BOILERS, PUMPS & VALVES


FULL STEAM AHEAD!


Michael Povey, TLV Euro Engineering’s general manager,


looks at the three main locations of steam leaks and examines a solution that will help facilities achieve significant energy savings


T


odays facilities and plants are designed to consume as little energy as possible, and


as such it is rare to find steam leaking from pipes and valves. Unless regularly inspected and maintained, however, steam will eventually leak as gaskets, fittings and so on age. Without proper maintenance, the number of leaks – usually found in pipe fittings, valves and steam traps – and the volume of leaked steam, will only ever increase. Leaks from valves and steam traps can be


further divided into: external leaks, such as those from gland packing; and internal leaks, where steam escapes through the seat and into the outlet.


PREVENTING LEAKS FROM PIPE FITTINGS The main causes of steam leaks from pipe/valve flanged and screwed connectors are stress from pipes expanding or contracting due to the heat of the steam; threaded components that have loosened due to that stress; and/or deterioration of gaskets. When pipes contract due to a drop in the


temperature of the steam, the nuts and bolts of the fitting can loosen, causing a gap to open between the two pipes from which steam will escape. If facilities managers find a steam leak,


rather than simply tightening nuts and bolts on the fitting or replacing the gaskets, they should also investigate the cause of the leak and consider changing the number and location of fixed pipe supports or adding expansion joints. If countermeasures like these


www.energymanagementmag.co.uk


are not taken, it is likely that the leak will only re-emerge in the future. Increasingly, facilities are choosing to


install stainless steel piping but, due to steam temperature, it is more susceptible to expansion and contraction than carbon steel piping. Care should therefore be taken to install the fittings of stainless steel piping tighter than for carbon steel piping.


PREVENTING LEAKS FROM VALVES The vast majority of external leaks from valves come from gland packing. Due to the construction of valves, gland leaks can be stopped temporarily by tightening the valve. However, in locations where the valve is opened and closed regularly, it is likely to start leaking again within a short period of time. In these locations, it is recommended that bellows seal valves be used. These are highly resistant to gland leakage because of their bellows, which closes off the internal and external gland packing. Internal leakages occur when steam escapes


– often through the valve seat – and flows through the outlet while the valve is in the ‘closed’ position. Internal leaks cannot be seen from the outside and are therefore difficult to spot, so using a maintenance tool such as a stethoscope or device that measures ultrasonic vibrations is helpful. It is common for steam to leak from the seat


of valves with both adjustable and closable valve openings. One way of preventing this is to use adjustable and closable valves where


necessary, which eliminates the need for dual-function valves. Another effective method of preventing internal leaks is to install a separator to remove the condensate entrained within steam. Supplying dry steam will prevent the valve seat from deteriorating.


PREVENTING LEAKS FROM STEAM TRAPS For valves and pipe fittings, leaks occur when the device stops functioning correctly, but for steam traps, the loss of steam that occurs during normal operation must also be considered.


STEAM LOSSES DURING NORMAL OPERATION The amount of steam that leaks from a steam trap during normal operation varies depending on the type of trap. Depending on steam pressure and condensate volume, when new, a disc trap can leak up to 10x the volume of steam compared to an energy-efficient Free Float trap from TLV Euro Engineering. For this reason, we recommend selecting Free Float traps to reduce steam loss during normal operation. Steam that leaks from even one failed trap can


represent a significant financial loss. Data from our own global steam trap assessments show that, prior to assessment, an average of 5-10% of all steam traps in facilities leaked steam. By identifying leaking traps and swapping them with energy-efficient Free Float traps, facilities can achieve significant energy savings.


TLV Euro Engineering www.tlv.co.uk


ENERGY MANAGEMENT - Summer 2021 13


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