Dangerous Goods Spillage on Ships: Onboard Emergency Response by IMDG Class

A dangerous goods spillage is not a drill scenario — it is a shipboard emergency with regulatory, operational, and environmental consequences that begin the moment the spill is detected. The correct response depends on the IMDG class of the substance involved, and the correct reference document is not SOPEP. SOPEP covers oil pollution from machinery spaces and cargo tanks; DG spillage response is governed by the Shipboard Marine Pollution Emergency Plan (SMPEP) and the EmS Guide.

This article covers the full onboard response: how to identify the correct EmS S-code from the IMDG Dangerous Cargo Manifest, the master’s notification obligations under MARPOL Annex III and the ISM Code, PPE requirements by hazard class, when to call the P&I club, and what the X-Press Pearl casualty exposed about gaps in DG emergency preparedness.

SOPEP vs SMPEP: Why the Distinction Matters

The Shipboard Oil Pollution Emergency Plan (SOPEP) is mandated under MARPOL Annex I Regulation 37 and covers accidental oil discharge from fuel systems, cargo tanks on oil tankers, and machinery spaces. It has nothing to do with packaged dangerous goods carried under the IMDG Code.

The Shipboard Marine Pollution Emergency Plan (SMPEP) — required under MARPOL Annex II Regulation 17 — extends that coverage to noxious liquid substances and, by flag state implementation, to harmful substances in packaged form under MARPOL Annex III. On vessels carrying IMDG-classified cargo, the SMPEP must include procedures specific to DG categories carried onboard.

In practice, many vessels consolidate both plans under a combined SOPEP/SMPEP document. The critical point is that when a deck officer responds to a DG spillage, the correct plan section to open is the one addressing packaged harmful substances — not the oil spill section. The two plans have different response hierarchies, different notification triggers, and different cleanup requirements.

The EmS Guide: Structure and How to Find the Right Schedule

The Emergency Response Procedures for Ships Carrying Dangerous Goods (EmS Guide), published by the IMO, is the primary operational reference during a DG emergency. Every substance carried under the IMDG Code has an EmS code assigned in column 15 of the Dangerous Goods List in IMDG Code Chapter 3.2.

The EmS code has two components. The F-code (Fire schedule, e.g. F-A through F-J) covers fire response. The S-code (Spillage schedule, e.g. S-A through S-Z) covers spillage response. Both codes must be consulted — a fire following a spill requires both schedules simultaneously.

To locate the correct schedule: identify the UN number from the Dangerous Cargo Manifest or from the package marking itself; look up column 15 in IMDG Code 3.2; note the F-code and S-code; turn to the corresponding schedule in the EmS Guide. The schedule specifies required PPE, immediate actions, first aid, and environmental precautions specific to that substance group.

EmS S-Code Structure

Each S-schedule is divided into five operational sections: general remarks and hazard summary; PPE required; emergency action steps; environmental information; and basic first aid. The schedules are substance-group based — goods with identical or near-identical emergency profiles share a schedule, which is why the F/S code in column 15 may be the same for multiple UN numbers within the same class.

S-codes run from S-A (general flammable liquids) through S-Z (radioactive materials, Class 7). Toxic substances frequently fall under S-U or S-V schedules, which require full encapsulating suits and SCBA before any approach. Corrosives typically use S-X, which mandates chemical splash goggles, acid-resistant gloves, and immediate water irrigation of any contact areas.

Onboard Response by IMDG Class

Response priority, PPE, and containment method differ substantially by hazard class. The following covers the primary response considerations for each IMDG class. All responses begin with the same first step: sound the general alarm, report to the master, and open the EmS Guide to the relevant S-schedule before approaching the spill.

Class 1 — Explosives

A Class 1 spillage — packaging failure causing propellant, detonator, or pyrotechnic material to become exposed — is primarily a shock and friction risk, not a chemical hazard. The immediate action is to prohibit all smoking, naked flames, electrical switches, and impact anywhere near the area.

No attempt should be made to sweep, vacuum, or apply water to an unknown Class 1 substance without confirming the specific division (1.1 through 1.6) and consulting the S-schedule. Division 1.1 and 1.2 goods with a mass explosion hazard require evacuation of the compartment and deck notification. The master must consider mustering crew to safe muster stations while assessment continues.

