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AcrAffirmative Actiors/Eqssal Opportunity Employu

ReviewedbyR Dreicer

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DISCf.AfMER

This report was prepared as an account of work sponsored by an agency of the United States Government.Neither the United Sfatea Government nor any agency thereof, nor any of their empIoyeea, makes anywarranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness,or usefulness of assy information, appasmua, product, or prccesa disclosed, or repre~nts that its use svuufdnot infringe privately owned rights. References herein to any s~lc commercial product, process, oraervlce by trade mme, trademark, manufacturer, or otherwise, does not newasarily conmitute or imply itsendorsement, recommendation, or favoring by the United States Government or any agency thereof. The?iews and opinions of authors expressed herein do not necessarily state or reflect those of the UnitedStates Government or any agency thereof.

LA-9707-MS

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UC-71Issued: December 1981

Shipping Containers for

Small Samples of High Explosives

Richard A. HildnerManuel J. Urizar

.

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~~~~u~~~~ L..Al...s,NewMex8758s5.sLosAlamos National Laboratory

SHIPPING CONTAINERS FOR SMALL SAMPLES OF HIGH EXPLOSIVES

by

Richard A. Hildner and Manuel J. Urizar

ABSTRACT

Two sizes of shipping containers for high explo-sives have been designed and tested at the Los AlamosNational Laboratory. The containers have been testedby detonating a powerful, HMX-based explosive in thecontainers. The containers were approved for shipping70% of the minimum weight of explosive that could causevessel failure.

I. INTRODUCTION

In the explosives field, it is imperative that there be amethod for shipping small quantities of explosives. These ex-plosives may be uncharacterized materials sent for laboratoryevaluation or standard explosives for test comparisons. In thepast, small samples (up to 25 g) have been shipped in steel pipesand have been classified as Class C explosives. This is an un-safe practice, because the pipe could be shattered by detonationof the explosive.

The Los Alamos National Laboratory design criteria providefor safe shipment of high explosives by requiring containers cap-able of complete confinement of a possible detonation of the con-tents. The Los Alamos containers use stand-off distance and ab-sorption of the detonation energy to reduce the shock to the con-tainer walls to a level below the failure strength of the walls.

II. CONTAINER DESIGN

A cutaway view of a Los Alamos container is shown in Fig. 1.The inner aluminum tube keeps the explosive away from the con-tainer walls and produces*small, low-mass fragments if an explo-sion occurs. Vermiculite is used as a filler around the innertube to absorb explosion energy. The stainless steel outer cyl-inder wall absorbs the remaining energy by a rapid deformation.The container is shipped in a styrofoam-lined wooden box and thestyrofoam prevents the container wall from reaching the box shellduring expansion.

*Vermiculite is any of a group of micaceous hydrated silicatesof different compositions. It is dehydrated for use asinsulation.

The outer wooden box* is manufactured to meet Departmentof Transportation (DOT) specification No. 173.25.** The styrofoamliners are fabricated from 0.016 g/cm (4.4 lb/ft3) foam. Thevessel end plugs are a modified l/2-in. NPT stainless steel pipeplug and a 7/8-14 hex-head machine bolt. The stainless steel ves-sel is a modified Hoke DOT gas sampling bottle Model LD-1OOO orModel LD-2250, depending on the size required. The vermiculite isinsulation-grade No. 4, 60 mesh or finer. The inner aluminum tubeis 1.91-cm (3/4-in.)-o.d., 0.09-cm (0.035-in.)-wall 6061-T6 tubing.

The components of the shipping vessel and the assembly areshown in Fig. 2. The Hoke vessel is modified for this use. Onel/2-in. NPT port is retapped to a standard 7/8-14 straight machinethread, and then the port threads on both ends of the vessel arerelieved on the inside for 0.16 cm (1/16 in.). The length of theinner tube is measured between the bottoms of the thread reliefs,and the inner aluminum tube is cut to length. The inner tube isinserted from the bottom through the 7/8-14 port with the vesselin a vertical position. Vermiculite is added around the innertube and lightly tamped until the space is filled. The inner tubeis now worked up from the bottom until it seats on the bottom ofthe thread relief area of the l/2-in. NPT port. The vessel isturned over and the inner tube is swaged into the thread relief onthe 7/8-14 end using a 10o tapered punch. The vessel is againturned over, and the inner tube is expanded to the diameter of thethread relief on the l/2-in NPT port. This completes the assembly.

Figure 2 shows the components and assembly of the closureplugs. A standard 7/8-14 machine bolt is modified to receive thehollow, vermiculite-filled absorber cap, and the assemblies arerolled together. A standard l/2-in. NPT pipe plug is modified bybolting an adapter stud to the plug and rolling a vermiculite-filled absorber cap in place. The finished vessels are shown inFig. 3.

III. TEST RESULTS

Five-gram pellets of PBX 9404,+ 1.59 cm (5/8 in.) in diame-ter by 1.27 cm (1/2 in.) long, were pressed to a density of about1.7 g/cm3 for use in the firing tests of the vessels. The ex-plosive was detonated using a RP-l~t electric bursting-bridge-wire detonator. The leads for the detonator were threaded througha 7/8-14 machine bolt with a 0.48-cm (3/16-in.)-diam hole throughit and the bolt was used to close one end of the vessel. The testsetup is shown in Fig. 4.

*The box shown in Fig. 1 was not made to DOT specifications.It was used for testing only.

**Graziano’s Tariff, Bureau of Explosives.~PBX 9404 is 94/3/3 wt% HMX/nitrocellulose/tris(B-chloroethyl)-phosphate.

ffSold by Reynolds Industries Inc., P. O. Box 1170, Marina DelRey, California 90291.

2

4

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The minimum weight of detonating explosive that causedfailure of the test vessels was determined. The LD-1OOO vesselfailed with the detonation of a minimum of 26 g of PBX 9404; theLD-2500 vessel failed at a minimum of 40 g of the same explo-sive. The LD-1OOO was rated acceptable for shipping 15 g of ex-plosive; the LD-2500 vessel was rated acceptable for shipping25 g of explosive.

The vessels were then tested with these explosive weightlimits. After these tests, the vessels were sawed apart and ex-amined to verify that the diameter and the wall thinning at thebulge were uniform, as shown in Figs. 5 and 6, and to verify thatthe calculated strains were less than published yield values.

The vessels were tested at ambient temperature only.Stainless steel does not exhibit any significant loss of ductili-ty or strength at any of the temperatures the containers wouldencounter during transportation and handling. High temperatures,such as those in a fire, would decompose the explosive before anygreat strength loss in the container. The 7/8-14 port is not gas-tight, so gases would be vented before high internal pressurescould occur. .

Iv. CONCLUSION

Group WX-2 has designed and tested shipping containers oftwo sizes that will ensure safety of the shipment of up to 15-gor 25-g samples of any high explosive. These containers can beused safely for any shipping classification of explosives.Therefore, the problems and costs in the shipment of small sam-plqs of explosives are greatly reduced.

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