DeZURIK Material Selection Guide
The DeZURIK Material Selection Guide is designed to be used as a guide in selecting the most cost-effective valve materials. This guide should only be used as a starting point in your selection process. There are a variety of conditions which can affect the material chosen. Careful consideration must be given to temperature, the presence of other materials in the solution, and the concentration of the media.
This guide is divided into two sections: one for elastomers and one for metals. The charts in this guide have been coded to simplify your selection process. If a material does not have a rating code for a particular media, there is insufficient data available to give a conclusive rating at this time. Refer to the Elastomer Selection Guidelines and Metal Selection Guidelines for additional factors that may influence the most suitable material for an application.
* | Indicates that pitting corrosion might occur. |
A | Suggested based on value usage experience, suggestions from suppliers, and data from standard references. |
B | May be used, however concentration and temperature may affect the elastomer or metal. Performance in specific applications may be lessened. Testing is recommended before usage. |
C | Not Used. |
No representation, warranty or guarantee, expressed or implied, is made by this Selection Guide due to the complexity and almost infinite variations of mixtures, concentrations, temperatures and flow conditions possible in actual service. |
Guidelines
View Material Data
Elastomer / Polymer
- CIIR
Print
DeZURIK Elastomer Compound Description and Rating
CIIR (Chloro-Isobutene-Isoprene)
CIIR has outstanding impermeability to gases, excellent dielectric properties, good resistance to tearing, good aging properties at elevated temperatures and good chemical stability.
Mechanical Resistance Properties:
IMPACT GOOD ABRASION GOOD TEAR GOOD CUT GROWTH EXCELLENT Maximum Temperature Rating: 250°F (122°C)
Note: Not recommended for dry service on PEC and PEF Eccentric Plug Valves.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- CR
Print
DeZURIK Elastomer Compound Description and Rating
CR (Chloroprene)
CR is resistant to gasoline, sunlight, ozone and oxidation. It is flame resistant and will not support combustion. It has good resistance to the corrosive action of chemicals and water.
Mechanical Resistance Properties:
IMPACT GOOD ABRASION GOOD to EXCELLENT TEAR GOOD CUT GROWTH GOOD Maximum Temperature Rating: 180°F (82°C)
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- EPDM
Print
DeZURIK Elastomer Compound Description and Rating
EPDM (Terpolymer of Ethylene, Propylene and a Diene)
EPDM is resistant to oxygen and ozone and has excellent color retention.
Mechanical Resistance Properties:
IMPACT GOOD ABRASION GOOD TEAR FAIR CUT GROWTH GOOD Maximum Temperature Rating:
- All Products except as noted below 250°F (121°C)
- AWWA Butterfly Valve 290°F (143°C)
- Air Valves, Check Valves, Surge Relief Valves, 300°F (150°C)
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- EU
Print
DeZURIK Elastomer Compound Description and Rating
EU (Urethane)
Urethane is recommended for dry solids and abrasive slurries. It has excellent qualities for wear, tear and abrasion. It is resistant to oil and ozone.
Mechanical Resistance Properties:
IMPACT EXCELLENT ABRASION EXCELLENT TEAR EXCELLENT CUT GROWTH FAIR to EXCELLENT Maximum Temperature Rating: 175°F (80°C)
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- FKM
Print
DeZURIK Elastomer Compound Description and Rating
FKM (Fluoro Rubber)
FKM has excellent resistance to oils, fuels, lubricants, most mineral acids and many aliphatic and aromatic hydrocarbons that act as solvents for other rubbers. Excellent resistance to ozone, oxygen and weathering.
Mechanical Resistance Properties:
IMPACT POOR to GOOD ABRASION GOOD TEAR FAIR to GOOD CUT GROWTH POOR to GOOD Maximum Temperature Rating:
- Eccentric Plug Valves, Air Valves, Check Valves, Surge Relief Valves, 450°F (232°C)
- Resilient Seated Butterfly Valves, KGC Knife Gate Valves 400°F (204°C)
- CRF Flapper Swing Check Valves 425°F (218°C)
- KGC-BD Knife Gate Valves and PGV Ported Gate Valves 350°F (177°C)
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- NBR
Print
DeZURIK Elastomer Compound Description and Rating
NBR (Acrylonitrile-Butadiene)
NBR is primarily used for applications requiring resistance to petroleum oils, gasoline, aromatic hydrocarbons, mineral and vegetable oils.
