TOYO valve pressure and temperature selection

TOYO valve pressure and temperature selection

Professional interpretation of pressure temperature ratings and practical valve selection

In industrial fluid control systems, the selection of valves is directly related to production safety, equipment lifespan, and operational efficiency. Faced with the bronze, brass, cast iron, ductile iron, and stainless steel valve product lines provided by TOYO (KITZ brand), engineers often need to quickly determine which model and pressure rating to choose for a given medium, working pressure, and temperature? This article provides a systematic selection logic and practical guide based on the Pressure Temperature Ratings data in the TOYO product catalog, combined with common industrial scenarios.

Understanding the core significance of pressure temperature ratings

The maximum allowable working pressure of a valve is not a fixed value, but decreases significantly with increasing temperature. The TOYO catalog strictly follows MSS SP-80, MSS SP-70/71/85, JIS B2011, and ASME standards, providing pressure temperature comparison tables for different materials and connection methods.

Key principle: When selecting, the maximum working pressure must be ≤ the rated pressure at that temperature, and the medium must not freeze. Special permission is required for flammable/toxic gases (the catalog clearly prohibits conventional products from being used for flammable or toxic gases).

1.1 Analysis of Rated Values for Bronze&Brass Valves

Taking the bronze/brass valve pressure temperature gauge on page 13 of the catalog (extracted from MSS SP-80) as an example:

Temperature (℃) Class 100 Class 125 Class 150 Thread Class 150 Flange Class 200 Class 300

-29 ~ 66 1.03 MPa 1.37 MPa 1.55 MPa 1.37 MPa 2.06 MPa 2.75 MPa

93 0.93 1.27 1.44 1.27 2.41 2.58

121 0.86 1.17 1.34 1.17 2.24 2.41

149 0.79 1.06 1.24 1.06 2.06 2.24

177 0.68 0.96 1.13 0.96 1.89 2.06

204 0.63 — — — — 1.89

208 0.62 0.86 1.03 0.86 — —

Saturated steam 0.68 0.86 1.03 0.86 1.37 2.06

Practical interpretation:

Class 125 threaded connection: allows 1.37 MPa at room temperature (-29~66 ℃), but drops to 1.17 MPa at 121 ℃ and only 0.86 MPa at 208 ℃. If used for saturated steam at 120 ℃, the rated pressure is only 0.86 MPa.

Class 150 Thread vs Flange: At the same temperature, the pressure rating of the threaded end is higher than that of the flange end (e.g. 1.55 vs 1.37 MPa at 66 ℃) because the threaded end is not limited by the flange gasket.

Prohibited use scenario: All conventional bronze/brass valves must not be used for flammable or toxic gases (as clearly stated on page 14 of the catalog).

Selection limitations of Cast Iron valves

Cast iron valves (Gate, Globe, Check) comply with MSS SP-70/71/85 standard. The pressure temperature data for typical Class 125 cast iron valves are as follows (catalog page 17):

Temperature (℃) Pressure (MPa) Remarks

-29~66 1.37 Size ≤ 300mm

93 1.31 

107 1.24 

121 1.21 

135 1.17 

149 1.14 

163 1.07 

178 1.03 

191 1.00 

208 0.97 

218 0.92 

232 0.90 

Saturated steam 0.86

Attention: Valves with a pressure rating greater than 350mm have lower pressure ratings (the "Above size 350" column in the table ranges from 0.69 to 0.86 MPa). Cast iron valves are also prohibited from being used for flammable/toxic gases.

Advantages of Ductile Iron Valves

Ductile iron (such as FCD-S material) has higher strength and toughness. TOYO catalog includes 10K, 16K, and 20K series ductile iron valves (Fig. 602A, 612A, 607L, etc.) with much higher pressure ratings than ordinary cast iron. For example:

10K ball valve (10-DBF-N-L): Maximum working pressure of 1.4 MPa (120 ℃ clean water), with PTFE seat, suitable for water, oil, and gas.

20K gate valve (20-DSR-N): 2.0 MPa allowed at room temperature.

Selection suggestion: For situations with large pressure fluctuations, low temperature impacts, or mild corrosiveness, ductile iron valve bodies are preferred.

High temperature and high pressure capability of stainless steel valves (U series/VA series)

Stainless steel valves (SCS13/CF8, SCS14A/CF8M) are suitable for corrosive media and high temperature conditions. The pressure temperature ratings (Class 150/300) of VA series stainless steel valves are provided on page 30 of the catalog

Temperature (℃) Class 150 (CF8) Class 150 (CF8M) Class 300 (CF8) Class 300 (CF8M)

-29 1.90 1.90 4.96 4.96

93 1.62 1.65 4.14 4.14

149 1.41 1.48 3.65 3.65

204 1.24 1.34 3.24 3.24

260 1.17 1.90 3.00 3.00

316 0.96 0.96 2.86 2.86

343 0.86 0.86 2.83 2.83

371 0.76 0.76 2.79 2.79

399 0.66 0.66 2.76 2.76

427 0.55 0.55 2.72 2.72

454 0.45 0.45 2.69 2.69

482 0.34 0.34 2.65 2.65

510 0.24 0.24 2.59 2.59

538 0.14 0.14 2.24 2.24

566 0.14 0.14 2.14 2.14

Key conclusion:

Stainless steel valves can be used up to 538 ℃ (but standard graphite packing is limited to 260 ℃, and special packing is required for higher temperatures).

