Specialist Hazard Control Solutions Kept Workers Safe During Vessel Maintenance of a Hunt Class Minesweeper

Project Overview

Between 1980 and 1989, 13 Hunt Class minesweepers and minehunters were commissioned, and eight remain in service with the UK's Royal Navy.

At 750t displacement, 60m length, 10.5m beam and 2.2m draught, the Hunt Class are the largest warships made of glass reinforced plastic (GRP). The GRP construction contributes to the vessel's very low magnetic signature, which is required for mine countermeasures operations. Vessels undergo regular Fleet Time Service Periods, a short-term maintenance programme to maintain technical specifications of the ship, avoid unwanted accidents or emergencies, and protect the ship's productivity.

Challenge

A vessel was due to undergo planned maintenance repairs, but because minesweepers primarily consist of a glass reinforced plastic hull, the works presented a range of harmful health hazards. GRP dust is created during activities such as drilling, grinding and sanding, and if inhaled, it can cause fluid to collect in the lungs and create respiratory irritation, as well as skin irritation. Other health hazards included zinc dust, created when repairing areas covered in paint and coatings. This dust is both combustible and an irritant. When styrene is used during repairs, uncontrolled fumes can affect vision, cause hearing loss, and impair concentration and balance.

There was also the challenge of maintenance works taking place in confined areas inside the vessel, posing the risk of workers experiencing loss of consciousness or asphyxiation caused by inhaling toxic fume or vapour, or from oxygen deficiency.

Solution

For this project, RAVEX® Wandafilta Plus Kits were installed with twin VENTEX® 300M Centrifugal fans to extract dust and fume at the source. We filtered to H14 (HEPA) standard, which captures an impressive 99.99% of 0.3-micrometer air particles, meaning that out of 1,000,000 particles, only 10 will not be captured. This system created a negative pressure, ensuring fumes and dust could not migrate into other areas of the vessel.

Multiple 100mm diameter hoses were installed to provide extraction at different locations throughout the vessel, covering up to 75m distance. The anti-static ducting was fitted with quick release connections at critical fire doors, allowing for fast containment in the event of a fire. All extraction systems on site were commissioned and demonstrated to be performing in accordance with RVT's design, meeting the requirements set out in HSG258, the HSE's guide to local exhaust ventilation.

Fresh air was introduced into maintenance areas, including Dieso tanks, using additional VENTEX® 300M Centrifugal fans, ensuring a safe working environment was maintained throughout the duration of the works.