Safety Design Considerations in Munition Plants Layout - ACS

1 Safety Design Considerations in Munition Plants Layout R I C H A R D M . R I N D N E R and

Downloaded by CARLETON UNIV LIBRARY on May 7, 2015 | http://pubs.acs.org Publication Date: April 6, 1979 | doi: 10.1021/bk-1979-0096.ch001

ARRADCOM,

IRVING F O R S T E N

Dover, NJ 07801

Criteria and methods "based on r e s u l t s of a c c i d e n t a l explosions have been used until the m i d - s i x t i e s f o r the design of h i g h e x p l o s i v e manufacturing and storage facilities. These criteria, however, d i d not i n c l u d e a d e t a i l e d or r e l i a b l e q u a n t i t a t i v e b a s i s f o r assessing a degree of p r o t e c t i o n a f f o r d e d by the protective facility, and as a r e s u l t P i c a t i n n y A r s e n a l (nov p a r t of ARRADCOM) in the e a r l y 60's entered i n t o a broad tri-service program o f a n a l y s i s , t e s t i n g , and e v a l u a t i o n of s t r u c t u r e s designed t o a f f o r d p r o t e c t i o n against the e f f e c t s of a c c i d e n t a l explosions. The experimental work i n v o l v e d model and full s c a l e t e s t i n g of r e i n f o r c e d concrete s t r u c t u r e s and t h e i r components. New designs were conceived and the t h r e s h o l d c a p a c i t i e s of various s t r u c t u r a l c o n f i g u r a t i o n s were determined. The validity o f the use of s c a l e d model t e s t i n g t o r e p l a c e full s c a l e t e s t s was demonstrated. The product o f t h i s 8 year systematic study was the p u b l i c a t i o n of the s a f e t y design manual e n t i t l e d , " S t r u c t u r e s t o R e s i s t the E f f e c t s o f A c c i d e n t a l E x p l o s i o n s " (Army's P u b l i c a t i o n TM5-1300). An o u t l i n e o f s t u d i e s l e a d i n g t o p u b l i c a t i o n o f t h i s manual is shown in F i g 1. The manual contains procedures, c h a r t s , and t a b l e s r e q u i r e d t o e s t a b l i s h the environment of an e x p l o s i o n and its output i n terms of b l a s t and fragments. The r e l a t i o n s are presented i n such a manner t h a t the type of p r o t e c t i v e s t r u c t u r e may be s e l e c t e d , analyzed, and designed t o provide a safe level o f p r o t e c t i o n f o r personnel, equipment, and f o r s e p a r a t i o n of p o t e n t i a l l y mass detonating m a t e r i a l s . In the course o f the a p p l i c a t i o n o f the manual t o the ArmyWide Munition Plant Modernization Program, p o t e n t i a l areas f o r improving and r e f i n i n g the manual appeared. Whenever s p e c i f i c information was not a v a i l a b l e , the most conservative approach was used. Consequently an extensive program, i n c l u d i n g t e s t i n g , was initiated t o e s t a b l i s h data and procedures t o supplement and/or modify the e x i s t i n g r e g u l a t i o n s and t o a s s i s t designers i n developing the most economical and safe facilities.

This chapter not subject to U.S. copyright. Published 1979 American Chemical Society In Toxic Chemical and Explosives Facilities; Scott, R.; ACS Symposium Series; American Chemical Society: Washington, DC, 1979.

TOXIC C H E M I C A L A N D EXPLOSIVES FACILITIES


2

In Toxic Chemical and Explosives Facilities; Scott, R.; ACS Symposium Series; American Chemical Society: Washington, DC, 1979.

1.

