Products
Steam Traps

Why are Steam Traps Required?

A steam trap is a special purpose valve which opens when condensate is present and closes when steam tries to pass thru it. The ultimate purpose of the steam trap is to allow the Condensate (water formed when steam condenses) and air to be discharged from the steam system while preventing the loss of live steam.

CONDENSATE (water): Any time steam releases its latent heat energy, the steam converts back into liquid. This water is referred to as condensate. This transformation of steam to condensate will occur in a radiator heating a room, a heat exchanger making hot water, a pipe transferring steam over long distances, or any other process that uses steam.

AIR: Before the steam is turned on, and the system is cold, air will exist in all of the pipes and process equipment, such as radiators and heat exchangers. This air must be removed from the entire system to allow the steam to enter and reach its intended points of use.

Steam Trap Selection Guidelines

Drip Applications: "Drip traps"

Drip Application refers to draining condensate that forms in distribution piping as steam is transported from the boiler to its point of use. Eliminating this condensate protects valves and piping from wiredrawing and water hammer. Since condensate loads tend to be minimal, steam traps with smaller orifices are typically selectred for extended service life. It is reasonable to consider a single trap that can operate over a wide pressure range in order to simplify selection and reduce inventory. Other factors to consider when selecting drip traps include: materials of construction, pressure rating, repairability, efficiency, installation orientation, as well as the trap’s ability to handle freezing climates, superheated steam, pipe scale, and debris.

Process Applications: "Process traps"

Process Application refers to draining condensate that is formed during a process utilizing steam’s inherent Latent Heat Energy. These applications typically require steam traps with relatively high condensate capacity. In most process applications, it is important to discharge air present in the system during start-up so the steam can quickly enter the system. Although separate air vents can be used for this purpose, it makes sense to select a trap with efficient air venting capability. Since many process applications are controlled by modulating steam supply, it is also important to select a steam trap that can handle varying condensate loads. The steam trap must have enough capacity to discharge the condensate even when the differential (spelling) pressure across the trap is low. These low pressure conditions commonly occur in process applications where control valves, or other types of modulating valves, are used to regulate the flow of steam into the process equipment. If the steam trap is significantly oversized, it may cause it to wear out more quickly and allow steam to pass into the condensate return piping. The most common type of steam trap used for process applications is the Float & Thermostatic (F&T) style.

Tracing Applications: "Tracing traps"

Tracing Applications refer to using steam to elevate the temperature of a product, process, or piece of equipment by using tubing or some type of jacketing device filled with steam. These applications are commonly used to promote flow of high viscosity fluids or prevent pipelines and equipment from freezing. The relatively small traps used for these applications are referred to as “Tracing traps”. A Non-Critical Tracing application may benefit from a thermostatic steam trap which sub-cools and backs up some condensate - an adjustable bimetal trap offers additional temperature control. Thermodynamic traps are ideal for Critical Tracing applications where condensate back-up is not permitted.

Types of Steam Traps

Most Common Use:
Process Applications from low pressure HVAC models for residential heating to Industrial cast steel and stainless steel models for Chemical and Petro-Chemical plants up to 450 PSI. Suitable alternative for drip applications to 200 psig.

Float & Thermostatic (F&T):

Float & Thermostatic Steam Traps contain a float-operated valve to continually discharge condensate and a thermostatic air vent which discharges air. Body materials available are Cast Iron, Ductile Iron, Cast Steel, & Stainless Steel for pressure up to 450 psig. (F&T Traps are referred to as mechanical traps.)

Typical Applications: F&Ts are the most commonly used trap for both batch type processes and continuous process applications with rapidly changing pressures and loads.

Advantages: F&Ts quickly respond to load and pressure changes, discharge large amounts of air present at start-up which allow steam to quickly enter the system, continuously discharge condensate as it forms and offer a wide range of capacities for any process application.

Other Factors to Consider: F&Ts narrow operating pressure ranges require more care during selection. Since they are not self-draining, they are subject to freezing. Trap body must be installed vertically for proper operation.

Most Common Use:
General service drip & tracing applications above 30 psig, as well as high-pressure drip applications with superheat.

Thermodynamic (TD, Disc):

The Thermodynamic Trap is simple and compact with a single moving part (disc) which opens to discharge condensate and closes in the presence of steam. Body materials available are Stainless and Alloy Steels for pressures up to 3,600 psig.

Typical Applications: Widely used on higher pressure drip applications and critical tracing applications (where condensate back-up is not permitted).

Advantages: Rugged design, operation is easy to check due to distinct cyclic operation, relatively small with lower capacities, single model operates over wide pressure range in contrast to mechanical traps, excellent for superheated steam, self-draining when mounted vertically to prevent freezing.

