Mechanical system start-up following an extended shutdown period

Following an extended shutdown period, parts and components can corrode and become seized and/or strained; potentially leading to breakdown, damage, or even catastrophic failure upon start-up. It is, therefore, good practice for commercial property owners/building managers to perform basic checks prior to mechanical system start-up.

Steam boilers/systems

If shutdown for extended periods, steam boilers/systems can experience an introduction of condensate in the pipework. This can lead to potential water hammer hazards (caused by the introduction of steam into cold pipework that has not been sufficiently drained) which can cause injury to operating personnel and others working within the vicinity of the plant.

Therefore, the following steps should be considered to minimize the hazard:

  •  Introduce steam into the cold pipework gradually to avoid the risk of thermal shock and to reduce the chance of water hammer.
  • Ensure the pipework system is completely drained when cold, and pay attention to areas where condensate can collect, which might include sagging lengths of pipework, vertical legs, changes of slope, dead ends, etc.
  • Inspect steam traps in accordance with manufacturers’ instructions.
  • Use isolating valves to permit the gradual warming of the system.

Compressed air systems

  • Check compressor oil levels are correct.
  • Ensure all compressors are well ventilated.
  • Drain all dryers, traps, pipework, and receivers of condensate.
  • Ensure all filters are clean. Hot water boilers/heaters
  • Ensure air is completely vented from the system.

All machinery/mechanical systems/installations being brought back online should have all protective devices tested under normal operating parameters to ensure they are suitable for further service. Any defects found should be rectified before machinery/mechanical systems/installations are brought back online.

Local exhaust and ventilation systems

When these systems have been out of use for some time, there is the possibility of occurrences that could lead to damage and/or reduction in operational efficiency.

Before the system is restarted, a visual check of the system should be undertaken to include:

  • Fans and filters
  • Water ingress
  • Dampness in the system (which could lead to heavy residue ‘caking’ in the filters)
  • Vermin ingress and nesting

Hot and cold water systems

Ideally, for extended shutdown periods, hot and cold water systems should be decommissioned and emptied of contents as far as practicable. If they have been isolated and not drained in the correct manner in preparation for a shutdown period, there is the potential for the presence of Legionella bacteria. This is the cause of Legionnaires’ disease. Still or stagnant systems offer Legionella bacteria favorable conditions to thrive.

Commonly found in hot and cold water systems, Legionella bacteria (the cause of Legionnaires’ disease; a type of pneumonia) can be contracted by the inhalation of water droplets. These water droplets are present at most system outlets such as showerheads, baths, taps, wet air conditioning systems, whirlpool baths, and hydrotherapy pools. Commercial property owners/building managers should carry out a full Legionella risk assessment of their hot and cold water systems following an extended shutdown period, and ensure satisfactory measures are in place to control the risk. The advice of a water treatment professional should be sought when reinstating these systems.

Our guidance for commercial property owners/building managers should not replace the defined maintenance start-up processes and prescribed procedures of equipment/ installation operation manuals or any applicable codes and local regulations. An inspection should be carried out and documented before start-up commences, and only qualified and authorized persons should be engaged in starting up machinery or electrical installations.

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© 2020 The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is for informational purposes only and is not intended to convey or constitute legal advice. HSB makes no warranties or representations as to the accuracy or completeness of the content herein. Under no circumstances shall HSB or any party involved in creating or delivering this article be liable to you for any loss or damage that results from the use of the information contained herein. Except as otherwise expressly permitted by HSB in writing, no portion of this article may be reproduced, copied, or distributed in any way. This article does not modify or invalidate any of the provisions, exclusions, terms or conditions of the applicable policy and endorsements. For specific terms and conditions, please refer to the applicable endorsement form.


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