Epichlorohydrin (ECH; CAS 106-89-8; UN 2023) is a chlorinated epoxide with a closed-cup flash point of 31 °C, a normal boiling point of 116 °C, a density of 1.18 g/cm³ at 20 °C, and a vapour pressure near 1.77 kPa at 20 °C. It is assigned to Class 6.1 toxic liquid and Packing Group II under the UN Model Regulations; because its flash point lies between 23 °C and 60 °C, some modal frameworks apply a subsidiary Class 3 flammable-liquid hazard. The packaging and storage strategy therefore addresses both toxicity and flammability, along with moisture exclusion because ECH hydrolyses slowly to chlorinated diols and hydrogen chloride. The primary packaging configurations are compared in the matrix below.

What Drives Steel Drum and Polyethylene Drum Selection?

Carbon steel drums are acceptable only when the interior is coated with a thermally cured epoxy-phenolic lining. Unlined carbon steel is not used because ECH hydrolysis produces hydrogen chloride, which corrodes the shell and can leave iron fines that discolour downstream epoxy resin batches. Stainless steel 316L drums are specified when the ECH feed is intended for high-clarity or high-purity resin production. Drums are filled at 20 °C to no more than 95 % of brim capacity, leaving an ullage that limits pressure build-up if the temperature increases to 40 °C. Bung closures are fitted with PTFE envelope gaskets and are not lubricated with hydrocarbon greases, because hydrocarbon contamination can appear as gel particles in cationic polymerisation processes. Drum storage is arranged in curbed, fire-resistive enclosures with 6 air changes per hour continuous ventilation; the common maximum pile height of 2 drums is governed by fire-code occupancy limits rather than drum compressive strength. High-density polyethylene drums are generally not suitable for ECH service beyond small sample containers under 20 L and short transit times. Published data for ECH permeation through fluorinated HDPE after 60 days is limited, so packagings must be validated by weight-loss and lining-integrity testing before use.

Drum filling lines use a lance that extends to the bottom of the drum and a nitrogen purge point at the bung. Filling is carried out under a nitrogen sweep of 2–5 L/min to reduce static-charge build-up and to keep the vapour space below 8 % O₂ by volume. Splash filling is avoided because it increases vapour release and can generate static discharge. Bonding leads are attached to the drum and the lance before the product valve opens; the grounding resistance is verified at less than 1 × 10⁶ Ω in accordance with NFPA 77. After filling, the headspace is allowed to settle for 30 seconds before the bung is closed, and the closed drum is checked by a photoionisation detector at the seal and chime. Drums that show leakage at the seal are reworked or rejected. The fill weight is checked against the target weight based on the density of 1.18 g/cm³; overfilled drums are corrected before shipment because thermal expansion can cause pressure build-up in transit.

Intermediate Bulk Containers Under 49 CFR 178.274 and IMDG 6.5

UN 31A/Y intermediate bulk containers with a nominal capacity of 1,000 L to 1,250 L are used for satellite storage and metered addition to resin reactors. The shell is either epoxy-phenolic lined carbon steel or 316L stainless steel. The IBC must be tested and marked in accordance with 49 CFR 178.274 or the corresponding IMDG Code Chapter 6.5 requirements; the marking includes stacking, lift, and leakproofness test acceptance. The top opening is connected to a dry-break coupler and a separate nitrogen inlet. A spring-loaded pressure-vacuum relief device set at 7–10 kPa gauge protects the tank from steam-cleaning or solar-induced pressure excursions. The discharge valve is a lockable PTFE-lined ball valve with a flanged outlet cap. In manufacturing areas, the IBC is placed on a load cell with a range of 0–1,500 kg; the load signal is interlocked with the ECH metering pump so that low-level below 25 kg stops the pump before air enters the reactor feed line. IBC storage is normally limited to 90 days where ambient relative humidity exceeds 60 %, because moisture ingress at mechanical connections can increase hydrolyzable chloride content and produce a viscous 3-chloro-1,2-propanediol lower layer. The bottom sump must be sampled for settled water and acid before each reuse; the acceptance criterion is below 100 ppm water and below 10 ppm chloride by weight. Such limits are site-specific and are verified by Karl Fischer titration and ion chromatography.