Other Factors to Consider: Limited air venting, wet climates can increase cycle rates, sensitive to excess back pressure, blast discharge may not be preferred in some systems

Most Common Use:
Industrial style Thermostatic Traps are extremely versatile. Their use can range from general service drip & tracing applications to small-to-medium batch process heating applications.

Thermostatic:

A Thermostatic Trap contains a heavy-duty, industrial-purpose welded stainless steel thermal element designed to control condensate discharge by sensing the temperature difference between steam and cooler condensate. Body materials available are Cast Iron, Stainless and Alloy Steels with thermal element designs available for pressures up to 650 psig. The WPN Series Bi-metallic design will handle presssures up to 2,260 psig.

Typical Applications: Extremely versatile and energy efficient, these traps are suitable for a wide range of applications. Thermal element designs are suitable for applications ranging from general service drip and tracing applications to small-to-medium batch style processes. Bi-metal designs can be used in high pressure, superheated drip applications or in lower pressure tracing applications.

Advantages: Self-draining when mounted vertically to prevent freezing, single model operates over wide pressure range in contrast to mechanical traps, small and compact with similar capacities to larger mechanical traps (F&Ts & IBs), superior air venting capabilities, welded stainless steel thermal element and bi-metal elements are extremely rugged, moderate discharge due to reduced flash steam, choose between fail-open or fail-closed bellows.

Other Factors to Consider: Some condensate back-up can be expected, thermal element design not recommended for superheated applications.

Most Common Use:
Used on drip applications where excessive dirt and debris may be of significant concern. They can serve as alternatives to F&T's in process applications where air venting is not required by the steam trap.

 

Inverted Bucket (IB):

The Inverted Bucket Trap uses an inverted bucket as a float device to control the opening and closing of the plug and seat to discharge condensate. Body materials available are Cast Iron and Stainless Steel for pressures up to 450 psig. (IB traps are referred to as mechanical traps.)

Typical Applications: These traps have a discharge orifice positioned at the top of the trap body which make them ideal for drip applications on systems containing excessive pipe scale and debris. They may be considered for process applications where air venting is less of a concern or handled by a separate air vent.

Advantages: Rugged and simple design, top-mounted discharge orifice less susceptible to failure from dirt and debris, service life often exceeds other style traps.

Other Factors to Consider: Limited air venting capabilities, can lose its prime causing it to fail, narrow operating pressure ranges require more care during selection, not self-draining therefore subject to freezing, single position installation, fixed orifice on bucket allows small steam leakage, physical size can be large and require additional support.

Drip Applications

Drip Application refers to draining condensate that forms in distribution piping as steam is transported from the boiler to its point of use. Eliminating this condensate protects valves and piping from wiredrawing and water hammer. Since condensate loads tend to be minimal, steam traps with smaller orifices are typically selected for extended service life. It is reasonable to consider a single trap that can operate over a wide pressure range in order to simplify selection and reduce inventory. Other factors to consider when selecting drip traps include: materials of construction, pressure rating, repairability, efficiency, installation orientation, as well as the trap’s ability to handle freezing climates, super heated steam, pipe scale, and debris.

Condensate in Steam Systems

Condensate is formed as steam gives up its energy as it travels through a steam system, causing it to turn from a gas back to a liquid. This condensate causes poor system performance and potential safety issues. As in the diagram below, when condensate is not properly removed from the system, it can build up into a “slug”. When this “slug” meets a point of resistance such as a bend in the pipeline or a pressure reducing valve, a tremendous impact occurs (i.e. water hammer effect) and could break or cause damage to the piping system.

Drip Leg in a Steam Main

Steam traps are drained through a drip leg and are spaced apart every couple hundred feet. A properly sized drip leg will have a diameter equal to the steam main pipe size up to 4”. Improperly sized pipe diameter will prevent proper drainage of the condensate. Strainers are recommended prior to the steam trap as debris or pipe scale may enter the steam trap causing premature failures.

Drip Leg before a Regulator or Control Valve

Regulators or Control Valves are typically utilized to reduce the high pressure mains into a more manageable pressure in a process. It is common to see drip legs installed directly ahead of regulators and control valves ensuring dry steam and to minimize erosion to valve trim and flooding of valve bodies.

Steam Separator in a Steam Main

Separators are used on steam mains and steam supply lines to remove entrained water in the steam. Steam flows through the separator and the condensate falls by gravity to the bottom where it needs to be discharged through a steam trap. F&T traps are recommended for this application.

