China piping solution supplier: www.epowermetals.com

Selection of valve material

There are many materials for manufacturing valve parts, including various brands of ferrous metals, non-ferrous metals and their alloys, various non-metallic materials, etc.
The materials for manufacturing valve parts shall be selected according to the following factors:

  • 1. Pressure, temperature and characteristics of working medium.
  • 2. The stress of the part and its role in the valve structure.
  • 3. Good processability.
  • 4. In the case of meeting the above conditions, there should be a lower cost.

Material of body, cover and disc

  • 1. Gray cast iron: gray cast iron is suitable for water, steam, air, gas, oil and other media with nominal pressure of PN ≤ 1.0MPa and temperature of – 10 ℃ ~ 200 ℃. The common grades of gray cast iron are HT200, HT250, HT300 and ht350.
  • 2. Malleable cast iron: suitable for water, steam, air and oil medium with nominal pressure PN ≤ 2.5MPa and temperature of – 30 ~ 300 ℃. The common brands are kth300-06, kth330-08 and kth350-10.
  • 3. Ductile iron: suitable for water, steam, air, oil and other media with PN ≤ 4.0Mpa and temperature of – 30 ~ 350 ℃. Common brands are: QT400-15, QT450-10, QT500-7.
  • 4. Carbon steel (WCA, WCB, WCC): it is suitable for medium and high pressure valves with nominal pressure PN ≤ 32.0mpa and working temperature between – 29 ℃ and + 425 ℃. The working temperature of 16Mn and 30mn is – 29 ~ 595 ℃. It is commonly used to replace ASTM A105. The common grades are WC1, WCB, ZG25, high quality steel 20, 25, 30 and Low Alloy Structural Steel 16Mn.
  • 5. Low temperature carbon steel (LCB): suitable for nominal pressure PN ≤ 6.4Mpa, temperature ≥ – 196 ℃, ethylene, propylene, liquid natural gas, liquid nitrogen and other media, commonly used brands are ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, zg0cr18ni9
  • 6. Alloy steel (wc6, wc9) is suitable for high temperature and high pressure valves in non corrosive medium with working temperature between – 29 ℃ and 595 ℃; wc5, wc9 are suitable for high temperature and high pressure valves in corrosive medium with working temperature between – 29 ℃ and 650 ℃.
  • 7. Austenitic stainless steel, suitable for valves with corrosive medium between – 196 ℃ and + 600 ℃.
  • 8. Monel alloy: mainly used for valves with hydrogen and fluorine medium.
  • 9. Cast copper alloy: mainly used for oxygen pipeline valve with working temperature between – 29 ℃ and 595 ℃.

Table 1-1 common materials of valve shell

Shell material

Standard

Applicable temperature / ℃

Applicable pressure / MPa

Applicable medium

Grey cast iron

-15200

1.6

Water and gas

Black core malleable iron

-15300

2.5

Water, seawater, gas, ammonia

Ductile iron

-30350

4.0

Water, sea water, gas, air, steam

Carbon steelWCAWCBWCC

ASTM A216

-29425

32.0

Non corrosive applications, including water, oil and gas

Low temperature carbon steelLCBLCC

ASTM A352

-46345

32.0

Low temperature application

Alloy steelWC6WC9

C5C12

ASTM A217

-29595

-29650

High pressure

Non corrosive medium and corrosive medium

Austenitic stainless steel

ASTM A351

-196600

Corrosive medium

Monel alloy

ASTM A494

400

Medium containing hydrofluoric acid

Hastelloy

ASTM A494

649

Strong corrosive medium such as dilute sulfuric acid

Titanium alloy

Various strong corrosive media

Cast copper alloy

-273200

Oxygen, seawater

Plastics, ceramics

60

1.6

Corrosive medium

Code

Material

Standard

Applicable conditions

Temperature range

WCB

Carbon steel

ASTM A216

Non corrosive applications, including water, oil and gas

-29+425

LCB

Low temperature carbon steel

ASTM A352

Low temperature application

-46+345

LC3

3.5% nickel steel

ASTM A352

Low temperature application

-101+340

WC6

1.25% Cr 0.5% Mo steel

ASTM A217

Non corrosive applications, including water, oil and gas

-30+593

WC9

2.25 Cr

C5

5% Cr 0.5% Mo

ASTM A217

Mild corrosive or aggressive applications and non corrosive applications

-30+649

C12

9% CR 1% Mo

CA15(4)

