In liquid processing industries, the need to recover product, clean pipelines, and transition between batches or products is vital for efficiency and profitability. Two common methods for clearing product from lines between batches are flushing and pigging.
While both serve the purpose of clearing product from the lines, they differ significantly in terms of cost, water usage, and operational efficiency. Most significantly, liquid product recovery (also known as “pigging“) recovers product so it can continue to be processed, packed or stored, whereas flushing nearly always results in product being discarded as effluent, or at the least downgraded.
This blog provides a detailed comparison to help businesses determine which method best suits their needs.
1. Cost Comparison
- Flushing: The cost of flushing systems includes the direct expenses related to water consumption, waste disposal, and labour. Since large volumes of water or cleaning agents are often required to flush out product residue, this results in high water bills and additional costs for treating and disposing of wastewater. If hot flushes are used, the energy use can be significant. Flushing nearly always leads to substantial product loss, which translates to lost revenue.
- Pigging: Pigging systems offer a high return on investment. While the initial setup costs may be higher than for a flushing system, the savings from product recovery, reduced water use, faster changeovers and lower cleaning agent costs quickly offset these expenses. Additionally, pigging systems can be automated, lowering labour costs and making the process more efficient in the long run.
Conclusion: Pigging systems generally provide more significant cost savings over time due to higher product recovery and lower operational costs.
2. water usage
- Flushing: One of the major downsides of flushing is the excessive water consumption. Depending on the length and diameter of the pipelines, flushing can require thousands of litres of water to clear product. This not only increases operational costs but also impacts environmental sustainability, as the effluent created needs to be treated, transported, stored and disposed of. Because of the high volumes of water used, it is particularly inappropriate for use in regions facing water scarcity.
- Pigging: Pigging uses minimal or no water. The pig (a projectile that travels through the pipeline) recovers most of the product, cleaning the line without the need for large amounts of water. In some cases, a small amount of water or cleaning solution may be used afterward for final sanitation, but the overall water usage is significantly reduced compared to flushing.
Conclusion: Pigging is far more water-efficient, making it the better choice for companies looking to reduce water consumption and improve sustainability.
3. product recovery
- Flushing: Flushing systems typically result in substantial product loss. The water or cleaning agents used to flush pipelines inevitably mix with the product, making it unrecoverable and leading to disposal. This is especially problematic when dealing with high-value or sensitive products, as the waste impacts profitability.
- Pigging: Pigging systems recover up to 99.5% of product from the full pipelines. The pig efficiently pushes the residual product through the line, allowing it to be collected for further processing, packaging, or sale. This significantly reduces product wastage, increases yields, and enhances overall profitability.
Conclusion: Pigging is the clear winner in terms of product recovery, making it ideal for businesses where maximizing yield and reducing waste is a priority.
4. efficiency and time savings
- Flushing: Flushing can be a time-consuming process. The need to flush large volumes of water through the pipeline, followed by the disposal and treatment of wastewater, can lead to extended downtime between product runs. This limits production flexibility and reduces overall efficiency, especially when frequent product changeovers are required.
- Pigging: Pigging systems dramatically speed up changeover times. Since most of the product is recovered and the pipeline is left nearly clean after pigging, the need for additional cleaning steps is minimized. This means faster transitions between batches, leading to reduced downtime and increased production capacity.
Conclusion: Pigging systems are far more efficient, enabling faster batch changeovers and improving overall production line efficiency.
5. environmental impact
- Flushing: The large volumes of water required for flushing contribute to significant environmental impacts, including high water usage, wastewater generation, and the need for chemical treatments. Often the effluent created may need transporting for treatment or disposal via road. This makes flushing less sustainable, especially for companies looking to reduce their ecological footprint.
- Pigging: By minimizing water usage, reducing product waste, lowering the need for chemical cleaning agents, and decreasing energy usage, pigging systems contribute to a more sustainable operation. Companies adopting pigging will reduce their environmental impact and meet regulatory or corporate sustainability goals more easily.
Conclusion: Pigging is the more environmentally sustainable option, particularly in industries where water conservation and waste reduction are priorities.
6. labour and maintenance
- Flushing: Flushing processes typically require more manual intervention, both in terms of operating the system and in post-flush cleaning and maintenance. Additionally, the labour-intensive disposal of wastewater can further increase operational costs and introduce potential risks for human error.
- Pigging: Pigging systems are usually fully automated, which reduces the need for manual labour. With less reliance on human intervention, pigging systems also reduce the risk of errors and improve workplace safety. Maintenance requirements are generally low, as pigging systems are designed to be durable and efficient over long periods of use.
Conclusion: Pigging systems offer lower labour costs and reduce the risk of manual errors, making them safer and more efficient to operate.
7. versatility and flexibility
- Flushing: Flushing works for basic cleaning but often struggles with more complex, viscous, or high-value liquids. It also limits a plant’s ability to handle different products on the same line without risking contamination or product mixing.
- Pigging: Pigging systems provide greater flexibility, allowing businesses to process multiple products on the same line without cross-contamination. This is especially important for industries such as food, cosmetics, or pharmaceuticals, where hygiene and product integrity are critical. Pigging is also highly effective for viscous products, such as honey, syrups, sauces, and creams, that are difficult to flush.
Conclusion: Pigging systems offer superior versatility for plants handling multiple products or working with high-viscosity liquids.
Is Pigging Right for Your Business?
When considering whether to switch from flushing to pigging, ask yourself the following questions:
- What is the value of the product you are losing?
- If your process involves high-value liquids or ingredients, pigging will significantly reduce product loss and boost profitability.
- How much water do you currently use in your cleaning process?
- If water consumption is high, or you’re looking to cut down on environmental impacts, pigging will dramatically lower your water use.
- How much downtime do you experience between batches?
- If batch changeovers take a long time, pigging can reduce that time by up to 90%, improving production efficiency.
- Is sustainability important to your company?
- Pigging systems help reduce waste, water use, and the need for cleaning chemicals, making your operation more environmentally friendly.
- Are you facing challenges with cross-contamination or product quality?
- Pigging systems prevent contamination between different product batches and ensure consistent quality by efficiently clearing pipelines.
- What are your long-term cost goals?
- While pigging may require a higher initial investment, it offers long-term savings in product recovery, reduced waste, lower water usage, and faster changeovers.
Conclusion: Pigging Outperforms Flushing in Most Key Areas
It’s important to note that Pigging doesn’t always eliminate the need for flushing, but it will significantly reduce it. When comparing the two methods, pigging systems clearly offer superior efficiency, product recovery, sustainability, and cost-effectiveness.
While flushing may seem like the cheaper option upfront, pigging delivers long-term savings and benefits that are hard to ignore, making it the better solution for businesses focused on maximizing yield, improving efficiency, and reducing their environmental impact.
If you process liquids, contact the product recovery experts today!