RINDNER AND FORSTEN

Munition

Plant

Layout

3


The o v e r a l l program was d i v i d e d i n t o s e v e r a l separate "but i n t e r r e l a t e d phases, which w i l l "be presented i n t h e f o l l o w i n g d i s c u s s i o n as shown i n F i g 2. These a r e : (a)

TNT Equivalency I n v e s t i g a t i o n

(b)

Safe Separation Distance

(c)

E x p l o s i v e S e n s i t i v i t y t o Impact by Primary and Secondary Fragments

(d)

B l a s t E f f e c t s and S t r u c t u r a l Response Studies

(e)

Hazard C l a s s i f i c a t i o n S t u d i e s o f In-Process Hazardous Materials

(f)

Development o f S p e c i a l Purpose Water Deluge Systems

Determination

In the f o l l o w i n g pages the i n d i v i d u a l phases w i l l be d i s cussed i n some d e t a i l . TNT Equivalency Study The purpose o f t h i s study i s t o generate peak pressure and impulse data on e x p l o s i v e s , p r o p e l l a n t s , and other hazardous m a t e r i a l s which are compared t o s i m i l a r parameters obtained from a hemispherical surface b u r s t o f TNT ( F i g 3). The r e s u l t s are reduced t o a TNT equivalency v a l u e , which i s d e f i n e d as the weight r a t i o o f TNT t o t e s t m a t e r i a l f o r a given output c o n d i t i o n . Various f a c t o r s i n f l u e n c e t h e magnitude o f TNT equivalency. These i n c l u d e ; charge geometry, c r i t i c a l mass/dimensions, confinement, distance from t h e charge b u r s t , and method o f i n i t i a t i o n . Measurements o f a i r b l a s t overpressure and impulse were made at 12 gage l o c a t i o n s along a double b l a s t l i n e ( F i g h). The gages were spaced at s e l e c t e d s c a l e d distances ranging from a p p r o x i mately 2 - 2 0 f t / l b s / 3 . The pressure transducers were i n s t a l l e d f l u s h e d with the top surface o f a concrete s l a b i n mechanically i s o l a t e d s t e e l p l a t e s . The t e s t item was p l a c e d on a s t e e l witness p l a t e l o c a t e d on the surface o f the s l a b . Fastax motion p i c t u r e s were taken o f a l l t e s t s . On the b a s i s o f experimental data on a v a r i e t y o f explosives, p r o p e l l a n t s , and p y r o t e c h n i c s , we have observed t h a t these mater i a l s f a l l i n t o two c a t e g o r i e s , which can be described i n terms of t h e i r TNT equivalency-distance curves. The two c a t e g o r i e s are c h a r a c t e r i z e d as marginal e x p l o s i v e s and high e x p l o s i v e s . The shape o f these curves f o r m a t e r i a l s t h a t we c a l l marginal explos i v e s , such as Black Powder, can be seen i n F i g 5. The TNT equivalency i n c r e a s e s with s c a l e d d i s t a n c e t o approximately 10 f t / l b ! / 3 and then decreases. In a l l cases, however, the maximum value o f TNT equivalency i s w e l l below 100 percent. Materials, 1


TOXIC CHEMICAL AND EXPLOSIVES FACILITIES

4

OBJECTIVES •

SUPPORT MODERNIZATION & EXPANSION

PROGRAM

•

MODIFY OR SUPPLEMENT S A F E T Y M A N U A L & DESIGN

GUIDES

PURPOSE •

U P G R A D E PROTECTIVE S T R U C T U R E S , PROCESSES & FACILITIES DESIGNS AGAINST A C C I D E N T A L

EXPLOSIONS


PROJECTS •

T N T EQUIVALENCY TESTS

•

SAFE SEPARATION DISTANCE

•

PRIMARY A N D SECONDARY FRAGMENTS INVESTIGATIONS

•

BLAST E F F E C T S A N D S T R U C T U R A L RESPONSE STUDIES

•

IN-PROCESS M A T E R I A L

•

DELUGE SYSTEM DEVELOPMENT Figure 2.

DETERMINATIONS

HAZARDS

CLASSIFICATION

Protective technology for accidental explosions

OBJECTIVE •

•

D E T E R M I N E E X P L O S I V E O U T P U T (PEAK P R E S S U R E & IMPULSE) •

EXPLOSIVES

•

PROPELLANTS

•

OTHER HAZARDOUS MATERIALS

TNT EQUIVALENCY V A L U E =

W

T

0

F

T

N

T

(%)

W T O F MAT'L * * G I V E S S A M E E X P L O S I V E O U T P U T A T S A M E D I S T A N C E AS T N T AIRBLAST CHARACTERISTICS •

D E P E N D E N T UPON M A N Y V A R I A B L E S •

SPECIFIC F O R M O F M A T E R I A L

#

•

Q U A N T I T Y ( C H A R G E WEIGHT)

#

•

PHYSICAL S T A T E (DENSITY, T E M P , C O N C E N T R A T I O N . )

#

•

GEOMETRY DISTANCE STIMULI ( M E T H O D O F BOOSTERING)

CONFINEMENT

TESTS •

V A R I E T Y O F T E S T S E T U P S ( I N - P R O C E S S & E N D ITEM) Figure 3.