12% chromium steel

ASTM A217

Corrosive applications

+704

CA6NM(4)

12% chromium steel

ASTM A487Corrosive applications

-30+482

CF8M

316 stainless steel

ASTM A351

Corrosive or ultra low or high temperature non corrosive applications

-From 268 ℃ to + 649 ℃ and above 425 ℃, carbon content of 0.04% or above shall be specified

CF8C

347 stainless steel

ASTM A351

Mainly used in high temperature, corrosive applications

-From 268 ℃ to + 649 ℃, carbon content of 0.04% and above shall be specified above 540 ℃

CF8

304 stainless steel

ASTM A351

Corrosive or ultra low or high temperature non corrosive applications

-From 268 ℃ to + 649 ℃ and above 425 ℃, carbon content of 0.04% or above shall be specified

CF3

304 stainless steel

ASTM A351

Corrosive or non corrosive applications

+425

CF3M

316L stainless steel

ASTM A351

Corrosive or non corrosive applications

+454

CN7M

Alloy steel

ASTM A351

It has good corrosion resistance to hot sulfuric acid

+425

M35-1

Monel

ASTM A494

Weldable grade. It has good corrosion resistance to all common organic acids and brine. It also has high corrosion resistance to most alkaline solutions

+400

N7M

Hastelloy B

ASTM A494

It is especially suitable for hydrofluoric acid of various concentrations and temperatures. It has good corrosion resistance to sulfuric acid and phosphoric acid

+649

CW6M

Hastelloy C

ASTM A494

It has good corrosion resistance in strong oxidation environment. It has good corrosion resistance to formic acid (formic acid), phosphoric acid, sulfite and sulfuric acid

+649

CY40

Inconel

ASTM A494

Good performance in high temperature applications. It has good corrosion resistance for strong corrosive fluid medium

Sealing surface material

The sealing surface is the most critical working surface of the valve. The quality of the sealing surface is related to the service life of the valve. Usually, the material of the sealing surface should consider factors such as corrosion resistance, abrasion resistance, erosion resistance and oxidation resistance. It is usually divided into two categories:

Soft material

  • 1. Rubber (including polybutadiene rubber, fluororubber, etc.)
  • 2. Plastics (PTFE, nylon, etc.)

Hard sealing material

  • 1. Copper alloy (for low pressure valves)
  • 2. Chromium stainless steel (for common high and medium pressure valves)
  • 3. Stellite Alloy (used for high temperature and high pressure valve and strong corrosion valve)
  • 4. Nickel base alloys (for corrosive media)

Stem material

In the process of valve opening and closing, the valve stem bears tensile, compressive and torsional forces, and is in direct contact with the medium. At the same time, there is relative friction movement between the valve stem and the packing. Therefore, the material of the valve stem must have sufficient strength and impact toughness at the specified temperature, certain corrosion resistance and scratch resistance, and good processability. Commonly used stem materials are as follows.

Carbon steel

For water and steam medium with low pressure and medium temperature less than 300 ℃, A5 ordinary carbon steel (now Q275, A3 is Q235) is generally selected.
For medium pressure and medium temperature not more than 450 ℃ water, steam medium, generally choose 35 high quality carbon steel.

Alloy steel

For medium pressure and high pressure, medium temperature does not exceed 450 ℃ of water, steam, oil and other media, generally choose 40Cr (chromium steel).
38CrMoAlA nitriding steel can be used for high pressure, medium temperature not exceeding 540 ℃ water, steam and other media.
25Cr2MoVA chromium molybdenum vanadium steel is generally used for steam medium with high pressure and medium temperature not exceeding 570 ℃.

