steel cutting charges action: calculate and place steel cutting charges. conditons: given a 2 hour...

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 CHARGESplit the charge

• Continuous• Contact• Width• Priming

Charge is placed on the side of target Charge is split in half

Placed opposite side of each otherOffset the web thickness

Pg. 3-11

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 CHARGEBLOCK CHARGEwalk throughwalk through

Cut each I-Beams 1 time, using C-4Flanges 16 x 1, Web 12 x .55 Beams

BLOCK SOLUTIONStep 1 : Flanges = 16 x 1 x 2, Web = 12 x .5

1 cut, C-4, 5 BeamsStep 2 : 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 TNTStep 3 : 14.25 = 10.63 lbs C4 (M112) 1.34Step 4 : 10.63 = 8.5 1.25Step 5 : 5 Beams x 1 cut = 5 Charges

Step 6 : 9 x 5 = 45 pkgs C4 (M112)

9 pkgs C4 (M112)

15 X 1

15 X 1

12 X 1

Use C4Use C4Total of 4 beamsTotal of 4 beams

BLOCK CHARGE #1

Step 1 : Flanges = 15 x 1 x 2 = 30 Sq inWeb = 12 x 1 = 12 Sq in

TOTAL = 42 Sq in

Step 2 : 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 : 11.75 = 9.4 10 pkgs C4 (M112) 1.25

Step 5 : 4 Beams = 4 Charges

Step 6 : 10 x 4 = 40 pkgs C4 (M112)

BLOCK SOLUTION # 1BLOCK SOLUTION # 1

19.5” x 2”19.5” x 2”

19.5” x 2.5”19.5” x 2.5”

14” x 1.5”14” x 1.5”

How many packages of C-4are required to cut the 15 beams shown using a block charge

BLOCK CHARGE

STEP 1 : Given: C4, 15 I-beams Flanges 19.5 x 2 = 3919.5 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 25 pkgs C4

STEP 5: 15 Beams = 15 charges

STEP 6: 25 x 15 = 375 pkgs C-4 (M112)

AverageThickness

ofSection

(in)

Pounds of Explosive (TNT) for Rectangular steel sections of given Dimensions

Height of Section (in)

2 3 4 5 6 7 8 9 10 11 12 141/4

17/83/45/81/23/8

0.20.30.40.50.60.70.8

222016 18 242.33.4

4.55.76.87.9

9

2.13.1

4.25.26.37.3

8.3

1.92.8

3.84.75.76.6

7.5

1.72.63.44.35.16

6.8

1.52.3 33.84.55.3

6

1.3 22.73.3 44.6

5.3

1.21.72.32.93.4 4

4.5

1.11.62.12.73.13.7

4.2

11.41.92.42.83.3

3.8

0.91.91.72.22.63

3.4

0.81.21.51.92.32.7

3

0.71.11.41.7 22.4

2.7

0.60.91.21.41.72

2.3

0.30.50.60.70.91

1.2

0.40.60.8 11.21.4

1.5

0.50.7 11.21.41.7

1.9

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.

1/2

10

1.9

AverageThickness

ofSection

(in)

Pounds of Explosive (TNT) for Rectangular steel sections of given Dimensions

Height of Section (in)

2 3 4 5 6 7 8 9 10 11 12 141/4

17/83/45/81/23/8

0.20.30.40.50.60.70.8

222016 18 242.33.4

4.55.76.87.9

9

2.13.1

4.25.26.37.3

8.3

1.92.8

3.84.75.76.6

7.5

1.72.63.44.35.16

6.8

1.52.3 33.84.55.3

6

1.3 22.73.3 44.6

5.3

1.21.72.32.93.4 4

4.5

1.11.62.12.73.13.7

4.2

11.41.92.42.83.3

3.8

0.91.91.72.22.63

3.4

0.81.21.51.92.32.7

3

0.71.11.41.7 22.4

2.7

0.60.91.21.41.72

2.3

0.30.50.60.70.91

1.2

0.40.60.8 11.21.4

1.5

0.50.7 11.21.41.7

1.9

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.

