Spirax Sarco TD120M High Pressure Thermodynamic Steam Trap

A high pressure thermodynamic trap with a replaceable seat

The Spirax Sarco TD120M is a maintainable high pressure thermodynamic steam trap with an integral strainer and a replaceable seat that eases maintenance. It is supplied in 1/2, 3/4 and 1 inch sizes with socket weld, butt weld or flanged connections, and Spirax Sarco describes it as a low capacity trap designed specifically for superheated mains drainage at pressures up to 250 bar g (3626 psi g). The body is alloy steel ASTM A182 F22, which suits the high temperatures involved.

Technical specifications

Parameter	Specification
Model	TD120M, high pressure thermodynamic steam trap with replaceable seat
Sizes	1/2, 3/4 and 1 inch (DN15, DN20, DN25)
Connections	Butt weld to Schedule 160 pipe; socket weld to ASME B16.11 Class 6000; integral flanges EN 1092 PN100, PN160 and PN250 and ASME Class 600, 900 and 1500 (per size list in the sheet)
Body design	PN250; PMA 250 bar g at 300 °C
TMA / TMO	550 °C at 80 bar g; minimum allowable temperature -29 °C
PMO, saturated steam	220 bar g at 374 °C
Max. operating backpressure	50 percent of upstream pressure
Min. operating differential pressure	8 bar g
Cold hydraulic test pressure	375 bar g
Body, top and bottom cover	Alloy steel ASTM A182 F22
Disc and seat	Disc: steel per BS EN ISO 4957; seat: steel BS 4659 Gr. BD2 with stainless ferrule
Strainer screen	Stainless steel BS 970 304 S15 / sintered stainless
Gaskets	Spirally wound stainless steel with exfoliated graphite filler
Weight (flanged examples)	About 17.8 kg for a DN15 flanged PN100, PN160 or PN250 version, per the dimension tables
Certification	EN 10204 3.1 available; request at order. Complies with Pressure Equipment Directive 2014/68/EU

Condensate capacity at high differential pressure

The capacity table in the sheet follows ISO 7842. Hot condensate capacity rises slowly with pressure because the orifice is small, which is why the trap is described as low capacity.

Differential pressure	Cold water kg/h (lb/h)	Hot condensate kg/h (lb/h)
8 bar g	98 (217)	71 (156)
34 bar g	183 (403)	127 (280)
69 bar g	245 (540)	167 (369)
121 bar g	311 (685)	209 (461)
172 bar g	361 (796)	241 (532)
250 bar g	423 (932)	280 (617)

Selection, inspection and documents

Spirax Sarco recommends regular inspection of the seat when the trap is used above 170 bar g (2466 psi g). The minimum operating differential of 8 bar g and backpressure limit of 50 percent mean it suits mains drains discharging to low-pressure headers rather than elevated return lines. Compare with the

Spirax Sarco TD42.

for medium pressure mains, or see the Yarway 751/761 repairable drip and tracer trap and the wider steam trap range. The attached technical information sheet TI-P150-11 lists the pressure-temperature regions for each flange class and the full dimension tables. Send the pressure, temperature, size and end connection with your enquiry, and confirm the final model against current Spirax Sarco documents before ordering.

How the Spirax Sarco TD120M thermodynamic steam trap works

A steam trap removes condensate from a steam line without letting live steam escape. The TD120M is a thermodynamic trap with a single moving part, a disc that sits between the inlet and a ring of outlet ports. Cool condensate lifts the disc and flows out. When hot condensate or steam arrives, it flashes and moves faster under the disc, the pressure drops, and the disc snaps shut on the seat. The pressure then builds above the disc and holds it closed until it cools and the pressure falls, and the cycle repeats. The orifice is small, so the trap is a low capacity device suited to draining mains and tracing lines of high pressure steam.

Where the TD120M is used

• Superheated steam mains drainage at high pressure.
• Power plant steam lines and headers.
• High pressure process steam in refineries and chemical plants.
• Drip legs and low points where small quantities of condensate collect.

Selection checklist for the TD120M

• Line size: DN15, DN20 or DN25 (1/2, 3/4 or 1 inch).
• Pressure up to 250 bar g and the temperature, up to 550 degrees C at 80 bar g.
• End connection: socket weld, butt weld or flanged, to the pipe specification.
• Minimum differential pressure of 8 bar g, and backpressure up to 50 percent of the upstream pressure.
• Condensate load, against the capacity table at the operating differential pressure.
• Material certificates, with EN 10204 3.1 available if requested at order.
• Integral strainer and replaceable seat for maintenance.
• Pressure Equipment Directive 2014/68/EU compliance.

Installation, commissioning and maintenance notes

Fit the trap below the point to be drained, with the disc cover upward in the horizontal position, and keep a drip leg ahead of it so dirt does not reach the seat. Blow down the line before installation to remove weld debris. After starting, check the cycling of the trap by listening or with an ultrasonic tool, and look for continuous leakage. Clean the strainer screen at maintenance intervals, and replace the seat or disc when they wear. Isolate and depressurise the line before opening the trap.

Requesting a quotation for the Spirax Sarco TD120M

Send the size, connection type, operating pressure and temperature, and any certificate needed. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Capacity and sizing

Hot condensate capacity rises slowly with differential pressure because the orifice is small. The capacity table shows values from 8 bar g up to 250 bar g, so compare the actual load at the working pressure with the table before choosing.

Trap survey and condensate management

Traps should be checked regularly, since a failed trap either wastes steam or floods the line with condensate. Keep a record of each trap and its test result and replace failures promptly.

Materials and construction

The body, top and bottom cover are alloy steel ASTM A182 F22, which suits the high temperature, and the disc and seat are hardened steel with a stainless ferrule. The strainer screen is stainless steel, and the gaskets are spirally wound stainless steel with a graphite filler. A cold hydraulic test pressure of 375 bar g is stated for the body.