Combustible-Dust Explosions in Indian Pharma and Food Plants 2026: A Process-Safety and Underwriting Problem

On 30 June 2025 an explosion and fire at Sigachi Industries' plant at Pashamylaram in Sangareddy district, Telangana, killed 46 people and injured 33. The likely cause was a dust explosion of microcrystalline cellulose (MCC), a fine combustible powder that the plant manufactured. The company announced an ex-gratia payment of Rs 1 crore to the family of each deceased worker, and operations were halted for about 90 days because of the damage. The event is a hard reminder that a material as apparently benign as a pharmaceutical excipient powder can, in the wrong conditions, destroy a plant and kill dozens of people in a fraction of a second.

A dust explosion is a distinct and frequently underestimated hazard because the materials do not register as dangerous to the people handling them. Microcrystalline cellulose, flour, sugar, starch, milk powder, many pharmaceutical actives and excipients, and a long list of organic and metal powders are not flammable liquids or obvious explosives; they are everyday process materials. Yet when the same material is present as a fine dust, dispersed as a cloud in air, in a confined space, with an ignition source and enough oxygen, it can deflagrate. The fineness that makes a powder useful (large surface area, fast dissolution, easy handling) is exactly what makes its dust explosive, because the large surface area lets the material burn almost instantaneously when dispersed.

The classic framing is the dust explosion pentagon: the three sides of the fire triangle (fuel, oxygen, ignition) plus two specific to dust, dispersion into a cloud and confinement in an enclosed space. Remove any one side and there can be no explosion, so every control measure is an attempt to break one or more sides. The danger is that all five come together routinely in normal processing: dust is generated by milling, sieving, drying, conveying and packing; dispersed by the act of moving the powder; accumulated in ducts, on beams and in equipment; and confined within the dryers, mills, dust-collectors, silos and ducting the process runs in.

The foundation of managing dust risk, and the first thing a serious underwriter wants to see, is a dust hazard analysis (DHA): a systematic study of where in a plant combustible dust is present, how explosive it is, where it can form a cloud and accumulate, and what controls address each location. A plant that has not characterised its own dust and mapped its own hazard is, from an underwriting standpoint, an unquantified risk.

Characterising the material

The analysis starts with the material. A combustible dust is characterised by laboratory testing for the properties that determine how dangerous it is: whether it is explosible at all, its minimum ignition energy (how small a spark can set it off), its minimum explosible concentration, the severity of the explosion it produces (the rate of pressure rise and maximum pressure), and its minimum ignition temperature. A powder with a very low minimum ignition energy can be set off by a static discharge a worker cannot feel. The same nominal material varies in explosibility with particle size and moisture, so the testing must reflect the dust as actually produced, not a generic handbook value. Microcrystalline cellulose, the material involved at Sigachi, is a recognised combustible dust, and any plant handling it should know its tested explosibility rather than assume an excipient is harmless.

Mapping the plant

With the material characterised, the analysis maps the plant: every unit operation that generates, conveys, dries, mills, stores or packs the powder, and every place dust can form an explosive cloud (inside dryers, mills, dust-collectors, conveyors, silos) or accumulate on surfaces (beams, ledges, ductwork, equipment tops). The high-hazard equipment is well known: dryers (especially spray and fluid-bed dryers), mills and grinders, dust-collectors and baghouses, pneumatic conveying lines, and storage silos. These are the points where a cloud at explosible concentration is most likely to coincide with confinement, and where explosion-protection measures concentrate.

The DHA then drives the control plan: for each hazard location, which combination of ignition control, explosion prevention and explosion protection applies, and what housekeeping and inspection regime keeps accumulations below dangerous levels. A documented, current DHA an underwriter can review is the single strongest signal that a plant understands and manages its dust risk; its absence is a red flag that the risk is unmeasured.

Controlling dust explosion risk means breaking one or more sides of the explosion pentagon, and the controls fall into three layers: stopping ignition, preventing an explosible atmosphere, and protecting against the consequences if an explosion occurs anyway. A well-run plant uses all three rather than relying on any one.

