Poor water quality can have a significant impact on the efficiency, productivity and output of the heat treatment process. However, these effects can be very gradual and often go unnoticed. Poor water quality or inconsistent treatment and control can lead to excessive energy and water costs, corrosion of key system components, production downtime and product quality issues from the inadequate heat recovery process.
What signs should maintenance managers watch out for to help detect these effects on their equipment and how can they spot them before they become an operational issue?
Signs your site could benefit from improved water treatment solutions
1. Corrosion of critical system components
The corrosion of system metals and key components is often one of the clearest indicators of poor water quality. Even in the early stages, corrosion can be visible as pits across metallic surfaces and may be accompanied by further progression of rust.
System pH is a contributing factor in corrosion control and should be tightly monitored and controlled within the recommended parameters for the given system and its metallurgy. Monitoring this along with other indices (for example, LSI, Langelier Saturation Index) to determine the scale/corrosion tendencies of the water is key and allows customising water treatment programs to maximise asset life.
If you recognise any sign of corrosion, an inhibitor should be used to protect system metals. The inhibitor selection will vary depending on local water quality and system operational design. It is important to understand that there are many types of corrosion (galvanic/stress/pitting/microbiological induced, etc.) and there is no one-size-fits-all method of combatting its effects. It will take expert water treatment knowledge to identify the type of corrosion present in your system and the appropriate treatment required.
2. Blockages caused by microbiological fouling
Another sign that the water quality is poor can be the growth and build-up of soft, slimy deposits within the system; the root cause of these is generally microbiological. To begin with, observation glasses and flow meters may become stained. A noticeable indicator could be an odour, as some microbes emit unpleasant-smelling gases. Adequate water analysis will reveal the presence of harmful microorganisms. Left untreated, they will lead to system blockages from blocked strainers, filters and pump sets. This will incur costly downtime and repair.
Moreover, they significantly accelerate system corrosion, as microbes’ metabolites are highly acidic.
Factors that encourage biofouling include water temperature, corrosion deposits, calcium carbonate deposits (scale), oxygen and general organic contaminants which provide nutrient sources for microorganisms to feed on.
Increased water viscosity will itself indicate a higher level of key nutrients for the microorganisms to grow, creating a fertile breeding ground leading to the formation of biofilm, where different types of bacteria settle across heat exchange surfaces, distribution pipework and storage tanks.
System pipework with no or reduced water flow, as well as dead legs, are one of the main causes promoting microbiological proliferation and the formation of biofilms.
Try to maintain dissolved solid levels at less than 2000ppm to reduce the concentration of compounds bacteria can feed on and keep water viscosity down.
Ensure regular addition of microbiocides to keep microbiological proliferation under control.
3. Higher energy usage due to reduced heat transfer efficiency across H/E, AC and chillers
When corrosion occurs across re-circulation pumps and heat exchangers, it can significantly impact heat transfer efficiency. If routine maintenance checks are not carried out, operators will notice their energy usage go up long before they recognise the pitting or microbiological-induced corrosion across the system pipework.
Corrosion is not the only cause of reduced energy efficiency. Scale deposition on heat exchange surfaces can lead to a similar effect, driving up operating costs. Established biofilms are even more insulating than scale or rust: a small 0.1 mm layer of biofilm is four times more insulating than an equivalent coating of scale!
Maintain alkalinity levels less than <350ppm to reduce the risk of carbonic acid formation and scale deposition and keep heat exchangers and pump sets operating in optimal conditions.
4. Increased number of unplanned maintenance leading to costly downtime
When a site experiences damage to critical heat treatment equipment and machinery failure, one of the factors that should be investigated is potential water-related causes. Failure may be down to structural damage because of corrosion and scaling or blockages that have caused the process to break down. In some cases, production may have to be halted and the integrity of critical loads may be affected.
Depending on the nature of the failure, different solutions/strategies can be deployed: one of these would include controlling specific water parameters within certain limits (eg. Chloride and Conductivity) to help control the corrosion mechanisms, in conjunction with a robust and tailored water treatment program.
As referenced above, an adequate inhibitor and microbiocides will help prevent the future formation of scale and corrosion and control microbial growth. Proactive corrosion monitoring would further support the overall performance and system condition and can be provided in a number of different ways best suited to fit each application.
The best course of action to prevent equipment failure from happening and to protect production is to incorporate water treatment into a site’s routine planned preventative maintenance (PPM) schedule and include water treatment providers in system design discussions.
Leave your water treatment to us
If you have any doubts about the proficiency of your PPM schedules or are uncertain about how to stay on top of your water treatment before it becomes a problem, we are here to help. VFE’s Service Care servicing plans are tailored to meet individual requirements, meaning we can tailor them to incorporate water quality and characteristic maintenance as necessary.
If treatment is required, we offer a comprehensive range of Water Treatment Solutions and management services, including in-depth technical guidance, all delivered in partnership with one of the world’s leading water treatment solution providers, NCH Chem-Aqua. Through a combination of expertise with chemical treatment — scale, corrosion inhibitors and microbiocides — our specialists will maintain your water quality and your machines, reducing the risk of large scale failures resulting in interruptions to production.
Finally, if water-related issues have already led to machine failure, we can act quickly to repair your equipment and get your production back up and running. Our ServiceCare contracts can be tailored to include emergency call-out support, while our engineers have the skills, training and experience to service any make or model of heat treatment equipment for any industry.
When it comes to site maintenance, it’s easy to feel swamped. Leave your water treatment to us and have the peace of mind that your equipment — and your operations — are in safe hands.
To discuss a ServiceCare contract, or ask about our free, on-site water system health and cleanliness review (with detailed chemistry and microbiological analysis), click the image below and get in touch.