I. Project Background
A chemical company in Chongqing (name withheld to protect privacy) primarily produces adhesives for wood-based panels, with formaldehyde as its core raw material. The anti-corrosion coating on the inner walls of the existing carbon steel storage tanks had deteriorated, posing a safety hazard. Coinciding with the imminent implementation of the mandatory safety standard *Safety Management Specifications for Atmospheric Pressure Storage Tank Areas of Flammable Liquids in Chemical Enterprises* (AQ 3063-2025) issued by the Ministry of Emergency Management, the company decided to replace the tanks with 304 stainless steel tanks, thereby resolving both safety and compliance issues in one go.
The company’s existing carbon steel storage tanks had been in use for many years, with localized damage to the inner wall coating. Prolonged exposure of the carbon steel substrate to formaldehyde had accelerated corrosion, resulting in thinner tank walls. If not replaced promptly, there was a risk of leakage under high-temperature conditions during the summer. After conducting extensive research, the company’s technical director ultimately selected Heigu Tianfu as the equipment supplier for three reasons: first, we have an excellent industry reputation in the Southwest region; second, we can provide a complete set of compliance documentation; and third, we possess on-site survey and custom design capabilities, ensuring that the storage tanks integrate seamlessly with the existing piping system.
II. Equipment Configuration and Technical Specifications
| Parameters | Configuration |
|---|---|
| Media | 37% Formaldehyde Aqueous Solution |
| Material | 304 stainless steel (parts in contact with the product); original manufacturer's material certificate provided |
| Structure | Upright, supported by legs |
| Inner surface | Pickling and Passivation Treatment |
| Welding Processes | Automatic TIG welding, resulting in a smooth, even weld |
| Operating Temperature | Room temperature (0–25°C) |
| Work-related stress | Atmospheric pressure |
| Safety Accessories | Temperature sensors, magnetic float level gauges, vent valves, lightning protection grounding, static dissipation grounding |
| Tank Farm Support Facilities | Firebreak/Coffer Dam Design, Toxic Gas Detectors |
| Compliance Documents | Material Certificates, Welding Records, Pickling and Passivation Reports, Pressure Test Reports |
III. Key Points for Safety and Compliance Design
Formaldehyde is a flammable, toxic, and hazardous chemical; improper storage can lead to serious consequences. During the design and manufacturing process, Heigu Tianfu strictly adhered to the new AQ 3063-2025 regulations and implemented the following specialized design measures:
Material Guarantee: 304 stainless steel meets the requirements for resistance to formaldehyde corrosion. However, it should be noted that if the formic acid content in the formaldehyde solution exceeds 0.015% or the temperature exceeds 70°C, the risk of weld corrosion increases significantly. Therefore, this project strictly controls the formic acid content in the raw materials and performs acid washing and passivation on the welds to eliminate the risk of stress corrosion.
Temperature Monitoring: Equipped with a PT100 temperature sensor to monitor the temperature inside the tank in real time and trigger an automatic alarm if the temperature exceeds the limit.
Liquid Level Monitoring: Magnetic flip-plate level gauge + remote signal transmission, allowing real-time monitoring from the central control room.
Lightning Protection and Electrostatic Discharge Protection: A complete grounding system that complies with code requirements.
Breather Valve + Nitrogen Sealing: Reduce formaldehyde off-gassing and lower VOC emissions.
Coffer Dam Design: Install a fire wall in accordance with GB 50351 to ensure that leaks do not spread.
Toxic Gas Detection: Formaldehyde detectors have been installed in the tank farm for 24-hour monitoring.