Mechanical Resistance Properties:
IMPACT FAIR ABRASION EXCELLENT TEAR GOOD CUT GROWTH GOOD Maximum Temperature Rating:
- All products except as noted below 180°F (83°C)
- Air Valves, Check Valves, Surge Relief Valves 250°F (121°C)
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- NR
Print
DeZURIK Elastomer Compound Description and Rating
NR (Natural Rubber)
NR provides a balance of tear strength, high resilience and tensile strength, good abrasion resistance and good flexural properties at low temperatures.
Mechanical Resistance Properties:
IMPACT EXCELLENT ABRASION EXCELLENT TEAR EXCELLENT CUT GROWTH EXCELLENT Maximum Temperature Rating: 180°F (82°C)
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- NRH
Print
DeZURIK Elastomer Compound Description and Rating
NRH (Hard Natural Rubber)
NRH is a special natural rubber, graphite loaded ebonite with resistance to wet or dry chlorine gas, chlorinated brine and chlorine water solutions.
Mechanical Resistance Properties:
IMPACT POOR to FAIR ABRASION POOR to FAIR TEAR POOR to FAIR CUT GROWTH POOR to FAIR Maximum Temperature Rating: 180°F (82°C)
Notes: The leak rate of a hard natural rubber lined valve is equivalent to a metal-to-metal seated valve.
Not recommended for abrasive slurry applications. Where hard natural rubber and Chloroprene (CR) are recommended for a specific service, a CR soft rubber overlay on the plug is available for tight shut-off.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- PTFE
Print
DeZURIK Compound Description and Rating
PTFE (Polytetraflouroethylene)
PTFE provides excellent chemical resistance to most non-abrasive fluids. It is a polymer, not an elastomer. To be used as a sealing member in a valve. Other factors such as fluid forces, elastomers, mechanical devices or a combination of these must be present to provide "elasticity" or memory to the PTFE sealing member.
Mechanical Resistance Properties:
IMPACT POOR to FAIR ABRASION POOR to FAIR TEAR POOR to FAIR CUT GROWTH POOR to FAIR Maximum Temperature Rating:
- High Performance Butterfly Valve (BHP)
- (TT) 450°F (232°C)
- (RT) 500°F (260°C)
- V-Port Ball Valve (VPB)
- (RT) 500°F (260°C)
Note: The PTFE temperature rating is dependent on pressure. Please see the appropriate bulletin for pressure-temperature ratings.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- High Performance Butterfly Valve (BHP)
Metal
Pressure Temperature Ratings Guide
- 304 S.S.
Print
DeZURIK Pressure Temperature Rating Guide
304 Stainless Steel - ASTM A351, CF8
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 100
-30 to 40275
1900720
5000200
93230
1600600
4100300
150205
1400540
3700400
200190
1300495
3400500
260170
1200455
3200600
320140
970440
3000650
340125
860430
3000700
370110
760420
2900750
40095
660415
2900800
43080
550405
2800850
45065
450395
2700900
48050
340390
2700950
51035
240380
26001000
54020
140355
2400Notes
- ASME B16.34
- At temperatures over 1000°F (540°C), use only if carbon content is 0.04% or higher.
- Flanged End Valve Ratings terminate at 1000°F (540°C).
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- 316 S.S.
Print
DeZURIK Pressure Temperature Rating Guide
316 Stainless Steel - ASTM A351, CF8M
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 100
-30 to 40275
1900720
5000200
93235
1600620
4300300
150215
1500560
3900400
200195
1300515
3600500
260170
1200480
3300600
320140
970450
3100650
340125
860440
3300700
370110
760435
3000750
40095
660425
2900800
43080
550420
2900850
45065
450420
2900900
48050
340415
2900950
51035
240385
27001000
54020
140365
2500Notes
- ASME B16.34
- Flanged End Valve Ratings terminate at 1000°F (540°C).
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- 317 S.S.
