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seamless steel tube:
Tube length: 1 000 mm at least,
Nominal external diameter: 114 mm at least,
Nominal wall thickness: 5 mm at least,
booster: the type and mass of the booster chosen shall be such as to maximise the detonation pressure applied to the sample in order to determine its susceptibility to the transmission of detonation,
temperature of the sample: 15 °C to 25 °C,
witness lead cylinders for detecting detonation: 50 mm diameter and 100 mm height,
placed at 150 mm intervals and supporting the tube horizontally.
NOTE: The test is to be carried out twice. The test is deemed conclusive if in both tests one or more of the supporting lead cylinders is crushed by less than 5 %.U.K.
The test sample is confined in a steel tube and subjected to detonation shock from an explosive booster charge. Propagation of the detonation is determined from the degree of crushing of lead cylinders on which the tube rests horizontally during the test.
Plastic explosive containing 83 % to 86 % penthrite
density: 1 500 kg/m3 to 1 600 kg/m3
detonation velocity: 7 300 m/s to 7 700 m/s
mass: (500 ± 1) g;
or any other plastic explosive with similar detonation characteristics.
Seven lengths of flexible detonating cord with non-metallic sleeve
filling mass: 11 g/m to 13 g/m
length of each cord: (400 ± 2) mm.
Compressed pellet of secondary explosive, recessed to receive detonator
explosive: hexogen/wax 95/5 or similar secondary explosive, with or without added graphite
density: 1 500 kg/m3 to 1 600 kg/m3
diameter: 19 mm to 21 mm
height: 19 mm to 23 mm
mass of the compressed pellet: maximum 10 g
central recess to receive detonator: maximal diameter 7,0 to 7,3 mm, depth about 12 mm. In case of detonators with large diameters, the diameter of the recess shall be slightly larger (e.g. 0,5 mm) than the diameter of the detonator.
Seamless steel tube as specified in ISO 65 – 1981 – Heavy Series, with nominal dimensions DN 100 (4'')
outside diameter: 113,1 mm to 115,0 mm
wall thickness: 5,0 mm to 6,5 mm
length: 1 005 ± 2 mm.
Bottom plate
material: steel of good weldable quality
dimensions: 160 mm × 160 mm
thickness: 5 mm to 6 mm.
Six lead cylinders
diameter: 50 ± 1 mm
height: 100 mm to 101 mm
materials: soft lead, at least 99,5 % purity.
Steel block
length: at least 1 000 mm
width: at least 150 mm
height: at least 150 mm (alternatively a stack of several beams can be used to achieve this height)
Mass: at least 300 kg if there is no firm base for the steel block.
Plastic or cardboard cylinder for booster charge
wall thickness: 1,5 mm to 2,5 mm
diameter: 92 mm to 96 mm
height: 64 mm to 67 mm.
Detonator (electric or non-electric) with initiation force 8 to 10
Wooden or plastic disc
diameter: 92 mm to 96 mm. Diameter to be matched to the internal diameter of the plastic or cardboard cylinder (point (h))
thickness: 20 mm.
Wooden or plastic rod of same dimensions as detonator (point (i))
Small split pins (maximum length 20 mm)
Split pins (length about 20 mm)
Depending on the availability of equipment, the explosive can be initiated in the booster charge either
by seven-point simultaneous initiation as referred to in point 4.4.4.1.1, or
by central initiation by a compressed pellet as referred to in point 4.4.4.1.2.
The booster charge prepared for use is shown in Figure 2.
The booster charge prepared for use is shown in Figure 3.
Taking the necessary safety precautions, place maximum 10 g of a secondary explosive (point (c) under point 4.4.3) in a mould with an inside diameter of 19 mm to 21 mm and compress to the correct shape and density (the ratio of diameter: height should be roughly 1:1). In the centre of the bottom of the mould there is a peg, 12 mm in height and 7,0 mm to 7,3 mm in diameter (depending on the diameter of the detonator used), which forms a cylindrical recess in the compressed cartridge for subsequent insertion of the detonator.
Place the explosive (point (a) under point 4.4.3) into the cylinder (point (h) under point 4.4.3) standing upright on a level surface, then press it down with a wooden or plastic die to give the explosive a cylindrical shape with a central recess. Insert the compressed pellet into this recess. Cover the cylindrically shaped explosive containing the compressed pellet with a wooden or plastic disc (point (j) under point 4.4.3) having a central hole 7,0 mm to 7,3 mm in diameter for insertion of a detonator. Fix the wooden or plastic disc and the cylinder together with a cross of adhesive tape. Ensure that the hole drilled in the disc and the recess in the compressed pellet are coaxial by inserting the wooden or plastic rod (point (k) under point 4.4.3).
At one end of the steel tube (point (d) under point 4.4.3), drill two diametrically opposed holes 4 mm in diameter perpendicularly through the side wall at a distance of 4 mm from the edge. Butt weld the bottom plate (point (e) under point 4.4.3) to the opposite end of the tube, completely filling the right angle between the bottom plate and the wall of the tube with weld metal around the entire circumference of the tube.
See Figures 2 and 3.
Note: Make sure that the tube is in contact with all six lead cylinders; a slight curvature of the tube surface can be compensated for by rotating the tube about its longitudinal axis; if any of the lead cylinders is too tall, tap the cylinder in question carefully with a hammer until it is the required height.U.K.
Note: Detonation can cause steel fragments to be projected with high kinetic energy, therefore, firing shall be carried out at a suitable distance from dwellings or thoroughfares.
Values for the following parameters are to be given in the test report for each of the detonation resistance tests:
the values actually measured for the outside diameter of the steel tube and for the wall thickness,
the Brinell hardness of the steel tube,
the temperature of the tube and the sample shortly before firing,
the packing density (kg/m3) of the sample in the steel tube,
the height of each lead cylinder after firing, specifying the corresponding cylinder number,
method of initiation employed for the booster charge.
If, in each firing, the crushing of at least one lead cylinder is less than 5 %, the test shall be considered conclusive and it shall be considered that the sample presented is resistant to detonation.
Booster charge with seven-point initiation
:
Steel tube
:
Wooden or plastic disc with seven holes
:
Plastic or cardboard cylinder
:
Detonating cords
:
Plastic explosive
:
Test sample
:
4 mm hole drilled to receive split pin
:
Split pin
:
Wooden or plastic rod surrounded by 4
:
Adhesive tape for securing 4 around 9
:
Steel tube
:
Wooden of plastic disc
:
Plastic or cardboard cylinder
:
Wooden of plastic rod
:
Plastic explosive
:
Compressed pellet
:
Test sample
:
4 mm hole drilled to receive split pin
:
Split pin
:
Wooden or plastic die for 5
Numbers in circles:
:
Steel tube
:
Lead cylinders
:
Steel block or stack of beams
:
Bottom plate
:
Booster charge
Numbers in squares:
Lead cylinders 1 to 6
The diameter of the disc must always correspond to the inside diameter of the cylinder.
NB: When the six peripheral lengths of cord are taut after assembly, the central cord must remain slightly slack.