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).