Life Cycle And Critical Maintenance Of Autoclaves

As we all know, autoclaves are widely used in several industries and fall under the critical and risky equipment categories. Autoclaves under pressure are heated in hot air or steam (i.e. wet) conditions. Due to the pressure and temperature, autoclaves are specially designed, manufactured, tested, transported and installed under strict rules and conditions. These conditions are not dictated by manufacturer specific guidelines, but rather governed by international organizations in different regions, countries and juristictions.

There are already well-known world wide required certifications such as CE, ASME, EAC and other country specific markings and certifications. The manufacturers of autoclaves must adhere these rules in every aspect of the design, manufacturing, installation and servicing of the equipment.

It is unfortunate that in some countries the pressure vessel and autoclave manufacturing rules are ignored and not strictly followed and enforced by local authorities. In some cases, customers, knowingly or not, do not pay any attention to the legal aspect of purchasing an autoclave. Those buyers only make their decision based on purchasing cost and do not assess the capability and resources of the manufacturer, and ignore the required certifications provided by well-known organizations such as TUV and Bureau Veritas (although it is also the responsibility of the manufacturer). Another common practice is that customers buy a second-hand autoclave thinking that it will function just the same as a brand new autoclave. Unfortunately, they do not recognize the fact that an autoclave has a certain lifespan to operate safely, and it must follow a thorough inspection process and annual tests.

Considering the frequency of their operations and working conditions, the autoclaves can be subject to fatigue particularly for autoclaves working under steam facing corrosion. These autoclaves must be regularly checked by the well-trained maintenance team of the plant in operation and preferably go through regular periodical check-ups and inspections. Although the autoclaves are designed with significantly high tolerances, regular inspections should still be undertaken by the users.

The lifetime of an autoclave is certainly linked to its frequency of operation cycle and working parameters. In general, ten years is a standard lifetime of an autoclave. However, its life can be extended over 30-35 years in some cases by applying regular maintenance work and inspections. As an example, a steam heat autoclave used for manufacturing rubber hoses operates 50-60 cycles in a day, and the number of cycles must be considered at the design stage of the autoclave. Furthermore, the corrosion, pressure and vacuum process also have a direct impact on the life of the autoclave. Applying vaccum and pressure consistently in each cycle cause extra fatigue for an autoclave. This can be resembled to bending a steel belt back and forth numerous times and eventually there is a risk of breaking the steel belt.

At the design stage, the autoclave design should be simulated using special software tools factoring in real life working conditions. There are good tools such as ANSYS software to perform these simulation studies.

Following the proper design and manufacturing work, the autoclave should also be installed by authorized and qualified technical personnel. The installation should start with the proper levelling of the autoclave and good condensated water discharge. The design and installation drawings must be strictly followed for connection points and piping. The operators and maintenance staff should join the installation phase and take over the autoclave after extensive training. Anything that may be considered as ”unnecessary or not critical” during operating an autoclave may cause enormous safety risks and significantly shorten the lifetime of the autoclave. We witness a lot of cases where the users only look after their autoclaves when they do not work, and they do not regularly inspect them, and hesitate to pay for regular periodical maintenance and tests. The users ignore the fact that they would continue to have a high-value autoclave and use it safely by minimizing downtime risks. The frequency of the periodical maintenance work depends on the number of cycles used, but we recommend that at least once a year maintenance should be in a plant’s maintenance program schedule. The autoclaves heated with steam should be checked for the quality of the steam, and condensated water should be analyzed regularly with the results carefully reviewed and archived. The plants usually prefer to plan their autoclave maintenance work during the factory shut down times and holidays. However, they should not be under pressure to do so especially when it comes to delaying the maintenance work for lack of staff, or the busy schedule of a third party or supplier. Depending on the size of the autoclave and working parameters, periodic maintenance should be planned for a minimum of two days. Qualified in-house service technicians and/or operators, who are familiar with the working logic of the autoclave, or a third party including autoclave manufacturers, should be employed for the job.

In summary, due to pressure and risks involved, the autoclaves are perhaps the most critical equipment in a typical plant, having a direct impact on product quality. Any production problems and delays caused by an autoclave accident or extended repair work would negatively affect the plant. The risks may not become zero but they can be significantly minimized.

Akarmak, with over 30 years of design, manufacturing and service excellence in autoclaves, has extended its periodical maintenance and test programs to its customers in its new projects worldwide. The customers can purchase the maintenance programs as part of purchasing their new autoclaves and the program can be extended further. The maintenance service is provided not only for Akarmak manufactured autoclaves but also for autoclaves sold by other manufacturers. When we engage our customers in maintenance discussions, we always ask them how many times they take their cars for an oil check and other regular maintenance to their local mechanic in a year. We tell them that their hundred thousands EURO value autoclave, which creates risks for all employees at their plants, deserves as much attention as their cars, if not more. When did you get your autoclave inspected last?