Transcript Document

STEEL CUTTING
CHARGES
ACTION: Calculate and place steel cutting charges.
CONDITONS: Given a 2 hour block of instruction, students
handout, FM 5- 250, and Demolition Card GTA 5-10-33.
STANDARD: Students will correctly calculate and place steel
cutting charges.
SAFETY: Specific safety considerations will be discussed
where appropriate throughout the lesson.
SPECIAL
CONSIDERATIONS
• Target Configuration
– Structured Steel
• Target Materials
– High-Carbon Steel
– Alloy Steel
– Cast Iron
• Type of Explosives
• Size of Explosives
Pg. 3-10
PLACEMENT OF CHARGE
Split the charge
• Continuous
• Contact
• Width
• Priming
Charge is placed
on the side of target
Pg. 3-11
Charge is split in half
Placed opposite side of each other
Offset the web thickness
BLOCK CHARGES
P = 3/8 A
P = pounds of TNT
3 / 8 = Constant
A = area of cross section of target in
square inches
Pg. 3-12
AREA OF CROSS SECTION
Flanges
Web
BLOCK CHARGE
walk through
Cut each I-Beams 1 time, using C-4
Flanges 16 x 1, Web 12 x .5
5 Beams
BLOCK SOLUTION
Step 1 :
Step 2 :
Step 3 :
Step 4 :
Step 5 :
Step 6 :
Flanges = 16 x 1 x 2,
Web
= 12 x .5
1 cut, C-4, 5 Beams
Flanges = 16 x 1 x 2 = 32 Sq in
Web
= 12 x .5
= 6 Sq in
TOTAL
= 38 Sq in
P = 3/8 x 38 = 14.25 lbs TNT
14.25 = 10.63 lbs C4 (M112)
1.34
10.63 = 8.5
9 pkgs C4 (M112)
1.25
5 Beams x 1 cut = 5 Charges
9 x 5 = 45 pkgs C4 (M112)
BLOCK CHARGE #1
15 X 1
Use C4
Total of 4 beams
12 X 1
15 X 1
BLOCK SOLUTION # 1
Step 1 :
Step 2 :
Flanges = 15 x 1 x 2 = 30 Sq in
Web
= 12 x 1
= 12 Sq in
TOTAL
= 42 Sq in
P = 3/8 A
P = 3/8 x 42 = 15.75 lbs TNT
Step 3 :
15.75 = 11.75 lbs C4 (M112)
1.34
Step 4 :
Step 5 :
11.75 = 9.4
10 pkgs C4 (M112)
1.25
4 Beams = 4 Charges
Step 6 :
10 x 4 = 40 pkgs C4 (M112)
How many packages of C-4
are required to cut the
15 beams shown using a
block charge
19.5” x 2”
14” x 1.5”
19.5” x 2.5”
BLOCK CHARGE
STEP 1 : Given: C4, 15 I-beams Flanges 19.5 x 2 = 39
19.5 x 2.5 = 48.75
14 x 1.5 = 21
Total Area = 108.75
STEP 2: P = 3/8A
.375 x 108.75 =40.78 lbs TNT
STEP 3: 40.78 / 1.34 = 30.43 lbs C4
STEP 4: 30.43 / 1.25 = 24.34 Pkg C4
STEP 5: 15 Beams = 15 charges
STEP 6: 25 x 15 = 375 pkgs C-4 (M112)
25 pkgs C4
Average
Thickness
of
Section
(in)
1/4
3/8
1/2
5/8
3/4
7/8
1
Pounds of Explosive (TNT) for Rectangular steel sections of given Dimensions
Height of Section (in)
