Committee of Experts on the Transport of Dangerous Goods
and on the Globally Harmonized System of Classification
and Labelling of Chemicals

Sub-Committee of Experts on the Transport of Dangerous Goods

Forty-first session

Geneva, 25 June – 4 July 2012
Item 2 (a) of the provisional agenda

Explosives and related matters: test series 8

               Manual of Tests and Criteria

               Recommendations for improvement of the Series 8(b) ANE Gap Test and other Gap Tests

                   Transmitted by the Instituteof Makersof Explosives (IME)[1]

               Introduction

1.         During the thirty-ninth session, IME raised certain issues regarding the 8(b) test of the Manual of Tests and Criteria and made recommendations to resolve those issues[2], including Table 18.5.1.1 errors and the following test components:

(a)    The pentolite donor,

(b)   The steel tube used to hold the test substance,

(c)   The PMMA rod, and

(d)   The steel witness plate.

2.         IME’s issues and proposals regarding the 8(b) test were discussed by the Working Group on Explosives that met in parallel, and it was agreed by the Sub-Committee that IME, taking into account the conclusions of the Working Group, should prepare formal proposals for the forty-first session[3].

3.         The Test 7(b): EIDS Gap Test employs similar apparatus and materials to the Test 8(b): ANE Gap Test, and hence suffers from similar difficulties in sourcing materials.

4.         At the same session, the expert from Canadapresented the results from a recent survey to the Working Group on Explosives[4]. This survey had been conducted amongst the IGUS[5]stakeholders to establish the scope of problems in obtaining materials for TDG testing according to the Manual of Tests and Criteria. Of all the tests in the Manual, the category of gap tests received the highest number of adverse comments, with difficulties in obtaining the confining steel tubes for these gap tests being of the greatest concern within this category.

5.         Both the current Series 1(a): UN Gap Test and the Series 2(a): UN Gap Test specify that “ … The test sample is contained in cold-drawn, seamless, carbon steel tube with an external diameter of 48 ± 2 mm, a wall thickness of 4.0 ± 0.1 mm and a length of 400 ± 5 mm…”. While the external diameter can be accommodated by tubing of internationally standard sizing[6], the wall is of non-standard thickness. Furthermore, the tolerance of ± 0.1 mm is only a third of the ± 0.3 mm tolerance allowed by international standards[7]for steel tubing of this size and wall thickness. Consequently, no steel tubing manufactured and sized to current international standards meets the current specifications in the test manual.

6.         In the annex (English only), IME discusses how the proposed amendments to the dimensions of the steel tubing would permit the use of tubing manufactured and sized to international standards.

               Proposals

                         Section 18

7.         Amend 18.5.1.2.1(b) of the 8(b) test procedure to read:

(b) 95 mm diameter by 95 mm long pellet with a density of 1 600 kg/m³ ± 50 kg/m³ of either 50/50 pentolite or 95/5 RDX/WAX;

8.         Amend 18.5.1.2.1(c) of the 8(b) test procedure to read:

(c) Tubing, steel, cold drawn seamless, with an outer diameter of 95.0 ± 7.0 mm, a wall thickness of 9.75 ± 2.75 mm and an inner diameter of 73.0 ± 7.0 mm, and with a length of 280 mm;

9.         Amend 18.5.1.2.1(e) of the 8(b) test procedure to read:

(e) Polymethyl methacrylate (PMMA) rod, of 95 mm diameter by 70 mm long. A gap length of 70 mm results in an incident shock pressure at the ANE interface somewhere between 3.5 and 4 GPa, depending on the type of donor used (see Table 18.5.1.1 and Figure 18.5.1.2);

 

10.       Amend 18.5.1.2.1(f) of the 8(b) test procedure to read:

(f) Mild steel plate, 200 mm × 200 mm × 20 mm;

11.       Delete 18.5.1.2.1(g) in its entirety and renumber current 18.5.1.2.1(h) to be 18.5.1.2.1(g).

12.       Amend Table 18.5.1.1 of the 8(b) test procedure as follows:

(a) Revise the “Barrier Pressure Value” for the 55mm gap length entry to read “4.91” instead of “4.76”.

(b)   Revise the “Barrier Pressure Value” for the 60mm gap length entry to read “4.51” instead of “4.31”.

                         Section 17

13.       Amend 17.5.1.2(b) of the 7(b) test procedure to read:

(b) 95 mm diameter by 95 mm long pellet with a density of 1 600 kg/m3 ± 50 kg/m3 of either 50/50 pentolite or 95/5 RDX/WAX;

14.       Amend 17.5.1.2(c) of the 7(b) test procedure to read:

(c) Tubing, steel, cold drawn seamless, with an outer diameter of 95.0 ± 7.0 mm, a wall thickness of 9.75 ± 2.75 mm and an inner diameter of 73.0 ± 7.0 mm, and with a length of 280 mm;

15.       Amend 17.5.1.2(e) of the 7(b) test procedure to read:

(e) Polymethyl methacrylate (PMMA) rod, of 95 mm diameter by 70 mm long;

16.       Amend 17.5.1.2(f) of the 7(b) test procedure to read:

(f) Mild steel plate, 200 mm × 200 mm × 20 mm;

17.       Delete 17.5.1.2(g) in its entirety and renumber current 17.5.1.2(h) to be 17.5.1.2(g).

                         Section 11

18.       Amend the second sentence of 11.4.1.2.1 of the 1(a) test procedure to read:

The test sample is contained in cold-drawn, seamless, carbon steel tube with an external diameter of 48.0 ± 2.0 mm, a wall thickness of 4.8 ± 0.9 mm, an inner diameter of 39.3 ± 3.0 mm and a length of 400 ± 5 mm.