TNT equivalency


RINDNER AND FORSTEN

Munition

Plant

Layout

MESS PLATE


IAL MARKERS

Figure 4.

Typical test setup, equivalency tests

IMPULSE TNT EQUIVALENCY, PERCENT

PRESSURE TNT EQUIVALENCY, PERCENT

102-

10

3

PRESSURE

-102

10IMPULSE

10O-

10

10-' 10°

10 SCALEDvDISTANCE, A, F T / L B

Figure 5.

10°

1 10 1

/

2

3

TNT equivalency (black powder weights of 500-4500 pounds)


6


that we c l a s s i f y as high e x p l o s i v e , such as N i t r o g l y c e r i n e , have a TNT equivalency (as shown i n F i g 6) w e l l above 100$ at c l o s e d i s t a n c e s , and decreasing t o l e s s than 100$ a t f a r - o u t d i s t a n c e s . F i n a l l y F i g 7 summarizes r e s u l t s o f the TNT equivalency studies f o r a few s e l e c t e d e x p l o s i v e s , p r o p e l l a n t s , a n d p y r o t e c h n i c s .


Safe Separation Distance

Determination

The purpose o f t h i s program i s t o e s t a b l i s h safe separation distances r e l a t i v e t o e x p l o s i v e end-items and in-process materials, as w e l l as c r i t i c a l and safe depths o f bulk explosives on conveyors, hoppers, tubes, o r other t r a n s f e r l i n e s . Safe separation s t u d i e s were conducted t o achieve increased production and cost e f f e c t i v e n e s s with improved s a f e t y . A t y p i c a l ammunition production l i n e flow diagram ( i n t h i s case f o r the manu f a c t u r e o f 105 mm p r o j e c t i l e ) c o n s i s t s o f s e v e r a l work areas as shown i n F i g 8. ( ( l ) Receiving and storage, (2) Box open and i n s p e c t (3) Melt Pour (k) Cool (5) Hold (6) Funnel P u l l and (T) R i s e r Preparation.) E x p l o s i v e m a t e r i a l i s t r a n s f e r r e d by automatic conveyor between these work areas. The requirement was t o e s t a b l i s h safe separation between e x p l o s i v e boxes, p a l l e t s with and without f u n n e l s , buckets, and t o determine c r i t i c a l height o f continuous feed f l a k e Comp B and TNT. The o b j e c t i v e o f these t e s t s was t o e s t a b l i s h minimum nonpropagation distances between these items so t h a t an explosion chain r e a c t i o n w i l l be prevented. The next few photos i l l u s t r a t e the t e s t set-up f o r v a r i o u s t e s t c o n f i g u r a t i o n s s i m u l a t i n g , as c l o s e l y as p o s s i b l e , t h e p l a n t o p e r a t i o n a l l i n e . F i g 9 shows a t e s t set-up f o r e s t a b l i s h i n g c r i t i c a l height o f Comp B f l a k e u t i l i z i n g a commercially a v a i l a b l e corrugated rubber conveyor. F i g 10 shows a t y p i c a l set up f o r establishment o f safe s e p a r a t i o n d i s t a n c e between p a l l e t s c o n t a i n ing s i x t e e n (l6) 105 mm s h e l l , and F i g 11 shows a t e s t set-up t o e s t a b l i s h safe separation between t h e t o t e b i n s t r a n s p o r t i n g 165 l b o f Comp AT i n a t u n n e l s t r u c t u r e s i m u l a t i n g a p l a n t t u n n e l o r ramp. The t e s t s c o n s i s t e d o f an e x p l o r a t o r y phase t o e s t a b l i s h the safe non-propagation d i s t a n c e , and a confirmatory phase t o confirm s t a t i s t i c a l l y the v a l i d i t y o f the e x p l o r a t o r y t e s t results. Along with the safe separation distance c r i t e r i a , an attempt i s made t o evaluate, by s t a t i s t i c a l a n a l y s i s , t h e p r o b a b i l i t y o f an explosion propagation o c c u r r i n g . The p r o b a b i l i t y o f the occurrence o f an e x p l o s i o n propagation,is dependent upon t h e confidence l e v e l i n v o l v e d and has a lower and upper l i m i t . The lower l i m i t f o r a l l confidence l e v e l s i s zero; whereas, t h e upper or p r a c t i c a l l i m i t i s a f u n c t i o n o f the number o f observations o r acceptors t e s t e d . F i g 12 represents a f a m i l y o f curves r e l a t i n g the number o f t e s t s t o t h e p r o b a b i l i t y o f the occurrence o f e x p l o s i o n propagation f o r acceptable l e v e l s o f confidence.