When ISO Tank Containers Become the Preferred Feedstock Buffer

Bulk ECH consumers receive product in T11-type ISO tank containers with nominal capacity of 24,000 L. The tank shell is constructed from 316L stainless steel and is insulated to reduce solar gain; the container frame, shell, and pressure relief arrangement follow ISO 1496-3:2019. The design is certified to ASME Section VIII Division 1 with an MAWP of 4 bar (400 kPa). ECH is transferred by nitrogen pressure pad or top-mounted eductor rather than by reliance on the bottom outlet alone, which reduces external leakage points. Nitrogen pressure for unloading is controlled to 0.3–0.5 bar g; the primary relief device is set at or below the MAWP and the rupture-disc material is selected for acidic condensate resistance. ISO tank storage can be extended to 12 months if the nitrogen pad is maintained with a dew point of −40 °C or lower and the tank is protected from sustained temperatures above 35 °C. Published long-term stability data for ECH in ISO tanks under tropical ambients are limited; terminal operators therefore re-test hydrolyzable chloride, colour, and density after 12 months. The residual heel after pressure-assisted discharge is typically 10–50 L, depending on sump geometry; this heel is collected during cleaning and neutralised under site wastewater permits.

Nitrogen Blanketing: Oxygen Thresholds and Pressure Decay

Nitrogen blanketing in ECH service performs two functions: it keeps the ullage oxygen concentration below the limiting oxygen concentration for flammable vapour, and it excludes moisture that would hydrolyse the epoxide ring. NFPA 69 provides the inerting framework; the LOC for ECH vapour should be determined by testing such as ASTM E681 or equivalent, because published values for ECH vary with temperature and nitrogen-oxygen mixture. Operational set points for closed-loop systems are commonly an alarm at 5 % O₂ by volume and a shutdown trip at 7 % O₂, giving a safety margin below the LOC. The nitrogen supply is regulated to maintain a positive pressure of 20–50 mbar gauge on drums and IBCs, and 0.3–0.5 bar g on ISO tanks. Pressure-decay testing is performed before filling: the container is pressurised to 0.3 bar g with nitrogen, isolated for 15 minutes, and rejected if the pressure loss exceeds 5 % of the initial gauge pressure. Oxygen analysers are located downstream of the blanketing valve; a dew-point transmitter monitors the nitrogen header, with acceptance at −40 °C or lower. The blanketing system includes a check valve and a flame arrestor to prevent ECH vapour backflow into the nitrogen header.

Continuous online oxygen measurement is preferred over intermittent sampling because drum and IBC headspace oxygen can rebound after initial purging if there are microleaks at gasketed closures. The oxygen analyser should be located upstream of the pressure-relief device and downstream of the back-pressure regulator. Nitrogen header pressure is monitored by a differential-pressure transmitter across a filter element; a high differential pressure reading above 50 mbar indicates fouling from ECH oligomer or iron oxide carryover, triggering filter replacement. In ISO tank unloading, the nitrogen flow is ramped in steps of 0.1 bar g increments while observing the downstream pressure transmitter; pressure stagnation with rising flow indicates a blocked dip tube or solidified hydrolysis layer, and the transfer is stopped before exceeding 0.5 bar g.

316L stainless steel and PTFE are the reference wetted materials for ECH service. PTFE envelope gaskets and PTFE-filled spiral-wound gaskets are standard at flanges; elastomeric O-rings are limited to FFKM or PTFE-encapsulated FKM where continuous sealing is required. Natural rubber, nitrile rubber, and neoprene are not specified because the chlorinated epoxide and acidic hydrolysis products cause swelling or hardening. Transfer hoses are braided PTFE-lined stainless steel and are inspected under ISO 10380:2012. ECH must not be transferred through lines that have previously carried amines, ammonia, sodium hydroxide, or potassium hydroxide unless the residual alkalinity is below 10 ppm as aqueous extract. Strong bases initiate anionic ring-opening polymerisation of ECH; the exotherm can deposit a rubbery polymer film in flow meters, pump clearances, and relief-valve seats. Dedicated lines with keyed couplings are used in multi-product plants. When shared equipment is unavoidable, a neutralisation wash, water rinse, and dry nitrogen blow-down are performed; the final rinse is checked by pH and conductivity. Residual amine concentration after cleaning is maintained below 10 ppm by calibrated test kits, but this limit should be confirmed by adiabatic reaction calorimetry because the threshold varies with amine structure and temperature.

Storage temperature is maintained between 5 °C and 30 °C. Exposures above 35 °C accelerate hydrolysis and raise vapour pressure, while temperatures below 5 °C increase viscosity and may reduce pump net positive suction head margin. ECH is segregated from oxidizers, strong acids, strong alkalis, and amines in accordance with 49 CFR 177.848 and ADR Chapter 7.5. Containment curbs are sized for 110 % of the largest package. IBC and drum storage areas use 1-hour fire-rated separation from process equipment and are protected with alcohol-resistant AFFF or water fog. Direct water streams onto ECH spills are avoided because hydrolysis releases heat and hydrogen chloride. Fixed gas detection is set to alarm at 10 % of the lower flammable limit and at the occupational exposure limit; the ECH odour threshold is below 10 ppm, but odour is not used as a monitoring method. Emergency relief devices on storage tanks and IBCs discharge to a scrubber or safe location; discharge to a common sewer is prohibited.