Stainless acid resistant steel

For medium pressure and high pressure, medium temperature does not exceed 450 ℃ non corrosive medium and weak corrosive medium, can choose 1Cr13, 2Cr13, 3Cr13 chromium stainless steel.
When used in corrosive medium, stainless acid resistant steel such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, cr18ni12mo3ti and precipitation hardening steel ph15-7mo can be selected.

Heat resistant steel

4Cr10Si2Mo martensitic heat resistant steel and 4Cr14Ni14W2Mo austenitic heat resistant steel can be used for high temperature valves with medium temperature less than 600 ℃.

Stem nut material

In the process of valve opening and closing, the stem nut directly bears the axial force of the stem, so it must have a certain strength. At the same time, it and the valve stem are threaded transmission, requiring small friction coefficient, no rust and avoid biting phenomenon.

Copper alloy

Copper alloy is one of the commonly used materials because of its low friction coefficient and no rust. Zhmn58-2-2 cast brass can be used for low pressure valve with PG < 1.6Mpa. ZQAl9-4 bronze can be used for medium pressure valve with pg16-6.4mpa. For high pressure valves, zhal66-6-3-2 cast brass can be used.

Steel

When the working conditions do not allow the use of copper alloy, high quality carbon steel such as 35 and 40, stainless acid resistant steel such as 2Cr13, 1Cr18Ni9 and Cr17Ni2 can be selected. The following conditions are not allowed under working conditions.

  • 1. For electric valve, stem nut with melon clutch needs heat treatment to obtain high hardness or surface hardness.
  • 2. When the working medium or surrounding environment is not suitable for the selection of copper alloy, such as ammonia medium with corrosion to copper.

When selecting steel stem nut, special attention should be paid to the phenomenon of thread seizure.

Fastener, packing and gasket materials

Fastener material

Fasteners mainly include bolts, stud bolts and nuts. The fastener bears the pressure directly on the valve, which plays an important role in preventing the outflow of medium. Therefore, the selected material must ensure sufficient strength and impact toughness at the service temperature.
When selecting fastener materials according to medium pressure and temperature, it can be selected according to the table.

Name

Nominal pressure PG (MPA)

Medium temperature (℃)

300

350

400

425

450

530

Bolt
Stud bolt

1.6-2.5

Q235A3

35

30CrMoA

4.0-10.0

35

35CrMoA

25Cr2MoVA

16.0-20.0

30CrMoA

35CrMoA

25Cr2MoVA

Nut

1.6-2.5

Q235A3

30

35

4.0-10.0

30

35

35CrMoA

16.0-20.2

35

35CrMoA

The alloy steel material must be heat treated. When there are special corrosion resistance requirements for fasteners, stainless acid resistant steel such as Cr17Ni2, 2Cr13 and 1Cr18Ni9 can be selected.

Filler material

In the valve, the packing is used to fill the space of the valve cover packing chamber to prevent the medium from leaking through the space of the valve stem and the valve cover packing chamber.
Requirements for fillers

  • 1) Good corrosion resistance, filler and medium contact, must be able to resist the corrosion of the medium.
  • 2) Good sealing performance, no leakage of packing under the action of medium and working temperature.
  • 3) The friction coefficient is small to reduce the friction torque between the valve stem and packing.

