I. Introduction
Industrial equipment cleaning is one of the lowest-cost, highest-return maintenance measures in the full lifecycle management of equipment, yet it remains underappreciated in many enterprises. Some managers view cleaning as a "deferrable non-urgent expense," overlooking the hidden costs of escalating energy consumption, declining production capacity, and safety hazards that result from delayed cleaning. According to survey data from the China Industrial Cleaning Association, energy waste caused by equipment scaling accounts for 3%–5% of total industrial energy consumption. Based on national industrial electricity usage, annual losses exceed tens of billions of RMB. Meanwhile, equipment failure and downtime caused by scaling and corrosion result in direct production losses of several billion RMB annually. This article systematically demonstrates the necessity of regular industrial equipment cleaning from three dimensions—energy efficiency, safety, and economics—supported by engineering practice data, to provide decision-making references for enterprises establishing scientific cleaning maintenance systems.
II. Cleaning from an Energy Efficiency Perspective
2.1 Quantitative Impact of Fouling on Heat Transfer Efficiency
Heat exchange equipment is the "barometer" of industrial energy consumption. Fouling forms an insulating layer on heat transfer surfaces, with thermal conductivity typically only 1/10 to 1/50 that of the metal substrate. Taking CaCO₃ scale as an example, its thermal conductivity is approximately 0.5–2.0 W/(m·K), compared to carbon steel at approximately 45 W/(m·K) and stainless steel at approximately 16 W/(m·K). This means that just 1mm of scale can reduce a heat exchanger's overall heat transfer coefficient by 10%–20%. For a shell-and-tube heat exchanger with a 200m² heat exchange area, every 15% decrease in the heat transfer coefficient requires an 18%–22% increase in steam consumption to maintain equivalent heat exchange, resulting in annual steam cost increases of RMB 150,000–250,000. Statistical data from a chemical industry group shows that for its 12 critical heat exchangers left uncleaned for six months, total steam consumption increased by approximately 24% year-over-year, equivalent to an annual cost increase exceeding RMB 2 million.
2.2 Energy Loss Data by Equipment Type
The energy losses from fouling vary significantly across different equipment types. The following table compares measured data:
| Equipment Type | Typical Scale Thickness | Energy Increase | Annual Loss Estimate (per unit) |
|---|---|---|---|
| Shell-and-Tube Heat Exchanger | 1.5–2.5mm | Steam consumption +18%–25% | RMB 150,000–250,000 |
| Industrial Boiler | 2–5mm | Fuel consumption +5%–10% | RMB 200,000–500,000 |
| Power Plant Condenser | 0.3–1.0mm | Coal consumption +3–8g/kWh | Several million RMB (300MW unit) |
| Water Chiller | 0.5–1.5mm | Power consumption +10%–20% | RMB 50,000–150,000 |
| Air Cooler | Fin dust accumulation | Fan power +15%–30% | RMB 30,000–80,000 |
III. Cleaning from a Safety Perspective
3.1 Under-Deposit Corrosion: The Hidden Killer of Equipment Safety
Fouling is not only an efficiency and energy concern but also a significant safety hazard. When scale forms unevenly on metal surfaces, it creates an oxygen concentration cell effect—the area beneath the deposit (low oxygen) becomes the anode, while the exposed area (high oxygen) becomes the cathode, accelerating corrosion under the deposit. This "under-deposit corrosion" is one of the primary causes of perforation and leakage in industrial equipment, with corrosion rates 5–10 times higher than uniform corrosion. The localized corrosion rate of carbon steel equipment beneath CaCO₃ deposits can reach 0.5–2.0 mm/year. At one steel enterprise, a waste heat boiler that had not been cleaned for an extended period suffered severe under-deposit corrosion and tube perforation, leading to a high-pressure steam leak that forced an emergency shutdown. The direct production loss exceeded RMB 3 million.
3.2 Boiler Coking and Overheating Risks
Scaling on the water side of boilers is one of the most hazardous operating conditions. Scale has extremely low thermal conductivity. When scale thickness exceeds 3mm, furnace tube wall temperatures can rise from the designed 350–400°C to above 550°C, approaching the creep temperature range of carbon steel. Prolonged high-temperature operation causes metallurgical degradation and strength reduction, potentially leading to tube rupture incidents. According to the Boiler Safety Technical Supervision Regulations, industrial boiler heating surfaces with scale thickness exceeding 1.5mm should be scheduled for chemical cleaning. At one chemical plant, a 10t/h steam boiler developed localized overheating and bulging due to excessive scale. Fortunately, the damaged tubes were discovered during a routine inspection and replaced in time, averting a potential explosion.