Ignition control

The most direct control is to deny the dust an ignition source, and the catalogue is long: electrical sparks and faults, hot surfaces, friction and impact sparks (tramp metal in a mill), self-heating of stored material, open flames and hot work, and, importantly, static electricity. Static is a particular danger because handling and conveying fine powder generates charge, and a discharge can ignite a low-ignition-energy dust without any obvious spark. Control measures include electrical equipment rated for the dust-hazard area classification, bonding and earthing to drain static, magnetic separators and metal detectors before milling, hot-work permits, and management of self-heating in storage. Ignition control is never treated as sufficient on its own, because ignition sources are too varied to eliminate completely, but it is the first line.

Explosion prevention

The next layer prevents an explosible atmosphere from forming. Inerting, reducing the oxygen in an enclosure below the level that supports combustion by adding nitrogen or another inert gas, removes the oxygen side of the pentagon inside critical equipment such as dryers and silos, and is a standard prevention measure where it is feasible. Containing and minimising dust generation, keeping process dust inside closed systems rather than letting it escape into the workroom, also limits where explosible clouds can form. Prevention is powerful inside enclosed equipment but cannot address dust that escapes into the general plant, which is why it is paired with the next layer.

Explosion protection. The final layer accepts that an explosion may start and limits its consequences. The standard techniques are explosion venting (relief panels that open at a set pressure to release the blast safely, sparing the equipment from bursting), explosion suppression (detectors that sense a deflagration and inject a suppressant within milliseconds to quench it), explosion isolation (devices that stop a flame front propagating through ducting from one item of equipment to the next, preventing a single explosion from becoming a plant-wide chain), and containment (equipment built to withstand the maximum explosion pressure). The choice depends on the equipment, dust severity and plant layout, and a serious plant engineers protection onto its high-hazard equipment rather than leaving it unprotected.

Running through all three layers is housekeeping, the discipline of preventing dust accumulation on surfaces. Because the secondary explosion (dust lifted off surfaces by a primary blast) is what causes the catastrophic, building-wide events, keeping surfaces clean is one of the highest-value controls of all, and it is cheap. An underwriter walking a plant reads the dust on the beams and ledges as a direct measure of the secondary-explosion risk.

Dust-explosion risk sits inside a statutory occupational-safety framework, and compliance with it is both a legal duty and a baseline that underwriters and claims teams treat as a minimum. The frame matters because breaches feed directly into liability, into prosecution exposure, and into the questions a fire or explosion claim raises.

The Factories Act, 1948 is the central statute for factory safety in India. It places duties on the occupier and manager to ensure the health, safety and welfare of workers, with specific provisions on the control of dust and fume, on precautions against explosive or inflammable dust, gas and vapour, on the safety of machinery, and on safe systems of work. The Act and the state Factories Rules require hazardous processes to be managed and, for certain operations, specific precautions against the build-up and ignition of explosive dust concentrations. It is administered through the state factory inspectorates, who inspect, can require remedial measures, and whose findings after an incident carry weight. A plant that has handled combustible dust without addressing the Act's dust and explosion provisions is exposed both legally and in any subsequent claim.

Beyond the Factories Act, plants handling hazardous materials may fall within wider safety and environmental regimes governing hazardous and chemical processes, the storage and handling of hazardous substances, and, for larger installations, safety reports and emergency planning. The new labour-code architecture consolidating occupational-safety duties is also part of the frame. The specific obligations depend on the material, the scale and the classification of the installation, so a plant should establish exactly which regimes apply rather than assume the Factories Act is the whole story.

A dust explosion is, from an insurance standpoint, unusually destructive across lines, because a single event fires several different covers at once and the interaction between them is where the claim is won or lost. A risk manager at a powder-handling plant needs to understand how the programme responds as a whole, not policy by policy.

Property and material damage

The fire and material-damage cover responds to the physical destruction of the plant: buildings, plant and machinery, and stock damaged or destroyed by the explosion and the fire that follows. The material damage loss in a serious dust explosion can be near-total for the affected block, because the blast destroys structure and the fire consumes what survives the blast. The adequacy of the sum insured and the basis of valuation (reinstatement versus market value) decide whether the rebuild is fully funded, and underinsurance brings the average clause into play to reduce the claim.

