September — 2012 — The Expansion Joints Blog

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Archive for September, 2012

Pressure Balanced Expansion Joint for a Nuclear Facility

September 25th, 2012 Comments off

This pressure balanced expansion joint was custom made for a nuclear facility in Texas. It is 66″ID x 169″ OAL. This expansion joint was fabricated with 304 stainless steel bellows and carbon tee, pipe and tie rods. 100% dye-penetrant and soap and air tested, its operating conditions were 15 PSIG at 300°F for 1 1/4″ axial compression.

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Fluoroplastic Material

September 24th, 2012 Comments off

Fluoroplastics (PTFE) — The chemical resistance of this material is unequaled by other materials.

Chemical resistance, temperature limitations, abrasion resistance, tensile strength and susceptibility to flutter/vibration are major considerations when selecting a fabric material. This article will give you a better understanding on FLEXXCEL Fluoroplastic products.

Evolution of FLEXXCEL Fluoroplastic Materials

fiberglass
  • Fiberglass substrate is thoroughly coated on both sides with a minimum of 35% to 40% by weight of PTFE resin for mechanical strength.
  • Fluoroplastic coating is 100% pure PTFE material.

Fiberglass Coating Process

Fiberglass + PTFE = Coated Fiberglass

  • Fiberglass reinforcement filaments are E grade or better providing excellent tensile strength.
magnified fabric cross section

Extruded, thin single ply film laminated to coated fiberglass.

  • All FLEXXCEL materials have a chemical barrier film to protect the fiberglass substrate and minimize porosity. The chemical barrier component of these materials is in the form of a film that is laminated to the fiberglass cloth.

FLEXXCEL MD4 and HD4 = FOR DRY SERVICE

 

magnified cross section
  • LFP CrossFilm based chemical barriers are laminated to the coated fiberglass. The use of LFP CrossFilm Chemical Barriers provides superior protection in corrosive environments.

A zero porosity chemical barrier is the most critical component for preventing chemical attack.

FLEXXCEL MD7, HD7, HD12, and HD20 = FOR WET SERVICE

 

FLEXXCEL HT
     

  • FLEXXCEL HT series fabric belts rated for temperatures up to 1000°F. Insulation is bonded to FLEXXCEL HD4 material to prevent hot gas from residing between the two components.
  • Extends like of insulation component.
  • Prevents insulation from falling into duct.
  • Makes installation of high temperature composite belts easier.

A zero porosity chemical barrier is the most critical component for preventing chemical attack.

FLEXXCEL HT1, HT3, and HT5 = FOR HOT-DRY SERVICE

FLEXXCEL Fluoroplastic Belt Materials

Fluoroplastic materials have been successfully used in challenging expansion joint applications since the early 1980′s. The expansion joint fabric is composed of two components— PTFE resins and fiberglass cloth. The fiberglass is used to give the fabric strength. The fiberglass can be of varying weights to give the fabric material the necessary tensile strength. The fiberglass alone is susceptible to degradation from chemicals and liquids. By thoroughly coating all surfaces of the fiberglass filaments, a strong and flexible base material is created. This base material can then be laminated to a PTFE film (Chemical Barrier) of varying thickness to provide a non-porous and chemically inert gas seal. Its virtual inertness to most chemicals make it an excellent choice for applications in wet corrosive environments.

Fluoroplastics also retain their structural integrity at extremely high or low temperatures, i.e., 600 degrees F to -110 degrees F (uninsulated). Fluoroplastics are capable of withstanding temperatures in excess of 1500 degrees F when properly insulated (composite belt).

Features of Fluoroplastics

  1. High strength to weight ratio. Easier to handle and install compared to Elastomers.
  2. Simple splice and repair by means of heat seal iron. Material does not age like Elastomers and therefore can be repaired for the life of the material.
  3. Temperature capability up to 600 degrees F without additional insulation.
  4. Materials are easy to drill and punch.
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Custom Designed Universal Expansion Joint

September 10th, 2012 Comments off

custom designed universal expansion joint

This custom designed universal expansion joint is to be used for a gas turbine application. Dimensions are 30” DIA x 90” OAL and materials used for fabrication were 321 ss bellows, liners, and carbon steel pipes. This expansion joint was 100% x-ray, dye-penetrant, and hydro tested. Operating conditions were 96 PSIG at 550°F for 2″ lateral and 3/8” axial compression.

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Additional Components for Fabric Expansion Joints

September 4th, 2012 Comments off

In addition to the standard frame styles for our fabric expansion joints, there are additional components that are designed to augment certain styles in specific applications:

Accumulation Barrier

- Provides a flexible, low density barrier for fly ash or dust accumulation in the expansion joint cavity
- Can be provided for any design that includes a flow liner
- Typically is constructed with low density fiberglass material wrapped in aluminized fiberglass cloth and wire mesh
- In applications with large movements, the barrier can be constructed with ”ears” that are clamped under the backing bars

Insulation Pillow for High Temperature Applications

- Insulation pillow ensures that the temperature at the gas seal membrane does not exceed it’s capability
- Constructed with high density needle felted ceramic insulation wrapped with high temperature cloth and wire mesh
- Pinned snuggly to the liners or frames

Bolt-On Liner for Style 500

- The liner is attached with the fasteners of the upstream clamping bar

Bolt-On Liner for Style 700


- The liner is designed to be removed from inside the ducting to allow access to the fabric belt. The liner is attached with studs field welded inside the duct

Weld-On Liner for Style 100, 600

- The liner is field welded to the upstream inside edge of the duct

Drain

- A drain fitting machined out of PTFE material can be installed in the belt at the bottom of the expansion joint
- If conditions are wet enough to cause pooling, specify a drain

Particulate Deflector

- A particulate deflector can be specified to reduce air born particulate from falling down into the expansion joint cavity
- Most common on vertical ducting with the flow direction up and an upstream liner overlapping the downstream duct

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