Trap Models for Drip Applications

The trap models are for drip applications for the protection of steam mains and steam supply lines. When traps listed are installed every 200 feet, they will have adequate capacity to handle typical warm-up loads in properly insulated 8” steam mains. See Warm-up Load Chart in Engineering Section. Models listed may handle steam mains considerably larger than 8”. Steam pipe size, the distance between traps, insulation quality, ambient temperatures and start-up conditions should all be considered.

Thermodynamic

The Thermodynamic Disc (TD) Steam Trap is simple and compact and one of the primary choices for drip applications over 30 psig. The TD600 Series with integral one piece body-seat design, are the most economical and commonly used for pressures up to 600 psig. The 1/2" & 3/4" TD600L will meet the capacity needs of most drip applications ("S" models have integral strainers). The TD600 Series cannot be welded in-line. The TD700S & TD900S Series are both in-line repairable and can be welded into the pipeline.

To Thermodynamic Section

Float & Thermostatic

The Float & Thermostatic (F&T) Steam Trap is the primary choice for process applications. However, for drip applications, they can be effectively used for pressures up to 125 psig on the WFT Series & 225 psig on the FTT Series; for higher pressures, the larger body sizes required make F&T traps a less economical and desirable solution for drip service. The 3/4" WFT-125, or 1/2" & 3/4" FTT-225 will meet the capacity needs of most drip applications. Other PMO (maximum operating pressure) ranges available. For drip applications, select a PMO that meets or exceeds the maximum pressure in the main steam distribution piping.

To Float & Thermostatic Section

Inverted Bucket (IB)

Inverted Bucket Traps are extremely rugged and have a discharge orifice mounted at the top of the trap body, making them less susceptible to clogging from dirt and pipe scale when compared to other trap types. The IB models selected are suitable choice for most drip applications.

To Inverted Bucket Section

Thermostatic

Thermostatic Steam Traps are extremely versatile and can be used on a wide variety of applications from general service drips to small-to-medium batch type processes. Using a welded stainless steel thermal element to control condensate discharge, these traps allow condensate to sub-cool, making them extremely energy efficient. As a result, the condensate discharged generates less flash steam which reduces back pressure build-up in condensate return lines. A single model will operate from 0 to 650 psig which simplifies selection. The WT2001, with stainless steel body and non-repairable design, is the most commonly used. The WT3001 and WT2501 have the same internals as the WT2001, however, their 4-bolt cover allows them to be in-line repairable. The WT3001 has a stainless steel body while the WT2501 is cast iron.

The WPN Series (not shown), uses a bi-metal element suitable for pressures to 2,260 psig, and will handle superheated steam.

To Thermostatic Section

Universal Quick-Change

The all stainless steel universal style steam traps feature a permanent installation of the universal connector with a 2-bolt mounting arrangement for the universal steam trap module, allowing the steam trap to be removed and replaced in minutes. These Quick-Change Steam Traps should be considered for all drip applications.
• Thermodynamic (Top Mount) & (Side Mount)
• Float & Thermostatic
• Thermostatic
• Inverted Bucket

To Universal Quick-Change Section

Process Applications

Process applications refer to removing condensate and air where the actual process using the steam is taking place. This process could be a heat exchanger making hot water, or a radiator heating a room, or anything else that requires the use of steam. Traps used for process applications require larger condensate handling capability in contrast to steam traps that are used for drip applications. Traps used in Process applications also need to be able to discharge large amounts of air present in the system at start-up.

Continuous Processes: Shell & Tube Heat Exchangers

Shell & Tube Heat Exchangers are used for continuous processes such as heating a continual flow of water or other liquid. The Shell & Tube heat exchanger contains multiple tubes inside to optimize heat transfer to the process. In the majority of applications, the process liquid goes through the inside of the tubes and the steam surrounds the outside of the tubes and is contained within the shell area. The condensate that is formed from the condensed steam is discharged out of the bottom through a steam trap. Steam Pressure to the heat exchanger is controlled by the Steam Supply (Control) Valve. The steam trap is placed a minimum distance below the heat exchanger to promote condensate drainage when low pressure or partial vacuum exists in the shell of the heat exchanger (14” is equivalent to 1/2 psi of head pressure)

How It Works: Shell & Tube Heat Exchangers

Start-Up (Air Vents Open)

On start-up, heat exchanger is filled with air which must first be discharged by the Air Vents to allow steam to enter for heating. Float & Thermostatic steam traps contain a separate thermostatic vent, and can discharge large volumes of air present during system startup. Additional air vents may be installed on the heat exchanger. The faster air is expelled, the faster steam can enter and heating can begin.

