Oesterbaai has been successfully carrying out validation measurements for the energy sector and individual companies since 2005. One such validation measurement concerned the cleaning and relining of asbestos cement pipes by Tubus System in 2013. Tubus System requested Oesterbaai Midden to validate this project.

Cleaning and relining sewer pipes
Tubus System, an organisation with its roots in Sweden, specialises in cleaning and relining sewer pipes. Briefly, this technique involves cleaning existing pipes and then spraying them with a new layer of glass reinforced polyester. This new layer forms a new and durable coating in the old tubes. According to Tubus, the expected lifetime is at least 50 years, which means demolition work can be avoided. However, it was unclear whether this cleaning and relining method could also be applied to existing asbestos cement pipes, which are widespread in buildings and residential complexes in the Netherlands.

Legal limits for asbestos
Briefly, this technique involves cleaning existing pipes and then spraying them with a new layer of glass reinforced polyesterIn late 2012. The request involved determining if and the extent to which asbestos exposure levels in the workplace would exceed the (then new) legal limits for asbestos.

Asbestos Removal Decree
The first concern was whether the cleaning and relining would be in violation of the Asbestos Removal Decree ('Asbestverwijderingsbesluit') and/or the Working Conditions Decree on asbestos (‘Arbobesluit inzake asbest’).

Action plan
A study of prevailing laws and regulations showed that this work could be classified as ‘carrying out maintenance' to asbestos-containing material, which is authorised. Obviously, the Working Conditions Decision on asbestos (‘Arbobesluit inzake asbest’) was fully applicable, so personal protective equipment was required where the legal limits for asbestos exposure were exceeded. Oesterbaai then drew up a detailed action plan specifying how the validation measurements would have to be carried out. This action plan met the requirements set out in Ascert’s SCi 547 directive (which was published later in 2015). 

Validation measurements
Then, on a cold winter day in March 2013, VKS built a weatherproof and windproof containment on the roof of a residential complex in Almelo where the validation measurements could be carried out in different shifts. The actual air measurements were carried out in the breathing zone of the test person (known as a PAS measurement) and at two stationary locations in the containment. In addition, a background measurement was also carried out, along with some air measurements in the wet areas of a number of flats in the residential complex.

Favourable analyses for Tubus System
The air filter analyses were carried out by Fibrecount in Rotterdam using scanning electron microscopy with X-ray microanalysis (SEM/EDX).
The results of the analyses were very favourable for Tubus System, as expected. In eight of the nine air measurements, no asbestos fibres were found. Just one air measurement showed a very slight increase, however this was significantly below the new threshold for chrysotile. It should also be noted that in ‘normal’ conditions, the work is carried out in the open air.


Work protocol for relining pipes with asbestos
The results of the validation measurements were listed in a final report. The main conclusions were that the cleaning and relining of bonded asbestos cement pipes did not lead to measurable amounts of asbestos. In other words, they would not lead to current and new legal limits for asbestos being exceeded. A strict condition is that such work is carried out in full compliance with Tubus System’s ‘Work protocol for relining pipes with asbestos-containing material’ (‘Werkprotocol Relinen van Afvoerleidingen met Asbesthoudend materiaal’).

Tubus System first company in the Netherlands
These conclusions were notified to the Inspectorate of the Ministry of Social Affairs and Employment (‘Inspectie SZW’). Thanks to the results of these validation measurements, Tubus System was the first company in the Netherlands able to carry out maintenance on asbestos-containing sewer pipes on a large scale. For clients, it meant big savings, because pipes did not have to be removed or demolished. It opened up a whole new and successful market for Tubus System.

*) Lowering of the legal limits for asbestos; measurements in a containment where amosite-containing material was removed and very high exposure levels were recorded.

Questions about the validation measurements? Please feel free to contact us.

Source: Shield Group

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