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.
Illustration: Components of a float type steam trap
| 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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