Employers' liability and workers' compensation

The human toll is covered, in part, through the workers' compensation and employers' liability cover. Statutory compensation to injured workers and the dependants of those killed flows under the employees-compensation framework, and employers' liability cover responds where the employer is liable beyond it. In an event with dozens killed and injured this exposure is large, and it interacts with any ex-gratia the company pays (as Sigachi did) and with civil claims that may exceed the statutory amounts. The strength of the safety case, and any statutory-breach findings, bear directly on the liability exposure.

Business interruption. The business-interruption cover responds to lost profit and continuing costs while the plant is out of action, which after a serious explosion runs to many months: the Sigachi plant was halted for about 90 days, and a worse event can be longer. Business interruption is frequently the largest single head of loss in a major industrial event, often exceeding the material damage, because lost income and the cost of meeting customer commitments elsewhere mount steadily over a long shutdown. The indemnity period must be long enough to cover the full rebuild and ramp-back to normal output, and the BI sum insured must reflect the real gross profit at risk; a short indemnity period or an inadequate BI sum insured is where large industrial BI claims fall short.

Product and recall interaction. For a plant whose output goes into a regulated supply chain (a pharmaceutical excipient or active, or a food ingredient), the event can also reach the product-liability and recall dimension. If a batch is contaminated by the incident, if supply disruption affects downstream product, or if the event raises questions about product made around it, product-liability and recall exposures can arise alongside the property and BI claim. This is specific to plants whose output is a regulated input to someone else's product, and it is easy to overlook when the focus is the fire and the casualties.

The lesson is that a major dust explosion is a multi-policy event, managed across property, employers' liability, BI and potentially product or recall together, with the consequential loss heads (BI above all) often dwarfing the direct damage. A programme adequate on property but thin on BI, or with gaps between the liability covers, leaves the insured exposed exactly where a real dust explosion does its largest financial damage.

Because a dust explosion is severe and multi-line, underwriters scrutinise dust-handling plants closely, and a plant that can demonstrate it manages the hazard well presents a materially better risk and earns better terms. The checklist below is, in effect, both the underwriter's survey and the operator's loss-prevention agenda.

1. A current, documented dust hazard analysis covering every unit operation and hazard location, with the plant's own dust tested for explosibility rather than relying on generic values.
2. Ignition control: area classification and correctly rated electrical equipment, bonding and earthing against static, tramp-metal removal before milling, and a hot-work permit system.
3. Explosion prevention and protection engineered on the high-hazard equipment: inerting where feasible, and venting, suppression and isolation on dryers, mills, dust-collectors, conveyors and silos so that a single equipment explosion cannot propagate plant-wide.
4. Housekeeping discipline that keeps dust accumulations on surfaces below dangerous levels, with a documented cleaning and inspection regime, because this is the control that prevents the secondary explosion that causes catastrophic events.
5. Statutory compliance with the Factories Act dust and explosion duties and any wider hazardous-process regime that applies, evidenced by inspection records and a clean relationship with the factory inspectorate.
6. Management systems: a process-safety management approach, training, maintenance of the protection systems, incident and near-miss reporting, and emergency response and evacuation planning sized to the hazard.

A plant that presents this well both reduces the probability and severity of an event and gives the underwriter the evidence to price the risk on its real merits rather than on a conservative assumption that the hazard is unmanaged. The gap in terms between a plant with a documented DHA, engineered protection and visible housekeeping and one without is large, because the unmanaged plant carries the tail risk of exactly the catastrophic, multi-line event the underwriter most fears.

Where this comes together for the broker and the risk manager is in matching the plant's real risk profile to the right programme structure across property, employers' liability, business interruption and product or recall, and in confirming the wordings respond as a connected whole rather than leaving gaps between the covers that a single explosion would expose. Sarvada gives commercial-insurance brokers and corporate risk teams structured, searchable access to insurer wordings and the intelligence around process-industry risks, so they can compare how property, BI, employers' liability and product or recall covers are triggered and how they interact, and structure a programme that responds across all the heads a dust explosion fires at once. Brokers and risk managers placing cover for pharma-API, food-processing and chemical plants can Request Access to evaluate the platform for these multi-line process-safety risks.