RINDNER AND FORSTEN

Munition

Plant

Layout


1.

Figure 6.

TNT equivalence of nitroglycerine


7

8

TOXIC CHEMICAL A N D EXPLOSIVES FACILITIES

IMPULSE EQUIV M A X I M U M (%)


MATERIAL

PRESS E Q U I V M A X I M U M (%)

B L A C K POWDER •

L A R G E SCALE TESTS

50

40

•

SMALL SCALE TESTS

24 (30 R E C O M M E N D E D FOR DESIGN)

11

N-5 PROPELLANT #

S L U R R Y (88% W A T E R )

0

0

•

P A S T E (30% W A T E R )

2

4

•

P A S T E (10% W A T E R )

70

90

NITROGUANIDINE

80

100

GUANIDINE NITRATE

85

55

GUANIDINE NITRATE REACTOR

55

85

190

240

NITROGLYCERINE PYROTECHNICS •

105MM I L L U M I N A N T

70

60

•

M49A1 T R I P F L A R E

80

78

•

105MM F I R S T F I R E

100

60

Figure 7.

TNT equivalency results


RINDNER AND FORSTEN

Munition

Plant

Layout


1.


9



Figure 9.

Figure 10.

Test set-up to establish crit. ht. of comp B

Test arrangement with 16 projectiles primed


RINDNER AND FORSTEN

Munition

Plant

Layout


1.


11

12



Primary and Secondary Fragments Impact I n v e s t i g a t i o n The purpose o f t h i s experimental program i s t o e s t a b l i s h a fragment mass-velocity r e l a t i o n s h i p below which no detonation propagation w i l l . o c c u r . By d e f i n i t i o n , primary fragments are those t h a t r e s u l t from a break-up o f t h e explosive casing i n t h e event o f a detonation. U s u a l l y these fragments are c h a r a c t e r i z e d by having high v e l o c i t y and b e i n g comparatively small i n s i z e . The experimental set-up i s shown s c h e m a t i c a l l y i n F i g 13. The s t e e l fragment impacting the acceptor charge simulates a fragment r e s u l t i n g from the break-up o f the s h e l l c a s i n g . The e n t i r e e x p l o s i v e t r a i n , i n c l u d i n g a booster charge, was p l a c e d on top o f a 5" square L u c i t e b u f f e r p l a t e o f v a r y i n g thickness which c o n t r o l l e d the fragment v e l o c i t y . Glued t o t h e L u c i t e was t h e s t e e l fragment o f d e s i r e d t h i c k n e s s and f r o n t a l area. Two types of t a r g e t s were used, namely; s o l i d and molten explosives with the acceptor cover p l a t e o f v a r y i n g t h i c k n e s s over t h e e x p l o s i v e . A h i g h speed camera was the only instrumentation used t o r e c o r d fragment v e l o c i t y data. Fragment v e l o c i t y was computed by d i v i d ing the distance t r a v e r s e d by the time i t took t o t r a v e l that d i s t a n c e . F i g ik i s a g r a p h i c a l r e p r e s e n t a t i o n f o r both s o l i d and molten Comp B. As expected, the molten Comp B i s more s e n s i t i v e t o fragment impact than s o l i d Comp B, however t h e d i f f e r e n c e i n s e n s i t i v i t y i s not very s i g n i f i c a n t . By d e f i n i t i o n , secondary fragments are those other than primary fragments that r e s u l t from the detonation o f e x p l o s i v e charges, such as w a l l break-up, pieces o f equipment^ e t c . They are u s u a l l y c h a r a c t e r i z e d by having a lower v e l o c i t y than primary fragments (seldom exceeding 1,000 f t / s e c ) and having large mass. A s e r i e s o f experiments were- conducted at the I l l i n o i s I n s t i t u t e of Technology Research I n s t i t u t e (IITRI) Test F a c i l i t y t o d e t e r mine e x p l o s i v e s e n s i t i v i t y t o impact by concrete fragments. F i g 15 simulates a s i t u a t i o n where w a l l fragments r e s u l t i n g from donor detonation impact the acceptor. The concrete fragments u t i l i z e d i n t h i s program were launched from a 12" gun as shown i n F i g 16. This a i r gun i s capable o f launching fragments at a wide range o f weights and v e l o c i t i e s . The experiments u t i l i z e d both s o l i d concrete c y l i n d e r s as w e l l as concrete rubble packed i n t o a cardboard container t o simulate a fragment from a concrete w a l l . T y p i c a l test, r e s u l t s (of t h e " j u s t f i l l e d " c o n f i g u r a t i o n r e p r e s e n t i n g a 155 mm s h e l l f i l l e d with molten Comp B) are shown i n F i g IT. As can be seen, h i g h order detonations were recorded at fragment v e l o c i t i e s o f approx. 1,100 f t / s e c and fragment s i z e o f 50 l b s . Other t e s t s i n the same s e r i e s i n v e s t i g a t e d s e n s i t i v i t y o f v a r i e t y o f items, e x p l o s i v e s , and p r o p e l l a n t s t o fragment impact. I t i s expected t h a t these and f u t u r e t e s t s w i l l p r o v i d e e m p i r i c a l r e l a t i o n s h i p s between fragment-mass/velocity, f o r v a r i o u s casing thicknesses and other chemical and p h y s i c a l c h a r a c t e r i s t i c s o f e x p l o s i v e


