The GHS Labelling and Packaging Checklist for Xylene Drums, IBCs and ISO Tanks begins with the classification recorded in EU CLP Regulation 1272/2008, Annex VI index 601-022-00-9, and in OSHA Hazard Communication Standard 29 CFR 1910.1200 Appendix C. Technical-grade xylene is placed under the transport entry Xylenes, UN 1307, Class 3, Packing Group III. The hazard statement set is H226, H304, H312, H332, H315, H319, H335 and H373. The signal word is Danger, and the required pictograms are GHS02, GHS07 and GHS08. A compliant package cannot be released for filling until the product identifier, supplier identifier, hazard statements, precautionary statements and the appropriate transport marks are present on the same face of the drum, IBC or tank container.

Mixed xylenes and technical xylene have a closed-cup flash point reported at 25–32 °C by ASTM D93-20 and a boiling range of 137–144 °C. Density at 15 °C is 0.86–0.88 g/cm³, vapour pressure is 0.8–1.2 kPa at 20 °C, and lower explosive limit is approximately 0.9 vol%. These values place xylene in Flammable Liquids Category 3 under GHS and justify Packing Group III. The package filling decision should use the density at the highest expected loading temperature; a 200 L drum filled to 95% capacity at 10 °C will expand by approximately 5.7 L when the liquid temperature rises to 40 °C at a cubic expansion coefficient of 0.0010 K⁻¹.

Vapour extraction at the filling head is required where the predicted 15-minute exposure exceeds the local workplace limit. The lower explosive limit of 0.9 vol% gives an alarm action point of 0.09 vol% at a 10% LEL setting. Photoionization detectors should be calibrated with xylene calibration gas or the manufacturer's documented correction factor; isobutylene units without response-factor adjustment under-report mixed xylene vapour composition.

What drives the Packing Group III assignment and its package-marking consequences?

Packing Group III reflects the flash point interval and the absence of high acute inhalation lethality. It does not remove the aspiration hazard. The package marking for UN 1307 must therefore include an X, Y or Z code appropriate to Packing Group III; a common steel drum mark is 1A1/Z/0.9/100/25/.../UN, where the relative density and hydraulic test pressure are actual values from the UN design-type test. The closure system must be re-qualified after any change in gasket formulation or bung retainer. Package design-type tests follow UN Model Regulations Chapter 6.1 for drums and Chapter 6.5 for IBCs, with the relevant drop height for Packing Group III set at 0.8 m.

The UN Packaging Instruction P001 permits combination packagings for xylene up to a maximum gross mass of 400 kg per package. Inner glass, aluminium or fluorinated plastic containers must be separated by absorbent packing material that retains the entire liquid content if the inner container fractures. For single packagings, 1A1 steel drums, 1H1 plastic drums and 1A2 removable-head steel drums are acceptable only when the closure orientation prevents liquid contact with the gasket during transport. Removable-head drums require a positive locking ring and a gasket with xylene immersion data; open-head drums without a closure indicator are not acceptable for UN 1307.

For marine drums and IBCs, label durability is verified by BS 5609 Section 2 immersion and abrasion tests. Labels applied to 200 L steel drums should cover the bung-facing head where possible, but must not obscure the UN mark, pressure test rating, or welding certifications. On 31HA1 composite IBCs, the label panel is often inserted into a polyethylene sleeve; the sleeve must not trap xylene vapour or allow the label adhesive to soften at service temperatures above 35 °C.

Adjacent drums must be earth-bonded before transfer. Static charge generation on xylene filling skids is controlled by limiting inlet velocity and by using a dip lance rather than top-splash filling. A 50 mm fill line should begin at 1 m/s until the lance outlet is submerged, then may be increased to 7 m/s after the liquid surface covers the outlet by at least 300 mm. These limits appear in electrostatic safety guidance such as IEC TS 60079-32-1. The fill-lance interlock should not open the supply valve unless the grounding clamp resistance is below 10 Ω.

Steel drum, IBC and ISO tank integrity boundaries

For a 200 L 1A1 closed-head steel drum, the body-to-lid seam should be examined for contamination-induced corrosion; experience from drum filling lines shows that minute pinholes occur at the bottom chime when the internal free water content exceeds 0.05%. The closure bung gasket is to be PTFE or fluoroelastomer; EPDM is unsuitable because aromatic solvents produce high volume swell. A drum of xylene must not be stored in direct sunlight above 45 °C surface temperature, as vapour pressure rises and the closure may weep at the bung boss.