Print
DeZURIK Pressure Temperature Rating Guide
317 Stainless Steel - ASTM A351, CG8M
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 100
-30 to 40275
1900720
5000200
93235
1600620
4300300
150215
1500560
3900400
200195
1300515
3600500
260170
1200480
3300600
320140
970450
3100650
340125
860440
3300700
370110
760435
3000750
40095
660425
2900800
43080
550420
2900850
45065
450420
2900900
48050
340415
2900950
51035
240385
27001000
54020
140365
2500Notes
- ASME B16.34
- Flanged End Valve Ratings terminate at 1000°F (540°C).
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Acid-Bronze
Print
DeZURIK Pressure Temperature Rating Guide
Acid-Bronze - ASTM B427 Alloy C90700
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 150
-30 to 65225
1600500
3400175
79220
1500490
3400200
93215
1500475
3300225
110210
1400465
3200250
120205
1400450
3100275
140200
1400440
3000300
150195
1300425
2900350
180180
1200400
2800400
200170
1200375
2600450
230160
1100350
2400500
260150
1000325
2200550
290140
970300
2100Notes
- ASME B16.24
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Alloy 20
Print
DeZURIK Pressure Temperature Rating Guide
Alloy 20 - ASTM A351, CN7M
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 100
-30 to 40230
1600600
4100200
93200
1400520
3600300
150180
1200465
3200400
200160
1100420
2900500
260150
1000390
2700600
320140
970360
2500Notes
- ASME B16.34
- Use solution annealed material only.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Bronze
Print
DeZURIK Pressure Temperature Rating Guide
Bronze - ASTM B62, C83600
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 0 to 150
15 to 65225
1600500
3400175
79220
1500480
3300200
93210
1400465
3200225
110205
1400445
2800250
120195
1300425
2900275
140190
1300410
2800300
150180
1200390
2700350
180165
1100350
2400406
210150
1000- 450
230135
930280
1900Notes
- ASME B16.24
- Some Codes (eg. ASME Boiler and Pressure Vessel Code, Section 1; ASME B31.1, ASME B31.5). limit the rating temperature to 406°F (210°C).
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Carbon Steel
Print
DeZURIK Pressure Temperature Rating Guide
Carbon Steel - ASTM A216, Grade WCB
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 100
-30 to 40285
2000740
5100200
93260
1800680
4700300
150230
1600655
4500400
200200
1400635
4400500
260170
1200605
4100600
320140
970570
3800650
340125
860550
3700700
370110
760530
3700750
40095
660505
3500800
43080
550410
2800850
45065
450320
1900Notes
- ASME B16.34
- Also applies for A516-70
- Permissible, but not recommended for prolonged use above 800°F (450°C) A216WCB and A516-70.
- Upon prolonged exposure to temperatures above 800°F (450°C), the carbide phase of steel may be converted to graphite.
- Not to be used over 850°F (450°C) A516-70.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Cast Iron
Print
DeZURIK Pressure Temperature Rating Guide
Cast Iron - ASTM A126, Class B
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 125 ASME Class 250 1"-12" 14"-24" 30"-48" 1"-12" 14"-24" 30"-48" -20 to 150
-30 to 65200
1400150
1000150
1000500
3400300
2100300
2100200
93190
1300135
930115
790460
3200280
1900250
1700225
110180
1200130
900100
690440
3000270
1900225
1600250
120175
1200125
86085
590415
2900260
1800200
1400275
140170
1200120
83065
450395
2700250
1700175
1200300
150165
1100110
76050
340375
2600240
1700150
1000325
160155
1100105
720- 355
2400230
1600125
860353
180150
1000100
690- 335
2300220
1500100
690375
190145
1000- - 315
2200210
1400- 406
210140
970- - 290
2000200
1400- 425
220130
900- - 270
1900- - 450
230125
860- - 250
1700- - Notes:
- ASME B16.1
- 353°F (max.) reflects the temperature of saturated steam at 125 psi.