IV. 304 vs. Carbon Steel: Selection Comparison and Life-Cycle Cost Analysis
During the tank selection phase, the customer was torn between carbon steel and 304 stainless steel. Heigu Tianfu provided a detailed life-cycle cost (LCC) comparison analysis to help the customer make an informed decision:
| Dimensions of Comparison | Carbon Steel Storage Tanks + Anti-Corrosion Coating | 304 Stainless Steel Storage Tank |
|---|---|---|
| Initial Investment | Lower (approximately 60%–70%) | Higher (Benchmark 100%) |
| Corrosion Prevention Maintenance Intervals | Repainting is required every 3–5 years | No preservative maintenance required |
| Service Life | 10–15 years | 20–30 years |
| Risk of Coating Damage | High (coating degradation, physical damage) | No coating; no risk of peeling |
| Impact on Product Quality | Discoloration of the product caused by the leaching of iron ions | No metal ions leach out, ensuring the purity of the material |
| Losses Due to Production Shutdowns for Maintenance | Production is suspended for about 2–3 weeks every 3–5 years | Virtually maintenance-free |
| Total Cost Over 10 Years | Approx. 120%–140% | Benchmark 100% |
After the comparative analysis described above, the customer ultimately chose the 304 stainless steel solution. The customer commented:“After crunching the numbers, I realized that the option that actually saved me money was the one that seemed more expensive.”
V. Project Review and Client Feedback
The storage tank was officially put into service in May 2026 and has been operating stably for over a month. Below are the actual operating data provided by the customer:
Temperature Control: The temperature inside the tank is maintained within the range of 18–22°C, with no records of over-temperature alarms.
Level Monitoring: The magnetic flip-plate level gauge provides accurate readings, and the remote transmission signals match the display in the central control room.
VOC Emissions: The breathing valves and nitrogen purging system are operating normally, and odors in the tank farm have been significantly reduced.
Safety Inspection: The lightning protection and static electricity grounding systems passed inspection; the formaldehyde detectors did not trigger any alarms.
Weld Inspection: After commissioning, a visual inspection of the welds revealed no abnormalities and no signs of leakage.
Feedback from the client's equipment manager:“Since this storage tank was put into service, it has been operating smoothly, with all metrics within the expected range. Heigu Tianfu also conducts regular follow-up visits, and their level of service gives us great peace of mind. Now that the new regulations have taken effect, we have all the necessary compliance documents ready and are not worried about inspections.”
VI. Why Choose Heigu Tianfu?
Brick-and-mortar factory: A 3,000+ square meter in-house factory; all equipment is manufactured in-house; we do not engage in OEM production.
Localization Services: Based in Chongqing, we serve Sichuan, Guizhou, Yunnan, Shaanxi, and the entire western region, with 24-hour on-site service available in Sichuan and Chongqing.
Highly Skilled: A team with 20 years of industry experience; proven 304 stainless steel welding techniques; smooth, even welds.
Government Endorsement: Listed as a Chongqing technology-based enterprise, with its R&D capabilities and compliance standards officially recognized.
All compliance documents are in order: We provide a full range of documentation—including material certificates, welding records, acid washing and passivation reports, and pressure test reports—to help our customers pass acceptance inspections on the first try.
VII. Introduction to Heigu Tianfu (Chongqing) Intelligent Equipment Co., Ltd.
Heigu Tianfu is a technology-based enterprise that integrates design, manufacturing, and services, and has been listed in the Chongqing Registry of Technology-Based Enterprises. Its main products include: stainless steel storage tanks, multifunctional extraction tanks, essential oil extractors, extraction and concentration units, low-temperature evaporators, bioreactors, chromatography columns, solution preparation tanks, rectification kettles, rectification columns, as well as production lines for fruit wine, fruit vinegar, concentrates, oral liquid production lines, as well as machinery and equipment for cosmetics and other fine chemical industries. With a proprietary factory spanning over 3,000 square meters and a team boasting more than 20 years of industry experience, the company provides end-to-end solutions ranging from process design, custom manufacturing, and equipment production to installation, commissioning, and validation services.
VIII. Related Cases
A pharmaceutical company in Chongqing: Multiple stainless steel storage tanks (GMP-compliant)
A Technology Company in Sichuan: Rice Wine Fermentation Tank (SC Certification)
A Food Company in Guangzhou: Emulsification Tank + Blending Tank + Complete CIP Line (Energy-Saving 25%)
A Plant Extract Company in Southwest China: Essential Oil Extraction Equipment (Recovery Rate: 90%+)
IX. Contact Us
Technical Support: 18758242867 / 19562136132
Website:hegutf.com