Types of fillers
The fillers can be divided into soft fillers and hard fillers
1) Soft filler: it is made of plant material, such as hemp, flax, cotton, jute, etc., or mineral material, such as asbestos fiber, or cord woven by asbestos fiber with metal wire inside and coated with graphite powder outside, as well as molded filler and flexible graphite filler developed in recent years.
Plant packing is commonly used in low pressure valve below 100 ℃, mineral packing can be used in 450-500 ℃.
In recent years, the temperature of structural medium using rubber O-ring as filler is generally limited below 60 ℃.
The packing on high temperature and high pressure valve is also made of pure asbestos and flake graphite powder.
2) Hard filler: that is, the filler made of metal or metal mixed with asbestos and graphite, and the filler formed by pressing and sintering of polytetrafluoroethylene. Metal filler is rarely used.
Selection of fillers
The selection of fillers should be based on the medium, temperature and pressure. The commonly used materials are as follows:
1) Oil impregnated asbestos rope can be selected according to table 5-2.
2) Rubber asbestos rope: it can be selected according to table 5-3.
3) Graphite asbestos rope: the asbestos rope is coated with graphite powder. The temperature can be above 450 ℃ and the pressure can reach 16MPa. It is generally suitable for high pressure steam. In recent years, it has gradually adopted the pressed herringbone packing, which is placed in a single ring and has good sealing performance.
4) Polytetrafluoroethylene: This is a kind of filler widely used at present. Especially suitable for corrosive media, but the temperature should not exceed 200 ℃. Generally, it is made by pressing or bar stock car, and the shape is shown in Figure 5-1.
20210306230724 36875 - Selection of valve material

Figure 5-1

Name  Grade Shape Specifications Applicable limit pressure Applicable limit temperature Purpose
(diameter or square side length) kgf/cm² (℃)
Oil impregnated asbestos rope YS450 F
3.4.5.6.8.10
13.16.19.22.25
       60 450 For steam, air, petroleum products
Y
5.6.8.10.13
16.19.22.25
N
3.5.6.8.10.13
16.19.22.25
YS350 FYN
3.5.6.8.10.13
16.19.22.25.
45 350
YS250 FYN
3.5.6.8.10.13.
16.19.22.25
45 250

Table 5-2

Note: shape code f means square, through the center or one to multi-layer braiding; y means round, with a twisted core in the middle and one to multi-layer braiding on the outside; n means twisted.

Name Grade Specification (straight formula or square side length) Applicable limit pressure kgf / cm 2 Applicable limit temperature (℃) Purpose
Rubber XS450
3 . 4 . 5 . 6 . 8
10 . 13 . 16 . 19
60 450 For steam, petroleum products
Asbestos XS350 45 350
Packing XS250 22 . 25 . 28 45 250

Table 5-3

Gasket material

The gasket is used to fill all the unevenness between the two joint surfaces (such as the sealing surface between the valve body and the valve cover), so as to prevent the medium from leaking from the joint surface.
Requirements for gaskets
The gasket material has certain elasticity and plasticity at working temperature and enough strength to ensure sealing. At the same time, it should have good corrosion resistance.
Types and selection of gasket materials
Gasket can be divided into soft and hard two kinds, soft generally for non-metallic materials, such as cardboard, rubber, asbestos rubber, PTFE, etc. Hard materials are generally metal materials or metal coated asbestos, metal and asbestos winding, etc.
There are many shapes of gaskets, including flat, round, oval, toothed, lens and other special shapes.

The metal gasket is made of 08, 10, 20 high-quality carbon steel and 1Cr13, 1Cr18Ni9 Stainless steel. It is suitable for high-temperature and high-pressure valves with high machining accuracy and surface finish.
Non metallic gasket material is generally good plasticity, with little pressure can achieve sealing. Suitable for low temperature and low pressure valves.
Gasket materials can be selected according to table 5-4.

Gasket material Medium Scope of application
Pressure (MPA) Temperature (℃)
Cardboard Water and oil ≤10 40
Oil impregnated paperboard Water and oil ≤10 40
Rubber sheet Water, air ≤6 50
Asbestos board Steam, gas ≤6 450
Teflon Corrosive medium ≤25 200
Rubber asbestos board xb-450 Steam, air, gas ≤60 450
           XB-350 Steam, air, gas ≤40 350
           XB-200 Steam, air, gas ≤15 200
Oil resistant rubber asbestos board Oils 160 30
08 steel and xb-450 filling Steam 100 450
08 steel and xb-350 filling Steam 40 350
1Cr13, 0Cr13 asbestos filling Steam 100 600
08 steel and oil resistant rubber asbestos filling Oils 100 350
Copper Water vapor, air 100 250
Aluminium Water vapor, air 64 350
#10 steel, #20 steel Water vapor, oil 200 450
1Cr13 Steam 200 550
1Cr13Ni9 Steam 200 600

