fabric expansion joints

Fabric expansion joints in Thai industries

What is heat?

Heat is energy and it can be found in wave like other forms of energy. It travels in 3 patterns 1) heat radiation 2) heat conduction and 3) heat convection. Heat generally transfers from a hot surface to colder surface. All most every factory creates heat for production and maintenance purposes, so we can say that heat is the most usage energy in the industries.

What is fabric expansion joint?

Fabric expansion joint is the non-metallic non-rubber flue duct to compensate expansion or misaglignment of ducting system. It is designed and produced to absorb thermal expansion and isolate any vibration from mechanical works and imbalanced of pipes and ducts. Fabric expansion joints can be found in square, rectangular, cylinder, and unsystematic shapes.

How is it important?

Fabric expansion jont is useful to reduce noise and stress from misalignment of ducting system, it also can eliminate the vibration from mechanical tolerance. Good quality and correct design of fabric expansion joints can extend service life of ducting and pipe system by decreasing chance of cracking from thermal shock and thermal expansion.

What make it to be a good quality expansion joints?

Reliable and good quality of expansion joints depend on the materials design and fabrication process. For instance, one must resist with acid, high temperature, sharp dust, abrasion, and severe weather. When experienced and professional fabricators know and understand the real inquiries and usages of expansion joints, they can select proper materials and the way to fabricate it suitably for the application.

How many types of expansion joints?

In general there are 3 types of expansion joints
1) metal expansion joints – normally fabricated by stainless steel 304 316 and 410
2) rubber expansion joints – produced from synthetic rubber with various kinds of thickness
3) fabric expansion joints – made from heat-protection fabric like fiberglass (with and without insulation)

How fabric expansion joints used in Thai industries?

Air or heat flow is designed as exhaust or inlet system for all production lines, so hot air must have the way to move or utilized. Indeed, steel pipes or ducts generate vibration and noise when hot air is flowing inside, and we typically found thermal expansion on steel ducts with high temperature inside. Fabric expansion joints are suitable for gas and hot air and it can perfectly adjust to different requirements (e.g. sealing conditions, different temperature and pressure variance). Fabric expansion joints are available in any systematic and unsystematic shapes at any sizes.
    Major benefits of fabric expansion joint

  • Reduce mechanical vibration from ducting system
  • Noise abatement from vibration issue
  • Abbreviate thermal expansion from steel pipes and ducts
    Pros of fabric expansion joint compare to metallic expansion joints

  • Fabric gives more elastic and reduce tensile stress better than metal
  • Fabric is easier than metal to install and maintenance
  • Fabric is better than metal to abated noise

Materials used in fabrication of expansion joints

We use variety of materials to make expansion joints e.g. steel, stainless steel, synthetic rubber, thermoplastic, composite materials, and heat-resistant fabric. Sometimes we need thermal insulation for expansion joints to reduce temperature to desire level and for
  • Decreasing flutter from circulate air
  • Abated noise from mechanical moving
  • Extending service life of high-temperature gas barrier
  • Stabilizing heat or temperature in the system

What is the most important of installation expansion joints?

Either old or new of fabric expansion joints need to be inspected thoroughly about physical damaged before installation. Fortification with flanges or pipes must be properly fitted without gap or opening area since leaking is normally come from this space. Broken spot on fabric expansion joints seen by eyes should be take a good care or advice person in charge or technical supervisors if it can be accepted or changed. During installation bolts, nuts, or clamps must be checked and confirmed to securely lock with right tools. Experienced technicians or installers will care for these factors as the most important of installation:
  • Cross check flanges for correct design and dimension before completing installation
  • Inspect size and physical look of fabric expansion joints with drawing
  • If flange and fabric expansion joint is unmatchable don’t make a force install on it

Why price is different?

Price of fabric expansion joints using in Thailand are varies from thousand to millions Baht. Cost is depending on conditions of usage, raw materials, supportive equipment, warranties and after sales service.

What effect to service life of fabric expansion joints?

Serviceability of fabric expansion joints counts on service area, flowing temperature, media, acid or alkaline, alignment, vibration, pressure and thermal expansion of ducting system. Good maintenance and periodical inspection can extend the service life of fabric expansion joints to their maximum limit. General inspection should pay attention to broken of sealing edge, damaged on flanges, corrosion on nuts and bolts, heat leak, chemical attacks, and high temperature (more than 180°C, on the surface of fabric expansion joint).

Case studies from our experience about fabric expansion joints:

- Informed correct temperature but broken
Actual temperature is 250°C and the material was designed to withstand up to 400°C, but the fabric expansion joint was failed after 2-week used. We had investigated and found that there was a line of broken around the circumference of expansion joint. Further info lead us to know that the operators misinformed the height of joint, and when it was installed next to the blower with high vibration it was finally broken. To solve this problem, we need abrasive-resistant fabric or multi-layer PTFE coated fabric rather than general heatproof fabric.
- Damaged from sharp media inside ducting
Customer correctly informed temperature and size, but they ignored to notify us about sharp media like fly ash, coal or loose sand inside ducting system. The fabric expansion joint in this case was damaged in 3 months after installation. We looked in to this problem and suggested them to use abrasive-resistant fabric instead of silicone-coated glass fabric.
- Leaking around the flange
The problem was occurred because of human error. The customer correctly chose materials to match the actual temperature, but there was leaking of hot air around the flange. From our inspection, we had found that one area was installed with loose clamp, and more important it had no sealing material to protect flow gas. It shown that this fabric expansion joint was installed by naïve operators.
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