RINDNER AND FORSTEN

Munition

Plant

Layout


1.


13

14


2.0

-

^


-

SOLID COMP B

• M O L T E N COMP B —

N O T E : A L L D A T A FOR 0.125 N C H THICK A C C EPTOR PL A T E S

0 0

1000

2000

3000

4000

5000

6000

F R A G M E N T V E L O C I T Y (FPS)

Figure 14.

Minimum velocity for detonation—molten and solid comp B

Secondary Fragment

Figure 15.

Secondary fragment effect


7000

RINDNER AND FORSTEN

Munition Plant Layout


1.


15

16

TOXIC CHEMICAL AND EXPLOSIVES

JUST FILLED

FACILITIES

CONFIGURATION

155 M M H O W I T Z E R P R O J E C T I L E , C O M P B A T 2 0 0 ° F; L O A D I N G F U N N E L IN P L A C E ; I M P A C T E D B Y 12 IN D I A M E T E R C O N C R E T E

FRAGMENT

CONCRETE FRAGMENT TEST

TYPE

LENGTH

WEIGHT

(IN)

(LB)


NO

A

B

VELOCITY (FPS)

KINETIC ENERGY

3

RESULTS'

JS - 1

SOLID

6

70

181

JS - 2

SOLID

6

50

1100

C

1.5

C

JS - 3

SOLID

6

50

1100

C

1.5

C

JS - 4

SOLID

6

53.5

800

0.86

NO GO

JS - 5

SOLID

6

52

900

1.1

NO GO

JS - 6

SOLID

6

53.5

869

1.0

NO GO

JS - 7

SOLID

6

53.5

1065

1.5

NO GO

1.2

NO GO HO HO

5

O N E E N E R G Y U N I T = 6.2 X 1 0 F T L B NO GO = NO REACTION HO = HIGH O R D E R

C

DESCRIPTION

DETONATION

ESTIMATED Figure 18.

Summary of pre-engineered building test results

TEST NO.

PRESSURE (PSD

1

0.27

MINOR D A M A G E T O W A L L & R O O F P A N E L S

2

0.55

SIMILAR T O T E S T 1

3

0.74

F U R T H E R D A M A G E TO W A L L P A N E L S & D A M A G E T O GIRTS

4

1.00

F U R T H E R D A M A G E T O W A L L P A N E L S & GIRTS

5

1.20

F U R T H E R D A M A G E T O W A L L P A N E L S & GIRTS, & MINOR D A M A G E T O F R A M E S

6

1.30

SIMILAR T O T E S T 5

DAMAGE

Figure 17.

