The complete guide for the maintenance of your steam boiler

How to save money while using your steam boiler

Once a new industrial steam boiler has been installed, what needs to be done in order to extend its service life and keep it running efficiently?

Proper boiler maintenance will ensure maximum efficiency and a longer average service life.
While certain treatments and measures may seem somewhat costly at first glance, they often ensure better efficiency and decreased consumption over the long term.
So what are the procedures and parameters to keep an eye on during the day-to-day management of industrial steam boilers?

Let’s examine them together.

Table of contents:

1. Preliminary checks
   a. “Boil-out” procedure.
2. Post-commissioning inspections
3. Downtime
   a. Wet storage;
   b. Dry storage.
4. Maintenance
   a. Periodic Maintenance;
   b. Ordinary Maintenance;
   c. Extraordinary Maintenance.
5. Conclusions

1. Preliminary checks

Let’s say we have a new boiler that’s just been delivered and installed.

What should I do before I begin using it at 100%?

Normally we would want to have the installer perform a brief inspection of all the components.

Following the instructions in the installation manuals, check the tightness of certain components subjected to thermal expansion. It is also necessary to check all the connections and the proper closure of the door.

Once these steps have been completed, we’re ready to carry out the first essential treatment for a new steam boiler: “boil-out” procedure.

a. “Boil-out” procedure

The boil-out procedure is a chemical treatment that’s carried out on new boilers and is normally performed by specialized companies.

Its purpose is to eliminate any oil, grease and metal oxide deposits resulting from the boiler’s assembly phase.

If these substances aren’t eliminated, they can cause corrosion due to the incomplete formation of the passivating film that the metal creates on the surface in contact with the water.

The steps for an effective boil-out procedure are as follows:

1. Filling of the boiler body with water;
2. Exclusion of all the instruments (pressure switches, pressure gauges, etc.);
3. Introduction of caustic soda, sodium carbonate or trisodium phosphate, based on the specific percentages required by the boiler and the total quantity of water;
4. Introduction of additional surfactants;
5. Activation of the boiler until the water reaches a temperature of 80-90°C, and making it circulate within the boiler for about 12-14 hours.
6. Slow drainage of all the boiler’s water content while gradually introducing freshwater in order to rinse it out thoroughly.

Once this treatment has been completed, the boiler can be turned on, making due reference to the user manual.

2. Post-commissioning inspections

Once activated and in use, the steam boiler needs to be continuously monitored and maintained in order to ensure maximum performance and longer service life.

So what checks and procedures need to be performed to keep it in good working condition?

The boiler’s supply water certainly plays the most important role.

In fact, in order to keep a steam boiler in good working condition, the physical/chemical properties of the water must be constantly monitored.

Although each manufacturer and product has different parameters, in all cases the supply water must be devoid of salts and dissolved gases.

It is therefore extremely important to have an excellent water treatment system and to regularly check the water’s parameters.

In addition to these parameters, it is also necessary to constantly monitor the water’s filling level and pressure.

These values must always remain within the operating range specified by the manufacturer, and the proper intervention of the safety devices must be verified in the event of any spikes.

If any significant pressure deviations should occur, request technical support in order to promptly identify the causes and avoid possible damage.

3. Downtime

During the course of the boiler’s service life, there will often be times when the demand for steam decreases for shorter or longer periods, and the boiler’s use is no longer required.

If this should occur, it should be kept in mind that the most serious corrosion typically occurs precisely during downtime.

For this reason, specific measures must be taken in order to prevent corrosion from occurring during downtime.

Wet or dry storage must be selected based on the expected duration of the downtime.

Wet storage is naturally used in cases where the downtime is brief (maximum a few days), or in cases where the boiler is used as a backup and must be able to be activated quickly, while dry storage is used for the more extended downtime.

a. Wet storage

The steps for the proper wet storage of the boiler are as follows:

1. Drainage of the water and thorough internal cleaning;
2. Filling of the boiler body up to normal operating level;
3. Brief activation and liquid evaporation phase;
4. Blowdown of the steam produced into the atmosphere, thus eliminating the dissolved gases;
5. Complete filling of the boiler and introduction of DEHA (diethyl hydroxylamine) until a residual concentration of 100 ppm is reached, thus preventing the corrosive effect of the dissolved oxygen. ;
6. Closure of all connections, making sure there are no leaks;
7. Performance of alkalinity checks at regular intervals to make sure there are no alterations.

a. Dry storage

Dry storage, on the other hand, is easier.