Class 2 — Gases

Compressed, liquefied, and dissolved gases present differently depending on division. Flammable gases (Class 2.1, e.g. LPG cylinders in general cargo) create an immediate explosion risk — all ignition sources must be eliminated before any entry. Toxic gases (Class 2.3) may be odourless and require atmospheric testing with a calibrated multi-gas detector before any personnel enter.

The S-schedule for most Class 2 substances requires SCBA as mandatory PPE — not optional and not substitutable with a dust mask. Ventilation must be confirmed as mechanical and directed away from accommodation and engine room intakes. A cargo hold ventilation assessment is required before initiating forced ventilation of an affected hold.

Class 3 — Flammable Liquids

Flammable liquid spillage is the most common DG emergency on general cargo vessels. Flash point determines the immediate ignition risk: substances with flash points below 23°C (e.g. petroleum distillates, acetone) create a vapour cloud that can reach ignition sources at distance.

Containment is the first priority: close all deck drains to prevent spill reaching the sea, which would trigger a MARPOL Annex III notification obligation. Absorbent materials must be non-sparking — dry sand or mineral absorbent, never sawdust in the presence of strong oxidisers. Spent absorbent is hazardous waste and must be logged in the ship’s garbage management plan.

Class 4 — Flammable Solids, Spontaneously Combustible, Dangerous When Wet

Class 4.2 (spontaneously combustible) and Class 4.3 (dangerous when wet) substances require particular caution. Applying water to a Class 4.3 substance — such as sodium metal, calcium carbide, or some phosphides — generates flammable or toxic gas and can cause violent reaction. The S-schedule must be confirmed before any water is used, and the officer in charge must brief all responders on this prohibition.

Class 4.1 flammable solids that are also desensitised explosives require the same approach as Class 1: no sweeping, no vacuum, and minimise friction and shock. Contaminated material must be kept wet with water only if the S-schedule confirms water compatibility.

Class 5 — Oxidising Substances and Organic Peroxides

Oxidisers (Class 5.1) dramatically accelerate combustion of other materials. A spill of ammonium nitrate, sodium chlorate, or calcium hypochlorite onto organic material — rope, timber, cargo dunnage — creates a serious fire risk even without an ignition source. The area must be cleared of all combustibles where practicable.

Organic peroxides (Class 5.2) are temperature-sensitive and may decompose if the spill is accompanied by temperature rise. Most Class 5.2 goods are required to be carried under temperature control; if cooling is lost, the master must be notified immediately and the SMPEP emergency contacts section opened.

Class 6 — Toxic and Infectious Substances

Class 6.1 toxic substances are the spillage scenario most likely to result in crew casualties. Response requires the full PPE specified in the S-schedule — typically: SCBA, chemical protective suit (Type 3 minimum for liquids), chemical-resistant gloves and boots. No entry without PPE; no exception.

The SDS (Safety Data Sheet) — formerly called MSDS — must be retrieved from the vessel’s DG documentation folder before approach. The SDS specifies exposure limits, routes of entry, first aid measures, and decontamination procedures. It is a shipboard document required under IMDG Code Regulation 5.4.3 and must be accessible to the officer on watch at all times during the voyage.

Class 6.2 (infectious substances, e.g. medical research samples, diagnostic specimens) require biohazard containment procedures. Most ships carrying Class 6.2 will have been given specific handling instructions at loading; the master should contact the shipper and the flag state authority if the consignment is breached.

Class 7 — Radioactive Material

A breached Class 7 package is a flag state and coastal state notification event regardless of dose rate at the package surface. The master is not expected to remediate radioactive contamination — the correct action is to establish a 3-metre exclusion zone, mark the area, and immediately notify the company DPA and flag state.

No attempt should be made to clean up radioactive material without guidance from the competent authority. Crew who may have been in contact with the material must be kept from showering (to prevent contamination spread) and documented for later health assessment. A port state control inspection team will typically request crew exposure documentation.

Class 8 — Corrosives

Spilled corrosives cause rapid tissue damage on contact and can generate toxic fumes. S-X is the most common schedule for Class 8 substances and mandates full face chemical splash goggles or full face mask, a chemical-resistant apron, and gloves rated for the specific corrosive type — acid-resistant nitrile or neoprene for strong acids, a different specification for alkalis.