Table 5-4

Table 5-5 common materials of valve internals

Interior material

Applicable temperature / ℃

Interior material

Applicable temperature / ℃

304

-268 – 316

Type 400 stainless steel 60RC

-29427

316

-268316

17-4PH

-40427

Bronze

-273232

No.6 alloy steel (Co-Cr)

-273816

Inconel alloy

-240649

Electroless nickel plating

-268427

K Monel alloy

-240482

Chromium plating

-273316

Monel alloy

-240482

Nitrile rubber

-4093

Hastelloy alloy B

-198371

Fluororubber

-23204

Hastelloy alloy C

-198538

teflon

200

titanium alloy

-29316

nylon

-7393

Nickel base alloy

-198316

polyethylene

-7393

No.20 alloy

-46316

Chloroprene rubber

-4082

Type 416 stainless steel 40RC

-29427

Schedule 5-6  Common materials and applicable temperature of valve sealing surface

Sealing surface material

Applicable temperature / ℃

Hardness

Applicable media

Bronze

-273~232

Water, sea water, air, oxygen, saturated steam, etc

316L

-268~316

14HRC

Steam, water, oil, gas, liquefied gas, etc. with slight corrosion and no erosion

17-4PH

-40 – 400

40 – 45HRC

Medium with slight corrosion but erosion

Cr13

-101~400

37 – 42HRC

Medium with slight corrosion but erosion

Stellite Alloy

-268~650

40 – 45HRC (normal temperature)

38HRC ( 650 ℃ )

Erosive and corrosive media

Monel alloy KS

-240~482

27 – 35HRC

30 – 38HRC

Alkali, salt, food, acid solution without air, etc

Hastelloy CB

371

538

14HRC

23HRC

Corrosive mineral acid, sulfuric acid, phosphoric acid, wet hydrochloric acid gas, no chloric acid solution, strong oxidizing medium

No.20 alloy

-45.6~316

-253~427

Oxidizing medium and sulfuric acid of various concentrations

Material list of cast iron valve stem, sealing surface, gasket, packing and fastener

Name

Standard

Material grade

Remarks

Stem

ASTM A 182

F6a

ASTM A 276

410 、420

GB/T 1220

1Cr13 、 2Cr13

Sealing surface

GB/T 1176

ZCuZn25Al6Fe3Mn3

Cast aluminum brass

ZCuZn38Mn2Pb2

Cast manganese brass

ZCuAl9Mn2 、 ZCuAl10Fe3

Cast aluminum bronze

GB/T 1220

1Cr13 、 2Cr13 、 1Cr18Ni9 、 1Cr18Ni9Ti

Polytetrafluoroethylene( PTFE )

Rubber

shim

GB/T 3985

XB350 、 XB450

Rubber asbestos board

1Cr13 / XB450

Spiral wound gasket

GB/T 3985

1Cr18Ni9 / XB450

filler

Polytetrafluoroethylene( PTFE )