                         Section 12

19.       Amend the second sentence of 12.4.1.2 of the 2(a) test procedure to read:

The test sample is contained in cold-drawn, seamless, carbon steel tube with an external diameter of 48.0 ± 2.0 mm, a wall thickness of 4.8 ± 0.9 mm, an inner diameter of 39.3 ± 3.0 mm and a length of 400 ± 5 mm.

 

 

Annex

English only

               Discussion of steel tubing dimensions in Gap Tests

               Introduction

1.         At the thirty-ninth session of the Sub-Committee, the expert from Canadapresented the results from a recent survey to the Working Group on Explosives [1]. This survey had been conducted amongst the IGUS [2] stakeholders to establish the scope of problems in obtaining materials for TDG testing according to the Manual of Tests and Criteria [3] (referred to subsequently as test manual). Of all the tests in test manual, the category of Gap tests received the highest number of adverse comments, with difficulties in obtaining the confining steel tubes for these Gap tests being of the greatest concern within this category.

2.         Many of these difficulties have arisen because the dimensions specified in test manual for the confining steel tubing do not match the dimensions and tolerances of the standard sizes specified for steel tubing by current international standards [4, 5]. While paragraph 1.1.2 of the General Introduction to test manual states that “The competent authority has discretion to dispense with certain tests, to vary the details of tests, and to require additional tests when this is justified to obtain a reliable and realistic assessment of the hazard of a product”, such discretion should not be a necessary prerequisite to allow the tests to be conducted at all.

3.         The intention of such gap tests is to measure the shock sensitivity of the substance under confined conditions. It is well known in detonation science that the three primary factors that determine whether or not shock initiation of explosive substances will occur in a gap test are (1) the peak pressure of the shock delivered at the interface between the substance and the donor/attenuator system, (2) the duration of the pressure pulse delivered to the interface, and (3) the curvature of the shock delivered to the interface. The reproducibility of these three primary factors is assured under the gap test conditions by controlling (1) the composition, density and physical dimensions of the donor explosive pellet, (2) the location of the detonator, and (3) the physical dimensions of the chosen attenuator. Each of these elements is adequately controlled by the specifications in test manual.

4.         The confinement plays a secondary role in these gap tests, promoting the propagation of any reactive shock away from the interface with the donor/attenuator and throughout the length of the test substance towards the witness plate. The controlling elements in the effectiveness of a confining tube are in order (1) its inner diameter, (2) the material’s shock impedance (namely the product of its density and its speed of sound), and (3) the inertia of the wall (controlled by its density and its wall thickness). It is the shock impedance that controls the initial deflection of the interface between the test substance and the wall upon shock arrival; the inertia only begins to have an influence once there has been time for multiple internal shock reverberations between the inner and outer surfaces of the wall. All grades of steel have similar densities and sound velocities (and hence shock impedances and inertias), so only the inner diameter and the wall thickness need to be specified within suitable tolerances to ensure reproducibility of gap test results.

5.         This annex will discuss the justification behind the three proposals in this document recommending changes to each of the four gap tests in test manual to align the dimensions of their confining steel tubing with current international standard steel tubing sizes.

The Series 1(a) and 2(a) Gap Tests

6.         Price and co-workers [6, 7] have described the development of the original Naval Ordnance Laboratory Large Scale Gap Test (NOL LSGT), starting from the early 1950s. The confining steel tubes in this test were described as “cold drawn, mechanical steel (MT-1015) seamless tube”, with nominal dimensions of outer diameter (OD) " (47.63 mm), inner diameter (ID) " (36.51 mm) and hence by subtraction, wall thickness " (5.56 mm); their length was " (139.7 mm). The tolerances on these dimensions are not known here since this is a non-standard tubing size. Erkman et al. [8] provided a calibration of peak shock pressure versus gap length for their combination of a pressed Pentolite donor and polymethyl methacrylate (PMMA) attenuator.

7.         The NOL LSGT was adopted by the Sub-Committee (TDG) as the basis for the Series 2(a) Gap Test. The only major change was that the length of the confining tube was more than doubled to be 400 mm in order to discriminate more reliably against fading detonations. The length and diameter of the donor explosive pellet and the diameter of the PMMA attenuator were converted from their original imperial units to the metric system and rounded off. The length of the PMMA attenuator was fixed at 50 mm, which would correspond to an incident shock pressure at the interface between the PMMA and the test substance of 2.15 GPa according to the calibration [8].

8.         The Series 1(a) Gap Test is identical to the Series 2(a) Gap Test with the exception that no PMMA attenuator is used, with the explosive donor being in intimate contact instead with the test substance.

9.         Of particular significance to this annex, the dimensions of the steel tubing were converted to the metric system and rounded off. The specification in test manual is currently “cold-drawn, seamless, carbon steel tube with an external diameter of 48 ± 2 mm, a wall thickness of 4.0 ± 0.1 mm, …” It is notable that the wall thickness is reduced by over a quarter from its original NOL LSGT value of 5.56 mm (for reasons unknown here), and furthermore, is specified with the unrealistically small tolerance of ± 0.1 mm. Current international standards [9] allow a tolerance of 7.5%, equivalent to ± 0.3 mm in the wall thickness, for cold-worked tubing of this inner diameter and wall thickness. Hence it is the case that no off-the-shelf steel tubing manufactured to international standards can meet current test manual specifications on the tolerance of the wall thickness.

