Grey P91 LR 90degree Stainless Steel Reducing Elbow ASME Standard

Pipe Elbow Fittings P91 Alloy Steel Elbow LR 90degree

Alloy elbow is a kind of general name of many kinds of elbow, the function is the connection of pipe bend, it is to connect two pipes with the same nominal diameter, so that the pipe can make 90 or other angle turn. It has a variety of materials, alloy elbows are widely used.
Ordinary bronze alloy elbows are more common in general tap water pipes, but with the improvement of living standards, many tap water pipes use stainless steel elbows.
Overview
The alloy elbow of manganese steel material is usually used in concrete conveying pipeline, mud conveying pipeline and so on because manganese steel has excellent performance of bearing impact, extrusion, material wear and so on. High manganese steel alloy bends are used in pipes with strong fluid flow and strong impact. Nickel steel alloy bends are usually used in normal temperature conveying pipes with high concentration of oxidized acid (nitric acid, sulfuric acid), but are severely corroded in conveying pipes with reduced acid (hydrochloric acid, dilute sulfuric acid, etc.) unless the concentration of hydrochloric acid is very low; martensite alloy bends below 650℃ have higher high temperature strength, oxidation resistance and water vapor corrosion resistance, but poor weldability. Therefore, it is often used in high temperature water vapor pipeline, water gas pipeline. Enforcement criteria: GB/T12459-2005,GB/T13401,GB/T10752-1999.

Production methods
Thermal Push Form
The forming process of hot-push elbow is the process of using special elbow pushing machine, core die and heating device to make the blank set on the die move forward under the push of the pushing machine, and be heated, expanded and bent in motion. The deformation characteristic of hot push elbow is to determine the diameter of pipe billet according to the law of constant volume before and after plastic deformation of metal material. The diameter of pipe billet is smaller than the diameter of elbow. Compensate to other parts of the inner arc thinning due to diameter expansion, thus obtaining a uniform wall thickness elbow.
The hot-push elbow forming process has the characteristics of beautiful appearance, uniform wall thickness and continuous operation, which is suitable for mass production, so it has become the main forming method of carbon steel and alloy steel elbows, and has also been applied in the forming of stainless steel elbows of some specifications.
The heating mode of forming process includes intermediate frequency or high frequency induction heating (heating ring can be multi-ring or single ring), flame heating and reflecting furnace heating. The heating mode depends on the requirements of forming product and energy situation.
Stamping formingstamping forming elbow is the earliest forming process used in batch production of seamless elbow. it has been replaced by hot push method or other forming process in the production of elbow of common specifications, but in some specifications of elbow due to less production quantity, too thick wall thickness or too thin.
The product is still in use when it has special requirements. The punching forming of the elbow adopts the pipe billet equal to the outer diameter of the elbow, and the press is used to press the die directly.
Before stamping, the tube billet is placed on the lower die, the inner core and the end die are loaded into the tube billet, the upper die moves down and begins to press, and the elbow is formed by the constraint of the outer die and the support of the inner die.
Compared with the hot push process, the appearance quality of stamping forming is not as good as that of the former, and the outer arc of stamping elbow is in the tensile state when forming, and there is no extra metal in other parts to compensate, so the wall thickness at the outer arc is about 10% thinner. But because it is suitable for single piece production and low cost, stamping elbow process is mostly used in the manufacture of small batch and thick wall elbow.
Stamping elbows are divided into cold stamping and hot stamping, usually according to the material properties and equipment capacity to choose cold stamping or hot stamping.
The forming process of cold extrusion elbow is to use a special elbow forming machine to put the tube billet into the outer die. After the upper and lower die is molded, the tube billet moves along the gap reserved for the inner die and the outer die under the push rod.
The elbow made by internal and external die cold extrusion process is beautiful in appearance, uniform in wall thickness and small in size deviation. The precision of internal and external die used in this process is high, and the deviation of wall thickness of pipe billet is also harsh.