Common defects of steam boilers and hot water heating boilers

Industrial steam boilers and high-pressure hot-water boilers over 110°C must be inspected annually.

This is to ensure that they comply with the Pressure Systems Safety Regulations (PSSR) 2000. These boilers are generally in constant use and any downtime has to be planned.

Unpromulgated shutdowns can be very expensive and in some cases, dangerous.

Regular, thorough detailed examination regimes have the benefit of highlighting to the boiler owner the condition of the boiler and remedial actions that are required. These examinations, if carried out correctly, have the added benefit of keeping the boiler and its associated equipment safe. An industrial steam boiler or Industrial hot water boiler stores a vast amount of energy which if released uncontrollably could be a risk to personnel and equipment.

Steam boilers and hot water boilers are complex items of plant and as such, a significant amount of experience is required to be able to conduct a thorough and working examination of such high energy equipment. Thurra has a vast amount of experience in carrying out boiler examinations. We work extensively with the boiler service engineers and the Non-Destructive Test (NDT) engineers to ensure that high-energy equipment operates safely and within the confines of their design specification.

The 5 most common defects Steam Boilers and Associated Plant.

1 Poor Boiler Water Chemistry Management: Arguably the most common source of all boiler defects is poor boiler water chemistry management. This can result in a large build-up of ‘boiler water scale’ below and sometimes above the furnace tube. Any such build-up generally causes unequal heat removal from the furnace tube, resulting in excessive strain on certain areas. NDT engineers, as part of their 5-yearly test, specifically look for these areas and if found can result in a very expensive repair bill.

Annually, Thurra’s engineers review the chemistry log and assess the status of any chemical scale within the boiler. These examinations should give an early indication of the boiler water chemistry and remedial actions required.

2 Incorrect boiler water level indication: When the boiler water is too high, there is the possibility that water could be sent down the steam pipework causing extensive damage and potential failure of the downstream components. When the boiler water is too low there is the potential to uncover the furnace and boiler tubes thereby ultimately causing the boiler to overheat and fail.

During the course of the examination Thurra’s engineer will have the boiler water level control system stripped down, examined and when assembled, checked to be working on the operating boiler. In addition, our engineer will look at the operating log to see that the daily, weekly and monthly maintenance schedule is being completed.

3 Tube failure: Identifying and correcting the root cause of tube failures is essential to help lessen the chance of future problems. The tubes can fail for a number of reasons, including oxygen-pitting and flame impingement of the tube ends. In either case a partial retube or in some cases a full retube will be required, which is very costly and time consuming.

As part of the inspection programme, Thurra’s engineers inspect the condition of the tubes both internally and externally. Checking for any oxygen pitting which is generally caused by not having sufficient oxygen scavenger within the boiler water and flame impingement caused by the burner not being set up correctly. Early identification of these situations by Thurra will allow the boiler owner to make changes to his maintenance and operating settings that will prevent very costly and time-consuming repairs. Any defects identified with the boiler tubes will be explained to the boiler owner.

4 Passing Safety Valves: Safety valves are one of the features that give the boiler its ultimate safety mechanism. The devices will stop the boiler over-pressurising should one of the operating systems fail. If the safety valves are passing it will reduce the likelihood of the safety valves operating at the correct pressures and in some extreme cases cause the valves springs to rust which could prevent the safety valves from operating at all.

During the examination, the safety valves are stripped down, examined, reconditioned and reassembled. If required, Thurra’s engineer will ask for new valves to be fitted with all the supporting documentation. The final part of the examination is to see that the safety valves actually operate whilst the boiler is at operating temperature and design pressure. All results following the examination and test are communicated to the boiler owner.

5 Poor insulation: When the boiler is in operation it operates at extremely high temperatures. If the insulation is not sufficient there is the possibility that someone could receive a nasty burn.

At every examination, Thurra’s engineers assess the status of the insulation. This is carried out when the boiler is shut down and where insulation is exposed and can be carefully inspected, also, when the boiler is in operation when hot spots are very apparent. The results of any these examinations are communicated to the boiler owner before Thurra’s engineer leaves site.

If you require advice or help on any of the above, please speak to your Insurance Broker who will be happy to arrange a call or a visit from Thurra, or alternatively, get in touch.

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