Explosion Onboard INS Ranvir — HVAC or HFACS?

An explosion onboard Indian Navy’s guided missile destroyer INS Ranvir claimed the lives of three senior sailors on Jan 18, 2022. Eleven others have been admitted with injuries to naval hospital INHS Ashwini at Colaba. The ship was reportedly in Mumbai harbour, at the fag end of a three months cross-coast deployment from navy’s Eastern Naval Command, Visakhapatnam to Mumbai on the west coast.

An official update was tweeted by navy’s spokesperson morning of Jan 19. The deceased (all Master Chief Petty Officers, the highest rank among sailors) have been identified as Krishan Kumar MCPO I, Surinder Kumar MCPO II and AK Singh MCPO II. As per news reports, the blast took place in the AC compartment, a deck below the cabin occupied by these senior sailors. The cabin reportedly caved-in due to the blast, causing fatal injuries to the three sailors. A Board of Inquiry (BoI) has been ordered into the accident.

Indian Navy tweet Jan 19, 2022 on Ranvir accident a day before

Omnipresent Dangers

Fire and flooding are omnipresent dangers on any warship. All three elements of the ‘fire triangle’ — oxygen, heat and fuel — are always available in abundance aboard ships. Managing these hazards within constrained spaces and enclosed compartments while running a daily exercise routine that includes planned forays into harm’s way (all-weather, day & night weapon firing, missile launches, embarking fuel and ammunition, etc) is achieved safely through a combination of military grade ‘fit-for-purpose’ equipment, sound seamanship & engineering practices, and recurrent training of all onboard. IN ships sail today like never before; clocking thousands of miles in each commission; cumulatively totalling millions of nautical miles each year.

It is too early to weigh-in on the safety aspects (or the lack of it) based on crumbs of information available on this accident as on date. Even as the BoI gets underway, a few generic points can be made.

An Indian Navy Kamov-28 helicopter landing on INS Ranvir (Indian Navy pic)

Vintage of the ship

INS Ranvir (D54), the first of the two Ranvir class destroyers, was commissioned in April 1986, roughly a year after the 1985 discovery of the ozone hole (relevance of this nugget follows further in the story). She is the fourth among five Russian Kashin class destroyers (also known as SNFs or Surendranath Frigates) procured from Russia. At about 36 years, D54 is older than most capital ships in commission today. However, the ship has undergone modernisation and periodic refits, some of which included mid-life upgrades (MLU), addition of weapons and sensors, deep inspections and depot-level maintenance.

While more ‘teeth’ have certainly been added during these MLU and refits, whether fire hazards have grown, or whether fire mitigating equipment like fixed and portable fire fighting systems received an equivalent update needs scrutiny. In my experience, Russian ships, like Russian aircraft, are usually high on performance (read seakeeping for SNFs) but low on ergonomics and crew comfort. Often, crew stations appear to have been added as an afterthought. Habitability onboard SNFs is impacted by its high crew complement (mandated by weapon/sensor manning for action stations). Crew are often stuffed into obtuse corners and ‘hot bunking’ is the norm at lower levels.

HVAC, refrigerants and fire safety

The heating, ventilation and air conditioning (HVAC) system onboard a warship runs 24/7/365. Refrigerants used in air conditioning systems of early last century were either flammable or toxic. Over time, these were replaced by chlorofluorocarbons and hydrochlorofluorocarbons (CFCs and HCFCs). They are non-toxic and non-flammable but were later found to cause ozone layer depletion. Based on the Montreal Protocol of 1987, a worldwide agreement was reached to gradually phase out the consumption and production of CFCs and HCFCs, roughly a year after Ranvir was commissioned. Today, we have a ‘fully-air conditioned navy’ with many a ship’s HVAC often complemented by locally procured split ACs. Whether such supplements were meant to buffer central ACs struggling to deliver cooling despite using greenhouse gases with high Global Warming Potential (GWP), or were installed for convenient, localised cooling should be an interesting study by itself.

At commissioning, INS Ranvir was (& continues to be) one of the most potent surface platforms in IN’s arsenal. The refrigerant in use onboard Ranvir’s HVAC would in all probability be a hydrofluorocarbon (HFC) — again a greenhouse gas — that replaced CFC & HCFC. With the gradual drawdown of HFC, CFC and HCFC, the HVAC industry has again veered towards some of the early refrigerants (carbon dioxide with butane, propane and propylene, for example). These are either flammable or operate under very high pressure. In an enclosed space, if such gas leaks out and the concentration exceeds its ‘lower flammability level (LFL)’, an explosion is imminent. If indeed the explosion took place inside Ranvir’s AC compartment (as reported in media), the integrity of ship’s central AC, leak detection systems, and nature of refrigerant used onboard would be a key point of inquiry. In responding to an environmental concern, did we increase the fire risk onboard?

NBCD readiness and accident history

Very little data is available in public domain on fire/flooding accidents in the navy caused due vintage equipment or operational cycle of warships. However, personal experience tells me that IN has managed to keep these hazards under control given the wide spectrum of ships, their origins (western/eastern), maintainability challenges and the increasing days spent at sea due to our global footprint. From an NBCD* perspective, both men and material readiness have certainly seen a sea change over last three decades. The state-of-art resources at NBCD School, Lonavala, the setting up of office of the Flag Officer Sea Training (FOST) & Indian Naval Safety Team (INST), Kochi, the submarine fire and flooding simulator at Shipwright School, Hull Inspection and Testing Unit (HITU), Visakhapatnam — all these are milestones in the voyage from past to present. (*NBCD is an acronym for ‘nuclear, biological and chemical defence, including fire fighting’).

