Hydraulic Accumulators are classified as a pressure vessel under the Pressure Systems Safety Regulations and above 250 bar litre in pressure and volume they require a Written Scheme of Examination. These are largely forgotten and misunderstood by others.
Accumulators require a safety system in case of problems, such as heat or fire. In British Steel in the 1990’s there was a fire at a scrap bailer and there was a hydraulic system with an accumulator in the area. I warned the Fire Brigade there was an accumulator in the area and they asked what it was. My reply was it was a pressure vessel and they should take precautions like any other pressure vessel.
When the fire was extinguished I went down to view the damage. The accumulator was still in place but the connecting pipework had peeled open. The accumulator had no local relief valve or a way to vent the gas hen it heated up and increased in pressure. The weakest point, luckily was the pipework, and not the accumulator connection. A safety block would have vented the excess pressure, and the gas once the bag had failed.
This problem was before the PSSR were introduced and following the legislation and the failure all systems had to have Written Schemes of Examination and specified safety systems. Risk assessments were performed in all areas to detail what could happen to the accumulators in each part of the site and actions taken to mitigate the risks.
