Pressure Vessels Selection Guide

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Parr Instrument Company 211 Fifty Third Street
Moline, Illinois 61265-1770
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Pressure and Temperature Limits

The maximum pressure and temperature at which any reactor or pressure vessel can be used will depend upon the design of the vessel, its material of construction, and other components integral to its design. Since all materials lose strength at elevated temperatures, any pressure rating must be stated in terms of the temperature at which it applies. The listings shown in this catalog show the maximum allowable working pressure (MAWP) for each vessel in pounds per square inch (psi) and in bar at the maximum rated temperature for that particular design when that vessel is constructed of Type 316 Stainless Steel. Maximum pressure and temperature limits for vessels constructed of other alloys are computed and assigned by the Parr Engineering Department in accordance with all applicable regulations.

Lower operating temperatures sometimes permit higher working pressures. For example, the 4560HT High Temperature reactors are rated at 2000 psi (138 bar) maximum pressure and 500 °C maximum temperature. Standard 4560 reactors are rated at 3000 psi (200 bar) maximum pressure at 350 °C maximum temperature.

One should not assume that any vessel being operated at a lower temperature can be used at pressures exceeding the rated MAWP. Factors other than the material strength of the vessel wall may well be the constraint controlling the rating. Other factors that can limit the pressure and temperature ratings are the closures design, the magnetic drive, the type of seal, the choice of other components used, as well as the material of construction.

The maximum operational temperature of some materials is much lower than what is permissible with stainless steel as shown in the table below. Users are encouraged to contact the Parr Customer Service Department with any questions.

Maximum Allowable Temperatures
Materials of Construction Maximum Temperature
T316/316L Stainless Steel 800 °C
Alloy A-286 371 °C
Alloy 20 426 °C
Alloy 230 980 °C
Alloy 400 482 °C
Alloy 600 625 °C
Alloy 625 Gr 1 648 °C
Alloy B-2/B-3 426 °C
Alloy C-276 625 °C
Nickel 200 315 °C
Titanium Grade 2, 3, 4 & 7 315 °C
Zirconium Grade 702 & 705 371 °C

Multiple factors are involved in safely calculating the maximum working pressures and temperatures of Parr Pressure Vessels and Reactors. Please contact Parr Customer Service Department for more information and to assist you in making the correct purchase decision.

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