Forging process analysis and scheme comparison of large valve body

Valve body is a major component of the petroleum machinery valve, according to the pressure level there are different forming methods, such as: casting, forging, etc.. Valve body material according to the different process media, the use of different materials, commonly used materials are: cast iron, cast steel, stainless steel, alloy structural steel, etc.. Valve forging is divided into press die forging and forging hammer free forging, this paper mainly introduces the product through free forging forming, analysis and comparison of a variety of process options, and finally give an optimal valve forging process.

Forging process analysis of the forged valve body

The valve body (Figure 1 is the product parts diagram) is flange-shaped at both ends, the middle part of the upper and lower two symmetrical round tabs, the two tabs between the polygon design, forging process allows moderate collapse. The overall design is eccentric structure, the raw material used is ingot, the product material is AISI4130, the weight of the product parts is 1050kg, because the forging size is large, the ingot shape used is also large. In order to ensure that the heart of the ingot is forged through, internal inclusions and dendritic crystalline tissue can be effectively broken, and defects such as sparseness can be effectively welded together, the forging temperature range should be controlled. The higher the forging temperature is, the easier the internal defects of the ingot can be forged together, so the forging should be kept at high temperature as much as possible.
3134939133 - Forging process analysis and scheme comparison of large valve body
Figure 1 Part diagram
Forging forgings with ingots, it is necessary to consider the forging ratio, the basic forging process of valve body forging billet is divided into forging ratio control and forging billet forming. According to the forging equipment forging capacity and forging material size selected 6t electro-hydraulic hammer, heating equipment selected natural gas furnace, forging material starting forging temperature of 1180 ℃, the final forging temperature of 850 ℃, forging cooling method for the pit cooling.

Forging valve body process of the program

Due to the complex shape of the forgings, the overall forging difficulty, according to the characteristics of the part, our process personnel to analyze its forming feasibility, combined with the actual production situation of our company, research and development of three valve body forging forming process program.

Plan 1

Direct forging into a square blank, size 492mm × 657mm × 915mm, after forging and cooling, drawing lines on the forging blank, and finally sawing the corner on the sawing machine (Figure 2 is the forging blank diagram).
3134939524 - Forging process analysis and scheme comparison of large valve body
Figure 2 Forging billet diagram

Plan 2

First forging into a transition square blank, forging square cross-section of 510mm × 690mm, to ensure the key size of the middle square, with a small round bar in both ends of the square billet for indentation, the indentation position as a benchmark with a chopper for manual parting, and then pressure shoulder pulling length, and then the forging billet on the valve body die for surface shaping (Figure 3), followed by the valve body two end faces for leveling, the final blank formed into a three-section square (Figure 4 ).
3134939555 - Forging process analysis and scheme comparison of large valve body
Figure 3 Forging billet
1 – Die 2 – Valve body
3134939571 - Forging process analysis and scheme comparison of large valve body
Figure 4 Forging billet

Plan 3

Forge the blank into a cylindrical shape with a cross-sectional circle diameter of φ480mm, then put the die ring on the top and bottom of the blank respectively, upsetting along the forging billet axis direction (Figure 5), when the middle forging square meets the process size, then place the forging billet and the die ring transversely on the hammer anvil to forge the billet eccentric structure. Finally, the die ring at both ends is removed and the blank is leveled to ensure that the process dimensions and surface quality of the forging (Figure 6) meet the requirements.
3134939602 - Forging process analysis and scheme comparison of large valve body
Figure 5 Forging process diagram
3134939633 - Forging process analysis and scheme comparison of large valve body
Figure 6 Forging billet diagram

Comparative analysis of the valve body forging process

  • (1) The valve body forging process in Option 1 is 2430kg, forging fire for two fires; Option 2 is 2335kg, forging fire for three fires; Option 3 is 2030kg, forging fire for three fires.
  • (2) Option 1 is to forge the billet as a whole into a square blank; Option 2 forging process increases the margin at both ends of the forging billet in order to facilitate manual parting and prevent concave center at both ends. These two solutions designed valve body in the subsequent mechanical processing process, there is a large machining allowance, and forging flow is cut off, reducing the service life of the parts, so that product quality can not be guaranteed.
  • (3) Program one after forging by sawing off two residual material, light weight, the use of value is not high, can only be treated as scrap, while using a sawing machine to increase the loss of the saw blade, and add a process, one more quality control risks, such as the existence of the sawing process will be the product sawing the possibility of waste. The second option in the forging process of human division process, in the division of the material location of the remaining block, and chopping knife not necessarily neatly cut surface, so that the location is easy to produce folding.

The test proves that although the forging process of option one is simple, the forging margin is large, and the material utilization rate is low, there are two production processes, the production cycle is long and the quality control risk is high. Option 2 increases the forging margin in order to facilitate manual splitting, while the splitting position is prone to cracking and the quality control of the forging billet is difficult. Option 3 has the advantages of economic and rapid forming method, the forging billet structure is closer to the part structure, which improves the utilization rate of raw materials, and the forging process adopts the collar process, the production pace is fast, and the product quality is effectively guaranteed. Comparing the first two process options, it is clear that option three is the best process option to meet the requirements.


In summary, for the selection of valve body forging process, should be analyzed from multiple perspectives, to be combined with production costs and actual production efficiency, a comprehensive assessment of the selection of the best forging process. Only through this process of continuous optimization can we produce valve body forgings of qualified quality. The success of the test of this process scheme makes our valve body forging technology rise to another level, while enhancing our competitiveness in the valve body forging market, and also laying a good foundation for the extension of the valve body collar process.

Source: China Forged Steel Valve Manufacturer – Yaang Pipe Industry Co., Limited (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Stainless Steel Valves, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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