Double waveform guardrail quality testing to analyse the focus of the

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Double waveform beam guardrail quality inspection

Waveform beam guardrail is mainly composed of waveform beam plate, column, block, end, bracket, fasteners and foundation. Its detection project is mainly divided into five parts: firmness, surface quality, external dimensions, raw material performance and corrosion layer quality.

Firmness test. Firmness of the quality of the test method is usually used to feel, mechanical impact to judge. Shake your hand, feel the grain; with a small loader slowly and uniformly push the guardrail, observe the guardrail, the foundation are not obvious deformation and cracks, indicating that the guardrail firmness test qualified; on the contrary, the observation of the guardrail, the foundation has obvious deformation and cracks, then the quality is unqualified.

Surface quality testing. Surface quality testing methods usually through visual inspection, feel to judge, if necessary, available vernier calipers to measure the appearance of defects. Detection of the main content including material properties, appearance quality and processing and moulding requirements of three aspects.

Raw material performance. Requirements for the product being tested must be accompanied by the original base steel quality inspection certificate and factory certificate. Each piece of waveform beam is marked at both ends of the manufacturer, time and other identification.

Appearance quality. The surface of the cold-formed black components of the waveform beam steel guardrail is free of cracks, bubbles, folding, inclusions and end delamination, and is allowed to have a slight bump, indentation, and abrasion that is not greater than 10% of the nominal thickness. Surface defects are allowed to be cleaned up by trimming, and its shaping thickness is not greater than 10% of the nominal thickness, and the shear section and mounting holes are not allowed to have rolled edges and serious burrs. The surface of galvanized components should have a uniform and complete coating, consistent colour, the surface has a practical smooth, not allowed to have flow hanging, drip tumor or excess caking. The surface of the galvanised members shall not be allowed to have defects such as leakage of plating and exposed iron.

Processing and moulding requirements. Waveform beam plate is generally suitable for continuous roll forming. Variable cross-section waveform beam plate using hydraulic cold forming, each plate must be pressed at once to complete, shall not be pressed in sections. Continuous roll forming of equal cross-section waveform beam plate processing into a variable cross-section, should be used for cold forming, can not be processed by stamping.

Outline dimension inspection. Corrugated beam plate. Corrugated beam plate shape, size of the test coefficient mainly has the plate width, plate thickness, outer wave height, inner wave height, screw hole diameter, hole distance and so on.

Anti-corrosion layer quality test. All components of corrugated beam guardrail are generally hot dip galvanised or hot dip aluminium plated for metal surface treatment, in order to ensure its anti-corrosion performance, it needs to be tested in four aspects, such as the amount of zinc plating (aluminium plating) adherence, uniformity of plating, adherence and salt spray resistance.

Galvanised layer quality test.

Galvanised layer adhesion test. Galvanised layer adhesion test can be done by antimony trichloride method or coating thickness gauge. The basic principle of antimony trichloride method: Since zinc can be completely dissolved in the concentrated hydrochloric acid solution of antimony trichloride, the amount of zinc adhesion per unit area is calculated by weighing twice before and after dissolution.

Galvanised layer uniformity test. (1) The uniformity test of galvanised layer generally adopts copper sulphate method. Principle: through the copper sulfate solution leaching specimen replacement of zinc metal monomers out of the time and degree, to determine the uniformity of its galvanisation. Specimen configuration: 36g of chemical copper sulfate dissolved in 100ml distilled water, heated to dissolve and cooled to room temperature, add copper hydroxide or copper carbonate (1g per 1L of copper sulfate solution), stirring and mixing, after standing for more than 24h, filtered clear liquid is the required specimen. Test method: take three specimens for the etching test, each placed in a solution of 18 ℃ plus or minus 2 ℃ static immersion 1min, can not be stirred and move the specimen, the specimen is removed and rinsed with water for the next time after the etching. If the zinc layer is uniform, the specimen is not red by copper sulphate etching five times (not plated with copper). Specimen solution can only be 15 times. Determination of the end point of the etching: after the above test, the specimen appears on the red metal copper for the specimen to reach the end point of the etching, the emergence of metal copper that etching is not counted in the number of times the copper sulphate specimen.

(2) However, to determine the end point of the etching should also pay attention to the following points: First, the attached metal copper with a non-sharp blade scraper to scrape it off, if the copper is still under the metal zinc, not counted as the end point of the etching. Secondly, the red deposition of metallic copper under the bottom surface of the existence of zinc layer doubt, can be scraped off the red deposition of metallic copper, in the place of one to several drops of dilute hydrochloric acid, if the presence of zinc, there is active hydrogen; In addition, can also be used to determine the stability of zinc test: i.e., with a small piece of filter paper or draw a liquid tube to the drop of the acid collected with ammonium hydroxide and neutralisation, so that the weak acidity, hydrogen sulfide through the solution to see whether it is generated white precipitate (hydrogen sulfide). Whether to produce a white precipitate (zinc sulphide) to determine.