Increased safety during maintenance
Steam System Isolation Upgrade
Upgrade to ensure safety during turbine and boiler maintenance activities.
Our client approached us with a concern over the isolation available when conducting maintenance on their steam turbine or boilers. The plant was designed to allow for operation of one steam generation line to either the turbine or condenser, whilst maintenance was being conducted on the other line. The concern related to opening and closing of the installed isolation valves, and whether adequate protection was in place.
We assessed the initial design and operating philosophy for the plant and identified a major concern relating to the sealing capability of the valves, and their ability to open under steam pressure. The original valves were butterfly valves and were purchased with cost as a deciding factor. Not only were the valves unsuitable for the purpose, they were also installed in inaccessible areas with no remote actuation capability.
We specified new parallel slide gate valves and engaged a team of specialist steam pipework contractors to complete the works during the upcoming outage period. The new valves also included remote actuation capability to allow for simple opening and closing depending on the plant requirements. This scope also included actuated valve bypasses, to simplify the warm through process for operators and position indication with lock off capabilities to ensure safety of maintenance teams.
As the modifications were to be undertaken on high pressure steam pipework, Pressure Equipment Directive Category 3 rules applied. These rules required thermal stress and loading calculations for the pipework and notifiable body review. We advised our client, who employed the necessary notifiable body and we acted as liaison during Third Party discussions and inspections.
We managed the pressure testing of the pipework modifications, ensuring that all the necessary criteria had been met. Once completed we commissioned the new valves and ensured that an operator training program was undertaken to prevent any confusion which may lead to unsafe incidents.
We ensured that a safe and practical solution was found to a complicated problem. The risks involved with high pressure steam systems required special considerations to ensure the safety of all concerned.
We provided specific training for operation and maintenance teams to prevent any unsafe conditions arising, as well as ensuring the longevity of the valves themselves.
The valves were successfully installed and have now been utilised during three outage periods. The new valves have simplified the procedure for the operations team and ensure the safety of the maintenance teams working on either the boiler units or the steam turbine – generator sets.