A typical chemical or petro-chemical plant employs countless amounts steam supply and condensate recovery lines with huge numbers of valves and steam traps for steam tracing purposes

The modern method of manifolding is to apply all-in one compact manifold as a standard piece of equipment. The forged distribution bodies have integral piston valves providing easy isolation of your tracing lines. The steam distribution manifolds come standard with integral piston valves, enabling isolation, depressurization and maintenance to be performed safely and efficiently. In order to prevent corrosion, steam distribution manifolds are most commonly sold with a bottom drain valve.

The standard condensate collection manifolds include an internal siphon pipe to promote even temperature distribution and ensure single-phase discharge of condensate. This will also help prevent corrosion, freezing and damage to the manifold.

The compact manifold can be complemented with a mounting frame/kit or insulation for tracing applications.

When designing a new steam heat tracing system, we prefer to consider the ‘manifold to manifold’ approach and take all components into consideration. Since the performance of the heating system heavily depend on the resistance and pressure drop over the circuit, the influence and selection of components is crucial.

When designing a new plant or system we focus on:

• Optimizing heat tracing circuit design;
• Optimization of heating performance and even temperature distribution;
• Reducing amount of manifold connections;
• Reduction of amount of steam traps;
• Standardize on designs and increase efficiency;
• Ease of installation.

Steam traps

Steam tracer lines are designed to maintain the fluid in a primary pipe at a designated uniform temperature. In most cases, these tracer lines are used outdoors, which makes ambient weather conditions a critical consideration.

The primary purpose of steam traps on tracer lines is to retain the steam until its latent heat is fully utilized, and then discharge the condensate and non-condensable gases. As is true with any piece of heat transfer equipment, each tracer line should have its own trap. Even though multiple tracer lines may be installed on the same primary fluid line, unit trapping is required to prevent short-circuiting.

Steam Trap Selection:

To assure proper operation of the Thermex TE circuits, attention must be given to the steam trap selection and the design of the condensate return system. Although this area does not fall within Vermeer Thermex scope, the following recommendations will assist in selecting steam traps that will work effectively with the Bolt-on Thermal Maintenance System. The most common styles of steam traps fall into one of the three categories:

1. Mechanical traps, including inverted bucket and float styles.
2. Thermodynamic traps, disc style being the most common.
3. Thermostatic traps, including bi-metallic strip and balanced pressure gas filled diaphragm styles.

Inverted bucket traps are the most robust choice for steam jacketed systems as they require no special considerations. They provide an orifice to purge air form the system and operate well with relatively small pressure difference between steam and the condensate return system.

Float style traps are acceptable, provided that some method of continuous air purging is incorporated into the trap design. Steam jacketed systems typically contain many intermediate high points that tend to trap air; the air will slowly trickle into the trap during normal operation. A float trap will fail closed if there is no mechanism to remove air. Common air removal mechanisms include a balance pressure, gas filled diaphragm air vent and fixed orifice between the trap vapour space and the condensate return.

Thermodynamic traps are acceptable provided that the condensate return pressure is carefully considered. Some condensate return systems operate at pressure relatively close to the steam pressure. Additionally, steam jacketed system can create a significant amount of pressure drop within the circuit. The thermodynamic traps typically require that the condensate return pressure be no greater than 50% of the steam pressure at the trap (calculation performed in absolute pressure).

Thermostatic traps are not recommended for use with steam jacketed systems. These traps require the condensate to sub-cool before the trap will open. For sub-cool to occur, the condensate must dwell for a period of time, while heat is lost to the ambient. This process can back up condensate into the jacketing and compromise the heating ability of the system.