The concerns, which have been raised by Spirax Sarco, centre on high limit valves that shut off the flow of the heating medium, such as steam, to prevent overheating or excess pressure. High limit control valves, which are widely used in commercial buildings, such as hospitals, schools and offices, require regular maintenance and testing to ensure that a valve not only performs an opening and closing operation, but also that it completely shuts off the steam supply.
“Introducing adequate maintenance and servicing regimes remains a challenge for all steam users in the UK,” says Dave Bell, field services manager at Spirax Sarco. “Many steam users do not have the resource to plan and carryout regular maintenance of equipment which may result in servicing and testing being seen as an “unnecessary cost” and consequently may be given a low priority.”
Bell says that the choice between ‘Planned Preventative Maintenance’ and ‘Breakdown Maintenance’ needs careful assessment of the risks associated with either choice. “In the case of high limit safety devices, designed to shut off the heating medium in the event of an over-temperature event or the loss of power to a control system, there may be severe consequences if the system fails to operate correctly.”
Failure to maintain and test high limit valves may result in high temperature water being circulated throughout a building, potentially leading to scalding or burns. “We are aware of an increasing numbers of cases where valves have not been maintained with resulting problems for the end-user.”
He continued: “I know of one case in which multiple high limit control valves failed to close during a power failure, sending 120oC steam around the hot water loop of a hospital, which presented a serious danger to patients and staff. Investigation later revealed that the valves had not been serviced and there was no record of them ever having been tested.”
Bell says that inadequate servicing and testing is becoming more common in the UK, with many end-users failing to recognise the importance of a regular maintenance regime. “Any maintenance regime for control and high limit valves should include regular visual inspection of the controllers, valves and actuators; dismantling of the valve prior to cleaning, the replacement of valve stem seals; the checking and cleaning of strainer screens and, an all-important functionality test and written report on the condition and operational status of the device.”
Hospital and social care buildings are often deemed to be high risk due to the vulnerable nature of many of the building’s users. However, Bell says that all occupants or users of any commercial building are protected by a raft of health and safety regulations and that those responsible for a building’s upkeep have a duty of care to ensure systems are safe to use.
“Those responsible for the plant and equipment within a building need to be aware that all building users are covered by a variety of regulations, including the PUWER Provision and Use of Work Equipment Regulations, the Management of Health and Safety at Work Regulations and the Health and Safety at Work Act.”