Manufacturing process of valve

Manufacturing process and processing process flow of valve

At first glance, the valve has few parts, simple structure and general accuracy. It is a simple component in the machinery industry, but the requirements for the core sealing part of the valve are particularly high. The valve manufacturing process is complex and technically difficult. What process characteristics do we need to pay attention to?

20210824140601 56594 - Manufacturing process of valve

Manufacturing materials of valves

Due to the wide variety and specifications of valves, such as gate valve, globe valve, check valve, ball valve, butterfly valve and hydraulic control valve; Industrial valves include solenoid valves, regulating valves, pressure reducing valves, high-temperature and high-pressure valves, low-temperature valves and other special valves, which are used in various fields of the national economy. Their application occasions vary greatly, such as high-temperature and high-pressure, low-temperature and deep cold, flammable and explosive, highly toxic, strongly corrosive media and other working conditions, which put forward harsh requirements for the material of the valve.
In addition to cast iron, carbon steel and alloy structural steel, CrNi stainless steel, CrMoAl nitriding steel, CrMoV heat resistant steel, CrMnN acid resistant steel, precipitation hardening steel, duplex stainless steel, low temperature steel, titanium alloy, Monel alloy, Inconel alloy, Hastelloy alloy and g0crw cemented carbide are also widely used. The casting, welding and processing properties of these high alloy materials are very poor, which brings great difficulty to the manufacturing process. In addition, most of these materials are valuable materials with high alloy, high strength and high hardness. There are many difficulties in material selection, material preparation and procurement. Some materials are difficult to purchase and supply due to their small use.

Structure of casting blank

Most of the valve blanks are thin shell castings with complex structure, which requires not only good appearance quality, but also dense internal quality and good metallographic structure, without defects such as pores, shrinkage cavities, sand inclusions and cracks. Therefore, the casting process is complex and the heat treatment technology is difficult. In the machinery industry, the casting of pressure bearing thin shell castings of valves is much more complex and difficult than that of other mechanical components.

Machining process of valve

Due to the poor cutting performance of most high-strength, high hardness and high corrosion-resistant materials, such as high alloy stainless steel and acid resistant steel, which have the disadvantages of high toughness, high strength, poor heat dissipation, large chip viscosity and strong work hardening tendency, it is difficult to achieve the required dimensional accuracy and finish, which brings some difficulties to the machining tools, processes and equipment. In addition, the valve sealing surface has high requirements for machining accuracy, matching angle, finish and matching sealing pair, which brings great difficulty to machining.

Process arrangement of valve parts

The number of main parts of the valve is small, the structure is relatively simple, the machining accuracy of most dimensions is not high, and the outside is rough, which gives people the impression that it belongs to simple machinery. In fact, the heart sealing part of the valve is unique. The “three degrees” (flatness, smoothness and hardness) of the sealing surface are very high, and the coincidence of the sealing pair composed of two sealing surfaces must reach zero to zero, so as to meet the zero leakage of the air tightness test. This rough benchmark to ensure the zero to zero requirements of the heart is a major process difficulty in valve processing.

Valve test and inspection

Valve is an important opening, closing and regulating element of pressure pipeline, and the service conditions of pressure pipeline are very different, high temperature and high pressure, low temperature and deep cold, flammable and explosive, highly toxic and corrosive. However, the test and inspection conditions of valve manufacturing can not meet the same requirements of working conditions. Various international and domestic valve test standards stipulate that the test is carried out with gas or water as the medium under the condition close to normal temperature. There is a fundamental hidden danger, that is, the valve products that pass the normal factory test may be difficult to meet the use requirements due to problems such as material selection, casting quality and seal damage under harsh actual working conditions, and major quality accidents will occur. No wonder some old valve experts who have worked all their lives are more cautious and worried as they get older.

20170603101277497749 - Manufacturing process of valve

Manufacturing process of Valve

Step 1: valve body manufacturing

Valve body (casting, sealing surface surfacing)
Casting procurement (according to standard) ➱ incoming inspection (according to standard) ➱ surfacing groove ➱ ultrasonic flaw detection (according to drawing) ➱ surfacing and post weld heat treatment ➱ finishing ➱ grinding sealing surface ➱ hardness inspection and dye detection of sealing surface.