Summary of test results


3

1.

RINDNER AND FORSTEN

Munition

Plant

17

Layout

m a t e r i a l s . T h i s could l e a d t o a b e t t e r understanding o f the phenomena governing s e n s i t i v i t y and i g n i t i o n mechanisms f o r detonation propagation. B l a s t E f f e c t s and S t r u c t u r a l Response f o r Acceptor S t r u c t u r e s In my i n t r o d u c t o r y p o r t i o n o f t h i s paper I mentioned t h a t i n the 60 s we developed a s a f e t y design manual (TM5-1300) which deals p r i m a r i l y with the design of p r o t e c t i v e s t r u c t u r e s l o c a t e d i n the h i g h pressure r e g i o n c l o s e - i n t o a detonation. At present, the work i n t h i s area i s d i r e c t e d towards d e v e l opment of design c r i t e r i a and procedures f o r acceptor s t r u c t u r e s l o c a t e d i n low and intermediate pressure ranges. In g e n e r a l , acceptor s t r u c t u r e s r e l a t e t o b u i l d i n g s l o c a t e d i n pressure range o f 10 p s i or l e s s . These buildings o f t e n contain personnel and equipment which r e q u i r e p r o t e c t i o n against the b l a s t and fragment output from a donor b u i l d i n g where hazardous operations are i n v o l v e d . The s e l e c t i o n of. the appropriate s t r u c t u r a l system and m a t e r i a l s f o r acceptor s t r u c t u r e design depends on over-pressure l e v e l , degree o f fragment hazard, contents of the acceptor b u i l d i n g and normal operations involving personnel. I t i s common i n the e x p l o s i v e i n d u s t r y t o be separated by e i t h e r "barricaded or unbarricaded i n t r a l i n e d i s t a n c e " ( c o r r e sponding t o b l a s t loadings of 10 and 3.,5 p s i r e s p e c t i v e l y ) or " i n h a b i t e d b u i l d i n g d i s t a n c e " (corresponding t o b l a s t l o a d i n g of 1.2 p s i ) . These distances are p u b l i s h e d i n the DARCOM Safety Manual (DRCR 385-100) based upon proven s c a l i n g laws. Conventional pre-engineered s t r u c t u r e s , i f used f o r b l a s t r e s i s t a n t design, would not cover pressure l e v e l s r e q u i r e d since t h e i r c a p a c i t y t o r e s i s t b l a s t overpressure (designed f o r snow and winds loads) seldom exceed 0.2 p s i . To design a p p r o p r i ate acceptor s t r u c t u r e s , t e s t s have been conducted t o evaluate the b l a s t c a p a c i t y o f t h e i r v a r i o u s components, namely, the s t e e l frames, g i r t s , p u r l i n s , s i d e panels and windows. The b l a s t r e s i s t a n t c a p a c i t i e s of pre-engineered b u i l d i n g s can be i n c r e a s e d by decreasing the spacing of frames or i n c r e a s ing the s i z e o f i n d i v i d u a l members while s t i l l r e t a i n i n g standard pre-engineered b u i l d i n g elements. Although these m o d i f i c a t i o n s w i l l u s u a l l y r e q u i r e a cost i n c r e a s e , the added costs are u s u a l l y more than o f f s e t by the cost savings achieved by b u i l d i n g separation r e d u c t i o n . A s e r i e s of t e s t s , a d e q u a t e l y instrumented, were performed t o v e r i f y those m o d i f i c a t i o n s , which w i l l produce increased c a p a c i t y and t o i d e n t i f y unknown shortcomings o f p r e engineered b u i l d i n g s . F i g 18 summarizes the pre-engineered b u i l d i n g t e s t r e s u l t s i n c l u d i n g the f r e e - f i e l d pressures, frame, g i r t a n d panel displacement and a b r i e f d e s c r i p t i o n o f t y p i c a l damage f o r each test. The c o l d formed s t e e l panels ( F i g 19) are widely used f o r


