MK45A Bimetallic Steam Trap | Gestra

The Gestra MK45A is used to discharge condensate from steam lines. The applicable media are steam and condensate, and the operating temperature should correspond to the saturated steam temperature. The valve uses a thermostatic membrane regulator and discharges condensate once it has cooled to the specified subcooling level. An integral Y-strainer and check function make the valve suitable for steam-trapping points where both contaminant retention and prevention of reverse flow are required. When selecting the configuration, the valve cloud warehouse can assist procurement personnel in considering line pressure, temperature, condensate load, and connection standards.

MK45A is available with three membrane capsules: the standard N capsule discharges condensate at a temperature approximately 10 K below the boiling temperature, the U capsule at approximately 30 K below, and the H capsule at approximately 5 K below. The H capsule may be considered when a lower subcooling level is required so that condensate is discharged closer to the saturation temperature. The U capsule may be considered when greater utilization of condensate sensible heat is desired and a larger subcooling level is acceptable. The N capsule provides a standard subcooling level of approximately 10 K. During selection, it must also be confirmed that the control capsule will not be exposed to superheated conditions exceeding 5°C.

MK45A-1 uses a tandem dual-seat design with double sealing and is particularly suitable for low condensate flow rates. MK45A-2 uses a single-seat design and is suitable for higher condensate flow rates. For engineering selection, first determine the seat type according to the actual condensate load, then verify the required discharge capacity against the corresponding capacity curve based on the selected capsule subcooling level.

MK45A is available in DN15, DN20, and DN25, corresponding to 1/2 inch, 3/4 inch, and 1 inch sizes. Connection options include EN 1092-1 PN40 flanges, ASME B16.5 Class 150 or Class 300 RF flanges, ISO 228-1 G threads, ASME B16.11 NPT threads, DIN EN 12760 or ASME B16.11 Class 3000 socket-weld ends, and butt-weld ends connected via transition fittings. The valve cloud warehouse recommends verifying the pipe nominal size, existing connection standard, and pressure rating during procurement to avoid connection mismatches.

The allowable pressure of MK45A varies with the end connection type and temperature. For PN40 flanges, the allowable pressure is 27.6 barg at 300°C and 25.7 barg at 400°C. For Class 150 flanges, it is 10 barg at 300°C and 6.5 barg at 400°C. For Class 300 flanges, threaded ends, and welded ends, it is 26.1 barg at 300°C and 24.3 barg at 400°C. The maximum allowable differential pressure is 32 bar for PN40, Class 300, threaded, and welded ends, and 15.9 bar for Class 150 flanges. Particular attention should be paid to the risk of intergranular corrosion at operating temperatures above 300°C. Unless this risk can be ruled out, the valve should not be used at temperatures above 300°C.