Step 2: valve trim manufacturing process

A. Internals requiring surfacing sealing surface, such as valve disc, valve seat, etc
Raw material procurement (according to standard) ➱ incoming inspection (according to standard) ➱ making blank (round steel or forging, according to the process requirements of the drawing) ➱ rough machining ultrasonic flaw detection surface (when required by the drawing) ➱ rough machining surfacing groove ➱ surfacing and post weld heat treatment ➱ finishing each department ➱ grinding sealing surface ➱ sealing surface hardness inspection and dye detection.
B. Valve stem
Raw material procurement (according to standards) ➱ incoming inspection (according to standards) ➱ blank making (round steel or forging, according to the process requirements of the drawing) ➱ rough machining of surfacing groove ➱ surfacing and post weld heat treatment ➱ finishing of each part ➱ grinding of outer circle ➱ valve stem surface treatment (nitriding, quenching, chemical coating) ➱ final treatment (polishing, grinding, etc.) ➱ grinding of sealing surface ➱ hardness inspection and dye flaw detection of sealing surface.
C. Internals without surfacing sealing surface, etc
Raw material procurement (according to standard) ➱ incoming inspection (according to standard) ➱ making blank (round steel or forging, according to the process requirements of the drawing) ➱ rough machining ultrasonic flaw detection surface (when required by the drawing) ➱ finishing all parts.

Step 3: Fastener manufacturing

Fastener manufacturing standard dl439-1991.
Raw material procurement (according to standard) ➱ incoming inspection (according to standard) ➱ making blank (round steel or forging, according to drawing process requirements) and sampling for necessary inspection ➱ rough machining ➱ finish machining ➱ spectral inspection.

Step 4: final assembly

Receiving parts ➱ cleaning and cleaning ➱ rough assembly (according to the drawing) ➱ hydrostatic test (according to the drawing and process) ➱ after passing the test, disassemble and wipe ➱ final assembly ➱ and electrical assembly or actuator commissioning (for electric valves) ➱ paint packaging ➱ shipping.

Step 5: valve production and inspection process

  • 1. Raw materials of various specifications purchased by the company.
  • 2. Use the spectrum analyzer to test the material of raw materials, and print the test report of raw materials for backup.
  • 3. Cut raw materials with blanking machine.
  • 4. The inspector shall inspect the cutting diameter and length of raw materials.
  • 5. The forging workshop carries out forging forming treatment for raw materials.
  • 6. The inspector shall inspect various dimensions of the formed blank.
  • 7. The worker is cutting off the scrap edge of the blank.
  • 8. The sanding worker shall carry out sand blasting on the surface of the blank.
  • 9. The inspector shall inspect the surface treatment after sand blasting.
  • 10. Workers carry out rough machining.
  • 11. Valve body sealing thread processing – employees conduct processing self inspection, and inspectors conduct post-processing inspection on products.
  • 12. Valve body connection thread processing.
  • 13. Medium hole machining.
  • 14. The inspector shall conduct general inspection.
  • 15. Qualified semi-finished products are sent to the semi-finished product warehouse.
  • 16. Semi finished products shall be electroplated.
  • 17. Inspection of electroplating surface treatment of semi-finished products.
  • 18. Inspection of various accessories (ball, valve stem, sealing valve seat).
  • 19. Product assembly in the final assembly workshop – assembly line inspectors inspect the products.
  • 20. After pressure test and drying, the assembled product enters the next process.
  • 21. Product packaging in the final assembly workshop — the inspectors of the packaging line inspect the tightness, appearance and torque of the products. Unqualified products must not be packaged.
  • 22. Qualified products are bagged and sent to the finished product warehouse.
  • 23. All inspection records will be classified and stored in the computer for query at any time.
  • 24. Qualified products are sent to domestic and foreign countries through containers.

Inspection for Finished Products

  • A: Dimension Measurement
  • B: Outer & Inner Surface Inspection
  • C: Chemical Composition: Chemical Analysis; Portable Spectrometer
  • D: Mechanical Properties: Flattening, Flaring, Hardness; Tensile Strength
  • E: Non-destructive Test: Eddy Current Test; Ultrasonic Testing;
  • F: Corrosion Test: Intergranular Corrosion Test; Pit Corrosion Test
  • G: Hydrostatic Test
  • H: Grain Size Test