10.       Standard steel tubing of size NPS-1½ (in the North American Nominal Pipe Size designation) or DN-40 (in the exactly equivalent European Diamètre Nominal designation) meets the test manual specification of the outer diameter. However, the wall of Schedule 40 tubing is too thin, while that of the next thicker Schedule 80 tubing is too thick, to meet the test manual specification on the wall thickness. The relevant dimensions, calculated taking into account the allowable tolerances specified by ASTM/A519 [9] for the NPS-1½/DN-40 tubing, are included in Table 1.

 

Table 1. Ranges of tubing dimensions relevant to the Series 1(a) and 2(a) Gap tests

Derived dimensions are listed in brackets.

11.       Price [7] described the results of investigations into the effect of confinement on the results of the NOL LSGT. It was found that confinement had a negligible effect on the results for cast Pentolite, with the length of the critical PMMA gap corresponding to 50% initiation being 67.56 mm for an unconfined test charge and 67.06 mm for a test charge confined in steel – this difference is within experimental scatter for this gap test. The results for cast Composition B did show greater dependence on confinement, with the critical gap increasing from 36.32 mm for an unconfined test charge to 45.47 mm for aluminium confinement and to 51.05 mm for steel confinement. However, increasing the inertia of the confinement further by replacing steel tubing by lead tubing made essentially no further difference, with the critical gap increasing only very slightly to 51.82 mm with the latter. So while the presence of confinement was important for cast Composition B, its specific details were not once a certain level of inertia had been exceeded. It may be inferred that increasing the inertia of the steel confinement by increasing the wall thickness would similarly have made no significant difference to the critical gap. These results for the NOL cast Composition B are highly relevant here, since the critical gap of 51.05 mm is only slightly longer than the 50 mm gap length adopted for the Series 2(a) Gap Test. The response of this cast Composition B would have been close to the boundary between returning either a positive or a negative result in the Series 2(a) Gap Test, and hence served as a valid probe of critical behaviour and conditions in this test.

12.       The current proposals are to specify the dimensions of the steel tubing in the Series 1(a) and 2(a) Gap Tests as having an outer diameter of 48.0 ± 2.0 mm, a wall thickness of 4.8 ± 0.9 mm and an inner diameter of 39.3 ± 3.0 mm. The resulting limits are included in the last line of Table 1.

13.       These proposals would permit the use of standard NPS-1½/DN-40 Schedule 80 steel tubing (highlighted in Table 1) for these two tests. The inner diameter would be greater than the minimum considered acceptable previously by test manual, while the wall thickness (of nominal 5.08 mm) would be slightly thicker than that specified in test manual, but closer to that of the originating NOL LSGT.

14.       Any steel tubing that complied with the test manual specifications would still comply under these proposals. Test results generated to test manual specifications could be brought forward.

15.       The NOL LSGT procedure was adopted as one of the key gap test methodologies by many explosive laboratories throughout the USA(and indeed, in all probability in many explosive laboratories worldwide). It is likely that many historical explosive and propellant compositions have been subjected to gap tests employing the NOL LSGT steel tubing. However, since its wall thickness (nominal 5.56 mm) lies outside the specification of 4.0 ±0.1 mm in test manual, any results from the NOL LSGT can only be accepted under the discretionary powers of the relevant Competent Authorities as being equivalent to testing under Series 1(a) and 2(a) conditions. The NOL LSGT steel tubing would comply under these current proposals, subject only to the proviso that its manufacturing tolerances complied with ASTM/A519 [9]. Test results generated under NOL LSGT conditions could be accepted without the need for discretionary exemptions.

The Series 7(b) and 8(b) Gap Tests

16.       Swisdak [10] has recounted some of the history behind the introduction of Hazard Class/Division 1.6 in the late 1980s for articles containing Extremely Insensitive Detonating Substances (EIDS). Following the development of new types of insensitive explosives during the 1970s and 1980s, it had been recognised that new classification and testing regimes were required for military explosives which had relatively small critical diameters but were still insensitive, as distinct from Class 1.5 which was devised for commercial blasting agents which were insensitive because of large critical diameters. The US Department of Defence Explosive Safety Board (DDESB) requested that the Naval Surface Warfare Center (NSWC) review the existing protocol for Class 1.5 and IHE materials.

17.       NSWC identified the need for a larger scale gap test for EIDS whose confined critical diameters were comparable to, or larger than, the diameter of the NOL LSGT. This led to the development [11] and calibration [12] of the NSWC Expanded Large Scale Gap Test (ELSGT). Basically, most dimensions of the NOL LSGT were doubled, with the major exception being the donor pellet diameter whose size increase was limited to a factor of only 1.875 due to limitations in the size of the available pressing moulds. The witness plate thickness was doubled, but its area was not “because of handling problems” associated with the greater mass to be manhandled.

18.       In particular, all dimensions of the confining steel tubing were doubled, becoming an outer diameter of " (95.25 mm), an inner diameter of " (73.03 mm) and hence by subtraction, a wall thickness of " (11.1 mm), and a length of 11" (279.4 mm). The tolerances on these dimensions are not known here since this is a non-standard tubing size.

