Don't know the quality of api 600 gate valve, cast iron ball valve, 4 check valve cast iron in your hand? Inspection, smelling, palpation these three methods can help you identify.
1.Visual Inspection for Defects
'Inspection', is to capture the details of the cast iron ball valve with your eyes. Strong flashlight to 45 ° oblique illumination of the valve body, trachoma 'crater' like depression will be in the light and shadow nothing to hide, especially the flange neck and the valve body at the junction of the need to focus on; moulding line flatness, only need to scrape the fingernails horizontally, the smoothness of high-quality casting and poor quality pieces of the card will be clear at a glance. Cast steel valves around the sealing surface of the oxide skin colour is also hidden mystery, grey and black is the normal state, rainbow or rust red is exposed to heat treatment defects. Stainless steel valves by pickling paste test, 304 and 316 material will show a different colour reaction, become the key to identify the material.
2.Auditory Assessment of Internal Quality
'Smelling', through the sound to determine the intrinsic quality. Tap the cast iron ball valve body with a copper rod, quality castings issued a crisp and long 'ting --' sound, poor quality castings are dull 'poof' sound. For large calibre valves, knocking four key aspects of the contrast sound, can let the shrinkage of loose and other problems nowhere to hide.
3.Tactile Examination for Surface and Material Integrity
'Palpation', is to rely on tactile perception. Reach out and touch the valve cavity runner, subtle longitudinal brushed grain is the mark of quality castings, granularity implies that the sand refractoriness is not good. Hands weighing the same specification valves, too light or too heavy may conceal the hidden material theft, mixed with recycled materials.
4.Additional Identification Techniques
In addition, the old workers have cigarette test method, oil immersion method and other unique skills. Cigarette paper pasted on the suspected parts of the haze, the wetting speed to reflect the denseness; paraffin smeared sealing surface, oil oozing that indicates the existence of penetrating defects. The cast iron ball valve, body tortoise back pattern, bolt holes whitening, nameplate without steel seal, etc., it is directly judged as unqualified products.