Spirax Thermodynamic Steam TD3

The Spirax Marshall TD-3 Thermodynamic Steam Trap is a robust, all-stainless steel condensate removal solution designed specifically for steam headers, mainlines, and drop legs. Featuring an inbuilt strainer screen and high-temperature tolerance, the TD-3 model offers superior corrosion resistance and longevity under severe water hammer conditions.

Technical Specifications & Operating Limits

• Sizes & End Connections: 15NB and 20NB in Screwed BSPT/NPT and Socket Weldable ends (ASA 150, 300 & 600 weld-on flanges available on request). Optional IBR certification is also available.
• Max Operating Pressure (PMO): 31.64 kg/cm² for screwed ends; 44.0 kg/cm² for socket-weld ends (special high-pressure version rated up to $55.0\text{ kg/cm}^2$).
• Max Operating Temperature (TMO): 427°C standard (450°C) for high-pressure variant).
• Min Inlet Pressure: 0.25 kg/cm².
• Max Back Pressure: Should not exceed 80% of inlet pressure.
• Hydraulic Test Pressure: 63.0 kg/cm² for screwed ends; 88.0 kg/cm² for socket-weld ends.

Materials of Construction

Key Features & Operational Benefits

• Induction Hardened Disc & Seat: Hardened to approx. 45 Rc to prevent premature wear caused by continuous water hammer.
• Integral Seat Design: Seat built directly into the body eliminates high-maintenance gaskets and leakage points.
• Concentric Condensate Entry: Inlet path under the disc ensures clean, parallel lifting to eliminate localized uneven wear.
• Inbuilt Strainer: High-area internal screen prevents debris from disrupting seal faces.
• Optional ISOTUB Insulating Cover: Prevents severe heat loss and false tripping from low outdoor ambient temperatures, wind, or rain.

Installation & Servicing Guide

Installation Preferably install on horizontal pipe runs; alternative orientations can be used when horizontal routing is unavoidable.

Refacing & Maintenance

1. Remove the optional ISOTUB (if fitted) and unscrew the top cap using a flat spanner (do not use Stillsons/pipe wrenches to avoid cap distortion).
2. For light wear, reface seating surfaces by hand-lapping in a figure-eight motion on a flat plate using a 1:6 diluted 6-micron Aluminium Oxide lapping compound.
3. For heavy wear, grind the body seat flat and re-lap (do not exceed total metal removal of 0.25 mm or 0.010 in Replace worn discs with new units.
4. Reassemble with the grooved side of the disc facing the body seat. Apply high-temperature anti-seize grease to threads; no gasket is required.

Cleaning the Strainer Unscrew the lower strainer cap with a spanner, withdraw the Type 304 screen, wash thoroughly (or replace if broken), re-seat into the cap, and apply a thin layer of Molybdenum Disulphide grease to the threads.

Ordering Available Spares

• Strainer Screen & Disc Pack (Pkt of 3): Ordering Ref A+B
  
  
• ISOTUB Cover: Ordering Ref C