Access Plug Flange, LLC. (APF) manufactures inspection ports that are installed on the insulation jacket of insulated pipelines, vessels, tanks, and equipment, allowing inspectors safe and easy access to perform nondestructive testing (NDT) for mechanical integrity purposes and to check for Corrosion Under Insulation (CUI). APF inspection ports are designed to meet process temperatures ranging from -185 to 1200ºF (-120.6 to 648.9ºC). They are available in a wide variety of shapes and sizes. APF inspection ports are weather-tight, reliable, durable, safe and easy to install. Our Products allow you to Match your Inspection Port to your Process Temperature. APF is the pioneer of patented Inspection Port Technologies - 42 years of expertise and product excellence.