Neutralisation of acid spills using soda ash or lime is appropriate only where the S-schedule confirms it and where the quantity is manageable by a trained crew. Large spills — anything that has spread beyond a single pallet footprint — should be contained with inert absorbent and left for shore emergency teams to handle in port.

Class 9 — Miscellaneous Dangerous Substances

Class 9 covers substances that present a hazard during transport but do not fit neatly into Classes 1–8. Lithium batteries (UN 3090, UN 3480, UN 3481) are now the dominant Class 9 concern on container and ro-ro vessels. A lithium battery fire following a spillage incident — particularly from a damaged EV battery — produces hydrogen fluoride and other toxic gases; the S-schedule requires thermal monitoring and extended ventilation post-response.

Dry ice (UN 1845), elevated temperature substances, and magnetised materials are also Class 9. Response depends entirely on the specific substance; the S-schedule and SDS are non-negotiable first references.

Notification Chain: Master, Company, Flag State, Coastal State

The ISM Code (Chapter 8) requires the master to report any accident or hazardous occurrence to the company Designated Person Ashore (DPA) without delay. This is the first notification trigger and applies regardless of whether the spill has reached the sea.

MARPOL Annex III Regulation 7 requires the master to report any spillage of harmful substances in packaged form to the nearest coastal state authority when the spill has entered or threatens to enter the marine environment. The IMO OPRC Convention sets out the reporting format. The report must include: ship identity, position, time of incident, substance involved (UN number and IMDG class), quantity estimated, and action taken.

The flag state must be notified in accordance with the flag state’s own reporting requirements — most flag states require notification of any DG incident regardless of environmental impact, and within specific timeframes (commonly 24 hours for a non-pollution incident, immediately for any sea discharge). The master should have flag state emergency contact details in the SMPEP.

Port state notification is required if the vessel is approaching port and the spill may have cargo, structural, or environmental implications affecting the port. Port authorities in many jurisdictions require prior notification of any DG incident within the previous port call cycle.

MARPOL Annex III Obligations

MARPOL Annex III regulates the prevention of pollution by harmful substances carried by sea in packaged form. It requires that such substances are properly identified, packaged, marked, labelled, documented, stowed, and quantity-limited — all before the voyage begins.

When a spillage occurs, Annex III Regulation 7 activates the master’s obligation to report. The regulation specifically covers substances meeting the criteria of the IMDG Code as marine pollutants — identified by the marine pollutant mark (P) in the IMDG Dangerous Goods List. A spill of a marine pollutant into the sea is a MARPOL violation, and documentary evidence of the incident, response, and reporting must be retained as part of the ship’s records under ISM Code Chapter 9.

Port state control officers routinely inspect DG documentation following any reported incident. The IMDG Dangerous Cargo Manifest, the cargo plan, the SDS file, and the SMPEP incident log are all auditable documents. Missing or incomplete records constitute a PSC deficiency and, in serious cases, grounds for detention.

PPE Requirements by Hazard Class

PPE selection must be driven by the EmS S-schedule and the SDS, not by what happens to be available in the nearest locker. The following summarises minimum requirements; the S-schedule always takes precedence if it specifies higher-grade protection.

• Class 1: Anti-static clothing, no-spark footwear, face shield. No rubber or PVC (triboelectric charge risk).
• Class 2.3 (toxic gases): SCBA, full encapsulating suit or Type 3 chemical suit, double gloves.
• Class 3 (flammable liquids, low flash point): SCBA or air-purifying respirator rated for vapour; chemical splash goggles; antistatic coverall.
• Class 6.1 (toxic liquids or solids): SCBA mandatory; Type 3–4 chemical suit; inner and outer chemical gloves; chemical-resistant boots.
• Class 8 (corrosives): Full face mask or splash goggles; acid/alkali-resistant gloves matched to substance type; chemical apron or suit; rubber boots.
• Class 9 (lithium batteries): Full face shield; heat-resistant gloves; no water on lithium metal — thermal blanket containment if available.

