Socket weld elbow is also welded to the pipe and fittings end. Unlike the butt weld elbow, the socket weld elbow has a trapezoidal area at the end. We can insert the pipe end into this area (the diameter of the SW elbow is matched with the outer diameter of the pipe), then do welding work to connect them together. Therefore, the actual diameter of the SW elbow end is greater than the elbow diameter.http://www.zhijusteel.com/elbow/90-degree-elbow/

Knowing the density of the alloy is important as the manufacturer needs to know how much it will shrink or expand. If the metal shrinks too much, it may not create the proper bond with other materials, or have the required strength it needs to withstand stresses. If it expands too much, it can become brittle when changing back into a solid as the alloy might fail during the operation of the product or equipment.http://www.wocmetal.com/low-melting-alloys/

Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer.http://www.sxcanreal.com/hvac-vent/

They are customizable – Manual toothbrushes have almost a limitless variation. They are obtainable in a wide range of head sizes: small, medium, and large sizes, and several have a convenient tongue cleaner on the back. They are also available in different grips, angles, lengths, and bristle stiffness, i.e. soft, medium, or hard. They also come in limitless color variations.http://www.sjzwlplastic.com/manual-toothbrush/

Most strings in an acoustic piano are grouped in threes, with each group tuned to the same note. When played normally, the hammer strikes all three at the same time giving a full, bright sound. On a grand piano, the una corda pedal shifts the entire mechanism to the right, so the hammer only hits two of the three strings.http://www.sihaimetal.com/piano-pedal/