Class 300 stainless steel valves have a pressure bearing capacity of over 2 MPa at high temperatures, making them an ideal choice for steam and high-temperature heat transfer oil pipelines.

The catalog explicitly prohibits the use of stainless steel valves for flammable/toxic gases (but if the user assesses the risk themselves, it can be specially ordered).

Specific precautions for ball valves and butterfly valves

5.1 Ball valve

TOYO offers bronze, brass, and stainless steel ball valves with a maximum pressure rating of Class 600 (600WOG). For example:

Brass ball valve 600RC-N (Fig. 5026): CWP (cold working pressure) 4.13 MPa (38 ℃), test pressure 6.20 MPa. Suitable for water, oil, and gas, but prohibited for steam (unless specially designed).

Stainless steel ball valve UZ-N (Fig. 3550): also Class 600, but with SCS14A body and PTFE seat, suitable for corrosive fluids.

Selection note: PTFE valve seats will soften at high temperatures. The specific temperature pressure curve is not provided in the catalog, and it is generally recommended to be ≤ 180 ℃. If the temperature exceeds this limit, metal seals or special polymer valve seats should be used.

5.2 Butterfly valve

Butterfly valves (aluminum bronze disc, EPDM/NBR seat) are suitable for high flow and low pressure conditions. The restrictions are given on page 26 of the table of contents:

NBR valve seat is not suitable for hot water systems (early aging).

EPDM valve seats shall not be used for any oily media.

When using JIS 5K flange, the maximum allowable working pressure is limited by the flange (static water 0.7 MPa, pulsation 0.6 MPa).

Special working conditions and product limitations

6.1 Non Asbestos Fillers

TOYO catalog page 32 states: The standard packing and gasket for bronze, brass, and cast iron valves have been made of asbestos free materials, which meet environmental requirements. If you need other materials (such as flexible graphite, PTFE), please consult specifically.

6.2 Prohibited Use Scope

Multiple pages repeatedly emphasize that TOYO conventional valves are strictly prohibited from being used for flammable or toxic gases (such as natural gas, hydrogen, chlorine, etc.). Special valves that comply with high-pressure gas safety laws must be used.

6.3 Temperature Limits for Welded End Valves

For stainless steel valves with welded ends, pressure temperature ratings above 1000 ° F (538 ℃) are still valid, but for flange end valves, the maximum is 1000 ° F. If the temperature exceeds 450 ℃, the manufacturer should be consulted.

Selection Decision Process (Practical Steps for Engineers)

Determine whether the medium is water, oil, gas, or steam? Is it corrosive? Is it flammable/toxic? If flammable/toxic, exclude standard products directly.

Check working temperature: Find the allowable pressure for each candidate material (bronze, cast iron, ductile iron, stainless steel) at that temperature.

Comparison of work pressure: The allowable pressure must be selected to be greater than or equal to the maximum working pressure of the system (including water hammer pressure).

Choose connection method: thread, flange, welding, clamp. Flange valves should pay attention to the pressure rating of the flange (such as JIS 5K flange limit butterfly valve pressure).

Special functions: whether adjustment type (globe valve), quick switch (ball/butterfly valve), check function (check valve), filtration (Y-shaped filter) are required.

Verification: Ensure installation space by comparing the dimensions (L, H, D) in the directory.

Common errors and troubleshooting

Possible causes and solutions for error phenomena

Bronze gate valves are used for leakage and overheating under steam at 150 ℃. When gaskets/packing aging, Class 300 or cast iron valves are used instead, and the steam rated pressure (0.86 MPa) is checked

Butterfly valve EPDM seat incompatible with expansion medium and rubber in oil system, switch to NBR seat or replace with stainless steel ball valve

Stainless steel ball valve experiences a significant increase in torque at high temperatures, while PTFE valve seat softens and deforms to reduce temperature, or a metal sealed ball valve can be used instead

Cracks in cast iron valve body (winter), increased heat tracing or drainage due to medium freezing and expansion, or use ductile iron instead

Maintenance and spare parts recommendations

Gaskets and Fillers: Non asbestos gaskets are used for cast iron valves in the catalog, and spare parts should be made of the same material to avoid mixing asbestos containing products.

Filter cleaning: The standard mesh size for Y-shaped filters (such as 150-BT-N) is 12-16 mesh, and finer or coarser filters can be customized according to needs.

Regular pressure testing: On site pressure testing should refer to the "test pressure" (shell water, seal air) in the catalog, such as Class 125 bronze valve shell test 2.06 MPa.