19.       The NSWC ELSGT was adopted by the SCETDG as the basis for the Series 7(b) EIDS Gap Test with minimal changes. All dimensions were converted from their original imperial units to the metric system and rounded off. The length of the PMMA attenuator was fixed at 70 mm. The most significant change involved the specification of tensile strength, elongation and hardness for the steel tubing and steel witness plate, replacing the NSWC ELSGT usage of mild steel for which no mechanical properties can be guaranteed.

20.       The methodology of the Series 7(b) EIDS Gap Test was adopted with minimal changes for the Series 8(b) ANE Gap Test. The requirement to machine the test substance was omitted, some information was added about the pressure delivered to the interface between the PMMA attenuator and the test substance, and the small air standoff gap between the test substance and the witness plate was omitted.

21.       In particular, the test manual specification of the steel tubing for both the Series 7(b) and 8(b) Gap Tests is in part “tubing, steel, cold drawn seamless, 95 mm outer diameter, 11.1 mm wall thickness ± 10% variations …” The relevant limits are listed in Table 2, where it has been assumed that the “± 10% variations” are meant to be applied to both the outer diameter and the wall thickness. An undesirable consequence of specifying outer diameter and wall thickness is that the inner diameter becomes poorly bounded, despite the inner diameter being the more important parameter affecting detonation propagation in explosive substances. The variation of the inner diameter allowed by test manual is ± 16%.

Table 2. Ranges of tubing dimensions relevant to the Series 7(b) and 8(b) Gap tests

Derived dimensions are listed in brackets.

22.       NATO also based its version of the Expanded Large Scale Gap Test directly on the original NSWC ELSGT, although choosing to specify the inner diameter rather than the wall thickness. The precise wording was “Acceptor explosives are either cast or pressed into a 4340 steel tube of 279 mm in length, 73.2 mm inner diameter, and 95.3 mm outer diameter. A tolerance of up to 10% for the inner and outer diameters is allowed to accommodate standard tube sizes available in Europe…”. It can be seen from Table 2 that the NATO choice has resulted in tighter specification of the inner diameter, though allowing greater leeway on the wall thickness, than the test manual specification.

23.       As noted above, the dimensions of the steel tubing chosen for the NSWC ELSGT were derived by doubling those of an already non-standard size used in the NOL LSGT. Whereas at least the outer diameter of the NOL LSGT/test manual tubing can be matched by a standard tubing size, the outer diameter of the NSWC ELSGT/test manual tubing now falls exactly midway between those of two standard tubing sizes, namely 88.90 mm for NPS-3/DN-80 and 101.60 mm for NPS-3½/DN-90. Table 3 summarises the various scheduled wall thicknesses and inner diameters that are defined for these two standard sizes, together with an indication of those that fall within the allowable ranges in Table 2 (P) and those that do not (O), taking the tolerances specified in ASTM/A519 [12] into account.

 

Table 3. Standard tubing sizes.

The combinations that meet all allowable ranges in Table 2 are highlighted.

24.       Only one standard tubing size, namely NPS-3/DN-80 Schedule 160, complies with test manual, though at the expense of reducing the nominal inner diameter to 66.65 mm, somewhat less than the intended inner diameter of 72.8 mm in test manual. Six standard tubing sizes comply with the specification of the NATO ELSGT test, though at the expense of allowing what might be considered excessively thin and excessively thick walls at the extremes.

25.       The current proposals are to specify the dimensions of the steel tubing in the Series 7(b) and 8(b) Gap Tests as having an outer diameter of 95.0 ± 7.0 mm, a wall thickness of 10.0 ± 2.50 mm and an inner diameter of 73.0 ± 7.0 mm. The resulting limits are included in Table 2, with the compliant standard tubing sizes highlighted in Table 3.

26.       These proposals would permit the use of two additional standard sizes, namely NPS-3/DN-80 Schedules 80 (also called XS for Extra Strong) and 120 steel tubing for these two tests. Both of these additional options have inner diameters that are closer to the intended inner diameter of 72.8 mm in test manual, albeit with slightly thinner walls, than the only current compliant standard size.

27.       The majority of the steel tubing that complied with the test manual specifications would still comply under these proposals. However, tubing with inner diameters at the extremes of the range allowed by test manual would no longer be compliant. Such tubes would have combined either the largest outer diameters with the thinnest walls, or the smallest outer diameters with the thickest walls, within the ranges allowed by test manual.

28.       Similar comments would apply to the majority the steel tubing that complied with the NATO specifications. Only tubing with either very thin or very thick walls would not comply with the current proposals.

Concluding remarks

29.       The current proposals would enable a selection of internationally standard tubing sizes to be utilised in the UN Gap Tests without requiring prior dispensation from the relevant Competent Authorities.

               References

[1]       Informal document INF.25 (39^th session), Difficulties in carrying out TDG classification tests.

[2]       http://www.oecdigus.org/

[3]       Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, Fifth Revised Edition, United Nations, New Yorkand Geneva, 2009.

[4]       ASME B36.10M – Welded and Seamless Wrought Steel Pipe.

[5]       http://en.wikipedia.org/wiki/Pipe_(fluid_conveyance), accessed 11/08/2011.

[6]       Donna Price, A.R. Clairmont, Jr., and J.O. Erkman, “The NOL Large Scale Gap Test. III. Compilation of Unclassified Data and Supplementary Information for Interpretation of Results”, Naval Ordnance Laboratory Report NOLTR 74-40, 8 March 1974.

[7]       Donna Price, “Safety Information from Propellant Sensitivity Studies”, Naval Ordnance Laboratory Report NOLTR 62-41, 20 March 1962.

