Seamless elbow forming method

Seamless elbow forming method

The seamless elbow is a kind of pipe fitting used in the bend of the pipeline. Among all the pipe fittings used in the piping system, it accounts for the largest proportion, about 80%. Usually, different forming processes are selected for elbows of different materials and wall thicknesses. The commonly used seamless elbow forming processes in manufacturing plants include hot pushing, stamping, extrusion, etc.

Classification of seamless elbows

Seamless elbow is also called seamless steel pipe elbow English name seamless elbow or seamless pipe elbow, seamless elbow pipe fittings are divided into hot-rolled (extruded) seamless elbow pipe fittings and cold-drawn (rolled) pipe fittings due to their different manufacturing processes ) Two types of seamless elbow fittings. Cold drawn (rolled) tubes are divided into two types: round tubes and special-shaped tubes.

The raw material for rolling seamless elbow is round tube billet, and the round tube embryo should be cut by cutting machine to grow a billet with a length of about 1 meter, and sent to the furnace by conveyor belt. Billet is fed into the furnace to heat, the temperature is about 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key issue. After the round tube is out of the furnace, it must be pierced through a pressure piercer. Generally, the more common piercer is the cone roll piercer. This kind of piercer has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of pipes. After piercing, the round tube billet is successively cross-rolled, continuous rolled or extruded by three rolls. After extrusion, the tube should be taken off for sizing. The sizing machine uses a conical drill to rotate at a high speed into the steel billet to punch holes to form pipe fittings.

Executive standard: GB/T12459-2017, GB/T13401-2017

Seamless elbow forming method

1. Forging method: Use a swage forging machine to stretch the end or part of the pipe to reduce the outer diameter. Commonly used swage forging machines include rotary type, connecting rod type, and roller type.
2. Rolling method: Generally, no mandrel is used, and it is suitable for the inner round edge of thick-walled tubes. The core is placed inside the tube, and the outer circumference is pushed by rollers for round edge processing.
3. Stamping method: Use a tapered core on the punching machine to expand the pipe end to the required size and shape.
4. Bending forming method: There are three commonly used methods, one method is called stretching method, the other method is called stamping method, and the third roller method has 3-4 rollers, two fixed rollers, and one adjustment roller. With a fixed roll gap, the finished pipe is bent.
5. Bulging method: one is to place rubber in the tube, and compress it with a punch to make the tube protrude; the other method is hydraulic bulging, filling the middle of the tube with liquid, and the pressure of the liquid bulges the tube into the desired shape. Shape, most of the production of corrugated pipes use this method.

Seamless elbow manufacturing process

Seamless elbows will not corrode, pit, rust or wear. Stainless steel is also one of the strongest materials among architectural metal materials. Because stainless steel has good corrosion resistance, it allows structural components to permanently maintain the integrity of the engineering design. The raw material for rolling seamless elbow pipe fittings is a round tube billet. The round tube billet is cut by a cutting machine into a billet with a length of about one meter, and sent to the furnace for heating by a conveyor belt. The billet is sent into the furnace for heating. The temperature is about 1200 degrees Celsius. The temperature control in the furnace is a key issue. After the round tube is out of the furnace, it must be pierced through a pressure piercer. The fuel is hydrogen or acetylene.
Generally, the more common piercing machine is the cone roll piercing machine. This piercing machine has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of pipe fittings. , Continuous rolling or extrusion. After extrusion, the tube should be taken off for sizing. The sizing machine rotates the conical drill at high speed into the billet to punch holes to form pipe fittings.

Summary of the advantages of seamless elbows

The seamless elbow has the following advantages: hygienic and non-toxic, light in weight, good heat resistance, good corrosion resistance, good heat preservation, good impact resistance and long service life
1. Hygienic and non-toxic: the material is completely composed of carbon and hydrogen, and no toxic heavy metal salt stabilizer is added. The hygienic performance of the material has passed the inspection of the national authority.
2. Light weight: The density of the stamped elbow is 0.89-0.91g/cm, which is only one tenth of that of the steel pipe. Due to the light weight, it can greatly reduce the transportation cost and the construction strength of the installation.
3. Good heat resistance: when the working water temperature is 70 degrees, the softening temperature is 140 degrees.
4. Good corrosion resistance: except for a few hydrogenating agents, it can resist the erosion of various chemical media, has excellent acid resistance, alkali resistance, corrosion resistance, will not rust, will not corrode, will not breed bacteria, and has no electricity chemical corrosion.
5. High impact resistance: Due to the unique impact strength performance, it has been significantly improved compared with other solid wall pipes, and its ring stiffness is equivalent to 1.3 times that of solid walls.
6. Long service life: Under the rated operating temperature and pressure, the service life of the pipe can reach more than 50 years. It is anti-ultraviolet and anti-radiation, so that the product will never fade.

Elbow involves standard

1. Japanese standard
Standard No. Description
JIS B2311 General-purpose steel butt-welding pipe fittings
JIS B2312 Steel Butt Welding Fittings
JIS B2313 steel plate butt welding pipe fittings
JIS B2316 steel socket welding pipe fittings

2. American standards for pipe fittings:
Standard No. Description
ASME/ANSI B16.9 Factory Made Forged Steel Butt Weld Fittings
ASME/ANSI B16.11 Socket Weld and Threaded Forged Fittings
ASME/ANSI B16.28 Steel Butt Welding Small Radius Elbows and Return Elbows
ASME B16.5 Pipe Flanges and Flange Fittings
MSS SP-43 Forged Stainless Steel Butt Welding Fittings
MSS SP-79 Socket Weld Reducing Inserts
MSS SP-83 Socket Weld and Threaded Unions
MSS SP-97 Integral reinforced sockets for socket weld, threaded and butt weld ends

3. Electricity standard
GB2000 Typical Design Manual for Steam and Water Pipeline Parts and Components in Thermal Power Plants
DL/T515-93 power station elbow
D-GD87-1101 Typical Design of Piping Parts and Components

4. The chemical standard of pipe fittings implementation standard:
HGJ514 carbon steel, low alloy steel seamless butt welding pipe fittings
HGJ528 steel seam butt welding pipe fittings
HGJ10 forged steel socket welding pipe fittings
HGJ529 Forged steel socket weld, thread and butt weld sockets

5. Sinopec standard
SH3408 -1996 Steel Butt Welding Seamless Pipe Fittings
SH3409-1996 forged steel socket welding pipe fittings
SH3410-1996 forged steel socket welding pipe fittings
SH3065-1994 technical standard for sharp bends of tube furnaces in petrochemical industry

6. National standard
GB/T12459-2017 Types and parameters of steel butt welding pipe fittings
GB/T13401-2017 Technical specification for steel butt welding pipe fittings
GBT 14383-2008 Forged socket welding and threaded pipe fittings
GB/T17185-1995 steel flange pipe fittings

7. Petroleum standards in the implementation of standards for pipe fittings:
SY/T0510-1998 steel butt welding pipe fittings
SY/T5257-2004 steel elbow
02S403 National Construction Standard for Steel Pipe Fittings

8. Marine standard
GB/T10752-1995 Marine steel pipe butt welding joints
CB/T3590-94 Aluminum Brass Elbow