Home › Tools › P/T Rating Calculator

ASME B16.34 P/T Rating Calculator

Calculate the maximum allowable working pressure for valve body materials at any operating temperature. Per ASME B16.34 Standard Class ratings.

Input Parameters

Disclaimer: This tool provides ASME B16.34 Standard Class ratings for reference only. It does not replace detailed engineering calculations. Verify all ratings against the applicable code edition. For valve selection assistance, contact us.

Results

Select material, class, and temperature,
then click Calculate to see the pressure rating.

Maximum Allowable Working Pressure
—bar
— psi
Material
—
Class
—
Temperature
—
Max Temp Limit
—

Full P/T Rating Table —

Request Quote for This Valve

About ASME B16.34 Pressure-Temperature Ratings

ASME B16.34 establishes the relationship between pressure class, body material, and operating temperature for industrial valves. As temperature increases, the allowable working pressure decreases because the material loses strength. This calculator performs the lookup against the Standard Class rating tables published in ASME B16.34, which are the same tables used by KSB and all major valve manufacturers worldwide.

The pressure class number (e.g., Class 300) does NOT represent the working pressure in any unit. Class 300, for example, allows 51 bar (740 psi) at ambient temperature for WCB, but only 6 bar (85 psi) at 538°C. Always verify the actual allowable pressure at your specific operating temperature using this calculator or the ASME code tables.

For temperatures between the standard reference points, ASME B16.34 allows linear interpolation, which this calculator performs automatically. For temperatures above the maximum listed for a material, the material is not permitted and this tool will indicate that.

Related Engineering Tools

Free tools for valve and steam-trap specifiers.

5-step decision
Valve Selection Guide
Pick gate, globe, ball, butterfly or check valves with KSB model recommendations.
ASME B16.10
Valve Dimensions Lookup
Face-to-face length and approximate weight for KSB SICCA gate, globe and check valves.
SIB / SBF / STH
Steam Trap Selector
Choose the right KSB steam trap by application, condensate load and pressure range.

P/T Rating Calculator — FAQs

What is ASME B16.34?
ASME B16.34 is the American Society of Mechanical Engineers standard that defines pressure-temperature ratings for flanged, threaded, and welding end valves. It covers steel, nickel alloys, and other materials. The standard establishes the maximum allowable working pressure at any given temperature for each material and pressure class combination. All KSB SICCA series valves are rated per ASME B16.34.
Does this apply to flanges as well?
Yes. The P/T ratings in ASME B16.34 (valves) align with ASME B16.5 (pipe flanges and flanged fittings) for matching material groups and pressure classes. The rating tables are effectively the same, so this calculator can be used for both valve body ratings and mating flange ratings.
What is the difference between Standard Class and Special Class?
Standard Class ratings apply to commercial valves that meet normal manufacturing and testing requirements. Special Class ratings are higher and require additional quality controls including 100% radiography of castings, more stringent dimensional tolerances, and enhanced pressure testing. KSB pressure seal valves (SICCA 900-3600 GTC) are available in both Standard and Special Class. This calculator shows Standard Class ratings.
Why does pressure decrease with temperature?
As temperature increases, the yield strength and tensile strength of steel decrease. Since the valve body must contain the internal pressure without exceeding the allowable stress, the maximum permitted pressure must decrease as the material weakens at higher temperatures. This is why high-temperature applications (above 400°C) often require alloy steels like WC6, WC9, or C12A, which retain more strength at elevated temperatures than carbon steel WCB.