Quality appraisal of aerated concrete equipment

aerated concrete equipment is the core equipment for the production of lightweight porous building materials. It achieves large-scale production of energy-saving wall materials through raw material mixing, casting molding, autoclaved curing and other processes. Its typical application scenarios include:

building walls: replacing traditional red bricks and used for frame structure infill walls (such as aerated concrete blocks used in Vanke’s green building projects);

insulation materials: insulation layers of cold storage and granaries (such as a cold chain logistics center using aerated concrete insulation panels);

prefabricated buildings: industrial production of prefabricated wall panels (such as Yuanda Housing PC component production line).

my country's aerated concrete equipment market exceeds 8 billion yuan, and technical standards cover "Autoclaved Aerated Concrete Equipment" (GB/T 17671), "Aerated Concrete Blocks" (GB/T 11968), etc.

0 As a third-party appraisal agency with court registration qualifications, Zhongke Testing can provide full-process appraisal services such as equipment material testing, process parameter verification, and failure mode analysis, providing scientific basis for judicial decisions.

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In the aerated concrete equipment quality dispute case, the judicial dispute focuses on:

1, performance indicator dispute:

Whether the cutting accuracy meets the standard (such as dimensional deviation ≤ ±2mm);

autoclave curing temperature uniformity (±5℃), pressure stability (±0.05MPa);

2, material and process defects:

0 mixing blade material has insufficient corrosion resistance (such as Misuse of 316L stainless steel 304);

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2 The autoclave weld was not fully welded, causing leakage;

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43, control system failure:

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6 Automatic batching system accuracy (±1%), maintenance time control logic loopholes;

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84, contract performance issues:

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0 The delivered equipment does not comply with the technical agreement (such as the German Siemens is not configured PLC system).

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2 Such cases require a combination of material testing, thermodynamic testing and process simulation to determine whether the equipment complies with the contract and national standards.

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Aerated concrete equipment quality identification technical methods include:

1, material performance testing

Metal parts: Spectrometer detects the mixing blade material (such as Cr, Ni content), ultrasonic flaw detection to detect autoclave weld defects;

seals: tensile testing machine to test seal ring elongation at break (≥300%), hot air aging test to evaluate life (≥5 years).

2, process parameter verification

0 cutting accuracy: three-coordinate measurement of block size deviation (standard ≤±2mm), laser rangefinder detection of cutting knife positioning accuracy (±0.5mm);

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2 Autoclave curing: thermocouple real-time monitoring of the temperature field in the kettle (uniformity ±5℃), the pressure sensor records pressure fluctuations (±0.05MPa).

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43, control system evaluation

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6 Automatic batching: weighing sensor calibration error (±0.5%), PID algorithm response time (≤3 seconds);

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8 Data traceability: retrieve PLC logs to verify the consistency of maintenance time, pressure curve and process setting values.

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04, failure mode analysis

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2 Block cracking: Scanning electron microscope (SEM) observes the fracture surface pore structure, energy dispersive spectrometer (EDS) detects raw material ratio (such as Ca/Si ratio deviation);

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4 Autoclave corrosion: X Ray diffraction (XRD) analyzes rust products to assess the risk of chloride ion corrosion (Cl⁻≤0.01%).

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A building materials company of the applicant signed an "Aerated Concrete Production Line Procurement Contract" with an equipment company of the respondent, agreeing to purchase one piece of equipment with an annual output of 200,000 m³. After being put into production, the strength of the blocks was only A3.5 (contract requirement A5.0), and the dimensional deviation exceeded ±5mm, resulting in project returns. The building materials company believed that the equipment had design defects and demanded compensation for losses.

Identification analysis results:

The quality analysis expert group discussed and comprehensively analyzed the relevant information of "aerated concrete equipment", contract technical agreements, on-site investigation case materials and other data, and made the following quality analysis opinions:

The mixing blade material of the aerated concrete equipment involved in the case is 304 stainless steel (316L required by the contract), and the Cr content is only 18% (standard ≥16%), insufficient corrosion resistance; the autoclave weld has incomplete penetration defects, and magnetic particle testing found surface cracks. The automatic batching system had a calibration error of ±3%, and insufficient CaO content resulted in low block strength.

The equipment company failed to provide 316L stainless steel mixing blades and qualified autoclave according to the contract, and the control system parameters were set incorrectly, which constituted a fundamental breach of contract.

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Aerated concrete equipment quality appraisal report should include the following content:

1. The purpose and basis of the appraisal.

2. Model, specification, manufacturer and other information of the equipment being identified.

3. Identification method.

4. Identification results (including whether there are quality problems, causes of problems, etc.).

05. Identification conclusion.

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26. Signature and seal of the appraiser, and official seal of the appraisal institution.

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