[8]       J.O. Erkman, D.J. Edwards, A.R. Clairmont, Jr. and Donna Price, “Calibration of the NOL Large Scale Gap Test; Hugoniot Data for Polymethyl Methacrylate”, Naval Ordnance Laboratory Report NOLTR 73-15, 4 April 1973.

[9]       ASTM/A519-06 Standard Specification for Seamless Carbon and Alloy Steel Mechanical Tubing.

[10]     Michael M. Swisdak, Jr., “Hazard Class/Division 1.6: Articles containing Extremely Insensitive Detonating Substances (EIDS)”, Naval Surface Warfare Center Report NSWC TR 89-356, 1 December 1989.

[11]     T.P. Liddiard and D. Price, “The Expanded Large Scale Gap Test”, Naval SurfaceWarfareCenterReport NSWC TR 86-32, March 1987.

[12]     Douglas G. Tasker and Robert N. Baker, Jr., “Experimental Calibration of the NSWC Expanded Large Scale Gap Test”, Naval SurfaceWarfareCenterReport NSWCDD/TR-92/54, January 1992.

[13]     NATO Standardization Agency, “STANAG 4488 PCS (Edition 1) – Explosives, Shock Sensitivity Tests”, NSA/0883-PPS/4488, 12 September 2002.

                    

联合国危险货物运输专家和全球化学品统一分类和标签制度专家委员会

危险货物运输专家分委员会

第四十一次会议

日内瓦，2012年6月25日 – 7月4日
议程第2 (a) 项

爆炸物和相关内容：试验系列8

               试验和标准手册

               对8(b) ANE隔板试验和其他隔板试验的改进建议

                   由炸药制造者协会（IME）提交[8]

               介绍

1.         第39次会议上，就试验和标准手册中的8(b)试验，IME提出了一些问题和解决这些问题的建议，包括表18.5.1.1中的错误和下面的试验组件：

(a)    彭托利特炸药供体装药，

(b)   装样的钢管，

(c)   聚甲基丙烯酸甲酯棒，和

(d)   钢制验证板。

2.         同时进行的爆炸品工作组会议讨论了IME提出的关于8(b)试验的问题和建议，工作组同意IME按工作小组讨论的结论进行41次会议正式提案的准备[9]。

3.              7(b)试验（极不敏感引爆物质的隔板试验）使用了与8(b)试验（硝酸铵乳胶的隔板试验）类似的设备和材料，因此在原材料获取方面存在同样的困难。

4.              在这次会议上，加拿大专家向爆炸品工作小组提交了最近的一个调查结果[10]。 该调查在IGUS[11]成员之间进行，目的在于确定根据《试验和标准手册》进行危险品运输相关试验时，哪些试验存在材料获取的问题。在《手册》的所有试验中，隔板一类试验收到的反面意见最多，因其难以获取封闭钢管而颇受关注。

5.         现行的1(a)和2(a)联合国隔板试验都规定：“试验样品装在一根冷拉无缝碳钢管中，钢管的外直径48±2mm，壁厚4.0±0.1mm，长度为400±5mm……”。然而，外直径可以符合国际管道标准尺寸，但是管壁却是非标准厚度。此外，该试验中规定的误差±0.1mm，仅是这一规格钢管的国际标准允许误差±0.3mm的三分之一。因此，按照国际标准制造的钢管都不符合试验手册中规定的钢管。

6.         在附件中，IME讨论了如何对钢管尺寸进行修正，才能使钢管的制造和尺寸符合国际标准。

               提议

                         第18部分

7.         将8(b)试验程序中的18.5.1.2.1(b)修改为：

 (b)直径95mm，长95mm的压制50/50彭托利特炸药或95/5 RDX/WAX，其密度为1 600 kg/m³ ± 50 kg/m³；

8.         将8(b)试验程序中的18.5.1.2.1(c)修改为：

 (c)冷拔无缝钢管，外直径95.0±7.0mm，壁厚9.75±2.75mm，内直径73.0±7.0mm，长280mm；

9.         将8(b)试验程序中的18.5.1.2.1(e)修改为：

 (e) 聚甲基丙烯酸甲酯(有机玻璃)棒块，直径95mm，长70mm。隔板长70mm，根据使用供体类型（见表18.5.1.1和图18.5.1.2），对硝酸铵乳胶界面造成的冲击压大约在3.5至4GPa之间。

 