Steel drum bungs should be torqued to 20–25 N·m for 2-inch bungs and 10–15 N·m for 3/4-inch bungs after filling; over-torque yields gasket extrusion and permanent leakage paths. A tap test of the closure after a 24 h rest period at 20 °C is used to identify slow weepage. The drum must not be stacked beyond the tested stacking load marked on the package.

Rigid plastic 31H1 and composite 31HA1 IBCs should be checked for mould release agent contamination on the inner wall; high-density polyethylene without fluorination may absorb xylene and lose container mass over extended storage. The filling line must fill the IBC only through a closed transfer line to minimize vapour release and static charge. If the IBC contains a bottom drain valve, the valve must be restrained in the closed position and tested for leak tightness at 20 kPa or at the manufacturer's test pressure before loading. Composite IBC labels should not be wrapped around the top edge, because vapours can condense and loosen the adhesive near the vent pocket.

The IBC packing instruction IBC03 in ADR Chapter 4.1.4 authorizes metal, rigid plastic, composite and wooden IBCs for Packing Group III xylene. 31A metal IBCs and 31H1 rigid plastic IBCs are common on filling lines. The UN marking on an IBC must include the stacking test load in kilograms, the maximum allowed gross mass and the date of the last leakproofness test; a 31HA1 xylene IBC often carries a penetration-test certificate from the manufacturer due to the aggressive aromatic vapour environment. If the IBC is used after a change of service from a non-flammable liquid, it must be re-certified or downgraded according to the ADR inspection interval of 2.5 years for visual inspection and 5 years for leakproofness.

When an ISO tank or residue container moves by road under UN 1307

An ISO tank container built to ISO 1496-3:2019 and approved for UN portable tank instruction T4 should be internally wiped dry before xylene loading. Residual water in a 25,000 L stainless steel tank can initiate a separate aqueous phase and accelerate pitting at the bottom discharge valve. The manlid gasket, typically PTFE envelope or spiral-wound stainless steel, is torqued in a diagonal sequence to the manufacturer's maximum value; over-torque distorts the gasket and is a known source of pressure-test failures. Ground continuity at the tank connection should measure below 10 Ω as specified in IEC TS 60079-32-1.

For ADR/RID transport in a tank vehicle, the applicable tank code for UN 1307 is LGBF, and the Class 3 placard must be displayed on both sides and the rear. Bottom loading arms require a dry-break coupler and capping after disconnection. Vapour recovery lines should be used if loading exceeds 5 m³/h; open-hatch top loading is not acceptable unless the dip pipe is submerged before flow exceeds 1 m/s through a 50 mm line. The ISO tank discharge valve must be locked closed with a tamper-indicating seal after the preload leak check.

The check after filling includes a signed dangerous goods declaration under ADR 5.4.1, a copy of the UN design-type certificate for the actual drum, IBC or tank, and the BS 5609 Section 2 label compliance record where sea freight is intended. For empty residue containers, the UN 1307 entry remains on the package until the container has been cleaned and purged, with the vapour concentration below 10% of the lower explosive limit at the bung opening. A carrier may reject a residue drum if the closure is not reinstalled with a new PTFE gasket after unloading.

Xylene must be segregated from oxidizing agents, strong acids, halogens and peroxides. Separation from Class 5.1 oxidizing substances is required by ADR Chapter 7.5.2. On a loading rack shared with nitric acid or hydrogen peroxide, the transfer skid should be drained and purged before xylene enters. Copper and copper alloys are not recommended for permanent xylene contact because trace metal pickup can discolour the product; stainless steel 316 or 304 is preferred for wetted components. Published data for long-term polypropylene piping exposure to xylene is limited; polypropylene is not recommended for transfer piping in the absence of immersion data.

The final container inspection should include a bung torque check, a leak-tightness retention test at the lowest ambient temperature, and a photograph of the GHS label and UN mark on the filled package. The packaged xylene should not be released to a carrier until the ground-continuity record and the dangerous goods declaration are time-stamped in the same shift.