3.3 Pipe Blockage and System Overpressure
Scaling in process piping and circulating water lines not only reduces flow capacity but also increases system resistance and pump discharge pressure. In severe blockages, pumps may operate near the shut-off point, causing mechanical damage or pipe rupture. Tube-side blockage in heat exchangers can also cause tubes to tear at the tubesheet joints due to uneven thermal expansion. Regular cleaning enables early detection of wall thinning, weld cracks, and other incipient defects, allowing preventive repairs before accidents occur.
IV. Cleaning from an Economic Perspective
4.1 ROI Analysis
Industrial equipment cleaning is a high-return preventive maintenance investment. An economic analysis for a shell-and-tube heat exchanger with a 150m² heat exchange area at a chemical enterprise yields the following: chemical cleaning costs approximately RMB 12,000–18,000 (including chemicals, labor, and inspection); annual steam savings after cleaning of approximately 120–180 tons, equivalent to RMB 24,000–36,000 at a steam unit price of RMB 200/ton; equipment life extension of 3–5 years, reducing annual depreciation by approximately RMB 8,000–12,000; and 1–2 fewer unplanned shutdowns per year, avoiding production losses of approximately RMB 50,000–100,000. Overall, the cleaning investment payback period is approximately 3–5 months, with a cumulative 3-year net benefit of RMB 150,000–250,000, representing an ROI exceeding 1:8.
4.2 Life Cycle Cost Perspective
From the equipment life cycle cost (LCC) perspective, the procurement cost of a heat exchanger (approximately RMB 150,000–300,000) accounts for only 10%–15% of its 20-year total lifecycle cost, while operating energy costs account for 60%–70% and maintenance costs for 15%–20%. Regular cleaning optimizes LCC far more effectively than any price negotiation during the initial procurement phase by reducing operating energy consumption and extending equipment life. Establishing a "preventive cleaning + periodic inspection" maintenance regime can reduce overall equipment operating costs by 20%–35%.
4.3 Product Quality Assurance
In industries with stringent product quality requirements—such as chemical, pharmaceutical, and food processing—scale and corrosion products on equipment interior walls may detach and contaminate products, leading to batch rejection and waste. One pharmaceutical enterprise experienced rust scale shedding from a reactor jacket that contaminated three batches of API worth approximately RMB 800,000, along with non-conformance findings during a customer quality audit. Regular cleaning and passivation are fundamental conditions for ensuring product purity and GMP compliance.
V. Establishing a Scientific Cleaning Maintenance System
Given the significant impact of cleaning on energy efficiency, safety, and economic returns, industrial enterprises are advised to establish a systematic cleaning maintenance regime. First, create a "cleaning file" for all critical heat exchange equipment in the plant, recording scaling rates, cleaning intervals, chemical formulations, and performance data for each unit. Second, develop differentiated cleaning schedules based on water quality and process conditions: circulating water system heat exchangers should be cleaned every 6–12 months; boilers should be cleaned based on water quality (when scale thickness exceeds 1.5mm); and process-side cleaning should be dynamically adjusted based on pressure drop and heat transfer efficiency trends. Finally, implement a dual-track system of "annual deep cleaning + quarterly online maintenance"—comprehensive chemical cleaning and mechanical descaling during annual shutdown overhauls, with low-concentration online circulation cleaning maintenance every quarter during operation to maintain optimal equipment conditions. For high-risk equipment (high-temperature, high-pressure boilers, toxic media heat exchangers, etc.), cleaning intervals should be appropriately shortened and online monitoring instruments should be installed to track scaling trends in real time.
VI. Conclusion
Industrial equipment cleaning is not an "optional" auxiliary task but a core management function that directly determines an enterprise's energy consumption level, operational safety, and equipment asset return rate. From 1mm of scale causing a 15% energy consumption increase in heat exchangers to boiler scale triggering tube rupture risks, from hundreds of billions of RMB in annual energy waste to an ROI of 1:8 from cleaning a single piece of equipment—the data clearly demonstrate that regular cleaning is one of the most worthwhile maintenance strategies an enterprise can invest in. Under the current "dual carbon" goals, industrial energy conservation has elevated from a financial calculation to a policy compliance requirement, and equipment cleaning—as the lowest-cost, fastest-acting energy-saving measure—will see its strategic value further highlighted. We recommend that enterprise managers shift equipment cleaning from a "reactive repair" model to a "proactive prevention" model, viewing cleaning expenses as energy-saving investments rather than cost expenditures, and achieving the triple objectives of safety, energy efficiency, and enhanced returns through scientific cleaning maintenance systems.