2
0.2
0.3
0.4
0.5
0.6
0.7
0.8
3
0.3
0.5
0.6
0.7
0.9
1
1.2
4
0.4
0.6
0.8
1
1.2
1.4
1.5
5
0.5
0.7
1
1.2
1.4
1.7
1.9
6
0.6
0.9
1.2
1.4
1.7
2
2.3
7
0.7
1.1
1.4
1.7
2
2.4
2.7
8
9
0.8
1.2
1.5
1.9
2.3
2.7
3
0.9
1.9
1.7
2.2
2.6
3
3.4
10
1
1.4
1.9
2.4
2.8
3.3
3.8
11
1.1
1.6
2.1
2.7
3.1
3.7
4.2
12
1.2
1.7
2.3
2.9
3.4
4
4.5
14
1.3
2
2.7
3.3
4
4.6
5.3
16
1.5
2.3
3
3.8
4.5
5.3
6
18
1.7
2.6
3.4
4.3
5.1
6
6.8
20
1.9
2.8
3.8
4.7
5.7
6.6
7.5
22
2.1
3.1
4.2
5.2
6.3
7.3
8.3
24
2.3
3.4
4.5
5.7
6.8
7.9
9
NOTE: to use this table –
1. Measure each rectangular section of total member separately.
2. Find the appropriate charge size for the rectangular section from the table.
If the section dimension is not listed in the table, use the next-larger dimension.
3. Add the individual charges for each section to obtain the total charge weight.
Average
Thickness
of
Section
(in)
1/4
3/8
1/2
5/8
3/4
7/8
1
Pounds of Explosive (TNT) for Rectangular steel sections of given Dimensions
Height of Section (in)
2
0.2
0.3
0.4
0.5
0.6
0.7
0.8
3
0.3
0.5
0.6
0.7
0.9
1
1.2
4
0.4
0.6
0.8
1
1.2
1.4
1.5
5
0.5
0.7
1
1.2
1.4
1.7
1.9
6
0.6
0.9
1.2
1.4
1.7
2
2.3
7
0.7
1.1
1.4
1.7
2
2.4
2.7
8
9
0.8
1.2
1.5
1.9
2.3
2.7
3
0.9
1.9
1.7
2.2
2.6
3
3.4
10
1
1.4
1.9
2.4
2.8
3.3
3.8
11
1.1
1.6
2.1
2.7
3.1
3.7
4.2
12
1.2
1.7
2.3
2.9
3.4
4
4.5
14
1.3
2
2.7
3.3
4
4.6
5.3
16
1.5
2.3
3
3.8
4.5
5.3
6
18
1.7
2.6
3.4
4.3
5.1
6
6.8
20
1.9
2.8
3.8
4.7
5.7
6.6
7.5
22
2.1
3.1
4.2
5.2
6.3
7.3
8.3
24
2.3
3.4
4.5
5.7
6.8
7.9
9
NOTE: to use this table –
1. Measure each rectangular section of total member separately.
2. Find the appropriate charge size for the rectangular section from the table.
If the section dimension is not listed in the table, use the next-larger dimension.
3. Add the individual charges for each section to obtain the total charge weight.
HASTY PROBLEM # 1
How many packages of C4, (M112)
are required to cut 5 I-beams with
dimensions of 8” x 1/2” for the flanges,
9” x 1” for the web ?
HASTY SOLUTION # 1
Step 2 :
[8” x 1/2”] [9” x 1”] [8” x 1/2”]
Table Value
8” x 1/2”
1.2 lbs
9” x 1”
2.9 lbs
8” x 1/2”
1.2 lbs
Total
= 5.3 lbs C4
Step 3 :
N/A
Step 4 :
Step 5 :
5.3 = 4.24
5 Pkgs C4 (M112)
1.25
5 beams = 5 charges
Step 6 :
5 x 5 = 25 pkgs C4
Step 1 :
(M112)
RIBBON CHARGE
• Step 2. Calculate the volume of explosives.
