The troubleshooting guides below can serve to help you independently assess issues, zero down on the root cause and resolve issues pertaining to steam trap failures with minimal external assistance. While we have attempted to make it as detailed as possible, there could be site specific design related aspects which could also lead to failure. If the above guide does not resolve the issue contact your local Forbes Marshall engineer to assist you with troubleshooting.
Troubleshooting guide for float type steam traps
Float type steam trap -troubleshooting guide
| Failure Mode | Symptom | Possible Causes and Recommended Actions |
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| Not discharging condensate at all | No condensate is discharged and the trap’s surface temperature is low. | - Check the installation i.e. check the flow direction arrow 5 on the cover casting and the name plate arrow 6 on the base casting.
- Check for blockage in the strainer.
- If the actual differential pressure is higher than the design pressure, the steam trap would have failed in closed position as the float buoyancy will not be adequate to open the valve seat.
- Check the valve and seat assembly for blockage.
- Check if the ball float is punctured, if so replace it. Post replacement, check for water hammering in process to avoid recurrence.
- Check to make sure the steam trap is not stalling. If stall is occurring replace the trap with a steam operated pumping trap.
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| No condensate is discharged and the trap’s surface temperature is high. | - The trap is getting steam locked. Adjust the steam lock release setting 10 by first closing it fully and then opening it by 1/4th turn.
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| Not discharging enough condensate | Reduced condensate discharge capacity of the trap | - The trap is undersized and may not be adequately sized to handle peak loads and running condensate loads.
- Check for back pressure and corresponding discharge capacities as per the capacity charts. For example if there is more than one trap discharging condensate in the return line then
– Replace/repair the leaking and non- working traps with working traps as the leaking traps may be causing a higher back pressure on the working traps connected to the same return – Ensure that the traps have an NRV installed on the outlet of each trap. – Ensure that all the by-pass valve are closed. If a by-pass valve is leaking or is kept open in a closed loop, it increases the back pressure on the traps, connected to the same return line. |
| Flooding of condensate | - Check to see if the inlet strainer is partially blocked
- Check the thermostatic valve seat orifice for blockage. If blocked, clean and lap.
- Check main valve seat orifice for blockage. If blocked, clean and lap.
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| Leaking steam | Live steam is leaking through the outlet | - Check the installation. The arrow 6 on the name plate should point downwards.
- Check the valve and seat assembly for any deposits / debris and clean it.
– Clean and lap the seating area
– Lightly stamp an SS ball on the seating area - Check for SLR leakage / setting 10
- Check for air vent leakage
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| Steam leaking from the joints between the base and the cover | - Tighten the cover bolts 2 to the recommended torque
- Check the gasket for damage and replace it if required.
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Troubleshooting guide for thermodynamic type steam traps
Troubleshooting guide for thermodynamic steam traps
| Failure Mode | Symptom | Possible Causes and Recommended Actions |
|---|
| Not discharging condensate at all | Trap is cold and not discharging any condensate | - Inlet drip leg is choked or strainer screen 4 is clogged with dirt / debris.
Flush the drip leg / clean the trap strainer screen. If the strainer screen 4 is rusted, replace it with a new one. - Differential pressure is low (Verify the inlet and outlet pressure of the steam trap. The minimum differential pressure required is 0.25 barg).
- Air binding of the disc.
First, unscrew the cap 2 and screw it back on tightly (to suitable torque). - Flash steam locked (trapped) inside the steam trap.
Pour water on cap 2 of the steam trap to release flash steam locked (trapped) inside the steam trap so that it discharges condensate.
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| Trap is hot and not discharging any condensate |
| Steam leakage | Steam is leaking continuously from the trap | - The bypass valve is open / leaking.
- Ensure that the bypass valve is fully closed. Replace the valve if it is found to be leaking Trap is not installed correctly.
Rectify the installation i.e. the cap 2 should be on top and the condensate should flow in the direction of the arrow provided on the steam trap body. - Dirt, debris, oil film, etc is present on the disc or seat preventing a proper sealing between the disc and seat.
Clean both the disc and body seat. If required lap the disc and seat individually.
Note: The total amount of metal from body seal face removed should not exceed 0.25mm. - Disc is stuck to the cap.
Give a light tap to the top of the cap to see if it resolves the problem. If the step i.e. the inner surface of the cap is worn out, replace the trap. - The back pressure exceeds the allowable value i.e. the outlet pressure of the trap should not exceed 80% of the inlet pressure.
- Scratch on disc or seat.
If the depth of the scratch is less the problem can be resolved by lapping the disc / seat, else the disc will require to be replaced.
Note: The total amount of metal from body seal face removed should not exceed 0.25mm.
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| Rapid Cycling | Continuous chattering of the disc | - Disc or seat is worn.
- Replace a worn disk with a new one. If the seat is slightly worn, lapping can address the issue. However, in case of excessive wear, replace the seat or the steam trap.
Note: It is important to promptly maintain a steam trap that is rapid cycling. Timely maintenance can prevent excessive wear of the disc / seat. |
