Steam Autoclave Components, Maintenance, and Anticipated Replacement Cycles: 3 Common Maintenance Questions

Maintaining steam autoclaves in proper working order improves productivity, reduces downtime, extends the life of the autoclave, and helps to ensure overall safety in the workplace. So to help you maintain your autoclave, we wrote about the importance of autoclave maintenance and shared some basic tips to maintain your equipment in a prior post.

In this post, we take the conversation a little deeper, answering common maintenance questions and identifying the critical components on an autoclave that should be inspected periodically by a trained service provider. This is not an exhaustive list of all the autoclave components that should be inspected but merely the major ones. 

Q.  How Often Should I Inspect My Steam Autoclave?

A.  Planned maintenance inspections that are part of a preventative maintenance (PM) plan typically occur based on elapsed time (i.e., quarterly, annually, etc.).  Although this is generally seen as Good Service Practice (GSP), it may also be worth initiating service inspections based on actual usage—say, every 300 cycles—versus time alone.

For example, you may have an autoclave that runs only once per week and is turned off in between runs. In this case, the unit only sees approximately 50 cycles in one year and may not even require an annual inspection. By contrast, if you have unit that runs 6 cycles/day 5 days/week, then a quarterly inspection is probably best.

Q.  What Contributes the Most to Steam Autoclave Damage?

A.   Aside from usage, environmental factors can significantly impact equipment longevity and frequency by which inspections should occur, including:

Steam & Water Quality

Steam and water quality contribute the most notable impacts. Ensuring that the equipment is fed saturated steam with acceptable dryness and particulate levels is vital.  Particulates can damage valves and cause steam traps to fail prematurely.

Water quality is also critical. Hard water in the form of calcium carbonate can cause scaling of heating elements, plumbing components, and sterilizer surfaces. Scale buildup will decrease the efficiency of the heating elements significantly—causing components to work harder and reducing life expectancy. Chlorides in the water source can be particularly damaging even to high quality stainless steel and can lead to corrosion, pitting, and other damage of the metal.

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Q.   Which Steam Autoclave Components Should I Be Most Aware of When It Comes to Routine Maintenance?

A.    The following steam autoclave components should be carefully monitored:


There are two primary types of automatic valves used: Valves for steam and valves for other applications like air, water and exhaust. Typically the steam valves will wear quicker than other valves.  Steam to jacket valves see the most use as most jackets remain at temperature while awaiting the next sterilization load. Thus the jacket valve is consistently pulsing while maintaining the appropriate temperature/pressure in the jacket. Manual valves like ball valves and needle valves will typically last the life of the stream autoclave.

Heating Coils

Steam autoclave life is highly dependent on incoming water quality and maintenance—particularly water hardness, frequency of blow-downs (draining the generator of water and flushing out deposits), and any descaling procedures performed. With proper boiler maintenance and attention to water quality, heating coils should last five to ten years on average, although decreasing efficiency and performance may be experienced. Depending on water quality, and the number of cycles run, it is recommended to blowdown the generator daily or weekly.


Contactors are basically high amperage electrical relays and are used on sterilizers equipped with electric steam generators and liquid ring pumps. Switching a high voltage connection on and off is a very demanding function and causes significant wear on the contactors. It is vital to ensure that all high voltage wires are periodically tightened as thermal cycling can cause them to loosen over time. Contactors should be regularly inspected and replaced when there are signs of pitting, heat damage, or excessive arcing on the points. The life of the contactors will depend greatly on the amount of use the sterilizer sees.

Steam Traps

Steam traps are heavily dependent on the quality of the steam delivery system and absence of debris. For facility-supplied steam, a steam trap inspection program should extend beyond the sterilizer to include all of the traps back to the boiler. Although various types of traps can be used in a steam delivery system/steam autoclave, they all perform the same function–removing condensate while allowing the passage of dry steam.

Safety Valves

Per the ASME pressure vessel standards, safety valves are calibrated and set to be equal to or less than the maximum allowable working pressure (MAWP) of the chamber and/or jacket, depending on sterilizer manufacturer. The MAWP will be shown on the stamped vessel plate visibly located somewhere on the vessel exterior. This is the final fail-safe device for the pressure vessel should all electronic controls fail. Therefore, it is imperative that the safety valve is inspected, tested and verified to be in proper working condition based on the recommendation of the sterilizer and/or valve manufacturer as well as local inspection and insurance agencies. It is common practice to inspect and test safety valves on a regular basis.


The controls should last the lifetime of the device assuming they are protected from excessive heat, humidity, and electrical noise/surges/spikes. Particularly, PLC controls have proven to be extremely reliable across industries and in various environments. Although devices vary, in most cases the backup battery should be replaced every 3-5 years to avoid loss of memory or programs. The electrical connections should be covered or within an enclosure to avoid direct contact with water, steam (when the door is opened, for instance), or vapor from the drain or other devices in the same area. Items like control screens may be located above the chamber door provided they are adequately protected from heat and excessive moisture. In rare cases where software updates are required, modern controls can typically be updated via laptop software, USB port, or remotely via an internet/Ethernet connection. 

Vacuum pump (Pre-Vacuum Units only)

Vacuum pumps should last the lifetime of the steam autoclave. Hard water can cause a build up to occur within the pump decreasing efficiency and placing greater strain on the motor and impeller. It is possible for the impeller to become nicked by debris that passes through the strainer and the impeller can become imbalanced. Monitor solid goods such as animal bedding that can be drawn through the drain by ensuring that the chamber drain strainer is clean and in good condition. Occasionally, pump bearings will wear depending on usage. If pump maintenance is needed, trained service technicians can often easily clean the pump head and replace worn components.

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To help you and your facility easily remember which common autoclave components to inspect during preventative maintenance, use the table below as your guide:

Table 1            Common Autoclave Components to Inspect During PM’s

Component Comments
Valves (Steam) Steam causes valves to require maintenance more often than air, water or exhaust.
Valves (Air) May not require replacement but should be inspected.
Heating Coils Water quality and ongoing maintenance, including blow-down, can affect longevity.
Steam Traps May not require replacement but should be inspected.
Contactors Replacement will depend greatly on usage.
Safety Valves Replace as recommended by local regulatory authorities; may only require testing or inspection.
Controls When protected from excessive heat and moisture, should last the life of the unit.
Vacuum pump Under normal circumstances and loads should last the life of the unit.
Door Lock Assembly On hinged door autoclaves, check the door locking mechanism. May not require replacement but should be inspected.

At CSS, we offer a list of Preventive Maintenance Plans and PM Parts Pax, and we support full-service steam autoclave maintenance with our expert steam autoclave service and maintenance department—complete with field engineers and technicians.

Contact CSS today to learn more. We have a team of sterilizations experts waiting to help you avoid unnecessary equipment failures, autoclave downtime, and costly repairs.

Protect Your Investment

Preventative and proactive maintenance are the keys to reducing downtime and ensuring the longevity of your autoclave. Read this eBook to learn how to properly maintain your autoclave and develop a comprehensive maintenance plan.

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