Preventive fire protection, early fire detection and firefighting water retention in the surface treatment industry

Werkstoffe 06. 03. 2024
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By Wolfram Willand, Freiburg Regional Council

Electroplating metal plating companies exhibit a certain risk of fire damage caused by the process. To avoid fire damage, some precautions are recommended when equipping galvanic systems in order to prevent fire from starting and to avoid the spread of fire. Furthermore, equipping companies to protect the environment in the event of a fire is an efficient method of reducing the amount of damage in the event of a fire.

In Germany, fire incidents occur frequently in surface treatment companies, especially in electroplating, anodizing and printed circuit board companies. A study conducted by the French Ministry of the Environment in June 2022 confirms that this trend has also been observed in France in recent years, with a strong upward trend [1]. Preventive fire protection and early fire detection play a key role in avoiding high damages and severe environmental pollution, caused by major fires. For the companies, this is often an existential concern. The top priority should be, to prevent a fire from breaking out right from the beginning. If it could not be avoided, the first few minutes after the outbreak of fire determine the further course of events. In the event of a major fire, damage to the aquatic environment and possible environmental and legal consequences can be avoided in advance by adequately dimensioned and maintained firefighting water retention. Some insurance companies have started to set up very high fire protection requirements, demand unusually high insurance premiums or no longer insure companies in the surface industry at all.

Frequency and reasons for fires in the surface treatment industry

A rough rule of thumbs indicates, that a major fire occurs in an electroplating company in Germany approximately every three months, thus around four major fires per year. A major fire is defined as an event with a loss of more than one million euros. The much more frequent smaller fires (about 80–100 per year) are not even counted here [2].

The German Surface Technology ­Association (Zentralverband Oberflächentechnik e. V. ZVO)comes to the following conclusions in its 2021 annual report: In recent years, countless major fire claims have alarmed the operators of electroplating and other surface technology companies and at the same time drew the attention of insurers on electroplating and surface technology. Fire and explosion damage usually leads directly to environmental damage and generally results in long-term business interruptions. Replacing customer orders by competitors, the loss of market share and customers, image or employees are just some of the major challenges that the entrepreneur has to master after a major fire damage in parallel to the management of the damage and reconstruction [3].

It is estimated that only around a third of companies survive a fire incident for a longer period of time after a fire incident [4]. In France, the number of reported cases has risen continuously and has recently strongly increased (Fig. 1).

Fig. 1: Number of reported environmental incidents in the surface sector in France; top, orange-brown line shows fire incidents in period form 2001 to 2021 [1]

 

Causes of fire

The main cause of fires in surface treatment plants is electrical current. According to sources, the combination of heat sources, corrosive atmospheres and the transmission of electrical energy represents a high potential of fires in galvanizing plants [4]. The possible range of ignition sources are completed in rarer cases by flammable work (e. g. welding), hydrogen explosions, acts of arson and by chemical ignition.

An example of accidental arson is a smoldering cigarette that was carelessly thrown into a dewatering shaft. The cigarette ended up in a pump sump for rainwater and – possibly leaking – acids and alkalis. Solvents were not involved. Particularly in the summer months, or during prolonged dry periods, dust, leaves, fine branches etc. can build up in these shafts, which in this case, in combination with the smoldering cigarette, led to a very clear and rapid fire (Fig. 2). It has been shown that it is very important to clean these shafts regularly. This also applies in the event that acids or alkalis get into the shaft intended for this purpose. A reaction with any organic components is to be expected.

Fig. 2: Fire in a dewatering shaft (Source: W.Willand)

 

A chemical ignition source, that should not be underestimated, is sodium dithionite, which is often used for reduction of chromium(VI) in waste water treatment. It self-ignites even with small amounts of water (e. g. when using a wet dosing shovel) and continues to burn on its own, like lithium ion batteries. Dried aerosols of oxidizing process solutions (e. g. ammonium nitrate, potassium nitrate) in ventilation systems may also ignite or contribute to a very rapid fire extension. Prof. Dr. W. Hasenpusch describes other possible ignition sources in a series of articles [5].