– T x W x L = volume of explosives in cu. in. needed
– T = Charge thickness = 1/2 TGT but never less than
1/2 inch
– W = Charge width = 3 times the charge thickness
– L = Charge length = length of TGT to be cut
• Step 4. Calculate packages of C4 or M118
– C4: 1” x 2” x 10” = 20 cu inches
– M118 sheet: .25” x 3” X 12” = 9 cu inches
• 4 SHEETS = 1 M118 PACKAGE (use in Step 6)
• Maximum target thickness = 3 inches
Pg. 3-15
RIBBON CHARGE PLACEMENT
Width of charge
= 3 times thickness
of charge
Thickness of charge
= 1/2 thickness of TGT
Length of charge
= length of TGT
Place ½ inch explosive around
cap or knot
Primed at center with a
blasting cap or det cord
knot
Det Cord or
Time Fuse
Pg. 3-16
< 2 inches offset edge to center
WEB
> 2 inches offset flange charges
edge to edge
Charge Thickness = 1/2
Thickness of the target
never less than .5
Beams > 2” thick
offset flange charge:
Edge to Edge
Beams < 2” thick
offset flange charge:
Edge to Center
Det Cord branch lines
are all of equal lengths
forming a (British Junction)
Charge Thickness (T)
Target thickness
RIBBON CHARGE
T
Charge
thickness
TF
(T)
Charge
WEB thickness
(T)
BF
W
Charge width
3xT
Charge width
3xT
Charge
Charge width
thickness 3 x T
(T)
L
Charge length Required
FL - WT =L
explosive
T x W x L=VOL
Charge length Required
WL - TCT - BCT explosive
=L
T x W x L=VOL
Charge length
FL - WT =L
Required
explosive
T x W x L=VOL
TOTAL
EXPLOSIVES
RIBBON CHARGE
WALK THROUGH
How much C4 (M112) is required to cut one plate?
2”
24”
RIBBON CHARGE
WALK THROUGH
Step 1.
Step 2.
Step 3.
Step 4.
2” x 24”
1” x 3” x 24” = 72 cu. in.
N/A
72 = 3.6
4 pkgs C-4 (M112)
20
Step 5. 1 Plate = 1 charge
Step 6. 4 x 1 = 4 pkgs C-4 (M112)
How many packages of C-4
are required to cut the
15 beams shown using a
ribbon charge
19.5” x 2”
14” x 1.5”
19.5” x 2.5”
RIBBON CHARGE
STEP 1 : Given: C4, 15 I-beams Flanges 19.5 x 2
19.5 x 2.5
Web
14 x 1.5
STEP 2: T
TF
1
Web
.75
BF
1.25
x W x L
= VOL cu. in. of explosives
x 3 x 18
= 54
x 2.25 x 11.75 = 19.82
x 3.75 x 18
= 84.37
TOTAL VOL = 158.19
STEP 3: N/A
STEP 4: 158.19 = 7.90
8 pkgs C-4 (M112)
20
STEP 5: 15 Beams = 15 charges
STEP 6: 8 x 15 = 120 pkgs C-4 (M112)
RIBBON CHARGE
PROBLEM #2
19.5”
2”
Use (M118 sheet explosive)
15 Beams
14”
2”
2”
RIBBON CHARGE
PROBLEM #2 SOLUTION
STEP 1 : Given: M118, 15 I-beams
STEP 2: T = 1” W = 3” L = Top Flange = 19.5” - 2” = 17.5”
Bottom Flange = 19.5” - 2” = 17.5”
Web = 14” - 2” = 12”
TOTAL = 47”
T x W x L = 1”x 3” x 47” = 141 cu. in. of explosives
STEP 3: N/A
STEP 4: 141 = 15.66
16 sheets (M118)
9
STEP 5: 15 Beams = 15 charges
STEP 6: 16 x 15 = 240 sheets (M118)
4
= 60 packages (M118)
RIBBON CHARGE
PROBLEM #3
8”
1.5”
16”
1.5”
1.5”
Use M118
12 Beams
RIBBON CHARGE
PROBLEM #3 SOLUTION
STEP 1 : Given: M118, 12 I-beams
STEP 2: T = .75” W = 2.25” L = Top Flange = 8” - 1.5” = 6.5”
Bottom Flange = 8” - 1.5” = 6.5”
Web = 16” - 1.5” = 14.5”
TOTAL = 27.5”
T x W x L = .75” x 2.25” x 27.5” = 46.4 cu. in. of explosives
STEP 3: N/A
STEP 4: 46.4 = 5.15
6 sheets M118
9
STEP 5: 12 Beams = 12 charges
STEP 6: 6 x 12 =
72 sheets
4 sheets per pkg = 18 pkgs M118
SUMMARY
BLOCK
CHARGE
Placement and Priming
Formula method
Table method
RIBBON CHARGE
Placement and Priming
Formula
M118
Round to SHEET in step 4
Round to PACKAGE in step 6