10.       将8(b)试验程序中的18.5.1.2.1(f)修改为：

 (f)软钢板，200mm×200mm×20mm；

11.       删除18.5.2.1(g)整条，并将18.5.1.2.1(h)重新编号为18.5.1.2.1(g)。

12.       将8(b)试验程序中的表18.5.1.1按如下修改：

 (a)隔板距离为55mm条目下的屏障压力值“4.76”修正为“4.91”。

 (b) 隔板距离为60mm条目下的屏障压力值“4.31”修正为“4.51”。

                         第17部分

13.       将7(b)试验程序中的17.5.1.2(b)修改为：

 (b)直径95mm，长95mm的压制50/50彭托利特炸药或95/5 RDX/WAX，其密度为1 600 kg/m³ ± 50 kg/m³；

14.       将7(b)试验程序中的17.5.1.2(c)修改为：

 (c)冷拔无缝钢管，外直径95.0±7.0mm，壁厚9.75±2.75mm，内直径73.0±7.0mm，长280mm；

15.       将7(b)试验程序中的17.5.1.2(e)修改为：

 (e)聚甲基丙烯酸甲酯(有机玻璃)棒块，直径95mm，长70mm；

16.       将7(b)试验程序中的17.5.1.2(f)修改为：

 (f) 软钢板，200mm×200mm×20mm；

17.       删除17.5.1.2(g)整条，并将17.5.1.2(h)重新编号为17.5.1.2(g)。

                         第11部分

18.       将1(a)试验程序11.4.1.2.1中第二句修正为：

试验样品装在一根冷拉无缝碳钢管中，钢管外直径48.0±2.0mm，壁厚为4.8±0.9mm，内直径39.3±3.0mm，长400±5mm。

                         第12部分

19.       将2(a)试验程序12.4.1.2中第二句修正为：

试验样品装在一根冷拉无缝碳钢管中，钢管外直径48.0±2.0mm，壁厚为4.8±0.9mm，内直径39.3±3.0mm，长400±5mm。

 

 

附件

隔板试验中钢管规格的讨论

               介绍

1.         分委员会第39次会议上，加拿大专家向爆炸品工作小组[1]提交了最近的一个调查结果。该调查在IGUS[2]成员之间进行，目的在于确定根据《试验和标准手册》进行危险品运输相关试验时，哪些试验存在材料获取的问题。在《手册》的所有试验中，隔板一类试验收到的反面意见最多，因其难以获取封闭钢管而颇受关注。

2.         许多问题的出现是因为目前试验手册上规定的密封钢管尺寸和允许误差不符合目前国际标准[4, 5]中规定的标准尺寸。虽然试验手册概述中1.1.2节说到：“为获取某种产品可靠和现实的危险性评估时，主管当局有权决定免除某些试验、改变试验细节和要求增加试验项目”，但是这个权利不应是这些试验进行的必要条件。

3.         这些隔板试验的目的是测量物质在封闭条件下对冲击的敏感度。众所周知，在爆炸学中，三个基本因素决定了物质是否能够在隔板试验中被冲击引爆：(1)冲击传播到物质和供体/衰减系统的接触表面时的压力峰值；(2)传播到该接触面的压力脉冲的持续时间；以及(3) 传播到该接触面的压力曲线。通过控制以下几点以确保隔板试验中三个基本要素的重复性：（1）供体炸药的组分、密度和物理尺寸；（2）雷管的放置位置；及（3）衰减器物理尺寸的选择。试验手册规定了每一要素的规格参数。

4.         在这些隔板试验中，封闭条件起着次要作用，促使离开供体/衰减器接触面的反应冲击波继续贯穿整个试验物质，朝向验证板进行传播。封闭钢管中，这些影响因素的有效性排序如下：(1)内直径，(2)物质的冲击阻抗（即密度和声速的乘积），(3)管壁的惰性（与密度和壁厚有关）。冲击阻抗影响冲击到达时试验物质和管壁接触面之间的初始偏差；管壁惰性仅在有足够时间使内外管壁之间产生大量内部反射冲击时起作用。所有等级的钢材都有相似的密度和声速（冲击阻抗和惰性也类似），所以只需将内直径和壁厚规定在一定公差范围内，即可确保隔板试验结果的重复性。

5.         本文件中的三个提案是对试验手册中四个隔板试验进行修改，以统一钢管尺寸，使其符合目前的国际标准中钢管尺寸。本附录将针对提议背后的缘由进行讨论。

1(a) 和2(a)隔板试验

6.         Price和他的同事[6, 7]描述了20世纪50年代早期以来原海军机械研究所大规模隔板试验(NOL LSGT)的发展。该试验对于密封钢管的描述为“冷拉、机械钢(MT-1015)、无缝钢管”，公称尺寸外径(OD) " (47.63 mm)，内直径 (ID) " (36.51 mm)，因此通过相减，壁厚 " (5.56 mm)；长 " (139.7 mm)。此处允许误差未知，因为这是非标准钢管尺寸。在使用压缩彭托利特炸药供体和聚甲基丙烯酸甲酯衰减器时，Erkman et al. [8]给出了隔板长度与冲击压力峰值之间的校准方法。

7.         .分委员会（TDG）所采用的2(a)隔板试验正是基于海军机械研究所大规模隔板试验。主要的改变只是将密封钢管的长度加长一倍，达到400mm，以便更可靠地区分爆轰波的衰减过程。压制爆炸品供体的长度和直径以及聚甲基丙烯酸甲酯衰减器的直径由原来的英制尺寸转变为公制，并四舍五入。聚甲基丙烯酸甲酯衰减器的长度固定为50mm，通过校准[8]， PMMA和试验物质接触面之间对应的冲击压力为2.15GPa。

8.         1(a)隔板试验未使用PMMA衰减器，炸药供体直接与试验物质接触，其他与2(a)试验相同。

9.         钢管尺寸转变为公制尺寸并四舍五入对本附录有重要意义。目前试验手册中的规格为“冷拉无缝碳钢管，外直径为48±2mm，壁厚4.0±0.1mm，……”值得注意的是，壁厚比最初的海军机械研究所大规模隔板试验中的值5.56mm少了四分之一，原因未知。此外，还指定了小得不切实际的允许误差±0.1mm。目前的国际标准对这个内直径和壁厚冷加工的钢管允许误差为7.5%，相当于壁厚误差±0.3mm。因此，现行符合国际标准的钢管成品都满足不了目前试验手册中对壁厚允许误差规定。

