Pipe fittings are used to connect pipes. There are different varieties of pipe fittings made of various materials and available in various shapes and sizes. Pipe adapters, couplings, elbows, tees, sleeves, flanges, bulkhead fittings, reducers, valves etc. are all different types of pipe fittings.
Pipe fittings are identified by their material of construction, inner and outer diameter of the pipe, and the type of fitting whether threaded or slip, male or female.
The elbow is a short length of pipe having a 90-degree bend. Elbow allows pipes to be connected securely at both ends, providing a clean turn.
No. The noticeable line is not a crack. This you can test by trying to open the crack. If you are unable to open it up by pulling on the part then that is knit-line which is an intrinsic part of the injection-molding process. A knit-line will not impact the integrity of the pipe fitting.
Material, Size, Temperature and Pressure Ratings, Durability, Standards etc.
Standards are certain authentication given in reference to manufacture and installation of the product . Some common standards are BSP, NPT, ANSI, ASME etc.