1 valve failure reason and the necessity of surface inspection diesel engine valve in the service process, can cause downtime because of failure, cause economic losses. Diesel engine valve failure reason mainly has the following three aspects: first, because of being hit by piston valve cannot be reset and touch off; Second, the body material adverse (raw materials Such as surface crack, inclusion, etc. ) , cause the defects in the manufacturing process ( Such as forging crack, machining mark caused by stress concentration and micro cracks formed in service) ； Third, the body is affected by the high temperature air thermal stress and stress corrosion produce micro cracks. Data show that the inlet and exhaust valve broken or loss serious, occurred off the fragments of the valve and cylinder head and the piston top combustion phenomena, sometimes in the exhaust pipe destroyed turbochargers and other major accidents, these accidents both affect the safe operation, and cause huge economic losses. According to the analysis, the crack is from the edge to the center of development, because the valve sealing surface surfacing welding heat resistant cemented carbide, band on this split out the slit, only after the band is due to air Industrial Valves material heat-resisting ability is lower than the surfacing material has the width of crack, and to the center of development, crack more hasten is narrow. When the crack on the curved edge direction development, soon dropped pieces. To prevent accidents, avoid unnecessary loss, should be in every time long, overhaul period, on the surface of the Industrial Valves to conduct a comprehensive inspection, including the macroscopic inspection and surface inspection etc. The surface crack, generally USES the dye penetrant inspection and magnetic particle testing, this two kinds of methods for detecting the shape of the different, have their own characteristics and limitations in the application. Before test only USES the dye penetrant inspection of valve surface macro check, or only but so easy to cause residual. To accurately detect air valve surface defects, the author try to use the combination of dye penetrant inspection and magnetic particle testing technology to detect air valve to obtain good effect. 2 testing process is generally selected dye penetrant flaw detection portable pressure tank penetrant testing, magnetic particle inspection general selection of portable magnetic yoke magnetic particle inspection machine. Considering the need to use the magnetic suspension magnetic powder flaw detection, cleaning trapped must, when the valve is used to detect the surface so that do penetrant inspection arrangement first, then do the magnetic particle inspection. 2. A dye penetrant flaw detection using solvent cleaning penetrant inspection agent, the general steps are: pre-cleaning & rarr; Penetration & rarr; Solvent cleaning & rarr; Development & rarr; Observation. Testing parts of the surface condition to a great extent, affects the quality of the dye penetrant testing, therefore must beforehand when cleaning should pay special attention to thoroughly remove obstruction of oil, carbon deposit of penetrant depth, scale and other attached objects. Attachments and residual defects in the grease and moisture, soaked the valve is the chemical method of processing. After the removal of contaminants, use detergent to clean the body, after being dry spray penetrating agent and keep wet state 15 ~ 30 min, humidity control in 15 ~ 50 ℃. Infiltration with dry cloth or toilet paper to wipe excess penetrant, next reoccupy dips in with cleaner cloth or scrubbing toilet paper in one direction, and cannot be used directly spray cleaning detergent spray cans to surface. Brush try to disable the cotton waste, because of the filaments debris easy to stay on the surface, not easy to remove, display form when, according to the pseudo affect testing result. Solvent penetrant inspection shows agent for fast dry as agent. Before spraying, developer spray cans to fully shake, spray equably on checked the developer surface. When spraying distance control in 300 ~ 400 mm, and checked surface spray cans Angle into 30 ~ 40 & deg; Advisable, adopts the scanning method, spraying to uniform and thin, with just cover area tested was advisable. After spraying developer 7 min to observe, defective parts red marks can be shown, this is due to capillary action principle, white appears as agent will air valve open defect into the surface of the red penetrating agent adsorption, show the shape of real defects contour traces. 2. 2 magnetic powder detection by the dye penetrant inspection of air valve, a cloth to wipe clean, can use a portable magnetic particle inspection machine magnetization on the surface of the valve. In order to ensure the sensitivity of magnetic particle inspection, generally choose A30/100 type specimens, the specimens are placed in the edge of the detection range, grooving facing checked surface, place a specimen from a certain distance. Specimens to make contact with the surface being checked is good, can use transparent adhesive tape to stick it is flat and level in were found on the surface, and pay attention to the adhesive tape can not cover the artificial defects on the specimens. Magnetized to pay attention to the direction of walking yoke and the position of the magnetic suspension, were found in each area should be at least two independent test, the two should roughly perpendicular lines of magnetic force direction detection, magnetized area every time should be 15 mm overlap, so that can be found that the longitudinal and transverse ( Circumferential) Surface and near surface defects, and to prevent undetection, improve the defect detection rate.
If you have a os&y valve business, be sure to choose a from Shenzhen Mech Valve Trading Co., Ltd.. After all, you need quality equipment in order to provide your customers with quality service.
Shenzhen Mech Valve Trading Co., Ltd., to be the world leader in products, services and solutions that enable and transform the way consumers and businesses gather, manage, distribute and communicate information.
resilient seated gate valve provider at Mech Valve offers a wide variety of in many options. quality is absolutely ensured if you choose us. welcome to visit our factory.