10.       标准钢管尺寸 NPS-1½ (北美管道公称尺寸中定义) 或者DN-40 (等效的欧洲直径标称中定义) 满足试验手册中外直径规定。但是，相比于试验手册中规定的壁厚，管表号 40的管子太薄，管表号 80的太厚。表一中列出了NPS-1½/DN-40相关尺寸，允许误差参照ASTM/A519 [9]规定。

 

表1.  1(a)和2(a)隔板试验中相关钢管尺寸的范围

导出尺寸用括号表示

11.       .Price [7]描述了对封闭条件对NOL LSGT结果影响的调查结果。对于浇铸彭托利特炸药，在无约束试验中50%触发的临界PMMA隔板长度为67.56  mm，而使用钢管约束的试验中其临界值为67.06  mm，这些差异在隔板试验的误差允许范围之内，由此可见，此时约束条件对结果的影响微乎其微。 而约束条件对B炸药的影响要稍微大点，无约束时隔板临界值36.32  mm，铝约束时为45.47  mm，钢约束时为51.05  mm。然而，通过使用铅管代替钢管来增加约束的惰性时，并无大的差别，隔板临界值只是稍微增加至51.82  mm而已。由上可以看出，虽然有无约束对于B炸药而言影响较大，但一旦约束的惰性值超过一定范围，对于具体参数的影响并不大。因此，可以认为通过增加壁厚值来增加钢约束的惰性，对于隔板临界值并无明显影响。NOL的压制B炸药的结果相关性比较大，因为，系列2（a）隔板试验采用的50  mm隔板长度只是比B炸药的临界值51.05  mm稍小点而已。B炸药的反应值非常接近于系列2（a）隔板试验中得出的阳性或阴性结果的边界值，因此，可以将其作为本实验中临界行为和条件的有效性证明。

 

12.       本提案建议规定1(a) 和 2(a)隔板试验中钢管的尺寸为外直径48.0±2.0mm，壁厚为4.8±0.9mm，内直径39.3±3.0mm。各个尺寸的区间范围见表1最后一行。

13.       这样一来就可以在这两个试验中使用NPS-1½/DN-40标准的Schedule 80钢管（表1中高亮）。这些内直径要大于先前试验手册规定的最小值，而壁厚（公称5.08mm）比试验手册中的规定稍微厚一点，但是这更接近于初始的海军机械研究所大规模隔板试验。

14.       本提案中，任何符合试验手册规定的钢管以及由此得出的试验结果仍可用。

15.       美国的许多爆炸实验室（事实上，很可能是全世界的爆炸实验室）都采用海军机械研究所大规模隔板试验程序作为一个关键的隔板试验研究方法。很可能历史上很多炸药和推进剂组分都使用NOL LSGT钢管进行过隔板试验。但是，它的壁厚（公称5.56mm）处于试验标准手册规定的4.0±0.1mm之外，由NOL LSGT得出的试验结果仅能被相关的主管当局酌情裁决其等价于1(a) 和 2(a)试验条件时接受。只要增加其制造公差的约束，即符合ASTM/A519的公差规定 [9]，NOL LSGT钢管即可符合我们现在的提案规定。NOL LSGT条件下得出的试验结果无需豁免就可被接受。

7(b)和8(b)隔板试验

16.       Swisdak [10]叙述了20世纪80年代末，针对含有极不敏感引爆物质的物品（EIDS）引进1.6项危险性分类的历史。随着二十世纪七八十年代新型不敏感爆炸品的发展，如军用爆炸品的临界直径比较小但仍具不敏感特性，对于此，人们意识到需要新的分类和试验体系，以区别于1.5项（用于商用爆炸品，由于有较大的临界直径而不敏感）。美国国防部爆炸安全委员会（DDESB）要求海军水面作战中心（NSWC）重新审视现行1.5项的标准和IHE材料。

17.       EIDS的临界限制直径与NOL LSGT差不多或者稍大，海军水面作战中心认为有必要进行EIDS的大规模隔板试验。这导致了NSWC扩展大规模隔板试验(ELSGT)的建立[11]和改进[12]。基本上， NOL LSGT的大部分尺寸在大规模隔板试验中都加倍了，但压制炸药供体直径除外，因受可获取的模具尺寸的限制，其直径只增加了1.875倍。验证板厚度加倍，但考虑到大质量带来的“操作问题”，面积不变。

18.       尤其是封闭钢管的所有尺寸都加倍，外直径 " (95.25 mm)，内直径 " (73.03 mm)，因此壁厚of " (11.1 mm)，长11" (279.4 mm)。这个尺寸的钢管是非标尺寸管，因此其允许误差未知。

19.       SCETDG 采用NSWC扩展大规模隔板试验作为7(b) EIDS隔板试验的基础，只是作了很小的改变。所有的尺寸均从其原始英制单位转化为公制，并四舍五入。PMMA衰减器的长度固定为70mm。最显著的改变包括规定了钢管和验证版抗拉强度、延伸率和硬度的规格参数， 以替代NSWC ELSGT使用的低碳钢，因为低碳钢未规定任何的机械特性。

20.       7(b)EIDS隔板试验的方法被稍加修改用作了8(b)ANE隔板试验。用机械制造试验物质的要求被省略了，增加了一些关于传播至PMMA衰减器和试验物质接触面的压力信息。试验物质和验证板之间的小空气平衡间隙也被省略了。