Fire protection – Fire prevention

Various measures and safety devices are recommended to prevent fire damage:

  • use of indirect bath heating based on hot water or steam
  • if electric bath heaters are unavoidable, only those with redundant safety monitoring against overheating should be used
  • regular checks of all electrical contact points (e. g. 12 times per year) such as product carrier contacts, contact anode bars and baskets. Contacts of the anode baskets on rails with hanging baskets easily heat up if the contact is insufficient. This can lead to electrical arcs and thus to the ignition of surrounding plastic components. This problem occurs especially with older baskets and rails, and temperatures of over 100 °C (measured using a thermographic camera) are quickly reached even due to a minimal contact point (Fig. 3). For anode baskets that are attached to the anode bar using screws, it is recommended that the contact screws are retightened using a torque wrench (e. g. to 25 Nm) not just 2 times per year but 12 times per year
  • in drum electroplating plants, the finger contacts must generally be checked for cleanliness, corrosion and function during maintenance in the plant in order to ensure the necessary contact surface for current transmission. As drum electroplating systems are sometimes subject to heavy splashing when the drums are moved out, it is recommended that the condition of the contacts is also checked during production and, if necessary, combined with suitable early detection methods (visually or better with a thermographic camera)
  • all-pole current disconnection during operating downtimes (ZVO recommendation)
  • sufficiently large diameter for current-carrying cables/bars; current supply on both sides of electroplating baths has proven to be advantageous
  • ensure sufficient waste air extraction to prevent hydrogen explosions (some pickling processes, electrolytic degreasing, chrome baths); note possible hydrogen accumulation if the extraction system shuts down due to a shut down and the power supply is suddenly restored
  • personal instruction of operators, combined with checklists for inspection, has been proven as suitable

    Detecting fires at an early stage

Fig.3: Contact block and cable in visible spectrum (above) and in infrared spectrum (approx. 150 °C) (below) (Source: W. Willand)

 

In addition to the challenge of preventing a fire, it makes sense to make efforts to detect fires early. Some important recommendations can also be made here:

  • use of modern automatic fire detection systems, e. g. aspirating smoke detectors (ARS system), which are designed for the special conditions in an electroplating process and can distinguish fire smoke from other typical operational contaminants
  • in the event of a fire, the exhaust air system of the electroplating automat intensively supplies fresh air, which considerably accelerates a fire. This problem can be minimized by ensuring that the exhaust air system is switched off immediately in the event of a fire alarm
  • installing fire detectors within electrical switch cabinets – including checking their effectiveness at regular intervals
  • regular or even permanent inspection of systems to detect unusual heat development using thermography/thermal imaging cameras. Good mobile systems, but also fixed systems with 24/7 use, are now available on the market that are suitable for monitoring
  • instead of the sprinkler systems often required by insurance companies, other measures such as the installation of thermal imaging cameras and/or the installation of PT100 temperature sensors on current-carrying bars and contacts can be taken
  • recommendations of the German Central Association for Surface Technology (ZVO)
    are:
    - annual inspection of all electrical systems by a VdS-approved expert incl. thermography;
    - ½-yearly inspection of portable equipment,
    - ¼-annual inspection of the safety equipment

    Positive practical example

A company in the surface treatment industry, which followed the above-mentioned ZVO recommendations, nevertheless suffered two electroplating fires in one year. As a consequence of the first fire, thermal imaging cameras with 24/7 monitoring and connection to the fire alarm control panel (FACP) were installed. This monitoring was accepted by the insurance as an alternative to a complete sprinkler system, which was also considerably cheaper, and has proved its worth. In the second fire, despite disadvantageous circumstances, the thermal imaging monitoring system was triggered 3 minutes before the aspirating smoke detection system (ARS system), enabling employees to extinguish the fire at an early stage. As a result, the fire brigade was only required to extract smoke from the production hall.

Organizational measures

Preventing fires and taking action in the event of a fire require some organizational measures:

  • risk assessment; instruction of internal and external employees – for regular operation and for disrupted operation - also for repairs: welding, cutting, soldering
  • evaluation of explosion risks (e. g. by hydrogen) and documentation in an explosion protection document
  • fire inspections and fire protection drills (recommended every 5 years)
  • ensuring sufficient supply of firefighting water
  • ensuring sufficient firefighting water retention (see below)

    Maintenance and repairing

Finally, to ensure reliable protection against fire, various maintenance and repair work must be carried out:

  • regular cleaning of all system ­components – including the exhaust air channels – according to a cleaning and maintenance plan monitored by the management (recommended at least twice a year)
  • regular check of the electrical systems (VDE 0105-100) by a qualified electrician; hint: isolation faults with currents of 100 mA can already cause fires
  • regular inspection of electrical system components using thermographic inspections (thermal imaging camera)

    Firefighting water retention

Firefighting water from surface ­technology companies is generally contaminated or highly contaminated, meaning it is de facto hazardous to water. It can also be contaminated with PFAS when using AFFF firefighting foams. The UNECE Safety guideline [6] therefore comes to the conclusion: Because firefighting water must always be considered contaminated, special considerations must be taken into account when disposing of it.

This sentence was impressively confirmed by an event in Berlin in 2019. In an electroplating fire with damage far higher than 100 million Euro, the firefighting water caused the total failure of the city’s sewage treatment plant and subsequent fish mortality. The tragedy of this case was, that the company was already in the process of installing sufficiently dimensioned firefighting water barriers in accordance with the German VdS 2557. However, the fire occurred before the works had been completed and the firefighting water still leaked out.