1/2

16

3

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 PROBLEM # 1HASTY PROBLEM # 1

HASTY SOLUTION # 1HASTY SOLUTION # 1Step 1 : [8” x 1/2”] [9” x 1”] [8” x 1/2”]

Table ValueStep 2 : 8” x 1/2” 1.2 lbs

9” x 1” 2.9 lbs8” x 1/2” 1.2 lbsTotal = 5.3 lbs C4

Step 3 : N/A

Step 4 : 5.3 = 4.24 5 Pkgs C4 (M112)1.25

Step 5 : 5 beams = 5 charges

Step 6 : 5 x 5 = 25 pkgs C4 (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

Thickness of chargeThickness of charge= 1/2 thickness of TGT= 1/2 thickness of TGTWidth of charge Width of charge

= 3 times thickness= 3 times thicknessof chargeof charge

Length of chargeLength of charge= length of TGT= length of TGT

Place ½ inch explosive Place ½ inch explosive around around cap or knotcap or knot

Primed at center Primed at center with a blasting cap with a blasting cap or det cord knotor det cord knot

Det Cord orDet Cord orTime FuseTime Fuse

Pg. 3-16

WEB

< 2 inches offset edge to center

> 2 inches offset flange charges edge to edge

Beams Beams >> 2” thick 2” thickoffset flange charge:offset flange charge:Edge to EdgeEdge to Edge

Det Cord branch lines are all of equal lengths forming a (British Junction)

Beams < 2” thickBeams < 2” thickoffset flange charge:offset flange charge:Edge to CenterEdge to Center

Charge Thickness = 1/2 Thickness of the target never less than .5

Charge Thickness (T) Target thickness

RIBBON CHARGE

Charge thickness (T)


Charge width3 x T

Charge width3 x T

Charge width3 x T

Charge lengthFL - WT =L

Charge lengthFL - WT =L

Charge lengthWL - TCT - BCT= L

Required explosiveT x W x L=VOL




TOTALEXPLOSIVES

T W L

TF

WEB

BF

RIBBON CHARGE WALK THROUGHRIBBON CHARGE WALK THROUGH

How much C4 (M112) is required to cut How much C4 (M112) is required to cut one plate?one plate?

24”

2”

Step 1. 2” x 24”

Step 2. 1” x 3” x 24” = 72 cu. in.

Step 3. N/A

Step 4. 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)

RIBBON CHARGE WALK THROUGHRIBBON CHARGE WALK THROUGH

19.5” x 2”19.5” x 2”

19.5” x 2.5”19.5” x 2.5”

14” x 1.5”14” x 1.5”

How many packages of C-4are required to cut the 15 beams shown using a ribbon charge

RIBBON CHARGE

STEP 1 : Given: C4, 15 I-beams Flanges 19.5 x 219.5 x 2.5

Web 14 x 1.5

STEP 2: T x W x L = VOL cu. in. of explosivesTF 1 x 3 x 18 = 54Web .75 x 2.25 x 11.75 = 19.82BF 1.25 x 3.75 x 18 = 84.37

TOTAL VOL = 158.19

STEP 3: N/A

STEP 4: 158.19 = 7.90 20

8 pkgs C-4 (M112)

STEP 5: 15 Beams = 15 chargesSTEP 6: 8 x 15 = 120 pkgs C-4 (M112)

19.5”

14”

2”

RIBBON CHARGE PROBLEM #2


2”

2”

Use Use (M118 sheet (M118 sheet explosive)explosive)

15 Beams15 Beams

STEP 1 : Given: M118, 15 I-beamsSTEP 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 explosivesSTEP 3: N/ASTEP 4: 141 = 15.66 16 sheets (M118)

9STEP 5: 15 Beams = 15 chargesSTEP 6: 16 x 15 = 240 sheets (M118)

4 = 60 packages (M118)

RIBBON CHARGE PROBLEM #2 SOLUTION


8”

16”

1.5”



1.5”

Use Use M118M11812 12 BeamsBeams

1.5”

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



SUMMARYBLOCK CHARGEBLOCK CHARGE

Placement and PrimingPlacement and PrimingFormula methodFormula methodTable methodTable method

RIBBON CHARGERIBBON CHARGEPlacement and Priming Placement and Priming FormulaFormula

M118M118Round to SHEET in step 4Round to SHEET in step 4Round to PACKAGE in step 6Round to PACKAGE in step 6

steel cutting charges action: calculate and place steel cutting charges. conditons: given a 2 hour...

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