21.       特别是，试验手册上7(b)和8(b)隔板试验对于钢管的规定为以下部分：“冷拔无缝钢管，外直径95mm，壁厚11.1mm，±10%的偏差……”相关的极限值在表2中列出，其中假设±10%变差同时应用于外直径和壁厚。规定的外直径和壁厚的不良后果是内直径变得很有限，但实际上，内直径是影响爆轰在爆炸性物质中传播的更为重要的因素。试验手册中内直径的允许范围为±16%。

表2. 有关7(b)和8(b)隔板试验的钢管尺寸范围

导出尺寸用括号表示

22.       虽然北大西洋公约组织的扩展大规模隔板试验指定的是内直径而不是壁厚，但其也是直接基于原始的NSWC ELSGT试验。准确的措辞是“受体炸药被浇铸或者压制到4340钢管（长279mm，内直径73.2mm，外直径95.3mm）。内外直径的允许误差上限为10%，以适应欧洲的标准管道尺寸……”从表2中可以看出，虽然NATO允许的壁厚偏差比试验手册中的规定值大，但其更严格地规定了内直径。

23.       如上所述，NSWC ELSGT钢管尺寸的选择由NOL LSGT使用的非标尺寸加倍而来。然而，至少NOL LSGT/试验手册钢管的外直径可以与标准管尺寸匹配，但NSWC ELSGT/试验手册钢管外直径恰好落在两个标准尺寸之间，也就是NPS-3/DN-80的88.90 mm和NPS-3½/DN-90的101.60 mm。表3概括了这两个标准尺寸中定义的壁厚和内直径的偏差，同时指出表2允许范围之内的(√)和之外的(×)参数。误差值参考ASTM/A519 [12]的规定。

 

 

表3. 标准钢管尺寸

满足所有允许范围的组合在表2中高亮标出

24.       仅有一个标准管道尺寸，也就是NPS-3/DN-80 管表号 160，与试验手册相符，不过需要减少公称内径至66.65mm，略小于试验手册中指定的内径72.8mm。六个标准管道尺寸符合NATO ELSGT试验中的规定，但是其管壁可能会很薄或者很厚。

25.       本提案旨在规定7(b)和8(b)隔板试验中钢管的尺寸，外直径95.0 ± 7.0 mm，壁厚10.0 ± 2.50 mm，内直径73.0 ± 7.0 mm。表2包括了限值的结果，在表3中给出了符合钢管尺寸的数值。

26.       这些提案将允许在这两个试验中使用另外两个标准尺寸的钢管，即NPS-3/DN-80 管表号 80 (也用XS表示特强号) 和120钢管。虽然管壁比现行的标准尺寸稍薄，这两个新增钢管的内径都接近于试验手册中规定的内径72.8mm。

27.       大多数符合试验手册规定的钢管将仍然符合这些提案的规定。但是，试验手册中内直径允许范围边缘处的一些钢管将不再适用，因为在试验手册规定的范围内，这些钢管要么大外径、薄管壁，要么就是小外径、厚管壁。

28.       类似的解释可以用于大多数符合NATO规定的钢管。只有非常薄或者厚的管壁将不符合目前的提案。

结束语

29.       现在的这些提案将确保在进行联合国隔板试验时，可以选择使用符合国际标准管道尺寸的钢管，而不需要预先得到相关主管当局的豁免。

               参考文献

[1]       Informal document INF.25 (39^th session), Difficulties in carrying out TDG classification tests.

[2]       http://www.oecdigus.org/

[3]       Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, Fifth Revised Edition, United Nations, New Yorkand Geneva, 2009.

[4]       ASME B36.10M– Welded and Seamless Wrought Steel Pipe.

[5]       http://en.wikipedia.org/wiki/Pipe_(fluid_conveyance), accessed 11/08/2011.

[6]       Donna Price, A.R. Clairmont, Jr., and J.O. Erkman, “The NOL Large Scale Gap Test. III. Compilation of Unclassified Data and Supplementary Information for Interpretation of Results”, Naval Ordnance Laboratory Report NOLTR 74-40, 8 March 1974.

[7]       Donna Price, “Safety Information from Propellant Sensitivity Studies”, Naval Ordnance Laboratory Report NOLTR 62-41, 20 March 1962.

[8]       J.O. Erkman, D.J. Edwards, A.R. Clairmont, Jr. and Donna Price, “Calibration of the NOL Large Scale Gap Test; Hugoniot Data for Polymethyl Methacrylate”, Naval Ordnance Laboratory Report NOLTR 73-15, 4 April 1973.

[9]       ASTM/A519-06 Standard Specification for Seamless Carbon and Alloy Steel Mechanical Tubing.

[10]     Michael M. Swisdak, Jr., “Hazard Class/Division 1.6: Articles containing Extremely Insensitive Detonating Substances (EIDS)”, Naval Surface Warfare Center Report NSWC TR 89-356, 1 December 1989.

[11]     T.P. Liddiard and D. Price, “The Expanded Large Scale Gap Test”, Naval SurfaceWarfareCenterReport NSWC TR 86-32, March 1987.

[12]     Douglas G. Tasker and Robert N. Baker, Jr., “Experimental Calibration of the NSWC Expanded Large Scale Gap Test”, Naval SurfaceWarfareCenterReport NSWCDD/TR-92/54, January 1992.

[13]     NATO Standardization Agency, “STANAG 4488 PCS (Edition 1) – Explosives, Shock Sensitivity Tests”, NSA/0883-PPS/4488, 12 September 2002.