PPE equipment must be inspected and inventoried as part of onboard emergency drills specifically addressing DG incidents. Donning time matters: a Class 6.1 incident gives responders very little time before vapour concentrations reach dangerous levels in a confined or semi-enclosed cargo space.

SDS / MSDS: Location, Access, and Use

The Safety Data Sheet (SDS) — the term MSDS (Material Safety Data Sheet) is the older designation, still in common use at sea — is a 16-section document providing full hazard, handling, PPE, first aid, spill response, and disposal information for a specific substance.

Under IMDG Code Section 5.4.3 and the requirements of most flag state implementations, the SDS must be accessible to crew and emergency responders during the voyage. In practice, this means a physical copy in the cargo documentation folder on the bridge and, increasingly, a digital copy accessible on the vessel’s document management system.

In an emergency, the SDS is the fastest way to confirm: flash point, explosion limits, vapour density (critical for knowing whether vapour sinks to bilge level or rises to the deckhead), personal protection requirements, first aid for inhalation/skin contact, and whether the substance reacts with water. The SDS supplements the EmS schedule — it does not replace it.

P&I Club Notification and When a Surveyor Is Called

Notification of the P&I club is not a legal obligation under MARPOL or SOLAS, but it is a contractual one under the vessel’s P&I entry rules. Most clubs require immediate notification of any incident likely to result in a liability claim — and a DG spillage that causes crew injury, cargo damage, or environmental contamination qualifies on all three counts.

The DPA should initiate P&I notification. The club will assign a correspondent in the nearest port, and the correspondent will advise on whether a surveyor should attend. A surveyor is typically called when: cargo has been damaged or contaminated by the spill; third-party cargo has been affected; there is personal injury to crew or third parties; or the vessel has made a sea discharge reportable under MARPOL.

A cargo and damage survey following a DG incident serves two purposes: documenting the extent of damage for the P&I claim, and establishing whether the ship’s crew followed the required procedures under SMPEP and the EmS Guide. A surveyor who finds that the wrong PPE was used, that the notification chain was not followed, or that the SDS was not accessed during response can undermine the club’s defence of any resulting claim.

X-Press Pearl: What the Casualty Exposed

The X-Press Pearl fire and sinking off Colombo in May–June 2021 is the defining DG casualty of the past decade. The vessel was carrying 1,486 containers, including nitric acid, sodium hydroxide, master batches of synthetic polymers, and approximately 75 billion nurdle pellets — pre-production plastic granules classified as a marine pollutant under the IMDG Code.

The initial incident was a nitric acid (UN 2031, Class 8, marine pollutant) leak from a damaged container, first reported to the master on 20 May 2021. The master’s response — attempting to discharge the leaking container in Hazira and Hamad ports before proceeding to Colombo — illustrated the gap between technical DG response knowledge and flag state/coastal state notification obligations. Both ports refused to accept the container; neither incident generated the MARPOL Annex III reports that should have been filed.

The subsequent fire, which investigators linked to an interaction between the nitric acid and other cargo, burned for 13 days. The sinking released the full nurdle cargo, causing one of the worst recorded plastic pollution events in the Indian Ocean. The Sri Lanka Marine Environment Protection Authority (MEPA) investigation found systemic failures in DG documentation, onboard emergency response, and multi-port notification compliance — failures that the SMPEP and EmS Guide, properly implemented, should have prevented.

Containment and Cleanup: Practical Considerations

Containment takes priority over cleanup in every DG spillage. Stop the spread first: close deck scuppers and drains, use portable containment booms or inflatable sill barriers if available, and position absorbent pads to arrest the leading edge of the spill. Only after containment is established should cleanup begin.

Absorbent material selection matters. Dry sand and mineral clay absorbents are inert and appropriate for most liquid spills. Sawdust is not appropriate near oxidisers or in enclosed cargo spaces — it is combustible and can intensify a Class 5.1 reaction. Activated carbon absorbents are suitable for some toxic liquids. The S-schedule specifies compatible absorbents for each substance group.

All spent absorbent, contaminated PPE, and cleanup materials are hazardous waste under MARPOL and must be documented, segregated, and landed ashore at the next port with appropriate waste reception facilities. Disposal at sea of contaminated absorbent is a MARPOL violation. The SMPEP log entry must record quantities of absorbent used and disposal method.

Frequently Asked Questions