- 406°F (max.) reflects the temperature of saturated steam at 250 psi.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Ductile Iron
Print
DeZURIK Pressure Temperature Rating Guide
Ductile Iron - ASTM A536, Grade 65-45-12
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 ASME Class 300 -20 to 100
-30 to 40250
1720640
4410200
90235
1620600
4135300
150215
1480565
3895400*
200200
1380525
3620500*
260170
1170495
3410600*
315140
965465
3205650*
345125
860450
3100Notes
- ASME B16.42
- *ASTM A395, Grade 60-40-18 above 450°F (230°C)
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Hastelloy C
Print
DeZURIK Pressure Temperature Rating Guide
Hastelloy C - ASTM A494, CW-12MW
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 100
-30 to 40230
1600600
4100200
93210
1400550
3800300
150200
1400520
3600400
200190
1300490
3400500
260170
1200465
3200600
320140
970440
3000650
340125
860430
3000700
370110
760420
1900750
40095
660410
2800800
43080
550400
2800850
45065
450395
2700900
48050
340385
2700950
51035
240380
26001000
54020
140365
2500Notes
- ASME B16.34
- Flanged End Valve Ratings terminate at 1000°F (540°C).
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Monel
Print
DeZURIK Pressure Temperature Rating Guide
Monel - ASTM A494, M-35-1
Temperature
(°F / °C)Pressure (psi / kPa) ASME Class 150 300 -20 to 100
-30 to 40230
1600600
4100200
93200
1400525
3600300
150190
1300490
3400400
200180
1300475
3300500
260170
1200475
3300600
320140
970475
3300650
340125
860475
3300700
370110
760475
3300750
40095
660470
3200800
43080
550460
3200850
45065
450340
2300900
48050
340245
1700Notes
- ASME B16.34
- Use annealed material only.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
Material Characteristics Guide
- 17-4PH Stainless Steel
Print
DeZURIK Material Characteristics Guide
17-4PH Stainless Steel
17-4PH stainless steel is a martensitic precipitation or age hardening alloy offering high strength and hardness along with excellent corrosion resistance. In general, the corrosion resistance is similar to that of 304 stainless steel. In addition, 17-4PH retains its corrosion resistance to temperatures about 50°F (10°C) less than the aging temperature. It also has excellent resistance to stress-corrosion cracking when hardened at 1025°F (552°C) or above. Hardening is achieved at temperatures from 900°F (482°C) to 1150°F (621°C). It may be machined in the annealed condition but it is not used until hardened.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- 440C Stainless Steel
Print
DeZURIK Material Characteristics Guide
440C Stainless Steel
440C stainless steel is a high carbon martensitic chromium steel alloy designed to provide stainless properties with maximum hardness. It is generally used in the hardened and tempered condition. When fully heat treated 440C attains the highest hardness of any stainless steel, about Rockwell C 60. It is used primarily for parts subjected to high wear applications. 440C resists normal domestic and mild industrial environments, including many petroleum products and organic materials.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Aluminum
Print
DeZURIK Material Characteristics Guide
Aluminum ASTM B26, Alloy 356 & Alloy 713
Corrosion resistance of aluminum is dependent on the formation of a protective oxide film on the surface of the metal. This film is stable in aqueous media when the pH range is between 4.5 and 8.5. Corrosion resistance is dependent on the media that forms the film. Galvanic corrosion is a potential problem when aluminum is used in complex structures. Aluminum is anodic to most of the common materials such as iron , steel, stainless, titanium and nickel alloys.
Mechanical Properties Alloy 356 Alloy 713 Tensile Strength 30,000 psi min. 32,000 psi min. Yield Strength 20,000 psi min. 22,000 psi min. Elongation (in.) 3% min. 3% min. Hardness,Brinell 70 BHN 75 BHN No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- 2205 Duplex
Print
DeZURIK Material Characteristics Guide
2205 Duplex Stainless Steel ASTM A995, Type CD3MN
Duplex Stainless steel is a grade that in the annealed state is composed of about equal parts of ferrite and austenite. Duplex stainless offer several advantages over austenitic grades. Duplex stainless grades are highly resistant to chloride stress corrosion cracking, have excellent pitting/crevice corrosion resistance and exhibit about twice the mechanical properties of austenitic stainless steels.
MECHANICAL PROPERTIES:
Mechanical Properties Duplex SST Tensile Strength 100,000 psi minimum Yield Strength 70,000 psi minimum Elongation (in.) 25% minimum No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- GrafoilR
Print
DeZURIK Material Characteristics Guide
GrafoilR
GrafoilR Gaskets and packing are all-graphite products containing no resin binders or organic fillers. Their outstanding resistance to corrosion, even at high temperatures, and their ability to retain compressibility at all temperatures, allows them to be recommended for service in many organic and inorganic applications.
