We Super Steel Manufacturing Co.,Ltd(SMC) are amongst the top manufacturers and suppliers for the seamless steel pipe, welded steel pipe, OCTG products and fittings from China. We have been manufacturing and supplying these products to the industry since 1993, and received repeat orders and appreciation from our valued customers.
High quality piping products from approved manufacturers.
In order to continuously improve our offerings to our clients, we have consistently improved and upgraded our manufacturing facility and can hence offer material with stringent requirements.
Over the years, Super Steel Manufacturing Co.,Ltd(SMC) has developed an enviable reputation for project management for the Oil & Gas, Construction, Power Energy, Marine & Offshore, Water Treatment, Exploration & Drilling Services, Pipeline & Petrochemical and other heavy industries.
The many years of experience that we have means that there is always someone who has the ability to carry a project forward.
Always up to date. In this column you can find the steel pipe related articles, including industry trends, product standards and materials, and some technical guidelines.
There is no fixed duration for the passivation treatment of seamless (SMLS) pipes. The process may last from just a few seconds to over an hour, depending on multiple variables. The goal of passivation is to create a dense and stable passive film—mainly composed of chromium-rich oxides—on the steel surface, thereby enhancing corrosion resistance. This is typically achieved in an acidic solution.
Key Factors Affecting Passivation Time
1. Type and Concentration of Passivation Solution
Acid type:
Nitric acid → Fast passivation speed, but toxic and more corrosive.
Citric acid → Environmentally friendly, but requires longer treatment time.
Concentration: Higher concentration generally shortens the required time.
2. Processing Temperature
Higher temperatures accelerate the passivation reaction and reduce processing time.
Excessive temperatures, however, may cause over-passivation or even localized corrosion.
3. Material Characteristics of the Pipe
Chromium content: A higher chromium percentage facilitates quicker and more effective passive film formation.
Surface condition: Clean, polished, or pickled surfaces passivate faster and more uniformly than untreated or contaminated surfaces.
4. Final Application Standards
Industries such as food, pharmaceuticals, and medical equipment typically require stricter passivation standards than general industrial uses, often leading to longer treatment times or multi-step processes.
Typical Passivation Time Ranges
Pickling + Passivation:
Pickling (removing rust/scale): ~6–8 minutes
Passivation (forming passive film): 4–5 seconds to 20+ minutes
Citric Acid Passivation: 20 minutes to 1 hour soaking time
Nitric Acid Passivation: Several minutes to about 10 minutes
Conclusion
The passivation time of SMLS pipes is not a fixed parameter but depends on material composition, solution type and concentration, process temperature, and required standards. In practice, manufacturers usually run small-batch trials to determine the optimal process window, balancing efficiency with product quality.
When purchasing seamless steel pipes with passivation treatment, always request the supplier’s Mill Test Certificate (MTC) to verify compliance with required standards. For example, Super Steel Manufacturing Co., Ltd provides MTCs confirming passivation process details and test results.
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