Steam Enters (Trap Fully Open; Air Vents Closed)

Since the water temperature is cold, the control valve is fully open to allow as much steam as possible to fill the heat exchanger. The steam trap must adjust to the high condensate load as the steam is entering and building pressure. This steam pressure in the shell of the heat exchanger pushes the condensate through the steam trap and into the return line.

Batch Processes: Steam Jacketed Kettle

Steam jacketed kettles are used for batch processing and are typically found in commercial food processing facilities. A steam jacketed kettle contains a liquid to be heated surrounded by an isolated jacket containing the steam (steam does not contact the fluid). Steam enters the kettle and its heat is then transferred to the liquid through the jacket wall and the condensate is discharged out the bottom. Steam Pressure to the kettle is controlled by the Steam Supply (Control) Valve. The steam trap is placed a minimum distance below the kettle to promote condensate drainage when low pressure or partial vacuum exists in the jacket of the kettle (14” is equivalent to 1/2 psi of head pressure).

How It Works: Steam Jacketed Kettle

Start Up - Air discharging from system

Air that entered the system during system shut-down must be purged so that steam may enter. Float & Thermostatic steam traps contain a separate thermostatic air vent for discharging air during system start-up.

Note: Additional air vents may be installed at high points in the system.

Operation – Condensate discharging from system

Steam now fills the jacket at full operating pressure, heating the contents of kettle. Steam is condensing and the steam pressure in the kettle is being relied upon to push the condensate through the steam trap and into the condensate return line.

Tracing Applications

Tracing Applications refers to using steam to indirectly elevate the temperature of a product or process by using tubing or some type of jacketing device filled with steam. In a typical steam tracing application, stainless steel or copper tubing is filled with steam and is coiled or wrapped around the outside of a pipe or tank containing material that requires heating. The steam inside the tubing transfers its heat to the material in the pipe or tank; to stop it from freezing or to lower its viscosity to allow it to flow more easily. A steam trap is required for tracing to remove the condensate and air from the system. The most common trap choice for tracing applications is the Thermostatic type. Depending on the particular tracing application, it is often desirable to have some amount of condensate backup in the tubing.

Steam Tracing Applications: Primary Trap Choice Special Notes
Typical Service Some condensate back-up preferable  Thermostatic  Thermostatic traps are suitable for the majority of steam tracing applications; for critical steam tracing applications, where no back-up of condensate can be tolerated, thermodynamic traps should be used.
Critical Service  No back-up of condensate permitted Thermodynamic


Tracing Vertical Pipelines

Tubing can be wrapped around the piping with a steam trap installed at the low point to allow condensate to freely drain by gravity. Partial back-up of condensate using thermostatic trap.

Tracing Horizontal Pipelines

Tubing should not be wrapped around horizontal pipelines or condensate will collect at low points. After shutdown, condensate retained in the system could potentially freeze. Therefore, tracing tubing should be run parallel to any piping and sloped slightly towards the steam trap to promote condensate drainage.

Bi-Metal Steam Trap with Adjustable Discharge Temperature

For applications where overheating of product fluids in a pipeline may be a concern, an Adjustable Bi-Metal Steam Trap, such as the WT5000 (shown), should be considered. The discharge temperature of the condensate can be manually adjusted to control the amount of condensate back-up in the tracing tubing. This technique can be used to control the temperature of the product in the pipeline.

Thermodynamic steam traps are most commonly used for drip applications. They are extremely compact and rugged with only a single moving part. Models available with strainer, in-line repairable options and ultra-high pressure.
Thermostatic traps are used on drip, tracing and process applications. Compact size with excellent air venting capability allowing for quick system start-up.
Float & Thermostatic traps are most commonly used in process applications such as heat exchangers, jacketed kettles, and air exchangers. They discharge condensate immediately as its formed and have excellent air venting capability.
Inverted Bucket traps are primarily used in drip applications. Rugged and simple design is less susceptible to failure from dirt and scale with long service life. They can be used on process applications where air venting is not required by the steam traps.
These steam traps can be replaced in minutes without having to unthread piping. An open end or socket style wrench is used to remove and replace the trap.
These traps are made from highly polished 316SS and used in clean or sanitary steam applications primarily found in Pharmaceutical, Biotech, and the Food and Beverage industry.
Bi-Metallic Steam Traps are used in Drip as well as some tracing applications and are a capable of extremely high pressures.
Manifolds are used for steam distribution to the tracing system and for condensate collection. Typically used in chemical plants and petrochemical refineries where multiple steam tracing applications are grouped together.
Radiator Traps are Thermostatic Steam Traps that were specifically designed for removing condensate and air from 2-pipe steam heating systems.
Steam trap test valves, Diffusers