GrafoilR is a registered trademark of Union Carbide Company.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- StelliteR
Print
DeZURIK Material Characteristics Guide
Cobalt-Chromium Alloys (StelliteR)
StelliteR is a registered trademark name for a series of cobalt based alloys with outstanding wear resistance. Cobalt-Chromium Alloys are available in most forms: wrought, cast, and powder metal parts. The most common use for Cobalt-Chromium Alloys is for hard facing on shafts, valve seats, and other high wear surfaces. This is done either by welding or spraying the alloy on a base metal surface. The most commonly used alloys are StelliteR 6, 4 and 12. Alloy 6 is the most frequently used because it is an excellent compromise of a hard wear resistant material with excellent resistance to corrosion, high temperatures, and shock loads. Alloys 4 and 12 are somewhat harder, but are less resistant to high temperatures and shock loads.
StelliteR is a registered trademark of Deloro Stellite, Holdings Corporation.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Tiodizing
Print
DeZURIK Material Characteristics Guide
Tiodizing
Tiodizing is a coating deposited on titanium or titanium alloys by an electrolytic process using an alkaline bath. The primary reasons for using this coating are to eliminate the severe galling and seizing tendencies of uncoated titanium and to improve the wear resistance of the metal surface. Tiodizing does not alter the corrosion resistance of the base titanium or titanium alloy. The only corrosion resistance improvement is to prevent surface corrosion from hypergolic fuels, such as hydrazine and nitrogen tetroxide.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Titanium
Print
DeZURIK Material Characteristics Guide
Titanium ASTM B367, Alloy C-2
As aluminum and stainless steel, titanium is dependent on an oxide film for its corrosion resistance. Titanium performs best in oxidizing media such as nitric acid. Titanium also has excellent corrosion properties in sea water, wet chlorine and organic chlorides.
MECHANICAL PROPERTIES:
Mechanical Properties Titanium Tensile Strength 50,000 psi minimum Yield Strength 40,000 psi minimum Elongation (in.) 15% minimum Hardness,Brinell 210 BHN maximum Hardness,Rockwell 96 B maximum No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
- Tungsten Carbide
Print
DeZURIK Material Characteristics Guide
Tungsten Carbide
Tungsten Carbide may be used as sintered powder metal parts or as a coating sprayed on the surface of a part. Carbides consist of finely divided grains held together with a binder, such as cobalt or nickel. Since tungsten is inert, the corrosion resistance of the tungsten carbide is dependent upon the binder used. Nickel is commonly used as the binder to provide optimum corrosion resistance. The hardness of a tungsten carbide surface is about Rockwell A90, which is similar to a hardness of Rockwell C76. The surface of tungsten carbide can be ground to a 15 to 20 micro inch surface finish and polished even smoother if required. The combination of hardness and smoothness give an exceptionally wear resistant surface. Tungsten carbide can be used effectively to 1000°F (538°C) in an oxidizing atmosphere and up to 1600°F (871°C) in a non-oxidizing atmosphere. It has been determined that it is also an excellent material at cryogenic temperatures.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
DeZURIK Elastomer Selection Guidelines
The DeZURIK Elastomer Selection Guide is intended to be of assistance in the selection of the most suitable elastomer for various chemical services. This guide should only be used as a starting point in the selection process. There are many factors that affect an elastomer's suitability that cannot be adequately expressed in chart form.
Factors Affecting Elastomer Selection
When selecting the most suitable elastomer for a particular application, many factors must be considered that can influence the service of the elastomer. These factors can include the type of chemical, temperature, concentration, abrasiveness, velocity, time of exposure and seating forces. These factors can lead to two basic types of failure: chemical deterioration and mechanical damage. When elastomer failure does occur, it will often be a combination of these two types of failure.
Chemical deterioration can occur by an actual chemical reaction between the media and the elastomer, or by an absorption of the media into the elastomer. Chemical deterioration leads to a decrease in the tensile strength and often to a swelling of the elastomer. The amount of chemical deterioration depends upon and generally increases with increasing temperature and concentration of the service. Chemical absorption can lead to a weakening of the bond with a resulting bond failure and a separating of the elastomer from the metal.
