General Requirements for Unattended Operation (H24 and H72)

General Requirements for Unattended Operation (H24 and H72)

The Technical Specification UNI/TS 11325-3 (February 2018) defines the surveillance methods for steam and/or superheated water generators with pressure (PS) greater than 0.5 bar and temperature (TS) greater than 110 °C. Unattended operation can be carried out for up to 72 hours.

General Requirements for Unattended Operation (H24 and H72):

• The generator must operate automatically and be PED certified for this specific purpose.
• The user and maintenance manual must be available in the boiler house or control room.
• The feedwater and boiler water characteristics must comply with the user/operating manual or with UNI EN 12952-12/12953-10 standards.
• Ignition and re-ignition of the generator must be performed manually by the designated operator.
• A Surveillance Log must be kept to record assigned personnel, checks, water analyses, anomalies, etc.

Checks and Tests for Unattended Operation:

• Every 24/72 hours: Observe abnormal noises/odors, check the operation of level indicators and blowdown devices, and check water quality (appearance, conductivity, pH, hardness, alkalinity).
• Every month: Check correct operation of lockout level controls, lockout pressure switch, lockout thermostat, devices for protecting water quality, and safety systems. Verify water quality according to UNI EN 12953-10.
• Every three months: Check the feedwater supply system.
• Every six months: Check safety valves, flow switch, level control system, pressure switches, lockout thermostats, water quality protection devices, safety systems, and pressure/temperature control systems.
• Every year: Check the burner.

Additional Requirements for H72 Unattended Generators:

• Permanent automatic monitoring of feedwater hardness and conductivity. Automatic shutdown if limits are exceeded.
• Permanent automatic monitoring of condensates in case of risk of contamination. Condensate diversion or automatic shutdown if limits are exceeded.
• Permanent automatic monitoring of boiler water conductivity for steam generators.
• Self-checking flame control for gas burners. Verification every 72 hours for other fuel types.

Additional Considerations:

• The UNI/TS 11325-3 (February 2018) replaces the previous version of October 2010.
• H24 certification is considered redundant, since UNI EN 12953-6 already requires flame control with self-checking for burners above 1200 kW on PED equipment.
• Article 73-bis of Legislative Decree 9/04/2008, no. 81, reintroduces the previous regulation (R.D.L. 9/7/1926, no. 1331) concerning licensing for the operation of steam generators.

Note: The information provided is based exclusively on the supplied document. It is recommended to consult current legislation and specific technical standards for a complete and updated interpretation.