MATERIAL REFERENCE LIST

MATERIAL

PIPES

WROUGHT FITTINGS

FORGING

PLATE

CASTING

TRADE NAME

Stainless steel&Super Stainless

A312 TP304

A403 WP304

A182 F304

A240 gr. 304

A351 CF8

304

A312 TP304L

A403 WP304L

A182 F304L

A240 gr. 304L

A351 CF3

304L

A312 TP310S

A403 WP310S

A182 F310S

A240 gr. 310S

A351 CK20

310

A312 TP316

A403 WP316

A182 F316

A240 gr. 316

A351 CF8M

316

A312 TP316L

A403 WP316L

A182 F316L

A240 gr. 316L

A351 CF3M

316L

A312 TP316Ti

A403 WP316Ti

A182 F316Ti

A240 gr. 316Ti

 

316Ti

A312 TP317L

A403 WP317L

A182 F317L

A240 gr. 317L

A351 CG8M

317

A312 TP321

A403 WP321

A182 F321

A240 gr. 321

 

321

A312 TP347

A403 WP347

A182 F347

A240 gr. 347

A351 CF8C

347

A312 S31254

A403 S31254

A182 F44

A240 S31254

A351 CK3MCuN

254 SMO

Duplex steel

A790 S31803

A815 S31803

A182 F51

A240 S31803

A890 Gr.4A

SAF2205

A790 S32304

A815 S32304

 

A240 S33304

 

SAF2304

A790 S32750

A815 S32750

A182 F53

A240 S32750

A890 Gr 5A

SAF2507

A790 S32760

A815 S32760

A182 F55

A240 S32760

A890 Gr 6A

 

Special alloy

B677/674 N08904

B366 WP904L

B459 N08904

B649 N08904

 

904L

B729/464 N08020

B366 WP20CB

B462 N08020

B463 N08020

A351 CN7M

Alloy 20

B161 N02200

B366  WPN

B564 N02200

B162 N02208

 

Nickel 200

B161 N02201

B366  WPNL

B160 N02201

B162 N02201

 

Nickel 201

B165 N04400

B366  WPNC

B564 N04400

B127 N04400

A494 M35-1

Monel 400

B407 N08800

B366  WPNIC

B564 N08800

B409 N08800

 

Incoly 800

B423 N08825

B366  WPNICMC

B564 N08825

B424 N08825

A494 CU5MCuC

Incoly 825

B167 N06600

B366  WPNCI

B564 N06600

B168 N06600

A494 CY40

Inconel 600

B444 N06625

B366  WPNCMC

B564 N06625

B443 N06625

A494 CW6MC

Inconel 625

B622 N10276

B366 WPHC276

B564 N10276

B575 N10276

 

Hastelloy C276

B622 N06455

B366  WPHC4

B564 N06455

B575 N06455

A494 CW2M

Hastelloy C4

B622 N06022

B366  WPHC22

B564 N06022

B575 N06022

A494 CX2MW

Hastelloy C22

B622 N10665

B366  WPN\HB-2

B564 N10665

B333 N10665

A494 N7M

Hastelloy B2

Carbon steel

A106 Gr.B

S234 WPB

A105/N

A515 Gr65

A216 WCB

 

Low temp. service

A333 Gr.3

A420 WPL3

A350 LF3

A516 Gr.70

A352 gr. LC3

 

A333 Gr.6

A420 WPL6

A350 LF2

A516 Gr.65

A352 gr. LCB

 

High temp. service (Chrome-Moly Alloy)

A335 P1

A234 WP1

A182 F1

A204 gr B

A217 gr.B

 

A335 P5

A234 WP5

A182 F5

A387 gr.5

A217 gr. C5

 

A335 P9

A234 WP9

A182 F9

A387 gr.9

A217 gr.C12

 

A335 P11

A234 WP11

A 182 F11

A387 gr.11

A217 gr.WC6

 

A335 P22

A234 WP22

A182 F22

A387 gr.22

A217 gr.WC9

 

A335 P91

A234 WP91

A182 F91

A387 gr.91

A217 gr.WC12

 

Line pipe material (High Yield)

API 5L B

A234 WPB

A105/N

 

 

 

API 5L X42

A860 WPHY42

A694 F42

 

 

 

API 5L X46

A860 WPHY46

A694 F46

 

 

 

API 5L X52

A860 WPHY52

A694 F52

 

 

 

API 5L X60

A860 WPHY60

A694 F60

 

 

 

API 5L X65

A860 WPHY65

A694 F65

 

 

 

API 5L X70

A860 WPH70

A694 F70

 

 

Comments:

  • The list is for reference only. Pls make a final confirming before order.
  • If your material is not in this list, pls contact Yaang without any hesitate.

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