Although elastomers can be damaged by mechanical means only, the mechanical damage often occurs because of chemical deterioration. In a deteriorated condition, the weakened elastomer is more susceptible to damage from the flowing media especially if the media are highly abrasive and flowing at a high velocity. If a deteriorated elastomer has also swelled, the lost strength coupled with the resulting interference between the seating surfaces can lead to mechanical damage when the valve is closed.
An elastomer facing or lining, when in good physical condition, will often give abrasion resistance superior to metal. The actual size, shape, and hardness of the particles and their velocity are the determining factors in how well a particular elastomer resists mechanical damage from the media. Hard, sharp objects, including those foreign to the normal media, may cut or gouge the elastomer.
Seating forces higher than those recommended can put excessive strain on elastomer facings. Excessive strain on the elastomer will lead to shorter facing life especially if any chemical deterioration has occurred. Excessive seating forces may also lead to compression set of the elastomer. Compression set is a permanent deformation that remains in the elastomer after a compression force has been removed; this compression force occurs when the valve is closed. The area of the elastomer that has compression set is not only permanently deformed but is also less resilient than normal and may not offer the same shut-off. The possibility of compression set occurring increases with increasing temperature, compression force, and the length of time that the force is applied, and dependent upon the type of the elastomer.
Economics is not as important a factor in elastomer selection as it is in metal selection. Many of the available elastomers are the same price and the extra cost for others is often small when compared to the price of the complete valve.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.
DeZURIK Metal Selection Guidelines
Economics play an important role in the selection of the proper valve material. Since the more corrosion resistant materials such as stainless steel, Monel, etc., are also higher in cost, such considerations as increased valve life, cost difference, difficulty caused by valve failure and ease of replacement must be made in determining if the higher cost material is justified.
The pressure rating of the valve may also be a limiting factor in the valve material selection since the pressure rating differs with valve size and valve material. Carbon steel, stainless steel, and the more noble alloys have a higher pressure rating than bronze and bronze has a higher pressure rating than cast iron and Ni-Resist.
Types of Corrosion
There are many types of corrosion and each has a different effect on various metals. Two of the most important types that are frequently encountered in valves are general corrosion and pitting corrosion.
General corrosion attacks the metal uniformly, over the entire surface, forming oxides that go into solution or adhere to the metal surface. If adherence occurs, these oxides often act as a protective coating that retards further corrosion.
The most important factors that affect the rate of general corrosion are the temperature and concentration of the corrosive media. For all practical purposes, the rate of corrosion increases with increasing temperature. In general, the corrosiveness of a particular service also increases as its concentration increases. However, there are some services such as sulfuric acid where a lower concentration may be more corrosive than a higher concentration.
The velocity and abrasiveness of the media flowing past a metal surface also affects the rate of corrosion. A flowing media has a tendency to wear away any protective oxides that may have formed on the metal surface, thus leaving the metal more susceptible to further corrosion. As the velocity and abrasiveness of the media increases, the corrosion rate will also increase. This type of attack is often referred to as corrosion-erosion.
Pitting corrosion takes place when a protective coating of oxides is penetrated only at particular points. Once this penetration has occurred, pitting can proceed rapidly and deeply to a point of penetrating the metal. Pitting, which is most frequently found with stainless steels, is most apt to occur when the corrodents contain one of the halogens, such as chlorine.
Pitting is usually found under deposits from the corrosive media that have adhered to the metal surface, such as paper stock, due to a stagnant fluid condition. It is because of this formation that any velocity of the corrosive media may actually eliminate the possibility of this type of corrosion.
The addition of molybdenum to stainless steel will increase its resistance to pitting. Alloy 20 and 316 stainless steel, which have molybdenum, are more resistant to pitting than 304 stainless steel.
Good experience, backed up by good records of corrosion and valve life are valuable assets in the selection of the most suitable valve material. Particular characteristics of the service conditions which are not considered by the corrosion charts or recommendation guides can easily make experience the most important consideration in valve material selection.
Applications with service conditions that combine a mixture of corrosive media may result in more severe attack on the metal that any of the individual corrosive media handled separately. Selecting the correct material can only be accomplished through experience or by testing.
No representation, warranty or guarantee, express or implied, is made by this selection guide due to the complexity and almost infinite variations of mixtures, concentrations, temperature and flow conditions possible in actual service.