JB/T 6617

Flexible graphite ring

Screw fastener

GB/T 699

Bolt 35 / Nut 25

GB/T 3077

GB/T 699

Bolt 30CrMo 、 35CrMo / Nut 25 35

General valve material

General valve material API 600 Required trim material combination

Stem material type

hardness HB

Sealing surface

Seal No

Material type

Hardness

13Cr

two hundred – two hundred and seventy-five

1

13Cr

≥HB250

4

13Cr

≥HB750

5 or 5A

HF

≥HB350

6

13Cr/NiCu

≥HB750/≥HB175

7

13Cr/13Cr

≥HB250/≥HB750

8- 8A

13Cr/HF

≥HB250/≥HB350

18Cr-8Ni

Not specified

2

18Cr-8Ni

Not specified

25Cr-20Ni

3

25Cr-20Ni

Nickel copper alloy

9

Nickel copper alloy

11 or 11A

Nickel copper alloy /HF

Not specified /≥HB350

18Cr-8Ni-Mo

10

18Cr-8Ni-Mo

Not specified

12 or 12A

18Cr-8Ni-Mo/HF

Not specified /≥HB350

19Cr-29Ni

13

19Cr-29Ni

Not specified

14 or 14A

19Cr-29Ni/HF

Not specified /≥HB350

Common material combination of Internals

Stem material

Sealing surface material

Stem material

Sealing surface material

13Cr

13Cr/13Cr

321

321/321

13Cr

13Cr/STL

321

321/STL

13Cr

STL/STL

321

STL/STL

13Cr

13Cr/Monel

1Cr18Ni9Ti

1Cr18Ni9Ti/1Cr18Ni9Ti

17-4PH

STL/STL

1Cr18Ni9Ti

1Cr18Ni9Ti/STL

17-4PH

17-4PH/17-4PH

1Cr18Ni9Ti

STL/STL

Monel

Monel/Monel

1Cr18Ni12Mo2Ti

1Cr18Ni12Mo2Ti/1Cr18Ni12Mo2Ti

304

304/304

1Cr18Ni12Mo2Ti

1Cr18Ni12Mo2Ti/STL

304

304/STL

1Cr18Ni12Mo2Ti

STL/STL

304

STL/STL

twenty No.2 alloy

twenty No.2 alloy /20 No.2 alloy

316

316/316

Hastelloy B

Hastelloy B /Hastelloy B

316

316/STL

Hastelloy C

Hastelloy C /Hastelloy C

316

STL/STL

F51

F51/F51

304L

304L/304L

F51

F51/STL

304L

304L/STL

38CrMoALA

STL/STL

304L

STL/STL

25Cr2MoIV A

STL/STL

316L

316L/316L

4Cr10Si2Mo

STL/STL

316L

316L/STL

4Cr14Ni14W2Mo

STL/STL

316L

STL/STL

Inconel

Inconel/Inconel

Common fastener materials

Stud

Nut

temperature max ℃

Stud

Nut

Temperature max ℃

35

25

425

0Cr18Ni9

0Cr18Ni9

600

35CrMo

35、45

425

0Cr17Ni12Mo2

0Cr17Ni12Mo2

600

35CrMo

30CrMo

500

25Cr2Mo1VA

25Cr2MoVA

600

25Cr2MoVA

30CrMo

550

25Cr2MoVA

35CrMo

600

Matching of bolt and nut materials for American Standard valve

Bolt

Nut

Scope of application

standard

Brand

standard

Brand

ASTM A 193

B7

ASTM A 194

2H

-29-425℃

B7M

2HM

Anti sulfur valve of NACE standard at 29 – 425 ℃

B16

seven

-29-593℃

B8

eight

-196-700℃

B8M

8M

ASTM A 320

L7

four

-46 – 101 ℃ low temperature valve

Source: Network Arrangement – China Valve Supplier: www.epowermetals.com

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, 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.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@epowermetals.com

Summary
selection of valve material - Selection of valve material
Article Name
Selection of valve material
Description
There are many materials for manufacturing valve parts, including various brands of ferrous metals, non-ferrous metals and their alloys, various non-metallic materials, etc.
Author
Publisher Name
www.epowermetals.com
Publisher Logo
PREV
NEXT

RELATED POSTS

Leave a Reply

*

*

Inquery now

SUBSCRIBE TO OUR NEWSLETTER

FOLLOW US

YouTube
العربية简体中文繁體中文NederlandsEnglishFrançaisDeutschItaliano日本語한국어LatinPortuguêsРусскийEspañolTürkçe
  • Email me
    Mail to us