Testing of HDPE-Manholes for fire hazard ministry of works
Introduction :
Manholes made of Polyethylene have been used successfully for more than 40 years Worldwide. It is a growing market and the advantages of manholes made of thermoplastic materials are well known:
- No leakages
- Easy handling
- Low weight
- Durability > 50years
- Impact resistance
- Flexibility
- High Strength
- Tailor-made design for any load case
- Easily Fabricated – important for future connestions
In this case, the Ministry of Works – Bahrain had reservations concerning the possible flammability of the HDPE manholes during and after installation. These reservations had to be answered clearly and without any remaining doubt!
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Type testing for fire hazard resistance:
The test-procedure is developed for testing HDPE Manholes for fire hazard and resistance. The test should determine if HDPE Manholes will catch fire and continue to burn under two different scenarios. These scenarios should emulate the possibility of either an accidental incident or intentionally attempting to set the manhole on fire.
Specimen: 1400mm ID HDPE Manhole @ 1.8m DTI, including benching to MOW (Ministry of Work) specifications. Inlet and outlet are closed off via HDPE welding at the entry and exit points.
Apparatus: Match Stick, Ignited Cigarette Lighter, Burning Cigarette, Burning Kerosene Block, Petrol
Scenario 1:
Manhole stored at site in a securely bounded area, standing vertically. Acceptable storage conditions necessitate these manholes to be kept in vertical position, with safe distance from each other, stored in a locked yard near site office guarded by security (As is standard on all MOW sites).
Other assumptions:
Ambient temperature between 35oC and 45oC, with wind speed less than 15 km/h.
source :
“handbook on large plastic pipes” KRAH COMMUNITY
<https://www.krah.net/>
Of course everyone is aware that Polyethlene is a plastic material and is flammable. It can be classified e.g. according DIN 4102-Part 1 into class B2, what is representative for “normal flammable materials”. That is not really surprising because it is a plastic material. Having said this, the manufacturers are using the temperature-behaviour of Polyethylene very successfully for their production processes.
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