f

v

9




18


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RINDNER AND FORSTEN

Munition

Plant

19

Layout

r o o f i n g d e c k i n g , a n d s i d i n g i n the c o n s t r u c t i o n o f s t e e l s t r u c t u r e s and pre-engineered b u i l d i n g s at e x p l o s i v e manufacturing f a c i l i t i e s . Tests were performed at Dugway Proving Grounds, F i g 2 0 , s u b j e c t i n g the panels to overpressures ranging from 0 . 3 - 1 . 5 p s i which were produced by a detonation o f 2 , 0 0 0 l b s o f HE. The t e s t r e s u l t s i n d i c a t e d that the panels e x h i b i t e d considerably greater strength than p r e d i c t e d which u t i l i z e d the minimum y i e l d strength o f about 3 6 , 0 0 0 p s i . However t e s t s i n d i c a t e d that the a c t u a l y i e l d strength o f the panel averaged about 40% higher than the minimum. Glass used i n the b l a s t r e s i s t a n t s t r u c t u r e s can be separated into 2 categories. (1) r e g u l a r glass and (2) tempered g l a s s which c o n s i s t s o f r e g u l a r glass that has been r a p i d l y cooled from i t s near s o f t e n i n g p o i n t to increase i t s mechanical and thermal endurance. Tempered g l a s s i s commonly r e f e r r e d to as " s a f e t y g l a s s . " Tests have been conducted to evaluate the b l a s t r e s i s t a n t c a p a c i t i e s o f both r e g u l a r and tempered g l a s s . The r e s u l t s o f the t e s t s are summarized i n F i g 2 1 . As may be seen from the t a b l e the tempered glass can withstand s e v e r a l times the load o f r e g u l a r glass. Based upon r e s u l t s obtained i t was showi\ that the use o f preengineered b u i l d i n g s to provide p r o t e c t i o n at over-pressure ranges corresponding to i n h a b i t e d b u i l d i n g distances ( P Q = 1 . 2 p s i ) i s practical. I t should be understood that some b u i l d i n g m o d i f i c a t i o n s w i l l be needed to insure that the b l a s t r e s i s t a n t c a p a c i t y o f i n d i v i d u a l b u i l d i n g components are c o n s i s t e n t . T h i s may r e q u i r e the s u b s t i t u t i o n o f l a r g e r members used f o r conventional loads, spacing o f members may have to be reduced, and the number o f i n d i v i d u a l components may have to be increased.


f

S

Hazard C l a s s i f i c a t i o n Studies For In-Process Hazardous M a t e r i a l s Hazards c l a s s i f i c a t i o n i s the assignment of a m a t e r i a l or an end item ( i n t h i s case only in-process m a t e r i a l s ) to a p a r t i c u l a r hazard c l a s s which best describes the t h r e a t presented by the m a t e r i a l . This r e q u i r e s the use o f a hazards c l a s s i f i c a t i o n procedure which provides the g u i d e l i n e s and c r i t e r i a on which the choice o f the hazards c l a s s i s based. The assigned hazards c l a s s o f the m a t e r i a l i s then used as the b a s i s f o r s e l e c t i n g the proper q u a n t i t y - d i s t a n c e r e l a t i o n s h i p . Thus, i f the hazards c l a s s i f i c a t i o n procedure erroneously assigns a m a t e r i a l to the wrong c l a s s , e i t h e r s a f e t y i s compromised or excessive s a f e t y requirements are imposed. Both poss i b i l i t i e s are expensive. The o b j e c t i v e o f t h i s program i s to e s t a b l i s h hazard c l a s s i f i c a t i o n procedures, as a supplement t o the e x i s t i n g r e g u l a t o r y manual, f o r in-process m a t e r i a l s used during the v a r i o u s stages o f p r o p e l l a n t and e x p l o s i v e manufacture. To accomplish t h i s o b j e c t i v e , a review o f the current hazard c l a s s i f i c a t i o n schemes was conducted. Major d e f i c i e n c i e s were uncovered. They r e l a t e d to the c l a s s i f i c a t i o n procedures, to the implementation o f the procedures, and to the f i n a l usage o f the




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1.