In the event of insufficient retention, firefighting water can leak directly into water bodies via floor drains or into municipal sewage treatment plants via the sewerage system and damage or kill them. Firefighting water can also flow directly into water bodies via rainwater overflow basins in the case of indirect dischargers or infiltrate into the groundwater via house drainage systems, thus endangering the drinking water supply.

Technical protection equipment

Technical protective devices help ensure that, in addition to the actual damage caused by the fire, further damage occurs due to contaminated extinguishing water. In this context, the following should be mentioned in particular:

  • sufficiently dimensioned firefighting water retention and disposal
  • recommendation are given for permanent, preferably centralized firefighting water retention areas (install the entire electroplating and/or waste water treatment system in one retention basin)
  • install indoor water downpipes up to the maximum expected water retention level in fire resistance class F 90 (Fig. 4)
  • avoid flammable plastic waste water pipes that penetrate the firefighting water retention basin and melt away in the event of fire
  • firefighting water retention barriers – firefighting water bulkheads (Fig. 5)
  • for existing facilities, provide mobile sealing materials, manually insertable firefighting water bulkheads, channel seals, channel bladders on site [1]

Fig. 4: Indoor installed rainwater downpipes securely embedded in concrete up to the maximum expected water retention level (Source: W. Willand)

Fig. 5: Example of an automatically activated firefighting water bulkhead (Source: W. Willand)

 

Calculation of the fire ­water retention volume

For companies in the surface treatment industry, the German VdS 2557 [7] has proven to be the best and most realistic calculation model. This source of information, which is provided free of charge (in German and English) by the German Insurance Association including a calculation tool, covers all factors relevant to the surface industry. On one hand, it is taken into account that in the case of a major fire, both the quantity and the hazardousness of the firefighting water is significantly increased by the leakage of all liquid chemicals (for example baths or rinse water) into the firefighting water. On other hand, fire protection measures taken by the company are rewarded in the calculation and lead to a lower firefighting water retention volume. As figure 6 shows, the VdS 2557 is balanced in the middle range in international comparison when calculating extinguishing water retention volumes and therefore does not impose any excessive requirement.

Fig. 6: Extract from [6]; results of VdS 2557 are shown in the third lowest dark blue line

 

Conclusion

In order to prevent the occurrence of a ­major fire or to limit the impact in the event of a fire, it is important to check the points and recommendations listed above for own surface treatment plant and to derive and implement the appropriate measures. As it is a matter of preventing an existential risk, it is recommended to also implement measures that possibly exceed the requirements of the authorities.

A step-by-step approach to improving fire protection measures at a technical level and organizational measures is recommended. The retention of the firefighting water also has to be planned and implemented. Particular attention should be paid to the necessary maintenance, relatively short maintenance periods and the care required during ­operation.

A further important aspect is the safety culture and awareness of the personnel in the surface treatment plants, both when operating the plants and when dealing with critical situations. Regular training and safety inspections are the means of choice here.

Literature

[1] Ministere de la Transition Ecologique 06-2022: Accidents involving fires at surface treatment facilities; https://www.aria.developpement-durable.gouv.fr/wp-content/uploads/2022/11/2022_10_13_Synthese_TS_MG_VFinale_EN.pdf

[2] W. Willand: Brände und Löschwasserrückhaltung in Galvaniken; Galvanotechnik 2019, Heft 7

[3] ZVO Jahresbericht 2021, Seite 82; https://www.zvo.org/fileadmin/zvo/ZVOJahresbericht/2022/ZVO_Geschaeftsbericht_2021.pdf

[4] Frank Schüle: Brandschutz durch intelligente Anlagenplanung; WOMag, 2022/1-2

(5) W. Hasenpusch; Explosionsschutz in der Oberflächentechnik; Galvanotechnik 2019, Heft 1 – Heft 3

[6] UNECE 2019: Safety guidelines and good practices for the management and retention of firefighting water; https://unece.org/sites/default/files/2020-12/ece_mp.wat_58_ENG.pdf

[7] VdS 2557en/2013-03: Planning and Installation of Facilities for Retention of Extinguishing Water; free download: https://shop.vds.de/download/vds-2557en

(8) VdS 2557a_en/2013-07: Calculate sheet volume for contaminated extinguishing water (VdS 2557a_en) free download: https://shop.vds.de/download/vds-2557a-en/bc0158f6-548b-42f3-920f-81b945df4bd7

[9] VdS 3412 2018-01: Galvanotechnische Betriebe – Gefahren, Risiken, Schutzmaßnahmen; https://shop.vds.de/download/vds-3412

 

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