Yet, the risk from fire and flooding can only be mitigated and managed, not precluded. The sinking of Andaman (flooding, 1990) and Vindhyagiri (fire, then flooding due to excessive water intake, 2011), the dismembering of Agray due to an underwater explosion (2004), collision and sinking of Prahar (2006), pierside explosion and sinking of submarine Sindhurakshak (2013), sinking of Torpedo Recovery Vessel A-72 (2014), among others, informs us that we have miles to go before saying “all is well”. Eternal vigilance is the price of safety.

The men & women behind the machines

The human factor analysis and classification system (HFACS) approach to any accident brooks a deeper enquiry than what obtains traditionally in the general service (aviation has richly benefited from this approach). The navy is modernising at a rapid pace, with an eclectic mix of indigenous and imported platforms that fight for attention. No other navy has to contend with the challenges of operating and maintaining such a diverse mix of platforms. When a fleet puts out to sea, this mix faces the same vagaries of weather, the same punishing routine of a deployment programme. However, the load is hardly even on, say, a Kora class with a ships company of hundred and a Shivalik class with three times that.

Fatigue management systems are either absent or on paper. The HR department has a daunting task of keeping the best horse in the race while keeping the rest engaged gainfully. When I was a young subaltern, SNFs were coveted ships — attracting the hottest of the lot. Specialists were deep-selected, often toppers of their course. But times have changed. The oldest ships are not necessarily manned by best of the lot. NBCD was never considered a ‘hot’ specialisation despite its critical importance in warfare. An old cloak of the personnel branch “equal distribution of talent” may be coming apart at the seams. While the most upwardly mobile stand watch aboard navy’s latest ships, the mid-order and night watchmen should not be left holding together vintage ships with diminishing watertight and gastight integrity.

INS Ranvir was on a cross-coast deployment of three months. Such deployments often test limits of the ship, its crew and the long op-logistics tailcoat. Soon, they will return home without three shipmates. The trauma from any such accident on the ship’s morale lingers long. The crew of 36-year old D54 deserve our greatest respect. The victims and their families deserve an answer: did their kin die in vain? Was it a preventable accident? Did pushing ageing vessels out to sea contribute to this tragedy?

Corrective measures must flow sure and fast. I pray for early closure for the affected families, speedy recovery for the injured, and an early return to ‘sea and action’ for “Veer Veer Ranvir“.

Sham nau Varuna. May the seas be auspicious unto us. May truth be Samare Vijayee. Always Victorious.

Krishan Kumar MCPO I
Surinder Kumar MCPO II


©KP Sanjeev Kumar, 2022. All rights reserved. Views are personal. “Veer veer Ranvir” is the battle cry of D54, while “Samare Vijayee” is their motto. All photos used in this article are credited to Indian Navy.

An edited version of this story first appeared on The Quint. You can access it here.

10 thoughts on “Explosion Onboard INS Ranvir — HVAC or HFACS?

  1. Lest we forget the infamous fire accident on board INS Vikrant somewhere 160 nautical miles off Goa on 24May 1994 at 00:05 hours which left many dead & wounded including the doctor in board. Vikrant never “really”sailed after that & eventually decommissioned shortly after the unfortunate incident.

  2. RIP …MCPO 2 AK Singh, MCPO2 Surinder Kumar and MCPO1 Krishan Kumar…May the sea Gods give strength to the families to cope with the grief in these stressful times…

    This hugely tragic incident reiterated once again the fact that Fire is both friend and foe to the Navy…the former whence the ship discharges it’s weapons on the enemy…the latter whence the flames consume the innards of the Naval sea going unit…

  3. The refrigerants used in older AC plants, and later banned under the Montreal Agreement, were CFCs that were non-flammable. The modern substitute, Freon 134A, is safe for normal handling, although it is known to be explosive at conditions of very high pressure &temperature (around 8-10 Bar & 200 deg C). Unless the conditions were so in the AC compartment, it’s unlikely the explosion was due to Freon 134A. But R22A, the coolant used in Ref Plants, is a flammable hydrocarbon. I wonder if there was a Ref Plant near the site of the explosion.

  4. RIP,all brevhearts who unfortunately lost their life in this incident.I really wonder whether we can avoid such reoccurrence in future, since few core issues have never being acknowledged or addressed.I happened to be a BOI member and president for atleast 3 such incidents onboard.
    Sir,one suggestion we all spell INHS Ashwini which is right as we speak, but official it is Asvini.

  5. Honesty and loyalty to service is right there.And we still get to see what the authorities would only confuse in time as is their won’t.We do not want to be told if the truth will be otherwise.That is what we pray for.Not a sensation.Thanks for your service.

  6. RIP Brave-hearts and peace to the families of their loved ones who died in the line of duty.
    Kaypius, it seems that you have a detailed understanding of activities onboard, the age of the ship is albeit no reason for accidents, it not the hull which has collapsed, so your argument of an old ship does not hold ground.
    As with regard to the refrigerant used, I don’t see any reason to give a negative comment without checking the facts on ground. IN is and has always been responsible to follow International protocols, Montreal agreement being one of them, which I am sure as an aviator you can understand that well.
    All navies across the world who actively patrol the sea and are used as an instrument of diplomacy have had multiple accidents. It is no way indicative of lack of professionalism or competence and neither blaming the HR is going to fix it.
    The IN’s training and leadership runs it’s time tested course, therefore the Captain Knows his ship and the crew are competent to do there job.
    I think it is time to allow the investigations to run its course and stop articulating conjectures and scathing assumptions.
    Kindly the see the wisdom in totality.
    Hope you will see the light of it one day.

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