It’s achieved by emptying the boiler and drying it out thoroughly.

Once dried, the procedure is completed by applying hygroscopic substances (i.e. with high water absorption capacity).

Substances often utilized include quicklime and silica gel.

4. Maintenance for a Steam Boiler

Having seen what needs to be kept in mind during installation, use, and downtime, we now come to maintenance.

Good maintenance plays a fundamental role in maintaining high performance and maintaining the initial values indicated by the manufacturer.

Steam boiler maintenance operations are generally classified as follows:

1. Periodic;
2. Ordinary;
3. Extraordinary.

Let’s examine the most important operations covered by each type, in order.

a. Periodic Maintenance

Let’s start with periodic maintenance, which is even mandated by law in order to ensure the safety and durability of the equipment, and must only be entrusted to professionally qualified personnel.

These are the main operations to be carried out:

1. Periodic blowdown (level indicators, probe holder cylinder if present, boiler) to avoid sludge build-up;
2. Check the efficiency of the adjustment and control instruments by carefully inspecting their electrical parts, connections, and mechanical parts (pressure switches) (It is recommended to change the ceramic probe holders every year);
3. Carry out burner maintenance (according to the relevant instructions);
4. Check the tightness of the bolts on the flanges and the wear status of the seals/gaskets;
5. Check the status of the doors’ internal coating;
6. Clean the tube bundle and the turbulators;
7. Perform proper pump maintenance (bearings, mechanical seal);
8. Check the wear status of the drain valves and replace them if necessary.

b. Ordinary Maintenance

Like with periodic maintenance, the ordinary maintenance checks are also to be performed periodically.

Let’s examine them in greater detail:

1. Clean the ventilation and/or grilles and filters of the air conditioner (if present) at appropriate intervals, based on the cleanliness of the room;
2. Every 2-3 months, check whether there are dust deposits inside the electrical panel, and eliminate any deposits with a vacuum cleaner and/or compressed air;
3. Every 6 months, check the tightness of the connections to the internal components, paying particular attention to the power circuits;
4. Every 6 months, check the tightness of the connections to the control/safety devices used, including any junction boxes;
5. Once a year, check the proper grounding of the control panel, boiler, and the plant room equipotential connection;
6. Every 6 months, check the status of the safety devices (probes and pressure switches);
7. Every 6 months, check that the pump and burner control circuits are still in their original conditions.

Even if you have qualified personnel, it is nevertheless recommended to request an inspection by a service centre technician every 6 months.
This is to carry out a general check on all the parts and to keep the steam boiler in good condition.

c. Extraordinary Maintenance

In addition to periodic and ordinary maintenance, there’s also extraordinary maintenance.

Extraordinary maintenance is periodically carried out on each boiler based on the application, the hours of use, the supply water, and the fuel used.

For this type of maintenance, the boiler is completely stopped and emptied and is visually inspected.

The inspection must also be performed on the internal parts, with particular attention being paid to those under pressure.

Before starting the internal inspection, a check must always be performed to ensure that all the valves that can introduce steam or water into the boiler are closed.

The internal visual inspection must include checks for scale build-ups and corrosion, which can damage the boiler body.

Any areas in which deposits or scale are encountered must be thoroughly scraped and cleaned with wire brushes until the “bare” metal is exposed.

Thickness tests must be subsequently carried out, with appropriate instruments being used to check that the thickness of the internal parts has not been compromised by corrosion.

While visually inspecting the interior, it is recommended to check for any visible leaks around the welds.

If any leaks are encountered, contact the manufacturer immediately, as the boiler is a pressurized machine and must be treated and welded in compliance with the current standards.

Extraordinary maintenance is completed by inspecting all the safety accessories: the safety valve, safety level switches, and safety pressure switches.

Conclusions

As we have seen, various measures and procedures must be carried out in order to keep your steam boiler operating efficiently.

From those to be carried out prior to use, like the boil-out procedure, to all the checks and measures required during use and downtime.

Without forgetting the maintenance, which, together with the supply water, plays a decisive role in maintaining the boiler’s performance and extending its service life.

“Men sana in corpore sano” — Juvenal (Satires, X, 356)