimum overlap of at least 150mm must be provided between the inner and outer.
Struts should only be assembled using 1 inner and 1 outer.
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2.3.9Issue 4
150 Telescopic Strut Combinations
150 Telescopic Strut Adaptors
Range (mm) Inner Type Outer Type Strut Weight (kg)1000 - 1300 4.802 4.812 81.51400 - 1800 4.803 4.813 118.31900 - 2600 4.804 4.814 176.22700 - 3000 4.804 4.815 218.2
200 x 200 SHS - Drag Box Strut Adaptor (500mm and 600mm long)
These adaptor will allow MGF 200 Series strut extensions to be used as Drag Box struts.
Range (mm) 3000 - 5000
Product ID 9.206 (500mm) 9.207 (600mm)
Weight (kg) 40 (500mm) 45 (600mm)
Section 150x150x12.5 SHSMaterial Grade S355
Hog Back Drag Box Strut Adaptor (2300mm long)
This adaptor provides an additional 375mm clearance beneath the bottom strut. To be used with 600mm to
1050mm strut inners.
Range (mm) 3050 - 3500Product ID 4.840Weight (kg) 155
Section 180x180x10 SHSMaterial Grade S355
If the above 150 telescopic strut combinations cannot be achieved a minimum overlap of at least 250mm must be provided between the inner and outer.
Struts should only be assembled using 1 inner and 1 outer.
Tel. 0808 1153 122
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2.3.10Issue 4
MGF Drag Box