1910.109(g)(4) Bulk Storage Bins

The bin, including supports, shall be constructed of compatible materials, waterproof, and adequately supported and braced to withstand the combination of all loads including impact forces arising from product movement within the bin and accidental vehicle contact with the support legs.

Bin loading manways or access hatches shall be hinged or otherwise attached to the bin and be designed to permit locking.

Any electrically driven conveyors for loading or unloading bins shall conform to the requirements of subpart S of this part. They shall be designed to minimize damage from corrosion.

Bins containing blasting agent shall be located, with respect to inhabited buildings, passenger railroads, and public highways, in accordance with Table H-21 and separation from other blasting agent storage and explosives storage shall be in conformity with Table H-22.

TABLE H-22 - TABLE OF RECOMMENDED SEPARATION DISTANCES OF
AMMONIUM NITRATE AND BLASTING AGENTS FROM EXPLOSIVES
OR BLASTING AGENTS (Footnotes 1-6)

Donor weight		Minimum separation distance of receptor when barricaded(2)(ft.)		Minimum thickness of artificial barricades (5)(in.)
Pounds over	Pounds not over
		Ammonium nitrate(3)	Blasting agent(4)
	100	3	11	12
100	300	4	14	12
300	600	5	18	12
600	1,000	6	22	12
1,000	1,600	7	25	12
1,600	2,000	8	29	12
2,000	3,000	9	32	15
3,000	4,000	10	36	15
4,000	6,000	11	40	15
6,000	8,000	12	43	20
8,000	10,000	13	47	20
10,000	12,000	14	50	20
12,000	16,000	15	54	25
16,000	20,000	16	58	25
20,000	25,000	18	65	25
25,000	30,000	19	68	30
30,000	35,000	20	72	30
35,000	40,000	21	76	30
40,000	45,000	22	79	35
45,000	50,000	23	83	35
50,000	55,000	24	86	35
55,000	60,000	25	90	35
60,000	70,000	26	94	40
70,000	80,000	28	101	40
80,000	90,000	30	108	40
90,000	100,000	32	115	40
100,000	120,000	34	122	50
120,000	140,000	37	133	50
140,000	160,000	40	144	50
160,000	180,000	44	158	50
180,000	200,000	48	173	50
200,000	220,00	52	187	60
220,000	250,000	56	202	60
250,000	275,000	60	216	60
275,000	300,000	64	230	60

   Footnote(1) These distances apply to the separation of
stores only. Table H-21 shall be used in determining
separation distances from inhabited buildings, passenger
railways, and public highways.

   Footnote(2) When the ammonium nitrate and/or blasting
agent is not barricaded, the distances shown in the table
shall be multiplied by six. These distances allow for the
possibility of high velocity metal fragments from mixers,
hoppers, truck bodies, sheet metal structures, metal
container, and the like which may enclose the "donor".
Where storage is in bullet-resistant magazines
recommended for explosives or where the storage is
protected by a bullet-resistant wall, distances, and
barricade thicknesses in excess of those prescribed in
Table H-21 are not required.

   Footnote(3) The distances in the table apply to ammonium
nitrate that passes the insensitivity test prescribed in the
definition of ammonium nitrate fertilizer promulgated by the
National Plant Food Institute*; and ammonium nitrate failing
to pass said test shall be stored at separation distances
determined by competent persons. (*Definition and Test
Procedures for Ammonium Nitrate Fertilizer, National Plant
Food Institute, November 1964.)

   Footnote(4) These distances apply to nitro-carbo-nitrates
and blasting agents which pass the insensitivity test
prescribed in the U.S. Department of Transportation (DOT)
regulations.

   Footnote(5) Earth, or sand dikes, or enclosures filled
with the prescribed minimum thickness of earth or sand are
acceptable artificial barricades. Natural barricades, such
as hills or timber of sufficient density that the surrounding
exposures which require protection cannot be seen from the
"donor" when the trees are bare of leaves, are also acceptable.

   Footnote(6) When the ammonium nitrate must be counted in
determining the distances to be maintained from inhabited
buildings, passenger railways and public highways, it may be
counted at one-half its actual weight because its blast effect
is lower.

Bins containing ammonium nitrate shall be separated from blasting agent storage and explosives storage in conformity with Table H-22.

Sketch location of all potential donor and acceptor materials together with the maximum mass of material to be allowed in that vicinity. (Potential donors are high explosives, blasting agents, and combination of masses of detonating materials. Potential acceptors are high explosives, blasting agents, and ammonium nitrate.)

Consider separately each donor mass in combination with each acceptor mass. If the masses are closer than table allowance (distances measured between nearest edges), the combination of masses becomes a new potential donor of weight equal to the total mass. When individual masses are considered as donors, distances to potential acceptors shall be measured between edges. When combined masses within propagating distance of each other are considered as a donor, the appropriate distance to the edge of potential acceptors shall be computed as a weighted distance from the combined masses.

Calculation of weighted distance from combined masses:

Let M₂, M₃ . . . Mn be donor masses to be combined.
M₁ is a potential acceptor mass.
D₁₂ is distance from M₁ to M₂ (edge to edge).
D₁₃ is distance from M₁ to M₃ (edge to edge), etc.

To find weighted distance [D₁(2,3 . . . n)] from combined masses to M₁, add the products of the individual masses and distances and divide the total by the sum of the masses thus:


Propagation is possible if either an individual donor mass is less than the tabulated distance from an acceptor or a combined mass is less than the weighted distance from an acceptor.

In determining the distances separating highways, railroads, and inhabited buildings from potential explosions (as prescribed in Table H-21), the sum of all masses which may propagate (i.e., lie at distances less than prescribed in the Table) from "either" individual or combined donor masses are included. However, when the ammonium nitrate must be included, only 50 percent of its weight shall be used because of its reduced blast effects. In applying Table H-21 to distances from highways, railroads, and inhabited buildings, distances are measured from the nearest edge of potentially explodable material as prescribed in Table H-21, Note 5.

When all or part of a potential acceptor comprises Explosives Class A as defined in DOT regulations, storage in bullet-resistant magazines is required. Safe distances to stores in bullet-resistant magazines may be obtained from the intermagazine distances prescribed in Table H-21.

Barricades must not have line-of-sight openings between potential donors and acceptors which permit blast or missiles to move directly between masses.

Good housekeeping practices shall be maintained around any bin containing ammonium nitrate or blasting agent. This includes keeping weeds and other combustible materials cleared within 25 feet of such bin. Accumulation of spilled product on the ground shall be prevented.

The bin discharge gate shall be designed to provide a closure tight enough to prevent leakage of the stored product. Provision shall also be made so that the gate can be locked.