RINDNER AND FORSTEN

Munition

Plant

Layout

21

assigned c l a s s i f i c a t i o n ( q u a n t i t y - d i s t a n c e ) . As an i n i t i a l s t e p , the r e p o r t s o f 180 in-process a c c i d e n t s were viewed. A summary o f the type o f i n f o r m a t i o n obtained i s shown i n F i g 22. The process o p e r a t i o n and the probable causa t i v e s t i m u l i which l e d t o the accident are given i n terms o f the number o f accidents and the percentage o f the t o t a l number. Thus the most probable causes o f an accident were i d e n t i f i e d i n an accident a n a l y s i s . The causes v a r i e d by process o p e r a t i o n and m a t e r i a l type. However f r i c t i o n , impact, e l e c t r o s t a t i c discharge (ESD), and h e a t i n g were the most commonly i d e n t i f i e d c a u s a t i v e stimuli. The s t r u c t u r e o f the hazard c l a s s i f i c a t i o n procedure i s shown i n F i g 23. The procedure i s designed t o evaluate s e n s i t i v i t y and e f f e c t s independently. The s e n s i t i v i t y e v a l u a t i o n w i l l c o n s i s t of s p e c i f i e d t e s t s r e q u i r e d f o r a given process o p e r a t i o n . The t e s t s w i l l determine the m a t e r i a l ' s i g n i t i o n energy which w i l l be compared t o the energy developed by the s t i m u l i o c c u r r i n g i n the system. The r a t i o o f the m a t e r i a l s e n s i t i v i t y energy t o the p r o cess p o t e n t i a l energy w i l l give a s a f e t y f a c t o r f o r a s p e c i f i c process o p e r a t i o n . A t e n t a t i v e scheme i s t o c l a s s i f y a m a t e r i a l as h i g h l y s e n s i t i v e (Category A) i f i t s s a f e t y f a c t o r i s l e s s than 1.0; as s e n s i t i v e (Category B) i f the s a f e t y f a c t o r i s between 1 and 10; and not s e n s i t i v e (Category C) i f the s a f e t y f a c t o r is g r e a t e r than 10.0*: Hence,a s e n s i t i v i t y category w i l l be obtained f o r each stimulus w i t h i n a given o p e r a t i o n . The s e n s i t i v i t y c l a s s i f i c a t i o n w i l l be combined with the e f f e c t s e v a l u a t i o n t o determine the m a t e r i a l hazard c l a s s i f i c a t i o n . The e f f e c t s e v a l u a t i o n w i l l determine the l i k e l i h o o d o f a t r a n s i t i o n t o propagation and the consequences t h a t can occur. C r i t i c a l height/depth and c r i t i c a l diameter t e s t s w i l l be performed t o determine the d e t o n a b i l i t y of a m a t e r i a l i n bulk or l a y e r form (on a conveyor). Based on the t r a n s i t i o n r e s u l t s , a d e c i s i o n i s made t o complete one of the f o l l o w i n g e f f e c t s evaluat i o n t e s t s such as: a) f i r e s p r e a d t e s t which w i l l i n c l u d e r a t e o f flame spread, heat of f l u x , and occurrence of f i r e brands and b) a i r b l a s t t e s t s i n c l u d i n g fragment t e s t s . The r e s u l t s o f the e f f e c t s t e s t i n g w i l l be used t o p l a c e the m a t e r i a l i n a hazard category based on NATO-UN c l a s s i f i c a t i o n scheme and when combined w i t h the s e n s i t i v i t y data w i l l give the m a t e r i a l an o v e r a l l hazard c l a s s i f i c a t i o n . For example, a m a t e r i a l which i s found t o be an intense f i r e hazard (consequence 1.3) and s e n s i t i v e (Category B) t o i n i t i a t i o n by rubbing f r i c t i o n would be placed i n c l a s s 1.3B. The r e s u l t s o f the t e s t s w i l l be i n c l u d e d as a supplement t o the NATO-UN hazard c l a s s i f i c a t i o n manual f o r in-process hazardous materials. Water Deluge System A p p l i c a t i o n In Munition P l a n t s A s e r i e s o f p r o j e c t s have been c a r r i e d out t o develop water



22

P E A K PRESSURE (PSI) L O A D D U R A T I O N (MSEC)

1/8 IN. T E M P E R E D

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2.00 PSI

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1/8 IN. R E G U L A R

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Safety Design Considerations in Munition Plants Layout - ACS

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